2053 lines
64 KiB
C
2053 lines
64 KiB
C
/* Expands front end tree to back end RTL for GCC
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Copyright (C) 1987-2015 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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/* This file handles the generation of rtl code from tree structure
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above the level of expressions, using subroutines in exp*.c and emit-rtl.c.
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The functions whose names start with `expand_' are called by the
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expander to generate RTL instructions for various kinds of constructs. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "rtl.h"
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#include "hard-reg-set.h"
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#include "tree.h"
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#include "varasm.h"
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#include "stor-layout.h"
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#include "tm_p.h"
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#include "flags.h"
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#include "except.h"
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#include "hashtab.h"
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#include "hash-set.h"
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#include "vec.h"
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#include "machmode.h"
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#include "input.h"
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#include "function.h"
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#include "insn-config.h"
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#include "expr.h"
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#include "libfuncs.h"
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#include "recog.h"
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#include "diagnostic-core.h"
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#include "output.h"
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#include "langhooks.h"
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#include "predict.h"
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#include "insn-codes.h"
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#include "optabs.h"
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#include "target.h"
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#include "cfganal.h"
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#include "basic-block.h"
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#include "tree-ssa-alias.h"
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#include "internal-fn.h"
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#include "gimple-expr.h"
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#include "is-a.h"
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#include "gimple.h"
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#include "regs.h"
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#include "alloc-pool.h"
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#include "pretty-print.h"
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#include "params.h"
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#include "dumpfile.h"
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#include "builtins.h"
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/* Functions and data structures for expanding case statements. */
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/* Case label structure, used to hold info on labels within case
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statements. We handle "range" labels; for a single-value label
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as in C, the high and low limits are the same.
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We start with a vector of case nodes sorted in ascending order, and
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the default label as the last element in the vector. Before expanding
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to RTL, we transform this vector into a list linked via the RIGHT
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fields in the case_node struct. Nodes with higher case values are
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later in the list.
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Switch statements can be output in three forms. A branch table is
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used if there are more than a few labels and the labels are dense
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within the range between the smallest and largest case value. If a
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branch table is used, no further manipulations are done with the case
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node chain.
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The alternative to the use of a branch table is to generate a series
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of compare and jump insns. When that is done, we use the LEFT, RIGHT,
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and PARENT fields to hold a binary tree. Initially the tree is
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totally unbalanced, with everything on the right. We balance the tree
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with nodes on the left having lower case values than the parent
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and nodes on the right having higher values. We then output the tree
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in order.
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For very small, suitable switch statements, we can generate a series
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of simple bit test and branches instead. */
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struct case_node
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{
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struct case_node *left; /* Left son in binary tree */
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struct case_node *right; /* Right son in binary tree; also node chain */
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struct case_node *parent; /* Parent of node in binary tree */
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tree low; /* Lowest index value for this label */
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tree high; /* Highest index value for this label */
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tree code_label; /* Label to jump to when node matches */
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int prob; /* Probability of taking this case. */
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/* Probability of reaching subtree rooted at this node */
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int subtree_prob;
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};
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typedef struct case_node case_node;
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typedef struct case_node *case_node_ptr;
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extern basic_block label_to_block_fn (struct function *, tree);
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static bool check_unique_operand_names (tree, tree, tree);
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static char *resolve_operand_name_1 (char *, tree, tree, tree);
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static void balance_case_nodes (case_node_ptr *, case_node_ptr);
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static int node_has_low_bound (case_node_ptr, tree);
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static int node_has_high_bound (case_node_ptr, tree);
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static int node_is_bounded (case_node_ptr, tree);
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static void emit_case_nodes (rtx, case_node_ptr, rtx, int, tree);
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/* Return the rtx-label that corresponds to a LABEL_DECL,
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creating it if necessary. */
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rtx
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label_rtx (tree label)
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{
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gcc_assert (TREE_CODE (label) == LABEL_DECL);
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if (!DECL_RTL_SET_P (label))
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{
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rtx_code_label *r = gen_label_rtx ();
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SET_DECL_RTL (label, r);
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if (FORCED_LABEL (label) || DECL_NONLOCAL (label))
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LABEL_PRESERVE_P (r) = 1;
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}
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return DECL_RTL (label);
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}
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/* As above, but also put it on the forced-reference list of the
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function that contains it. */
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rtx
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force_label_rtx (tree label)
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{
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rtx_insn *ref = as_a <rtx_insn *> (label_rtx (label));
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tree function = decl_function_context (label);
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gcc_assert (function);
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forced_labels = gen_rtx_INSN_LIST (VOIDmode, ref, forced_labels);
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return ref;
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}
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/* Add an unconditional jump to LABEL as the next sequential instruction. */
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void
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emit_jump (rtx label)
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{
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do_pending_stack_adjust ();
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emit_jump_insn (gen_jump (label));
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emit_barrier ();
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}
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/* Handle goto statements and the labels that they can go to. */
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/* Specify the location in the RTL code of a label LABEL,
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which is a LABEL_DECL tree node.
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This is used for the kind of label that the user can jump to with a
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goto statement, and for alternatives of a switch or case statement.
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RTL labels generated for loops and conditionals don't go through here;
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they are generated directly at the RTL level, by other functions below.
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Note that this has nothing to do with defining label *names*.
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Languages vary in how they do that and what that even means. */
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void
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expand_label (tree label)
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{
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rtx_insn *label_r = as_a <rtx_insn *> (label_rtx (label));
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do_pending_stack_adjust ();
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emit_label (label_r);
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if (DECL_NAME (label))
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LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label));
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if (DECL_NONLOCAL (label))
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{
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expand_builtin_setjmp_receiver (NULL);
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nonlocal_goto_handler_labels
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= gen_rtx_INSN_LIST (VOIDmode, label_r,
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nonlocal_goto_handler_labels);
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}
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if (FORCED_LABEL (label))
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forced_labels = gen_rtx_INSN_LIST (VOIDmode, label_r, forced_labels);
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if (DECL_NONLOCAL (label) || FORCED_LABEL (label))
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maybe_set_first_label_num (label_r);
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}
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/* Parse the output constraint pointed to by *CONSTRAINT_P. It is the
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OPERAND_NUMth output operand, indexed from zero. There are NINPUTS
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inputs and NOUTPUTS outputs to this extended-asm. Upon return,
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*ALLOWS_MEM will be TRUE iff the constraint allows the use of a
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memory operand. Similarly, *ALLOWS_REG will be TRUE iff the
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constraint allows the use of a register operand. And, *IS_INOUT
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will be true if the operand is read-write, i.e., if it is used as
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an input as well as an output. If *CONSTRAINT_P is not in
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canonical form, it will be made canonical. (Note that `+' will be
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replaced with `=' as part of this process.)
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Returns TRUE if all went well; FALSE if an error occurred. */
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bool
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parse_output_constraint (const char **constraint_p, int operand_num,
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int ninputs, int noutputs, bool *allows_mem,
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bool *allows_reg, bool *is_inout)
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{
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const char *constraint = *constraint_p;
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const char *p;
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/* Assume the constraint doesn't allow the use of either a register
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or memory. */
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*allows_mem = false;
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*allows_reg = false;
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/* Allow the `=' or `+' to not be at the beginning of the string,
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since it wasn't explicitly documented that way, and there is a
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large body of code that puts it last. Swap the character to
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the front, so as not to uglify any place else. */
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p = strchr (constraint, '=');
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if (!p)
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p = strchr (constraint, '+');
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/* If the string doesn't contain an `=', issue an error
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message. */
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if (!p)
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{
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error ("output operand constraint lacks %<=%>");
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return false;
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}
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/* If the constraint begins with `+', then the operand is both read
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from and written to. */
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*is_inout = (*p == '+');
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/* Canonicalize the output constraint so that it begins with `='. */
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if (p != constraint || *is_inout)
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{
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char *buf;
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size_t c_len = strlen (constraint);
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if (p != constraint)
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warning (0, "output constraint %qc for operand %d "
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"is not at the beginning",
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*p, operand_num);
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/* Make a copy of the constraint. */
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buf = XALLOCAVEC (char, c_len + 1);
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strcpy (buf, constraint);
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/* Swap the first character and the `=' or `+'. */
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buf[p - constraint] = buf[0];
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/* Make sure the first character is an `='. (Until we do this,
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it might be a `+'.) */
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buf[0] = '=';
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/* Replace the constraint with the canonicalized string. */
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*constraint_p = ggc_alloc_string (buf, c_len);
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constraint = *constraint_p;
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}
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/* Loop through the constraint string. */
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for (p = constraint + 1; *p; p += CONSTRAINT_LEN (*p, p))
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switch (*p)
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{
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case '+':
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case '=':
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error ("operand constraint contains incorrectly positioned "
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"%<+%> or %<=%>");
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return false;
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case '%':
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if (operand_num + 1 == ninputs + noutputs)
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{
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error ("%<%%%> constraint used with last operand");
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return false;
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}
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break;
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case '?': case '!': case '*': case '&': case '#':
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case 'E': case 'F': case 'G': case 'H':
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case 's': case 'i': case 'n':
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case 'I': case 'J': case 'K': case 'L': case 'M':
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case 'N': case 'O': case 'P': case ',':
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break;
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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case '[':
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error ("matching constraint not valid in output operand");
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return false;
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case '<': case '>':
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/* ??? Before flow, auto inc/dec insns are not supposed to exist,
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excepting those that expand_call created. So match memory
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and hope. */
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*allows_mem = true;
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break;
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case 'g': case 'X':
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*allows_reg = true;
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*allows_mem = true;
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break;
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default:
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if (!ISALPHA (*p))
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break;
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enum constraint_num cn = lookup_constraint (p);
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if (reg_class_for_constraint (cn) != NO_REGS
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|| insn_extra_address_constraint (cn))
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*allows_reg = true;
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else if (insn_extra_memory_constraint (cn))
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*allows_mem = true;
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else
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{
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/* Otherwise we can't assume anything about the nature of
|
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the constraint except that it isn't purely registers.
