1500 lines
45 KiB
C
1500 lines
45 KiB
C
/* Lower GIMPLE_SWITCH expressions to something more efficient than
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a jump table.
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Copyright (C) 2006-2017 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
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 3, or (at your option) any
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later version.
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GCC is distributed in the hope that it will be useful, but WITHOUT
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ANY 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, write to the Free
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Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA. */
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/* This file handles the lowering of GIMPLE_SWITCH to an indexed
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load, or a series of bit-test-and-branch expressions. */
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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 "backend.h"
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#include "insn-codes.h"
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#include "rtl.h"
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#include "tree.h"
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#include "gimple.h"
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#include "cfghooks.h"
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#include "tree-pass.h"
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#include "ssa.h"
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#include "optabs-tree.h"
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#include "cgraph.h"
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#include "gimple-pretty-print.h"
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#include "params.h"
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#include "fold-const.h"
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#include "varasm.h"
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#include "stor-layout.h"
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#include "cfganal.h"
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#include "gimplify.h"
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#include "gimple-iterator.h"
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#include "gimplify-me.h"
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#include "tree-cfg.h"
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#include "cfgloop.h"
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/* ??? For lang_hooks.types.type_for_mode, but is there a word_mode
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type in the GIMPLE type system that is language-independent? */
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#include "langhooks.h"
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/* Maximum number of case bit tests.
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FIXME: This should be derived from PARAM_CASE_VALUES_THRESHOLD and
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targetm.case_values_threshold(), or be its own param. */
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#define MAX_CASE_BIT_TESTS 3
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/* Split the basic block at the statement pointed to by GSIP, and insert
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a branch to the target basic block of E_TRUE conditional on tree
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expression COND.
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It is assumed that there is already an edge from the to-be-split
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basic block to E_TRUE->dest block. This edge is removed, and the
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profile information on the edge is re-used for the new conditional
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jump.
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The CFG is updated. The dominator tree will not be valid after
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this transformation, but the immediate dominators are updated if
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UPDATE_DOMINATORS is true.
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Returns the newly created basic block. */
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static basic_block
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hoist_edge_and_branch_if_true (gimple_stmt_iterator *gsip,
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tree cond, edge e_true,
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bool update_dominators)
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{
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tree tmp;
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gcond *cond_stmt;
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edge e_false;
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basic_block new_bb, split_bb = gsi_bb (*gsip);
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bool dominated_e_true = false;
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gcc_assert (e_true->src == split_bb);
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if (update_dominators
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&& get_immediate_dominator (CDI_DOMINATORS, e_true->dest) == split_bb)
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dominated_e_true = true;
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tmp = force_gimple_operand_gsi (gsip, cond, /*simple=*/true, NULL,
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/*before=*/true, GSI_SAME_STMT);
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cond_stmt = gimple_build_cond_from_tree (tmp, NULL_TREE, NULL_TREE);
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gsi_insert_before (gsip, cond_stmt, GSI_SAME_STMT);
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e_false = split_block (split_bb, cond_stmt);
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new_bb = e_false->dest;
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redirect_edge_pred (e_true, split_bb);
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e_true->flags &= ~EDGE_FALLTHRU;
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e_true->flags |= EDGE_TRUE_VALUE;
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e_false->flags &= ~EDGE_FALLTHRU;
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e_false->flags |= EDGE_FALSE_VALUE;
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e_false->probability = REG_BR_PROB_BASE - e_true->probability;
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e_false->count = split_bb->count - e_true->count;
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new_bb->count = e_false->count;
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if (update_dominators)
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{
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if (dominated_e_true)
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set_immediate_dominator (CDI_DOMINATORS, e_true->dest, split_bb);
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set_immediate_dominator (CDI_DOMINATORS, e_false->dest, split_bb);
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}
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return new_bb;
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}
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/* Return true if a switch should be expanded as a bit test.
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RANGE is the difference between highest and lowest case.
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UNIQ is number of unique case node targets, not counting the default case.
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COUNT is the number of comparisons needed, not counting the default case. */
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static bool
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expand_switch_using_bit_tests_p (tree range,
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unsigned int uniq,
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unsigned int count, bool speed_p)
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{
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return (((uniq == 1 && count >= 3)
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|| (uniq == 2 && count >= 5)
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|| (uniq == 3 && count >= 6))
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&& lshift_cheap_p (speed_p)
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&& compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0
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&& compare_tree_int (range, 0) > 0);
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}
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/* Implement switch statements with bit tests
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A GIMPLE switch statement can be expanded to a short sequence of bit-wise
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comparisons. "switch(x)" is converted into "if ((1 << (x-MINVAL)) & CST)"
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where CST and MINVAL are integer constants. This is better than a series
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of compare-and-banch insns in some cases, e.g. we can implement:
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if ((x==4) || (x==6) || (x==9) || (x==11))
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as a single bit test:
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if ((1<<x) & ((1<<4)|(1<<6)|(1<<9)|(1<<11)))
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This transformation is only applied if the number of case targets is small,
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if CST constains at least 3 bits, and "1 << x" is cheap. The bit tests are
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performed in "word_mode".
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The following example shows the code the transformation generates:
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int bar(int x)
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{
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switch (x)
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{
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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 'A': case 'B': case 'C': case 'D': case 'E':
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case 'F':
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return 1;
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}
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return 0;
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}
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==>
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bar (int x)
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{
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tmp1 = x - 48;
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if (tmp1 > (70 - 48)) goto L2;
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tmp2 = 1 << tmp1;
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tmp3 = 0b11111100000001111111111;
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if ((tmp2 & tmp3) != 0) goto L1 ; else goto L2;
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L1:
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return 1;
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L2:
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return 0;
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}
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TODO: There are still some improvements to this transformation that could
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be implemented:
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* A narrower mode than word_mode could be used if that is cheaper, e.g.
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for x86_64 where a narrower-mode shift may result in smaller code.
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* The compounded constant could be shifted rather than the one. The
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test would be either on the sign bit or on the least significant bit,
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depending on the direction of the shift. On some machines, the test
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for the branch would be free if the bit to test is already set by the
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shift operation.
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This transformation was contributed by Roger Sayle, see this e-mail:
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http://gcc.gnu.org/ml/gcc-patches/2003-01/msg01950.html
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*/
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/* A case_bit_test represents a set of case nodes that may be
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selected from using a bit-wise comparison. HI and LO hold
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the integer to be tested against, TARGET_EDGE contains the
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edge to the basic block to jump to upon success and BITS
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counts the number of case nodes handled by this test,
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typically the number of bits set in HI:LO. The LABEL field
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is used to quickly identify all cases in this set without
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looking at label_to_block for every case label. */
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struct case_bit_test
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{
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wide_int mask;
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edge target_edge;
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tree label;
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int bits;
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};
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/* Comparison function for qsort to order bit tests by decreasing
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probability of execution. Our best guess comes from a measured
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profile. If the profile counts are equal, break even on the
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number of case nodes, i.e. the node with the most cases gets
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tested first.
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TODO: Actually this currently runs before a profile is available.
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Therefore the case-as-bit-tests transformation should be done
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later in the pass pipeline, or something along the lines of
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"Efficient and effective branch reordering using profile data"
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(Yang et. al., 2002) should be implemented (although, how good
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is a paper is called "Efficient and effective ..." when the
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latter is implied by the former, but oh well...). */
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static int
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case_bit_test_cmp (const void *p1, const void *p2)
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{
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const struct case_bit_test *const d1 = (const struct case_bit_test *) p1;
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const struct case_bit_test *const d2 = (const struct case_bit_test *) p2;
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if (d2->target_edge->count != d1->target_edge->count)
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return d2->target_edge->count - d1->target_edge->count;
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if (d2->bits != d1->bits)
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return d2->bits - d1->bits;
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/* Stabilize the sort. */
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return LABEL_DECL_UID (d2->label) - LABEL_DECL_UID (d1->label);
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}
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/* Expand a switch statement by a short sequence of bit-wise
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comparisons. "switch(x)" is effectively converted into
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"if ((1 << (x-MINVAL)) & CST)" where CST and MINVAL are
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integer constants.
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INDEX_EXPR is the value being switched on.
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MINVAL is the lowest case value of in the case nodes,
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and RANGE is highest value minus MINVAL. MINVAL and RANGE
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are not guaranteed to be of the same type as INDEX_EXPR
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(the gimplifier doesn't change the type of case label values,
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and MINVAL and RANGE are derived from those values).
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MAXVAL is MINVAL + RANGE.