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Treat it like "g" and hope for the best. */
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*allows_reg = true;
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*allows_mem = true;
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}
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break;
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}
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return true;
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}
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/* Similar, but for input constraints. */
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bool
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parse_input_constraint (const char **constraint_p, int input_num,
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int ninputs, int noutputs, int ninout,
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const char * const * constraints,
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bool *allows_mem, bool *allows_reg)
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{
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||
const char *constraint = *constraint_p;
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||
const char *orig_constraint = constraint;
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size_t c_len = strlen (constraint);
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size_t j;
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bool saw_match = false;
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||
|
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/* Assume the constraint doesn't allow the use of either
|
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a register or memory. */
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*allows_mem = false;
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*allows_reg = false;
|
||
|
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/* Make sure constraint has neither `=', `+', nor '&'. */
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for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j))
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switch (constraint[j])
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{
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||
case '+': case '=': case '&':
|
||
if (constraint == orig_constraint)
|
||
{
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error ("input operand constraint contains %qc", constraint[j]);
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return false;
|
||
}
|
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break;
|
||
|
||
case '%':
|
||
if (constraint == orig_constraint
|
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&& input_num + 1 == ninputs - ninout)
|
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{
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error ("%<%%%> constraint used with last operand");
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return false;
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}
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break;
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case '<': case '>':
|
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case '?': case '!': case '*': case '#':
|
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case 'E': case 'F': case 'G': case 'H':
|
||
case 's': case 'i': case 'n':
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||
case 'I': case 'J': case 'K': case 'L': case 'M':
|
||
case 'N': case 'O': case 'P': case ',':
|
||
break;
|
||
|
||
/* Whether or not a numeric constraint allows a register is
|
||
decided by the matching constraint, and so there is no need
|
||
to do anything special with them. We must handle them in
|
||
the default case, so that we don't unnecessarily force
|
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operands to memory. */
|
||
case '0': case '1': case '2': case '3': case '4':
|
||
case '5': case '6': case '7': case '8': case '9':
|
||
{
|
||
char *end;
|
||
unsigned long match;
|
||
|
||
saw_match = true;
|
||
|
||
match = strtoul (constraint + j, &end, 10);
|
||
if (match >= (unsigned long) noutputs)
|
||
{
|
||
error ("matching constraint references invalid operand number");
|
||
return false;
|
||
}
|
||
|
||
/* Try and find the real constraint for this dup. Only do this
|
||
if the matching constraint is the only alternative. */
|
||
if (*end == '\0'
|
||
&& (j == 0 || (j == 1 && constraint[0] == '%')))
|
||
{
|
||
constraint = constraints[match];
|
||
*constraint_p = constraint;
|
||
c_len = strlen (constraint);
|
||
j = 0;
|
||
/* ??? At the end of the loop, we will skip the first part of
|
||
the matched constraint. This assumes not only that the
|
||
other constraint is an output constraint, but also that
|
||
the '=' or '+' come first. */
|
||
break;
|
||
}
|
||
else
|
||
j = end - constraint;
|
||
/* Anticipate increment at end of loop. */
|
||
j--;
|
||
}
|
||
/* Fall through. */
|
||
|
||
case 'g': case 'X':
|
||
*allows_reg = true;
|
||
*allows_mem = true;
|
||
break;
|
||
|
||
default:
|
||
if (! ISALPHA (constraint[j]))
|
||
{
|
||
error ("invalid punctuation %qc in constraint", constraint[j]);
|
||
return false;
|
||
}
|
||
enum constraint_num cn = lookup_constraint (constraint + j);
|
||
if (reg_class_for_constraint (cn) != NO_REGS
|
||
|| insn_extra_address_constraint (cn))
|
||
*allows_reg = true;
|
||
else if (insn_extra_memory_constraint (cn))
|
||
*allows_mem = true;
|
||
else
|
||
{
|
||
/* Otherwise we can't assume anything about the nature of
|
||
the constraint except that it isn't purely registers.
|
||
Treat it like "g" and hope for the best. */
|
||
*allows_reg = true;
|
||
*allows_mem = true;
|
||
}
|
||
break;
|
||
}
|
||
|
||
if (saw_match && !*allows_reg)
|
||
warning (0, "matching constraint does not allow a register");
|
||
|
||
return true;
|
||
}
|
||
|
||
/* Return DECL iff there's an overlap between *REGS and DECL, where DECL
|
||
can be an asm-declared register. Called via walk_tree. */
|
||
|
||
static tree
|
||
decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED,
|
||
void *data)
|
||
{
|
||
tree decl = *declp;
|
||
const HARD_REG_SET *const regs = (const HARD_REG_SET *) data;
|
||
|
||
if (TREE_CODE (decl) == VAR_DECL)
|
||
{
|
||
if (DECL_HARD_REGISTER (decl)
|
||
&& REG_P (DECL_RTL (decl))
|
||
&& REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
rtx reg = DECL_RTL (decl);
|
||
|
||
if (overlaps_hard_reg_set_p (*regs, GET_MODE (reg), REGNO (reg)))
|
||
return decl;
|
||
}
|
||
walk_subtrees = 0;
|
||
}
|
||
else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL)
|
||
walk_subtrees = 0;
|
||
return NULL_TREE;
|
||
}
|
||
|
||
/* If there is an overlap between *REGS and DECL, return the first overlap
|
||
found. */
|
||
tree
|
||
tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs)
|
||
{
|
||
return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL);
|
||
}
|
||
|
||
|
||
/* A subroutine of expand_asm_operands. Check that all operand names
|
||
are unique. Return true if so. We rely on the fact that these names
|
||
are identifiers, and so have been canonicalized by get_identifier,
|
||
so all we need are pointer comparisons. */
|
||
|
||
static bool
|
||
check_unique_operand_names (tree outputs, tree inputs, tree labels)
|
||
{
|
||
tree i, j, i_name = NULL_TREE;
|
||
|
||
for (i = outputs; i ; i = TREE_CHAIN (i))
|
||
{
|
||
i_name = TREE_PURPOSE (TREE_PURPOSE (i));
|
||
if (! i_name)
|
||
continue;
|
||
|
||
for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
|
||
if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
|
||
goto failure;
|
||
}
|
||
|
||
for (i = inputs; i ; i = TREE_CHAIN (i))
|
||
{
|
||
i_name = TREE_PURPOSE (TREE_PURPOSE (i));
|
||
if (! i_name)
|
||
continue;
|
||
|
||
for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
|
||
if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
|
||
goto failure;
|
||
for (j = outputs; j ; j = TREE_CHAIN (j))
|
||
if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
|
||
goto failure;
|
||
}
|
||
|
||
for (i = labels; i ; i = TREE_CHAIN (i))
|
||
{
|
||
i_name = TREE_PURPOSE (i);
|
||
if (! i_name)
|
||
continue;
|
||
|
||
for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
|
||
if (simple_cst_equal (i_name, TREE_PURPOSE (j)))
|
||
goto failure;
|
||
for (j = inputs; j ; j = TREE_CHAIN (j))
|
||
if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
|
||
goto failure;
|
||
}
|
||
|
||
return true;
|
||
|
||
failure:
|
||
error ("duplicate asm operand name %qs", TREE_STRING_POINTER (i_name));
|
||
return false;
|
||
}
|
||
|
||
/* A subroutine of expand_asm_operands. Resolve the names of the operands
|
||
in *POUTPUTS and *PINPUTS to numbers, and replace the name expansions in
|
||
STRING and in the constraints to those numbers. */
|
||
|
||
tree
|
||
resolve_asm_operand_names (tree string, tree outputs, tree inputs, tree labels)
|
||
{
|
||
char *buffer;
|
||
char *p;
|
||
const char *c;
|
||
tree t;
|
||
|
||
check_unique_operand_names (outputs, inputs, labels);
|
||
|
||
/* Substitute [<name>] in input constraint strings. There should be no
|
||
named operands in output constraints. */
|
||
for (t = inputs; t ; t = TREE_CHAIN (t))
|
||
{
|
||
c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
|
||
if (strchr (c, '[') != NULL)
|
||
{
|
||
p = buffer = xstrdup (c);
|
||
while ((p = strchr (p, '[')) != NULL)
|
||
p = resolve_operand_name_1 (p, outputs, inputs, NULL);
|
||
TREE_VALUE (TREE_PURPOSE (t))
|
||
= build_string (strlen (buffer), buffer);
|
||
free (buffer);
|
||
}
|
||
}
|
||
|
||
/* Now check for any needed substitutions in the template. */
|
||
c = TREE_STRING_POINTER (string);
|
||
while ((c = strchr (c, '%')) != NULL)
|
||
{
|
||
if (c[1] == '[')
|
||
break;
|
||
else if (ISALPHA (c[1]) && c[2] == '[')
|
||
break;
|
||
else
|
||
{
|
||
c += 1 + (c[1] == '%');
|
||
continue;
|
||
}
|
||
}
|
||
|
||
if (c)
|
||
{
|
||
/* OK, we need to make a copy so we can perform the substitutions.
|
||
Assume that we will not need extra space--we get to remove '['
|
||
and ']', which means we cannot have a problem until we have more
|
||
than 999 operands. */
|
||
buffer = xstrdup (TREE_STRING_POINTER (string));
|
||
p = buffer + (c - TREE_STRING_POINTER (string));
|
||
|
||
while ((p = strchr (p, '%')) != NULL)
|
||
{
|
||
if (p[1] == '[')
|
||
p += 1;
|
||
else if (ISALPHA (p[1]) && p[2] == '[')
|
||
p += 2;
|
||
else
|
||
{
|
||
p += 1 + (p[1] == '%');
|
||
continue;
|
||
}
|
||
|
||
p = resolve_operand_name_1 (p, outputs, inputs, labels);
|
||
}
|
||
|
||
string = build_string (strlen (buffer), buffer);
|
||
free (buffer);
|
||
}
|
||
|
||
return string;
|
||
}
|
||
|
||
/* A subroutine of resolve_operand_names. P points to the '[' for a
|
||
potential named operand of the form [<name>]. In place, replace
|
||
the name and brackets with a number. Return a pointer to the
|
||
balance of the string after substitution. */
|
||
|
||
static char *
|
||
resolve_operand_name_1 (char *p, tree outputs, tree inputs, tree labels)
|
||
{
|
||
char *q;
|
||
int op;
|
||
tree t;
|
||
|
||
/* Collect the operand name. */
|
||
q = strchr (++p, ']');
|
||
if (!q)
|
||
{
|
||
error ("missing close brace for named operand");
|
||
return strchr (p, '\0');
|
||
}
|
||
*q = '\0';
|
||
|
||
/* Resolve the name to a number. */
|
||
for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++)
|
||
{
|
||
tree name = TREE_PURPOSE (TREE_PURPOSE (t));
|
||
if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
|
||
goto found;
|
||
}
|
||
for (t = inputs; t ; t = TREE_CHAIN (t), op++)
|
||
{
|
||
tree name = TREE_PURPOSE (TREE_PURPOSE (t));
|
||
if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
|
||
goto found;
|
||
}
|
||
for (t = labels; t ; t = TREE_CHAIN (t), op++)
|
||
{
|
||
tree name = TREE_PURPOSE (t);
|
||
if (name && strcmp (TREE_STRING_POINTER (name), p) == 0)
|
||
goto found;
|
||
}
|
||
|
||
error ("undefined named operand %qs", identifier_to_locale (p));
|
||
op = 0;
|
||
|
||
found:
|
||
/* Replace the name with the number. Unfortunately, not all libraries
|
||
get the return value of sprintf correct, so search for the end of the
|
||
generated string by hand. */
|
||
sprintf (--p, "%d", op);
|
||
p = strchr (p, '\0');
|
||
|
||
/* Verify the no extra buffer space assumption. */
|
||
gcc_assert (p <= q);
|
||
|
||
/* Shift the rest of the buffer down to fill the gap. */
|
||
memmove (p, q + 1, strlen (q + 1) + 1);
|
||
|
||
return p;
|
||
}
|
||
|
||
|
||
/* Generate RTL to return directly from the current function.
|
||
(That is, we bypass any return value.) */
|
||
|
||
void
|
||
expand_naked_return (void)
|
||
{
|
||
rtx end_label;
|
||
|
||
clear_pending_stack_adjust ();
|
||
do_pending_stack_adjust ();
|
||
|
||
end_label = naked_return_label;
|
||
if (end_label == 0)
|
||
end_label = naked_return_label = gen_label_rtx ();
|
||
|
||
emit_jump (end_label);
|
||
}
|
||
|
||
/* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE. PROB
|
||
is the probability of jumping to LABEL. */
|
||
static void
|
||
do_jump_if_equal (machine_mode mode, rtx op0, rtx op1, rtx label,
|
||
int unsignedp, int prob)
|
||
{
|
||
gcc_assert (prob <= REG_BR_PROB_BASE);
|
||
do_compare_rtx_and_jump (op0, op1, EQ, unsignedp, mode,
|
||
NULL_RTX, NULL_RTX, label, prob);
|
||
}
|
||
|
||
/* Do the insertion of a case label into case_list. The labels are
|
||
fed to us in descending order from the sorted vector of case labels used
|
||
in the tree part of the middle end. So the list we construct is
|
||
sorted in ascending order.
|
||
|
||
LABEL is the case label to be inserted. LOW and HIGH are the bounds
|
||
against which the index is compared to jump to LABEL and PROB is the
|
||
estimated probability LABEL is reached from the switch statement. */
|
||
|
||
static struct case_node *
|
||
add_case_node (struct case_node *head, tree low, tree high,
|
||
tree label, int prob, alloc_pool case_node_pool)
|
||
{
|
||
struct case_node *r;
|
||
|
||
gcc_checking_assert (low);
|
||
gcc_checking_assert (high && (TREE_TYPE (low) == TREE_TYPE (high)));
|
||
|
||
/* Add this label to the chain. */
|
||
r = (struct case_node *) pool_alloc (case_node_pool);
|
||
r->low = low;
|
||
r->high = high;
|
||
r->code_label = label;
|
||
r->parent = r->left = NULL;
|
||
r->prob = prob;
|
||
r->subtree_prob = prob;
|
||
r->right = head;
|
||
return r;
|
||
}
|
||
|
||
/* Dump ROOT, a list or tree of case nodes, to file. */
|
||
|
||
static void
|
||
dump_case_nodes (FILE *f, struct case_node *root,
|
||
int indent_step, int indent_level)
|
||
{
|
||
if (root == 0)
|
||
return;
|
||
indent_level++;
|
||
|
||
dump_case_nodes (f, root->left, indent_step, indent_level);
|
||
|
||
fputs (";; ", f);
|
||
fprintf (f, "%*s", indent_step * indent_level, "");
|
||
print_dec (root->low, f, TYPE_SIGN (TREE_TYPE (root->low)));
|
||
if (!tree_int_cst_equal (root->low, root->high))
|
||
{
|
||
fprintf (f, " ... ");
|
||
print_dec (root->high, f, TYPE_SIGN (TREE_TYPE (root->high)));
|
||
}
|
||
fputs ("\n", f);
|
||
|
||
dump_case_nodes (f, root->right, indent_step, indent_level);
|
||
}
|
||
|
||
#ifndef HAVE_casesi
|
||
#define HAVE_casesi 0
|
||
#endif
|
||
|
||
#ifndef HAVE_tablejump
|
||
#define HAVE_tablejump 0
|
||
#endif
|
||
|
||
/* Return the smallest number of different values for which it is best to use a
|
||
jump-table instead of a tree of conditional branches. */
|
||
|
||
static unsigned int
|
||
case_values_threshold (void)
|
||
{
|
||
unsigned int threshold = PARAM_VALUE (PARAM_CASE_VALUES_THRESHOLD);
|
||
|
||
if (threshold == 0)
|
||
threshold = targetm.case_values_threshold ();
|
||
|
||
return threshold;
|
||
}
|
||
|
||
/* Return true if a switch should be expanded as a decision tree.
|
||
RANGE is the difference between highest and lowest case.
|
||
UNIQ is number of unique case node targets, not counting the default case.
|
||
COUNT is the number of comparisons needed, not counting the default case. */
|
||
|
||
static bool
|
||
expand_switch_as_decision_tree_p (tree range,
|
||
unsigned int uniq ATTRIBUTE_UNUSED,
|
||
unsigned int count)
|
||
{
|
||
int max_ratio;
|
||
|
||
/* If neither casesi or tablejump is available, or flag_jump_tables
|
||
over-ruled us, we really have no choice. */
|
||
if (!HAVE_casesi && !HAVE_tablejump)
|
||
return true;
|
||
if (!flag_jump_tables)
|
||
return true;
|
||
#ifndef ASM_OUTPUT_ADDR_DIFF_ELT
|
||
if (flag_pic)
|
||
return true;
|
||
#endif
|
||
|
||
/* If the switch is relatively small such that the cost of one
|
||
indirect jump on the target are higher than the cost of a
|
||
decision tree, go with the decision tree.