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There *MUST* be MAX_CASE_BIT_TESTS or less unique case
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node targets. */
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static void
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emit_case_bit_tests (gswitch *swtch, tree index_expr,
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tree minval, tree range, tree maxval)
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{
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struct case_bit_test test[MAX_CASE_BIT_TESTS];
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unsigned int i, j, k;
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unsigned int count;
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basic_block switch_bb = gimple_bb (swtch);
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basic_block default_bb, new_default_bb, new_bb;
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edge default_edge;
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bool update_dom = dom_info_available_p (CDI_DOMINATORS);
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vec<basic_block> bbs_to_fix_dom = vNULL;
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tree index_type = TREE_TYPE (index_expr);
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tree unsigned_index_type = unsigned_type_for (index_type);
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unsigned int branch_num = gimple_switch_num_labels (swtch);
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gimple_stmt_iterator gsi;
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gassign *shift_stmt;
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tree idx, tmp, csui;
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tree word_type_node = lang_hooks.types.type_for_mode (word_mode, 1);
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tree word_mode_zero = fold_convert (word_type_node, integer_zero_node);
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tree word_mode_one = fold_convert (word_type_node, integer_one_node);
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int prec = TYPE_PRECISION (word_type_node);
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wide_int wone = wi::one (prec);
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memset (&test, 0, sizeof (test));
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/* Get the edge for the default case. */
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tmp = gimple_switch_default_label (swtch);
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default_bb = label_to_block (CASE_LABEL (tmp));
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default_edge = find_edge (switch_bb, default_bb);
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/* Go through all case labels, and collect the case labels, profile
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counts, and other information we need to build the branch tests. */
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count = 0;
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for (i = 1; i < branch_num; i++)
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{
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unsigned int lo, hi;
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tree cs = gimple_switch_label (swtch, i);
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tree label = CASE_LABEL (cs);
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edge e = find_edge (switch_bb, label_to_block (label));
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for (k = 0; k < count; k++)
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if (e == test[k].target_edge)
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break;
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if (k == count)
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{
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gcc_checking_assert (count < MAX_CASE_BIT_TESTS);
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test[k].mask = wi::zero (prec);
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test[k].target_edge = e;
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test[k].label = label;
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test[k].bits = 1;
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count++;
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}
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else
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test[k].bits++;
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lo = tree_to_uhwi (int_const_binop (MINUS_EXPR,
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CASE_LOW (cs), minval));
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if (CASE_HIGH (cs) == NULL_TREE)
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hi = lo;
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else
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hi = tree_to_uhwi (int_const_binop (MINUS_EXPR,
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CASE_HIGH (cs), minval));
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for (j = lo; j <= hi; j++)
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test[k].mask |= wi::lshift (wone, j);
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}
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qsort (test, count, sizeof (*test), case_bit_test_cmp);
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/* If all values are in the 0 .. BITS_PER_WORD-1 range, we can get rid of
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the minval subtractions, but it might make the mask constants more
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expensive. So, compare the costs. */
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if (compare_tree_int (minval, 0) > 0
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&& compare_tree_int (maxval, GET_MODE_BITSIZE (word_mode)) < 0)
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{
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int cost_diff;
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HOST_WIDE_INT m = tree_to_uhwi (minval);
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rtx reg = gen_raw_REG (word_mode, 10000);
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bool speed_p = optimize_bb_for_speed_p (gimple_bb (swtch));
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cost_diff = set_rtx_cost (gen_rtx_PLUS (word_mode, reg,
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GEN_INT (-m)), speed_p);
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for (i = 0; i < count; i++)
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{
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rtx r = immed_wide_int_const (test[i].mask, word_mode);
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cost_diff += set_src_cost (gen_rtx_AND (word_mode, reg, r),
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word_mode, speed_p);
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r = immed_wide_int_const (wi::lshift (test[i].mask, m), word_mode);
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cost_diff -= set_src_cost (gen_rtx_AND (word_mode, reg, r),
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word_mode, speed_p);
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}
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if (cost_diff > 0)
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{
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for (i = 0; i < count; i++)
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test[i].mask = wi::lshift (test[i].mask, m);
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minval = build_zero_cst (TREE_TYPE (minval));
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range = maxval;
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}
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}
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/* We generate two jumps to the default case label.
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Split the default edge, so that we don't have to do any PHI node
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updating. */
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new_default_bb = split_edge (default_edge);