|
||
|
||
If range of values is much bigger than number of values,
|
||
or if it is too large to represent in a HOST_WIDE_INT,
|
||
make a sequence of conditional branches instead of a dispatch.
|
||
|
||
The definition of "much bigger" depends on whether we are
|
||
optimizing for size or for speed. If the former, the maximum
|
||
ratio range/count = 3, because this was found to be the optimal
|
||
ratio for size on i686-pc-linux-gnu, see PR11823. The ratio
|
||
10 is much older, and was probably selected after an extensive
|
||
benchmarking investigation on numerous platforms. Or maybe it
|
||
just made sense to someone at some point in the history of GCC,
|
||
who knows... */
|
||
max_ratio = optimize_insn_for_size_p () ? 3 : 10;
|
||
if (count < case_values_threshold ()
|
||
|| ! tree_fits_uhwi_p (range)
|
||
|| compare_tree_int (range, max_ratio * count) > 0)
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
/* Generate a decision tree, switching on INDEX_EXPR and jumping to
|
||
one of the labels in CASE_LIST or to the DEFAULT_LABEL.
|
||
DEFAULT_PROB is the estimated probability that it jumps to
|
||
DEFAULT_LABEL.
|
||
|
||
We generate a binary decision tree to select the appropriate target
|
||
code. This is done as follows:
|
||
|
||
If the index is a short or char that we do not have
|
||
an insn to handle comparisons directly, convert it to
|
||
a full integer now, rather than letting each comparison
|
||
generate the conversion.
|
||
|
||
Load the index into a register.
|
||
|
||
The list of cases is rearranged into a binary tree,
|
||
nearly optimal assuming equal probability for each case.
|
||
|
||
The tree is transformed into RTL, eliminating redundant
|
||
test conditions at the same time.
|
||
|
||
If program flow could reach the end of the decision tree
|
||
an unconditional jump to the default code is emitted.
|
||
|
||
The above process is unaware of the CFG. The caller has to fix up
|
||
the CFG itself. This is done in cfgexpand.c. */
|
||
|
||
static void
|
||
emit_case_decision_tree (tree index_expr, tree index_type,
|
||
struct case_node *case_list, rtx default_label,
|
||
int default_prob)
|
||
{
|
||
rtx index = expand_normal (index_expr);
|
||
|
||
if (GET_MODE_CLASS (GET_MODE (index)) == MODE_INT
|
||
&& ! have_insn_for (COMPARE, GET_MODE (index)))
|
||
{
|
||
int unsignedp = TYPE_UNSIGNED (index_type);
|
||
machine_mode wider_mode;
|
||
for (wider_mode = GET_MODE (index); wider_mode != VOIDmode;
|
||
wider_mode = GET_MODE_WIDER_MODE (wider_mode))
|
||
if (have_insn_for (COMPARE, wider_mode))
|
||
{
|
||
index = convert_to_mode (wider_mode, index, unsignedp);
|
||
break;
|
||
}
|
||
}
|
||
|
||
do_pending_stack_adjust ();
|
||
|
||
if (MEM_P (index))
|
||
{
|
||
index = copy_to_reg (index);
|
||
if (TREE_CODE (index_expr) == SSA_NAME)
|
||
set_reg_attrs_for_decl_rtl (SSA_NAME_VAR (index_expr), index);
|
||
}
|
||
|
||
balance_case_nodes (&case_list, NULL);
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
int indent_step = ceil_log2 (TYPE_PRECISION (index_type)) + 2;
|
||
fprintf (dump_file, ";; Expanding GIMPLE switch as decision tree:\n");
|
||
dump_case_nodes (dump_file, case_list, indent_step, 0);
|
||
}
|
||
|
||
emit_case_nodes (index, case_list, default_label, default_prob, index_type);
|
||
if (default_label)
|
||
emit_jump (default_label);
|
||
}
|
||
|
||
/* Return the sum of probabilities of outgoing edges of basic block BB. */
|
||
|
||
static int
|
||
get_outgoing_edge_probs (basic_block bb)
|
||
{
|
||
edge e;
|
||
edge_iterator ei;
|
||
int prob_sum = 0;
|
||
if (!bb)
|
||
return 0;
|
||
FOR_EACH_EDGE (e, ei, bb->succs)
|
||
prob_sum += e->probability;
|
||
return prob_sum;
|
||
}
|
||
|
||
/* Computes the conditional probability of jumping to a target if the branch
|
||
instruction is executed.
|
||
TARGET_PROB is the estimated probability of jumping to a target relative
|
||
to some basic block BB.
|
||
BASE_PROB is the probability of reaching the branch instruction relative
|
||
to the same basic block BB. */
|
||
|
||
static inline int
|
||
conditional_probability (int target_prob, int base_prob)
|
||
{
|
||
if (base_prob > 0)
|
||
{
|
||
gcc_assert (target_prob >= 0);
|
||
gcc_assert (target_prob <= base_prob);
|
||
return GCOV_COMPUTE_SCALE (target_prob, base_prob);
|
||
}
|
||
return -1;
|
||
}
|
||
|
||
/* Generate a dispatch tabler, switching on INDEX_EXPR and jumping to
|
||
one of the labels in CASE_LIST or to the DEFAULT_LABEL.
|
||
MINVAL, MAXVAL, and RANGE are the extrema and range of the case
|
||
labels in CASE_LIST. STMT_BB is the basic block containing the statement.
|
||
|
||
First, a jump insn is emitted. First we try "casesi". If that
|
||
fails, try "tablejump". A target *must* have one of them (or both).
|
||
|
||
Then, a table with the target labels is emitted.
|
||
|
||
The process is unaware of the CFG. The caller has to fix up
|
||
the CFG itself. This is done in cfgexpand.c. */
|
||
|
||
static void
|
||
emit_case_dispatch_table (tree index_expr, tree index_type,
|
||
struct case_node *case_list, rtx default_label,
|
||
tree minval, tree maxval, tree range,
|
||
basic_block stmt_bb)
|
||
{
|
||
int i, ncases;
|
||
struct case_node *n;
|
||
rtx *labelvec;
|
||
rtx fallback_label = label_rtx (case_list->code_label);
|
||
rtx_code_label *table_label = gen_label_rtx ();
|
||
bool has_gaps = false;
|
||
edge default_edge = stmt_bb ? EDGE_SUCC (stmt_bb, 0) : NULL;
|
||
int default_prob = default_edge ? default_edge->probability : 0;
|
||
int base = get_outgoing_edge_probs (stmt_bb);
|
||
bool try_with_tablejump = false;
|
||
|
||
int new_default_prob = conditional_probability (default_prob,
|
||
base);
|
||
|
||
if (! try_casesi (index_type, index_expr, minval, range,
|
||
table_label, default_label, fallback_label,
|
||
new_default_prob))
|
||
{
|
||
/* Index jumptables from zero for suitable values of minval to avoid
|
||
a subtraction. For the rationale see:
|
||
"http://gcc.gnu.org/ml/gcc-patches/2001-10/msg01234.html". */
|
||
if (optimize_insn_for_speed_p ()
|
||
&& compare_tree_int (minval, 0) > 0
|
||
&& compare_tree_int (minval, 3) < 0)
|
||
{
|
||
minval = build_int_cst (index_type, 0);
|
||
range = maxval;
|
||
has_gaps = true;
|
||
}
|
||
try_with_tablejump = true;
|
||
}
|
||
|
||
/* Get table of labels to jump to, in order of case index. */
|
||
|
||
ncases = tree_to_shwi (range) + 1;
|
||
labelvec = XALLOCAVEC (rtx, ncases);
|
||
memset (labelvec, 0, ncases * sizeof (rtx));
|
||
|
||
for (n = case_list; n; n = n->right)
|
||
{
|
||
/* Compute the low and high bounds relative to the minimum
|
||
value since that should fit in a HOST_WIDE_INT while the
|
||
actual values may not. */
|
||
HOST_WIDE_INT i_low
|
||
= tree_to_uhwi (fold_build2 (MINUS_EXPR, index_type,
|
||
n->low, minval));
|
||
HOST_WIDE_INT i_high
|
||
= tree_to_uhwi (fold_build2 (MINUS_EXPR, index_type,
|
||
n->high, minval));
|
||
HOST_WIDE_INT i;
|
||
|
||
for (i = i_low; i <= i_high; i ++)
|
||
labelvec[i]
|
||
= gen_rtx_LABEL_REF (Pmode, label_rtx (n->code_label));
|
||
}
|
||
|
||
/* Fill in the gaps with the default. We may have gaps at
|
||
the beginning if we tried to avoid the minval subtraction,
|
||
so substitute some label even if the default label was
|
||
deemed unreachable. */
|
||
if (!default_label)
|
||
default_label = fallback_label;
|
||
for (i = 0; i < ncases; i++)
|
||
if (labelvec[i] == 0)
|
||
{
|
||
has_gaps = true;
|
||
labelvec[i] = gen_rtx_LABEL_REF (Pmode, default_label);
|
||
}
|
||
|
||
if (has_gaps)
|
||
{
|
||
/* There is at least one entry in the jump table that jumps
|
||
to default label. The default label can either be reached
|
||
through the indirect jump or the direct conditional jump
|
||
before that. Split the probability of reaching the
|
||
default label among these two jumps. */
|
||
new_default_prob = conditional_probability (default_prob/2,
|
||
base);
|
||
default_prob /= 2;
|
||
base -= default_prob;
|
||
}
|
||
else
|
||
{
|
||
base -= default_prob;
|
||
default_prob = 0;
|
||
}
|
||
|
||
if (default_edge)
|
||
default_edge->probability = default_prob;
|
||
|
||
/* We have altered the probability of the default edge. So the probabilities
|
||
of all other edges need to be adjusted so that it sums up to
|
||
REG_BR_PROB_BASE. */
|
||
if (base)
|
||
{
|
||
edge e;
|
||
edge_iterator ei;
|
||
FOR_EACH_EDGE (e, ei, stmt_bb->succs)
|
||
e->probability = GCOV_COMPUTE_SCALE (e->probability, base);
|
||
}
|
||
|
||
if (try_with_tablejump)
|
||
{
|
||
bool ok = try_tablejump (index_type, index_expr, minval, range,
|
||
table_label, default_label, new_default_prob);
|
||
gcc_assert (ok);
|
||
}
|
||
/* Output the table. */
|
||
emit_label (table_label);
|
||
|
||
if (CASE_VECTOR_PC_RELATIVE || flag_pic)
|
||
emit_jump_table_data (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE,
|
||
gen_rtx_LABEL_REF (Pmode,
|
||
table_label),
|
||
gen_rtvec_v (ncases, labelvec),
|
||
const0_rtx, const0_rtx));
|
||
else
|
||
emit_jump_table_data (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE,
|
||
gen_rtvec_v (ncases, labelvec)));
|
||
|
||
/* Record no drop-through after the table. */
|
||
emit_barrier ();
|
||
}
|
||
|
||
/* Reset the aux field of all outgoing edges of basic block BB. */
|
||
|
||
static inline void
|
||
reset_out_edges_aux (basic_block bb)
|
||
{
|
||
edge e;
|
||
edge_iterator ei;
|
||
FOR_EACH_EDGE (e, ei, bb->succs)
|
||
e->aux = (void *)0;
|
||
}
|
||
|
||
/* Compute the number of case labels that correspond to each outgoing edge of
|
||
STMT. Record this information in the aux field of the edge. */
|
||
|
||
static inline void
|
||
compute_cases_per_edge (gswitch *stmt)
|
||
{
|
||
basic_block bb = gimple_bb (stmt);
|
||
reset_out_edges_aux (bb);
|
||
int ncases = gimple_switch_num_labels (stmt);
|
||
for (int i = ncases - 1; i >= 1; --i)
|
||
{
|
||
tree elt = gimple_switch_label (stmt, i);
|
||
tree lab = CASE_LABEL (elt);
|
||
basic_block case_bb = label_to_block_fn (cfun, lab);
|
||
edge case_edge = find_edge (bb, case_bb);
|
||
case_edge->aux = (void *)((intptr_t)(case_edge->aux) + 1);
|
||
}
|
||
}
|
||
|
||
/* Terminate a case (Pascal/Ada) or switch (C) statement
|
||
in which ORIG_INDEX is the expression to be tested.
|
||
If ORIG_TYPE is not NULL, it is the original ORIG_INDEX
|
||
type as given in the source before any compiler conversions.
|
||
Generate the code to test it and jump to the right place. */
|
||
|
||
void
|
||
expand_case (gswitch *stmt)
|
||
{
|
||
tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE;
|
||
rtx default_label = NULL_RTX;
|
||
unsigned int count, uniq;
|
||
int i;
|
||
int ncases = gimple_switch_num_labels (stmt);
|
||
tree index_expr = gimple_switch_index (stmt);
|
||
tree index_type = TREE_TYPE (index_expr);
|
||
tree elt;
|
||
basic_block bb = gimple_bb (stmt);
|
||
|
||
/* A list of case labels; it is first built as a list and it may then
|
||
be rearranged into a nearly balanced binary tree. */
|
||
struct case_node *case_list = 0;
|
||
|
||
/* A pool for case nodes. */
|
||
alloc_pool case_node_pool;
|
||
|
||
/* An ERROR_MARK occurs for various reasons including invalid data type.
|
||
??? Can this still happen, with GIMPLE and all? */
|
||
if (index_type == error_mark_node)
|
||
return;
|
||
|
||
/* cleanup_tree_cfg removes all SWITCH_EXPR with their index
|
||
expressions being INTEGER_CST. */
|
||
gcc_assert (TREE_CODE (index_expr) != INTEGER_CST);
|
||
|
||
case_node_pool = create_alloc_pool ("struct case_node pool",
|
||
sizeof (struct case_node),
|
||
100);
|
||
|
||
do_pending_stack_adjust ();
|
||
|
||
/* Find the default case target label. */
|
||
default_label = label_rtx (CASE_LABEL (gimple_switch_default_label (stmt)));
|
||
edge default_edge = EDGE_SUCC (bb, 0);
|
||
int default_prob = default_edge->probability;
|
||
|
||
/* Get upper and lower bounds of case values. */
|
||
elt = gimple_switch_label (stmt, 1);
|
||
minval = fold_convert (index_type, CASE_LOW (elt));
|
||
elt = gimple_switch_label (stmt, ncases - 1);
|
||
if (CASE_HIGH (elt))
|
||
maxval = fold_convert (index_type, CASE_HIGH (elt));
|
||
else
|
||
maxval = fold_convert (index_type, CASE_LOW (elt));
|
||
|
||
/* Compute span of values. */
|
||
range = fold_build2 (MINUS_EXPR, index_type, maxval, minval);
|
||
|
||
/* Listify the labels queue and gather some numbers to decide
|
||
how to expand this switch(). */
|
||
uniq = 0;
|
||
count = 0;
|
||
hash_set<tree> seen_labels;
|
||
compute_cases_per_edge (stmt);
|
||
|
||
for (i = ncases - 1; i >= 1; --i)
|
||
{
|
||
elt = gimple_switch_label (stmt, i);
|
||
tree low = CASE_LOW (elt);
|
||
gcc_assert (low);
|
||
tree high = CASE_HIGH (elt);
|
||
gcc_assert (! high || tree_int_cst_lt (low, high));
|
||
tree lab = CASE_LABEL (elt);
|
||
|
||
/* Count the elements.
|
||
A range counts double, since it requires two compares. */
|
||
count++;
|
||
if (high)
|
||
count++;
|
||
|
||
/* If we have not seen this label yet, then increase the
|
||
number of unique case node targets seen. */
|
||
if (!seen_labels.add (lab))
|
||
uniq++;
|
||
|
||
/* The bounds on the case range, LOW and HIGH, have to be converted
|
||
to case's index type TYPE. Note that the original type of the
|
||
case index in the source code is usually "lost" during
|
||
gimplification due to type promotion, but the case labels retain the
|
||
original type. Make sure to drop overflow flags. */
|
||
low = fold_convert (index_type, low);
|
||
if (TREE_OVERFLOW (low))
|
||
low = wide_int_to_tree (index_type, low);
|
||
|
||
/* The canonical from of a case label in GIMPLE is that a simple case
|
||
has an empty CASE_HIGH. For the casesi and tablejump expanders,
|
||
the back ends want simple cases to have high == low. */
|
||
if (! high)
|
||
high = low;
|
||
high = fold_convert (index_type, high);
|
||
if (TREE_OVERFLOW (high))
|
||
high = wide_int_to_tree (index_type, high);
|
||
|
||
basic_block case_bb = label_to_block_fn (cfun, lab);
|
||
edge case_edge = find_edge (bb, case_bb);
|
||
case_list = add_case_node (
|
||
case_list, low, high, lab,
|
||
case_edge->probability / (intptr_t)(case_edge->aux),
|
||
case_node_pool);
|
||
}
|
||
reset_out_edges_aux (bb);
|
||
|
||
/* cleanup_tree_cfg removes all SWITCH_EXPR with a single
|
||
destination, such as one with a default case only.
|
||
It also removes cases that are out of range for the switch
|
||
type, so we should never get a zero here. */
|
||
gcc_assert (count > 0);
|
||
|
||
rtx_insn *before_case = get_last_insn ();
|
||
|
||
/* Decide how to expand this switch.