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if (update_dom)
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{
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bbs_to_fix_dom.create (10);
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bbs_to_fix_dom.quick_push (switch_bb);
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bbs_to_fix_dom.quick_push (default_bb);
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bbs_to_fix_dom.quick_push (new_default_bb);
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}
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/* Now build the test-and-branch code. */
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gsi = gsi_last_bb (switch_bb);
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/* idx = (unsigned)x - minval. */
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idx = fold_convert (unsigned_index_type, index_expr);
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idx = fold_build2 (MINUS_EXPR, unsigned_index_type, idx,
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fold_convert (unsigned_index_type, minval));
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idx = force_gimple_operand_gsi (&gsi, idx,
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/*simple=*/true, NULL_TREE,
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/*before=*/true, GSI_SAME_STMT);
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/* if (idx > range) goto default */
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range = force_gimple_operand_gsi (&gsi,
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fold_convert (unsigned_index_type, range),
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/*simple=*/true, NULL_TREE,
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/*before=*/true, GSI_SAME_STMT);
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tmp = fold_build2 (GT_EXPR, boolean_type_node, idx, range);
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new_bb = hoist_edge_and_branch_if_true (&gsi, tmp, default_edge, update_dom);
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if (update_dom)
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bbs_to_fix_dom.quick_push (new_bb);
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gcc_assert (gimple_bb (swtch) == new_bb);
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gsi = gsi_last_bb (new_bb);
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/* Any blocks dominated by the GIMPLE_SWITCH, but that are not successors
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of NEW_BB, are still immediately dominated by SWITCH_BB. Make it so. */
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if (update_dom)
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{
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vec<basic_block> dom_bbs;
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basic_block dom_son;
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dom_bbs = get_dominated_by (CDI_DOMINATORS, new_bb);
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FOR_EACH_VEC_ELT (dom_bbs, i, dom_son)
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{
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edge e = find_edge (new_bb, dom_son);
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if (e && single_pred_p (e->dest))
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continue;
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set_immediate_dominator (CDI_DOMINATORS, dom_son, switch_bb);
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bbs_to_fix_dom.safe_push (dom_son);
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}
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dom_bbs.release ();
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}
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/* csui = (1 << (word_mode) idx) */
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csui = make_ssa_name (word_type_node);
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tmp = fold_build2 (LSHIFT_EXPR, word_type_node, word_mode_one,
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fold_convert (word_type_node, idx));
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tmp = force_gimple_operand_gsi (&gsi, tmp,
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/*simple=*/false, NULL_TREE,
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/*before=*/true, GSI_SAME_STMT);
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shift_stmt = gimple_build_assign (csui, tmp);
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gsi_insert_before (&gsi, shift_stmt, GSI_SAME_STMT);
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update_stmt (shift_stmt);
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/* for each unique set of cases:
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if (const & csui) goto target */
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for (k = 0; k < count; k++)
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{
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tmp = wide_int_to_tree (word_type_node, test[k].mask);
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tmp = fold_build2 (BIT_AND_EXPR, word_type_node, csui, tmp);
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tmp = force_gimple_operand_gsi (&gsi, tmp,
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/*simple=*/true, NULL_TREE,
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/*before=*/true, GSI_SAME_STMT);
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tmp = fold_build2 (NE_EXPR, boolean_type_node, tmp, word_mode_zero);
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new_bb = hoist_edge_and_branch_if_true (&gsi, tmp, test[k].target_edge,
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update_dom);
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if (update_dom)
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bbs_to_fix_dom.safe_push (new_bb);
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gcc_assert (gimple_bb (swtch) == new_bb);
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gsi = gsi_last_bb (new_bb);
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}
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/* We should have removed all edges now. */
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gcc_assert (EDGE_COUNT (gsi_bb (gsi)->succs) == 0);
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/* If nothing matched, go to the default label. */
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make_edge (gsi_bb (gsi), new_default_bb, EDGE_FALLTHRU);
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/* The GIMPLE_SWITCH is now redundant. */
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gsi_remove (&gsi, true);
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|
||
if (update_dom)
|
||
{
|
||
/* Fix up the dominator tree. */
|
||
iterate_fix_dominators (CDI_DOMINATORS, bbs_to_fix_dom, true);
|
||
bbs_to_fix_dom.release ();
|
||
}
|
||
}
|
||
|
||
/*
|
||
Switch initialization conversion
|
||
|
||
The following pass changes simple initializations of scalars in a switch
|
||
statement into initializations from a static array. Obviously, the values
|
||
must be constant and known at compile time and a default branch must be
|
||
provided. For example, the following code:
|
||
|
||
int a,b;
|
||
|
||
switch (argc)
|
||
{
|
||
case 1:
|
||
case 2:
|
||
a_1 = 8;
|
||
b_1 = 6;
|
||
break;
|
||
case 3:
|
||
a_2 = 9;
|
||
b_2 = 5;
|
||
break;
|
||
case 12:
|
||
a_3 = 10;
|
||
b_3 = 4;
|
||
break;
|
||
default:
|
||
a_4 = 16;
|
||
b_4 = 1;
|
||
break;
|
||
}
|
||
a_5 = PHI <a_1, a_2, a_3, a_4>
|
||
b_5 = PHI <b_1, b_2, b_3, b_4>
|
||
|
||
|
||
is changed into:
|
||
|
||
static const int = CSWTCH01[] = {6, 6, 5, 1, 1, 1, 1, 1, 1, 1, 1, 4};
|
||
static const int = CSWTCH02[] = {8, 8, 9, 16, 16, 16, 16, 16, 16, 16,
|
||
16, 16, 10};
|
||
|
||
if (((unsigned) argc) - 1 < 11)
|
||
{
|
||
a_6 = CSWTCH02[argc - 1];
|
||
b_6 = CSWTCH01[argc - 1];
|
||
}
|
||
else
|
||
{
|
||
a_7 = 16;
|
||
b_7 = 1;
|
||
}
|
||
a_5 = PHI <a_6, a_7>
|
||
b_b = PHI <b_6, b_7>
|
||
|
||
There are further constraints. Specifically, the range of values across all
|
||
case labels must not be bigger than SWITCH_CONVERSION_BRANCH_RATIO (default
|
||
eight) times the number of the actual switch branches.
|
||
|
||
This transformation was contributed by Martin Jambor, see this e-mail:
|
||
http://gcc.gnu.org/ml/gcc-patches/2008-07/msg00011.html */
|
||
|
||
/* The main structure of the pass. */
|
||
struct switch_conv_info
|
||
{
|
||
/* The expression used to decide the switch branch. */
|
||
tree index_expr;
|
||
|
||
/* The following integer constants store the minimum and maximum value
|
||
covered by the case labels. */
|
||
tree range_min;
|
||
tree range_max;
|
||
|
||
/* The difference between the above two numbers. Stored here because it
|
||
is used in all the conversion heuristics, as well as for some of the
|
||
transformation, and it is expensive to re-compute it all the time. */
|
||
tree range_size;
|
||
|
||
/* Basic block that contains the actual GIMPLE_SWITCH. */
|
||
basic_block switch_bb;
|
||
|
||
/* Basic block that is the target of the default case. */
|
||
basic_block default_bb;
|
||
|
||
/* The single successor block of all branches out of the GIMPLE_SWITCH,
|
||
if such a block exists. Otherwise NULL. */
|
||
basic_block final_bb;
|
||
|
||
/* The probability of the default edge in the replaced switch. */
|
||
int default_prob;
|
||
|
||
/* The count of the default edge in the replaced switch. */
|
||
gcov_type default_count;
|
||
|
||
/* Combined count of all other (non-default) edges in the replaced switch. */
|
||
gcov_type other_count;
|
||
|
||
/* Number of phi nodes in the final bb (that we'll be replacing). */
|
||
int phi_count;
|
||
|
||
/* Array of default values, in the same order as phi nodes. */
|
||
tree *default_values;
|
||
|
||
/* Constructors of new static arrays. */
|
||
vec<constructor_elt, va_gc> **constructors;
|
||
|
||
/* Array of ssa names that are initialized with a value from a new static
|
||
array. */
|
||
tree *target_inbound_names;
|
||
|
||
/* Array of ssa names that are initialized with the default value if the
|
||
switch expression is out of range. */
|
||
tree *target_outbound_names;
|
||
|
||
/* The first load statement that loads a temporary from a new static array.
|
||
*/
|
||
gimple *arr_ref_first;
|
||
|
||
/* The last load statement that loads a temporary from a new static array. */
|
||
gimple *arr_ref_last;
|
||
|
||
/* String reason why the case wasn't a good candidate that is written to the
|
||
dump file, if there is one. */
|
||
const char *reason;
|
||
|
||
/* Parameters for expand_switch_using_bit_tests. Should be computed
|
||
the same way as in expand_case. */
|
||
unsigned int uniq;
|
||
unsigned int count;
|
||
};
|
||
|
||
/* Collect information about GIMPLE_SWITCH statement SWTCH into INFO. */
|
||
|
||
static void
|
||
collect_switch_conv_info (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
unsigned int branch_num = gimple_switch_num_labels (swtch);
|
||
tree min_case, max_case;
|
||
unsigned int count, i;
|
||
edge e, e_default;
|
||
edge_iterator ei;
|
||
|
||
memset (info, 0, sizeof (*info));
|
||
|
||
/* The gimplifier has already sorted the cases by CASE_LOW and ensured there
|
||
is a default label which is the first in the vector.
|
||
Collect the bits we can deduce from the CFG. */
|
||
info->index_expr = gimple_switch_index (swtch);
|
||
info->switch_bb = gimple_bb (swtch);
|
||
info->default_bb =
|
||
label_to_block (CASE_LABEL (gimple_switch_default_label (swtch)));
|
||
e_default = find_edge (info->switch_bb, info->default_bb);
|
||
info->default_prob = e_default->probability;
|
||
info->default_count = e_default->count;
|
||
FOR_EACH_EDGE (e, ei, info->switch_bb->succs)
|
||
if (e != e_default)
|
||
info->other_count += e->count;
|
||
|
||
/* See if there is one common successor block for all branch
|
||
targets. If it exists, record it in FINAL_BB.