|
||
The two options at this point are a dispatch table (casesi or
|
||
tablejump) or a decision tree. */
|
||
|
||
if (expand_switch_as_decision_tree_p (range, uniq, count))
|
||
emit_case_decision_tree (index_expr, index_type,
|
||
case_list, default_label,
|
||
default_prob);
|
||
else
|
||
emit_case_dispatch_table (index_expr, index_type,
|
||
case_list, default_label,
|
||
minval, maxval, range, bb);
|
||
|
||
reorder_insns (NEXT_INSN (before_case), get_last_insn (), before_case);
|
||
|
||
free_temp_slots ();
|
||
free_alloc_pool (case_node_pool);
|
||
}
|
||
|
||
/* Expand the dispatch to a short decrement chain if there are few cases
|
||
to dispatch to. Likewise if neither casesi nor tablejump is available,
|
||
or if flag_jump_tables is set. Otherwise, expand as a casesi or a
|
||
tablejump. The index mode is always the mode of integer_type_node.
|
||
Trap if no case matches the index.
|
||
|
||
DISPATCH_INDEX is the index expression to switch on. It should be a
|
||
memory or register operand.
|
||
|
||
DISPATCH_TABLE is a set of case labels. The set should be sorted in
|
||
ascending order, be contiguous, starting with value 0, and contain only
|
||
single-valued case labels. */
|
||
|
||
void
|
||
expand_sjlj_dispatch_table (rtx dispatch_index,
|
||
vec<tree> dispatch_table)
|
||
{
|
||
tree index_type = integer_type_node;
|
||
machine_mode index_mode = TYPE_MODE (index_type);
|
||
|
||
int ncases = dispatch_table.length ();
|
||
|
||
do_pending_stack_adjust ();
|
||
rtx_insn *before_case = get_last_insn ();
|
||
|
||
/* Expand as a decrement-chain if there are 5 or fewer dispatch
|
||
labels. This covers more than 98% of the cases in libjava,
|
||
and seems to be a reasonable compromise between the "old way"
|
||
of expanding as a decision tree or dispatch table vs. the "new
|
||
way" with decrement chain or dispatch table. */
|
||
if (dispatch_table.length () <= 5
|
||
|| (!HAVE_casesi && !HAVE_tablejump)
|
||
|| !flag_jump_tables)
|
||
{
|
||
/* Expand the dispatch as a decrement chain:
|
||
|
||
"switch(index) {case 0: do_0; case 1: do_1; ...; case N: do_N;}"
|
||
|
||
==>
|
||
|
||
if (index == 0) do_0; else index--;
|
||
if (index == 0) do_1; else index--;
|
||
...
|
||
if (index == 0) do_N; else index--;
|
||
|
||
This is more efficient than a dispatch table on most machines.
|
||
The last "index--" is redundant but the code is trivially dead
|
||
and will be cleaned up by later passes. */
|
||
rtx index = copy_to_mode_reg (index_mode, dispatch_index);
|
||
rtx zero = CONST0_RTX (index_mode);
|
||
for (int i = 0; i < ncases; i++)
|
||
{
|
||
tree elt = dispatch_table[i];
|
||
rtx lab = label_rtx (CASE_LABEL (elt));
|
||
do_jump_if_equal (index_mode, index, zero, lab, 0, -1);
|
||
force_expand_binop (index_mode, sub_optab,
|
||
index, CONST1_RTX (index_mode),
|
||
index, 0, OPTAB_DIRECT);
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* Similar to expand_case, but much simpler. */
|
||
struct case_node *case_list = 0;
|
||
alloc_pool case_node_pool = create_alloc_pool ("struct sjlj_case pool",
|
||
sizeof (struct case_node),
|
||
ncases);
|
||
tree index_expr = make_tree (index_type, dispatch_index);
|
||
tree minval = build_int_cst (index_type, 0);
|
||
tree maxval = CASE_LOW (dispatch_table.last ());
|
||
tree range = maxval;
|
||
rtx_code_label *default_label = gen_label_rtx ();
|
||
|
||
for (int i = ncases - 1; i >= 0; --i)
|
||
{
|
||
tree elt = dispatch_table[i];
|
||
tree low = CASE_LOW (elt);
|
||
tree lab = CASE_LABEL (elt);
|
||
case_list = add_case_node (case_list, low, low, lab, 0, case_node_pool);
|
||
}
|
||
|
||
emit_case_dispatch_table (index_expr, index_type,
|
||
case_list, default_label,
|
||
minval, maxval, range,
|
||
BLOCK_FOR_INSN (before_case));
|
||
emit_label (default_label);
|
||
free_alloc_pool (case_node_pool);
|
||
}
|
||
|
||
/* Dispatching something not handled? Trap! */
|
||
expand_builtin_trap ();
|
||
|
||
reorder_insns (NEXT_INSN (before_case), get_last_insn (), before_case);
|
||
|
||
free_temp_slots ();
|
||
}
|
||
|
||
|
||
/* Take an ordered list of case nodes
|
||
and transform them into a near optimal binary tree,
|
||
on the assumption that any target code selection value is as
|
||
likely as any other.
|
||
|
||
The transformation is performed by splitting the ordered
|
||
list into two equal sections plus a pivot. The parts are
|
||
then attached to the pivot as left and right branches. Each
|
||
branch is then transformed recursively. */
|
||
|
||
static void
|
||
balance_case_nodes (case_node_ptr *head, case_node_ptr parent)
|
||
{
|
||
case_node_ptr np;
|
||
|
||
np = *head;
|
||
if (np)
|
||
{
|
||
int i = 0;
|
||
int ranges = 0;
|
||
case_node_ptr *npp;
|
||
case_node_ptr left;
|
||
|
||
/* Count the number of entries on branch. Also count the ranges. */
|
||
|
||
while (np)
|
||
{
|
||
if (!tree_int_cst_equal (np->low, np->high))
|
||
ranges++;
|
||
|
||
i++;
|
||
np = np->right;
|
||
}
|
||
|
||
if (i > 2)
|
||
{
|
||
/* Split this list if it is long enough for that to help. */
|
||
npp = head;
|
||
left = *npp;
|
||
|
||
/* If there are just three nodes, split at the middle one. */
|
||
if (i == 3)
|
||
npp = &(*npp)->right;
|
||
else
|
||
{
|
||
/* Find the place in the list that bisects the list's total cost,
|
||
where ranges count as 2.
|
||
Here I gets half the total cost. */
|
||
i = (i + ranges + 1) / 2;
|
||
while (1)
|
||
{
|
||
/* Skip nodes while their cost does not reach that amount. */
|
||
if (!tree_int_cst_equal ((*npp)->low, (*npp)->high))
|
||
i--;
|
||
i--;
|
||
if (i <= 0)
|
||
break;
|
||
npp = &(*npp)->right;
|
||
}
|
||
}
|
||
*head = np = *npp;
|
||
*npp = 0;
|
||
np->parent = parent;
|
||
np->left = left;
|
||
|
||
/* Optimize each of the two split parts. */
|
||
balance_case_nodes (&np->left, np);
|
||
balance_case_nodes (&np->right, np);
|
||
np->subtree_prob = np->prob;
|
||
np->subtree_prob += np->left->subtree_prob;
|
||
np->subtree_prob += np->right->subtree_prob;
|
||
}
|
||
else
|
||
{
|
||
/* Else leave this branch as one level,
|
||
but fill in `parent' fields. */
|
||
np = *head;
|
||
np->parent = parent;
|
||
np->subtree_prob = np->prob;
|
||
for (; np->right; np = np->right)
|
||
{
|
||
np->right->parent = np;
|
||
(*head)->subtree_prob += np->right->subtree_prob;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Search the parent sections of the case node tree
|
||
to see if a test for the lower bound of NODE would be redundant.
|
||
INDEX_TYPE is the type of the index expression.
|
||
|
||
The instructions to generate the case decision tree are
|
||
output in the same order as nodes are processed so it is
|
||
known that if a parent node checks the range of the current
|
||
node minus one that the current node is bounded at its lower
|
||
span. Thus the test would be redundant. */
|
||
|
||
static int
|
||
node_has_low_bound (case_node_ptr node, tree index_type)
|
||
{
|
||
tree low_minus_one;
|
||
case_node_ptr pnode;
|
||
|
||
/* If the lower bound of this node is the lowest value in the index type,
|
||
we need not test it. */
|
||
|
||
if (tree_int_cst_equal (node->low, TYPE_MIN_VALUE (index_type)))
|
||
return 1;
|
||
|
||
/* If this node has a left branch, the value at the left must be less
|
||
than that at this node, so it cannot be bounded at the bottom and
|
||
we need not bother testing any further. */
|
||
|
||
if (node->left)
|
||
return 0;
|
||
|
||
low_minus_one = fold_build2 (MINUS_EXPR, TREE_TYPE (node->low),
|
||
node->low,
|
||
build_int_cst (TREE_TYPE (node->low), 1));
|
||
|
||
/* If the subtraction above overflowed, we can't verify anything.