|
||
Start with the destination of the default case as guess
|
||
or its destination in case it is a forwarder block. */
|
||
if (! single_pred_p (e_default->dest))
|
||
info->final_bb = e_default->dest;
|
||
else if (single_succ_p (e_default->dest)
|
||
&& ! single_pred_p (single_succ (e_default->dest)))
|
||
info->final_bb = single_succ (e_default->dest);
|
||
/* Require that all switch destinations are either that common
|
||
FINAL_BB or a forwarder to it. */
|
||
if (info->final_bb)
|
||
FOR_EACH_EDGE (e, ei, info->switch_bb->succs)
|
||
{
|
||
if (e->dest == info->final_bb)
|
||
continue;
|
||
|
||
if (single_pred_p (e->dest)
|
||
&& single_succ_p (e->dest)
|
||
&& single_succ (e->dest) == info->final_bb)
|
||
continue;
|
||
|
||
info->final_bb = NULL;
|
||
break;
|
||
}
|
||
|
||
/* Get upper and lower bounds of case values, and the covered range. */
|
||
min_case = gimple_switch_label (swtch, 1);
|
||
max_case = gimple_switch_label (swtch, branch_num - 1);
|
||
|
||
info->range_min = CASE_LOW (min_case);
|
||
if (CASE_HIGH (max_case) != NULL_TREE)
|
||
info->range_max = CASE_HIGH (max_case);
|
||
else
|
||
info->range_max = CASE_LOW (max_case);
|
||
|
||
info->range_size =
|
||
int_const_binop (MINUS_EXPR, info->range_max, info->range_min);
|
||
|
||
/* Get a count of the number of case labels. Single-valued case labels
|
||
simply count as one, but a case range counts double, since it may
|
||
require two compares if it gets lowered as a branching tree. */
|
||
count = 0;
|
||
for (i = 1; i < branch_num; i++)
|
||
{
|
||
tree elt = gimple_switch_label (swtch, i);
|
||
count++;
|
||
if (CASE_HIGH (elt)
|
||
&& ! tree_int_cst_equal (CASE_LOW (elt), CASE_HIGH (elt)))
|
||
count++;
|
||
}
|
||
info->count = count;
|
||
|
||
/* Get the number of unique non-default targets out of the GIMPLE_SWITCH
|
||
block. Assume a CFG cleanup would have already removed degenerate
|
||
switch statements, this allows us to just use EDGE_COUNT. */
|
||
info->uniq = EDGE_COUNT (gimple_bb (swtch)->succs) - 1;
|
||
}
|
||
|
||
/* Checks whether the range given by individual case statements of the SWTCH
|
||
switch statement isn't too big and whether the number of branches actually
|
||
satisfies the size of the new array. */
|
||
|
||
static bool
|
||
check_range (struct switch_conv_info *info)
|
||
{
|
||
gcc_assert (info->range_size);
|
||
if (!tree_fits_uhwi_p (info->range_size))
|
||
{
|
||
info->reason = "index range way too large or otherwise unusable";
|
||
return false;
|
||
}
|
||
|
||
if (tree_to_uhwi (info->range_size)
|
||
> ((unsigned) info->count * SWITCH_CONVERSION_BRANCH_RATIO))
|
||
{
|
||
info->reason = "the maximum range-branch ratio exceeded";
|
||
return false;
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
/* Checks whether all but the FINAL_BB basic blocks are empty. */
|
||
|
||
static bool
|
||
check_all_empty_except_final (struct switch_conv_info *info)
|
||
{
|
||
edge e;
|
||
edge_iterator ei;
|
||
|
||
FOR_EACH_EDGE (e, ei, info->switch_bb->succs)
|
||
{
|
||
if (e->dest == info->final_bb)
|
||
continue;
|
||
|
||
if (!empty_block_p (e->dest))
|
||
{
|
||
info->reason = "bad case - a non-final BB not empty";
|
||
return false;
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
/* This function checks whether all required values in phi nodes in final_bb
|
||
are constants. Required values are those that correspond to a basic block
|
||
which is a part of the examined switch statement. It returns true if the
|
||
phi nodes are OK, otherwise false. */
|
||
|
||
static bool
|
||
check_final_bb (struct switch_conv_info *info)
|
||
{
|
||
gphi_iterator gsi;
|
||
|
||
info->phi_count = 0;
|
||
for (gsi = gsi_start_phis (info->final_bb); !gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
unsigned int i;
|
||
|
||
info->phi_count++;
|
||
|
||
for (i = 0; i < gimple_phi_num_args (phi); i++)
|
||
{
|
||
basic_block bb = gimple_phi_arg_edge (phi, i)->src;
|
||
|
||
if (bb == info->switch_bb
|
||
|| (single_pred_p (bb) && single_pred (bb) == info->switch_bb))
|
||
{
|
||
tree reloc, val;
|
||
|
||
val = gimple_phi_arg_def (phi, i);
|
||
if (!is_gimple_ip_invariant (val))
|
||
{
|
||
info->reason = "non-invariant value from a case";
|
||
return false; /* Non-invariant argument. */
|
||
}
|
||
reloc = initializer_constant_valid_p (val, TREE_TYPE (val));
|
||
if ((flag_pic && reloc != null_pointer_node)
|
||
|| (!flag_pic && reloc == NULL_TREE))
|
||
{
|
||
if (reloc)
|
||
info->reason
|
||
= "value from a case would need runtime relocations";
|
||
else
|
||
info->reason
|
||
= "value from a case is not a valid initializer";
|
||
return false;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
/* The following function allocates default_values, target_{in,out}_names and
|
||
constructors arrays. The last one is also populated with pointers to
|
||
vectors that will become constructors of new arrays. */
|
||
|
||
static void
|
||
create_temp_arrays (struct switch_conv_info *info)
|
||
{
|
||
int i;
|
||
|
||
info->default_values = XCNEWVEC (tree, info->phi_count * 3);
|
||
/* ??? Macros do not support multi argument templates in their
|
||
argument list. We create a typedef to work around that problem. */
|
||
typedef vec<constructor_elt, va_gc> *vec_constructor_elt_gc;
|
||
info->constructors = XCNEWVEC (vec_constructor_elt_gc, info->phi_count);
|
||
info->target_inbound_names = info->default_values + info->phi_count;
|
||
info->target_outbound_names = info->target_inbound_names + info->phi_count;
|
||
for (i = 0; i < info->phi_count; i++)
|
||
vec_alloc (info->constructors[i], tree_to_uhwi (info->range_size) + 1);
|
||
}
|
||
|
||
/* Free the arrays created by create_temp_arrays(). The vectors that are
|
||
created by that function are not freed here, however, because they have
|
||
already become constructors and must be preserved. */
|
||
|
||
static void
|
||
free_temp_arrays (struct switch_conv_info *info)
|
||
{
|
||
XDELETEVEC (info->constructors);
|
||
XDELETEVEC (info->default_values);
|
||
}
|
||
|
||
/* Populate the array of default values in the order of phi nodes.
|
||
DEFAULT_CASE is the CASE_LABEL_EXPR for the default switch branch. */
|
||
|
||
static void
|
||
gather_default_values (tree default_case, struct switch_conv_info *info)
|
||
{
|
||
gphi_iterator gsi;
|
||
basic_block bb = label_to_block (CASE_LABEL (default_case));
|
||
edge e;
|
||
int i = 0;
|
||
|
||
gcc_assert (CASE_LOW (default_case) == NULL_TREE);
|
||
|
||
if (bb == info->final_bb)
|
||
e = find_edge (info->switch_bb, bb);
|
||
else
|
||
e = single_succ_edge (bb);
|
||
|
||
for (gsi = gsi_start_phis (info->final_bb); !gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
tree val = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
||
gcc_assert (val);
|
||
info->default_values[i++] = val;
|
||
}
|
||
}
|
||
|
||
/* The following function populates the vectors in the constructors array with
|
||
future contents of the static arrays. The vectors are populated in the
|
||
order of phi nodes. SWTCH is the switch statement being converted. */
|
||
|
||
static void
|
||
build_constructors (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
unsigned i, branch_num = gimple_switch_num_labels (swtch);
|
||
tree pos = info->range_min;
|
||
|
||
for (i = 1; i < branch_num; i++)
|
||
{
|
||
tree cs = gimple_switch_label (swtch, i);
|
||
basic_block bb = label_to_block (CASE_LABEL (cs));
|
||
edge e;
|
||
tree high;
|
||
gphi_iterator gsi;
|
||
int j;
|
||
|
||
if (bb == info->final_bb)
|
||
e = find_edge (info->switch_bb, bb);
|
||
else
|
||
e = single_succ_edge (bb);
|
||
gcc_assert (e);
|
||
|
||
while (tree_int_cst_lt (pos, CASE_LOW (cs)))
|
||
{
|
||
int k;
|
||
for (k = 0; k < info->phi_count; k++)
|
||
{
|
||
constructor_elt elt;
|
||
|
||
elt.index = int_const_binop (MINUS_EXPR, pos, info->range_min);
|
||
elt.value
|
||
= unshare_expr_without_location (info->default_values[k]);
|
||
info->constructors[k]->quick_push (elt);
|
||
}
|
||
|
||
pos = int_const_binop (PLUS_EXPR, pos,
|
||
build_int_cst (TREE_TYPE (pos), 1));
|
||
}
|
||
gcc_assert (tree_int_cst_equal (pos, CASE_LOW (cs)));
|
||
|
||
j = 0;
|
||
if (CASE_HIGH (cs))
|
||
high = CASE_HIGH (cs);
|
||
else
|
||
high = CASE_LOW (cs);
|
||
for (gsi = gsi_start_phis (info->final_bb);
|
||
!gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
tree val = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
||
tree low = CASE_LOW (cs);
|
||
pos = CASE_LOW (cs);
|
||
|
||
do
|
||
{
|
||
constructor_elt elt;
|
||
|
||
elt.index = int_const_binop (MINUS_EXPR, pos, info->range_min);
|
||
elt.value = unshare_expr_without_location (val);
|
||
info->constructors[j]->quick_push (elt);
|
||
|
||
pos = int_const_binop (PLUS_EXPR, pos,
|
||
build_int_cst (TREE_TYPE (pos), 1));
|
||
} while (!tree_int_cst_lt (high, pos)
|
||
&& tree_int_cst_lt (low, pos));
|
||
j++;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* If all values in the constructor vector are the same, return the value.