|
||
Otherwise, look for a parent that tests our value - 1. */
|
||
|
||
if (! tree_int_cst_lt (low_minus_one, node->low))
|
||
return 0;
|
||
|
||
for (pnode = node->parent; pnode; pnode = pnode->parent)
|
||
if (tree_int_cst_equal (low_minus_one, pnode->high))
|
||
return 1;
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Search the parent sections of the case node tree
|
||
to see if a test for the upper bound of NODE would be redundant.
|
||
INDEX_TYPE is the type of the index expression.
|
||
|
||
The instructions to generate the case decision tree are
|
||
output in the same order as nodes are processed so it is
|
||
known that if a parent node checks the range of the current
|
||
node plus one that the current node is bounded at its upper
|
||
span. Thus the test would be redundant. */
|
||
|
||
static int
|
||
node_has_high_bound (case_node_ptr node, tree index_type)
|
||
{
|
||
tree high_plus_one;
|
||
case_node_ptr pnode;
|
||
|
||
/* If there is no upper bound, obviously no test is needed. */
|
||
|
||
if (TYPE_MAX_VALUE (index_type) == NULL)
|
||
return 1;
|
||
|
||
/* If the upper bound of this node is the highest value in the type
|
||
of the index expression, we need not test against it. */
|
||
|
||
if (tree_int_cst_equal (node->high, TYPE_MAX_VALUE (index_type)))
|
||
return 1;
|
||
|
||
/* If this node has a right branch, the value at the right must be greater
|
||
than that at this node, so it cannot be bounded at the top and
|
||
we need not bother testing any further. */
|
||
|
||
if (node->right)
|
||
return 0;
|
||
|
||
high_plus_one = fold_build2 (PLUS_EXPR, TREE_TYPE (node->high),
|
||
node->high,
|
||
build_int_cst (TREE_TYPE (node->high), 1));
|
||
|
||
/* If the addition above overflowed, we can't verify anything.
|
||
Otherwise, look for a parent that tests our value + 1. */
|
||
|
||
if (! tree_int_cst_lt (node->high, high_plus_one))
|
||
return 0;
|
||
|
||
for (pnode = node->parent; pnode; pnode = pnode->parent)
|
||
if (tree_int_cst_equal (high_plus_one, pnode->low))
|
||
return 1;
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Search the parent sections of the
|
||
case node tree to see if both tests for the upper and lower
|
||
bounds of NODE would be redundant. */
|
||
|
||
static int
|
||
node_is_bounded (case_node_ptr node, tree index_type)
|
||
{
|
||
return (node_has_low_bound (node, index_type)
|
||
&& node_has_high_bound (node, index_type));
|
||
}
|
||
|
||
|
||
/* Emit step-by-step code to select a case for the value of INDEX.
|
||
The thus generated decision tree follows the form of the
|
||
case-node binary tree NODE, whose nodes represent test conditions.
|
||
INDEX_TYPE is the type of the index of the switch.
|
||
|
||
Care is taken to prune redundant tests from the decision tree
|
||
by detecting any boundary conditions already checked by
|
||
emitted rtx. (See node_has_high_bound, node_has_low_bound
|
||
and node_is_bounded, above.)
|
||
|
||
Where the test conditions can be shown to be redundant we emit
|
||
an unconditional jump to the target code. As a further
|
||
optimization, the subordinates of a tree node are examined to
|
||
check for bounded nodes. In this case conditional and/or
|
||
unconditional jumps as a result of the boundary check for the
|
||
current node are arranged to target the subordinates associated
|
||
code for out of bound conditions on the current node.
|
||
|
||
We can assume that when control reaches the code generated here,
|
||
the index value has already been compared with the parents
|
||
of this node, and determined to be on the same side of each parent
|
||
as this node is. Thus, if this node tests for the value 51,
|
||
and a parent tested for 52, we don't need to consider
|
||
the possibility of a value greater than 51. If another parent
|
||
tests for the value 50, then this node need not test anything. */
|
||
|
||
static void
|
||
emit_case_nodes (rtx index, case_node_ptr node, rtx default_label,
|
||
int default_prob, tree index_type)
|
||
{
|
||
/* If INDEX has an unsigned type, we must make unsigned branches. */
|
||
int unsignedp = TYPE_UNSIGNED (index_type);
|
||
int probability;
|
||
int prob = node->prob, subtree_prob = node->subtree_prob;
|
||
machine_mode mode = GET_MODE (index);
|
||
machine_mode imode = TYPE_MODE (index_type);
|
||
|
||
/* Handle indices detected as constant during RTL expansion. */
|
||
if (mode == VOIDmode)
|
||
mode = imode;
|
||
|
||
/* See if our parents have already tested everything for us.
|
||
If they have, emit an unconditional jump for this node. */
|
||
if (node_is_bounded (node, index_type))
|
||
emit_jump (label_rtx (node->code_label));
|
||
|
||
else if (tree_int_cst_equal (node->low, node->high))
|
||
{
|
||
probability = conditional_probability (prob, subtree_prob + default_prob);
|
||
/* Node is single valued. First see if the index expression matches
|
||
this node and then check our children, if any. */
|
||
do_jump_if_equal (mode, index,
|
||
convert_modes (mode, imode,
|
||
expand_normal (node->low),
|
||
unsignedp),
|
||
label_rtx (node->code_label), unsignedp, probability);
|
||
/* Since this case is taken at this point, reduce its weight from
|
||
subtree_weight. */
|
||
subtree_prob -= prob;
|
||
if (node->right != 0 && node->left != 0)
|
||
{
|
||
/* This node has children on both sides.
|
||
Dispatch to one side or the other
|
||
by comparing the index value with this node's value.
|
||
If one subtree is bounded, check that one first,
|
||
so we can avoid real branches in the tree. */
|
||
|
||
if (node_is_bounded (node->right, index_type))
|
||
{
|
||
probability = conditional_probability (
|
||
node->right->prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
GT, NULL_RTX, mode, unsignedp,
|
||
label_rtx (node->right->code_label),
|
||
probability);
|
||
emit_case_nodes (index, node->left, default_label, default_prob,
|
||
index_type);
|
||
}
|
||
|
||
else if (node_is_bounded (node->left, index_type))
|
||
{
|
||
probability = conditional_probability (
|
||
node->left->prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
LT, NULL_RTX, mode, unsignedp,
|
||
label_rtx (node->left->code_label),
|
||
probability);
|
||
emit_case_nodes (index, node->right, default_label, default_prob, index_type);
|
||
}
|
||
|
||
/* If both children are single-valued cases with no
|
||
children, finish up all the work. This way, we can save
|
||
one ordered comparison. */
|
||
else if (tree_int_cst_equal (node->right->low, node->right->high)
|
||
&& node->right->left == 0
|
||
&& node->right->right == 0
|
||
&& tree_int_cst_equal (node->left->low, node->left->high)
|
||
&& node->left->left == 0
|
||
&& node->left->right == 0)
|
||
{
|
||
/* Neither node is bounded. First distinguish the two sides;
|
||
then emit the code for one side at a time. */
|
||
|
||
/* See if the value matches what the right hand side
|
||
wants. */
|
||
probability = conditional_probability (
|
||
node->right->prob,
|
||
subtree_prob + default_prob);
|
||
do_jump_if_equal (mode, index,
|
||
convert_modes (mode, imode,
|
||
expand_normal (node->right->low),
|
||
unsignedp),
|
||
label_rtx (node->right->code_label),
|
||
unsignedp, probability);
|
||
|
||
/* See if the value matches what the left hand side
|
||
wants. */
|
||
probability = conditional_probability (
|
||
node->left->prob,
|
||
subtree_prob + default_prob);
|
||
do_jump_if_equal (mode, index,
|
||
convert_modes (mode, imode,
|
||
expand_normal (node->left->low),
|
||
unsignedp),
|
||
label_rtx (node->left->code_label),
|
||
unsignedp, probability);
|
||
}
|
||
|
||
else
|
||
{
|
||
/* Neither node is bounded. First distinguish the two sides;
|
||
then emit the code for one side at a time. */
|
||
|
||
tree test_label
|
||
= build_decl (curr_insn_location (),
|
||
LABEL_DECL, NULL_TREE, NULL_TREE);
|
||
|
||
/* The default label could be reached either through the right
|
||
subtree or the left subtree. Divide the probability
|
||
equally. */
|
||
probability = conditional_probability (
|
||
node->right->subtree_prob + default_prob/2,
|
||
subtree_prob + default_prob);
|
||
/* See if the value is on the right. */
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
GT, NULL_RTX, mode, unsignedp,
|
||
label_rtx (test_label),
|
||
probability);
|
||
default_prob /= 2;
|
||
|
||
/* Value must be on the left.
|
||
Handle the left-hand subtree. */
|
||
emit_case_nodes (index, node->left, default_label, default_prob, index_type);
|
||
/* If left-hand subtree does nothing,
|
||
go to default. */
|
||
if (default_label)
|
||
emit_jump (default_label);
|
||
|
||
/* Code branches here for the right-hand subtree. */
|
||
expand_label (test_label);
|
||
emit_case_nodes (index, node->right, default_label, default_prob, index_type);
|
||
}
|
||
}
|
||
|
||
else if (node->right != 0 && node->left == 0)
|
||
{
|
||
/* Here we have a right child but no left so we issue a conditional
|
||
branch to default and process the right child.
|
||
|
||
Omit the conditional branch to default if the right child
|
||
does not have any children and is single valued; it would
|
||
cost too much space to save so little time. */
|
||
|
||
if (node->right->right || node->right->left
|
||
|| !tree_int_cst_equal (node->right->low, node->right->high))
|
||
{
|
||
if (!node_has_low_bound (node, index_type))
|
||
{
|
||
probability = conditional_probability (
|
||
default_prob/2,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
LT, NULL_RTX, mode, unsignedp,
|
||
default_label,
|
||
probability);
|
||
default_prob /= 2;
|
||
}
|
||
|
||
emit_case_nodes (index, node->right, default_label, default_prob, index_type);
|
||
}
|
||
else
|
||
{
|
||
probability = conditional_probability (
|
||
node->right->subtree_prob,
|
||
subtree_prob + default_prob);
|
||
/* We cannot process node->right normally
|
||
since we haven't ruled out the numbers less than
|
||
this node's value. So handle node->right explicitly. */
|
||
do_jump_if_equal (mode, index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->right->low),
|
||
unsignedp),
|
||
label_rtx (node->right->code_label), unsignedp, probability);
|
||
}
|
||
}
|
||
|
||
else if (node->right == 0 && node->left != 0)
|
||
{
|
||
/* Just one subtree, on the left. */
|
||
if (node->left->left || node->left->right
|
||
|| !tree_int_cst_equal (node->left->low, node->left->high))
|
||
{
|
||
if (!node_has_high_bound (node, index_type))
|
||
{
|
||
probability = conditional_probability (
|
||
default_prob/2,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
GT, NULL_RTX, mode, unsignedp,
|
||
default_label,
|
||
probability);
|
||
default_prob /= 2;
|
||
}
|
||
|
||
emit_case_nodes (index, node->left, default_label,
|
||
default_prob, index_type);
|
||
}
|
||
else
|
||
{
|
||
probability = conditional_probability (
|
||
node->left->subtree_prob,
|
||
subtree_prob + default_prob);
|
||
/* We cannot process node->left normally
|
||
since we haven't ruled out the numbers less than
|
||
this node's value. So handle node->left explicitly. */
|
||
do_jump_if_equal (mode, index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->left->low),
|
||
unsignedp),
|
||
label_rtx (node->left->code_label), unsignedp, probability);
|
||
}
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* Node is a range. These cases are very similar to those for a single
|
||
value, except that we do not start by testing whether this node
|
||
is the one to branch to. */
|
||
|
||
if (node->right != 0 && node->left != 0)
|
||
{
|
||
/* Node has subtrees on both sides.
|
||
If the right-hand subtree is bounded,
|
||
test for it first, since we can go straight there.
|
||
Otherwise, we need to make a branch in the control structure,
|
||
then handle the two subtrees. */
|
||
tree test_label = 0;
|
||
|
||
if (node_is_bounded (node->right, index_type))
|
||
{
|
||
/* Right hand node is fully bounded so we can eliminate any
|
||
testing and branch directly to the target code. */
|
||
probability = conditional_probability (
|
||
node->right->subtree_prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
GT, NULL_RTX, mode, unsignedp,
|
||
label_rtx (node->right->code_label),
|
||
probability);
|
||
}
|
||
else
|
||
{
|
||
/* Right hand node requires testing.
|
||
Branch to a label where we will handle it later. */
|
||
|
||
test_label = build_decl (curr_insn_location (),
|
||
LABEL_DECL, NULL_TREE, NULL_TREE);
|
||
probability = conditional_probability (
|
||
node->right->subtree_prob + default_prob/2,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
GT, NULL_RTX, mode, unsignedp,
|
||
label_rtx (test_label),
|
||
probability);
|
||
default_prob /= 2;
|
||
}
|
||
|
||
/* Value belongs to this node or to the left-hand subtree. */
|
||
|
||
probability = conditional_probability (
|
||
prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->low),
|
||
unsignedp),
|
||
GE, NULL_RTX, mode, unsignedp,
|
||
label_rtx (node->code_label),
|
||
probability);
|
||
|
||
/* Handle the left-hand subtree. */
|
||
emit_case_nodes (index, node->left, default_label, default_prob, index_type);
|
||
|
||
/* If right node had to be handled later, do that now. */
|
||
|
||
if (test_label)
|
||
{
|
||
/* If the left-hand subtree fell through,
|
||
don't let it fall into the right-hand subtree. */
|
||
if (default_label)
|
||
emit_jump (default_label);
|
||
|
||
expand_label (test_label);
|
||
emit_case_nodes (index, node->right, default_label, default_prob, index_type);
|
||
}
|
||
}
|
||
|
||
else if (node->right != 0 && node->left == 0)
|
||
{
|
||
/* Deal with values to the left of this node,
|
||
if they are possible. */
|
||
if (!node_has_low_bound (node, index_type))
|
||
{
|
||
probability = conditional_probability (
|
||
default_prob/2,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->low),
|
||
unsignedp),
|
||
LT, NULL_RTX, mode, unsignedp,
|
||
default_label,
|
||
probability);
|
||
default_prob /= 2;
|
||
}
|
||
|
||
/* Value belongs to this node or to the right-hand subtree. */
|
||
|
||
probability = conditional_probability (
|
||
prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
LE, NULL_RTX, mode, unsignedp,
|
||
label_rtx (node->code_label),
|
||
probability);
|
||
|
||
emit_case_nodes (index, node->right, default_label, default_prob, index_type);
|
||
}
|
||
|
||
else if (node->right == 0 && node->left != 0)
|
||
{
|
||
/* Deal with values to the right of this node,
|
||
if they are possible. */
|
||
if (!node_has_high_bound (node, index_type))
|
||
{
|
||
probability = conditional_probability (
|
||
default_prob/2,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
GT, NULL_RTX, mode, unsignedp,
|
||
default_label,
|
||
probability);
|
||
default_prob /= 2;
|
||
}
|
||
|
||
/* Value belongs to this node or to the left-hand subtree. */
|
||
|
||
probability = conditional_probability (
|
||
prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->low),
|
||
unsignedp),
|
||
GE, NULL_RTX, mode, unsignedp,
|
||
label_rtx (node->code_label),
|
||
probability);
|
||
|
||
emit_case_nodes (index, node->left, default_label, default_prob, index_type);
|
||
}
|
||
|
||
else
|
||
{
|
||
/* Node has no children so we check low and high bounds to remove
|
||
redundant tests. Only one of the bounds can exist,
|
||
since otherwise this node is bounded--a case tested already. */
|
||
int high_bound = node_has_high_bound (node, index_type);
|
||
int low_bound = node_has_low_bound (node, index_type);
|
||
|
||
if (!high_bound && low_bound)
|
||
{
|
||
probability = conditional_probability (
|
||
default_prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->high),
|
||
unsignedp),
|
||
GT, NULL_RTX, mode, unsignedp,
|
||
default_label,
|
||
probability);
|
||
}
|
||
|
||
else if (!low_bound && high_bound)
|
||
{
|
||
probability = conditional_probability (
|
||
default_prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (index,
|
||
convert_modes
|
||
(mode, imode,
|
||
expand_normal (node->low),
|
||
unsignedp),
|
||
LT, NULL_RTX, mode, unsignedp,
|
||
default_label,
|
||
probability);
|
||
}
|
||
else if (!low_bound && !high_bound)
|
||
{
|
||
/* Widen LOW and HIGH to the same width as INDEX. */
|
||
tree type = lang_hooks.types.type_for_mode (mode, unsignedp);
|
||
tree low = build1 (CONVERT_EXPR, type, node->low);
|
||
tree high = build1 (CONVERT_EXPR, type, node->high);
|
||
rtx low_rtx, new_index, new_bound;
|
||
|
||
/* Instead of doing two branches, emit one unsigned branch for
|
||
(index-low) > (high-low). */
|
||
low_rtx = expand_expr (low, NULL_RTX, mode, EXPAND_NORMAL);
|
||
new_index = expand_simple_binop (mode, MINUS, index, low_rtx,
|
||
NULL_RTX, unsignedp,
|
||
OPTAB_WIDEN);
|
||
new_bound = expand_expr (fold_build2 (MINUS_EXPR, type,
|
||
high, low),
|
||
NULL_RTX, mode, EXPAND_NORMAL);
|
||
|
||
probability = conditional_probability (
|
||
default_prob,
|
||
subtree_prob + default_prob);
|
||
emit_cmp_and_jump_insns (new_index, new_bound, GT, NULL_RTX,
|
||
mode, 1, default_label, probability);
|
||
}
|
||
|
||
emit_jump (label_rtx (node->code_label));
|
||
}
|
||
}
|
||
}
|