|
||
Otherwise return NULL_TREE. Not supposed to be called for empty
|
||
vectors. */
|
||
|
||
static tree
|
||
constructor_contains_same_values_p (vec<constructor_elt, va_gc> *vec)
|
||
{
|
||
unsigned int i;
|
||
tree prev = NULL_TREE;
|
||
constructor_elt *elt;
|
||
|
||
FOR_EACH_VEC_SAFE_ELT (vec, i, elt)
|
||
{
|
||
if (!prev)
|
||
prev = elt->value;
|
||
else if (!operand_equal_p (elt->value, prev, OEP_ONLY_CONST))
|
||
return NULL_TREE;
|
||
}
|
||
return prev;
|
||
}
|
||
|
||
/* Return type which should be used for array elements, either TYPE,
|
||
or for integral type some smaller integral type that can still hold
|
||
all the constants. */
|
||
|
||
static tree
|
||
array_value_type (gswitch *swtch, tree type, int num,
|
||
struct switch_conv_info *info)
|
||
{
|
||
unsigned int i, len = vec_safe_length (info->constructors[num]);
|
||
constructor_elt *elt;
|
||
machine_mode mode;
|
||
int sign = 0;
|
||
tree smaller_type;
|
||
|
||
if (!INTEGRAL_TYPE_P (type))
|
||
return type;
|
||
|
||
mode = GET_CLASS_NARROWEST_MODE (GET_MODE_CLASS (TYPE_MODE (type)));
|
||
if (GET_MODE_SIZE (TYPE_MODE (type)) <= GET_MODE_SIZE (mode))
|
||
return type;
|
||
|
||
if (len < (optimize_bb_for_size_p (gimple_bb (swtch)) ? 2 : 32))
|
||
return type;
|
||
|
||
FOR_EACH_VEC_SAFE_ELT (info->constructors[num], i, elt)
|
||
{
|
||
wide_int cst;
|
||
|
||
if (TREE_CODE (elt->value) != INTEGER_CST)
|
||
return type;
|
||
|
||
cst = elt->value;
|
||
while (1)
|
||
{
|
||
unsigned int prec = GET_MODE_BITSIZE (mode);
|
||
if (prec > HOST_BITS_PER_WIDE_INT)
|
||
return type;
|
||
|
||
if (sign >= 0 && cst == wi::zext (cst, prec))
|
||
{
|
||
if (sign == 0 && cst == wi::sext (cst, prec))
|
||
break;
|
||
sign = 1;
|
||
break;
|
||
}
|
||
if (sign <= 0 && cst == wi::sext (cst, prec))
|
||
{
|
||
sign = -1;
|
||
break;
|
||
}
|
||
|
||
if (sign == 1)
|
||
sign = 0;
|
||
|
||
mode = GET_MODE_WIDER_MODE (mode);
|
||
if (mode == VOIDmode
|
||
|| GET_MODE_SIZE (mode) >= GET_MODE_SIZE (TYPE_MODE (type)))
|
||
return type;
|
||
}
|
||
}
|
||
|
||
if (sign == 0)
|
||
sign = TYPE_UNSIGNED (type) ? 1 : -1;
|
||
smaller_type = lang_hooks.types.type_for_mode (mode, sign >= 0);
|
||
if (GET_MODE_SIZE (TYPE_MODE (type))
|
||
<= GET_MODE_SIZE (TYPE_MODE (smaller_type)))
|
||
return type;
|
||
|
||
return smaller_type;
|
||
}
|
||
|
||
/* Create an appropriate array type and declaration and assemble a static array
|
||
variable. Also create a load statement that initializes the variable in
|
||
question with a value from the static array. SWTCH is the switch statement
|
||
being converted, NUM is the index to arrays of constructors, default values
|
||
and target SSA names for this particular array. ARR_INDEX_TYPE is the type
|
||
of the index of the new array, PHI is the phi node of the final BB that
|
||
corresponds to the value that will be loaded from the created array. TIDX
|
||
is an ssa name of a temporary variable holding the index for loads from the
|
||
new array. */
|
||
|
||
static void
|
||
build_one_array (gswitch *swtch, int num, tree arr_index_type,
|
||
gphi *phi, tree tidx, struct switch_conv_info *info)
|
||
{
|
||
tree name, cst;
|
||
gimple *load;
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (swtch);
|
||
location_t loc = gimple_location (swtch);
|
||
|
||
gcc_assert (info->default_values[num]);
|
||
|
||
name = copy_ssa_name (PHI_RESULT (phi));
|
||
info->target_inbound_names[num] = name;
|
||
|
||
cst = constructor_contains_same_values_p (info->constructors[num]);
|
||
if (cst)
|
||
load = gimple_build_assign (name, cst);
|
||
else
|
||
{
|
||
tree array_type, ctor, decl, value_type, fetch, default_type;
|
||
|
||
default_type = TREE_TYPE (info->default_values[num]);
|
||
value_type = array_value_type (swtch, default_type, num, info);
|
||
array_type = build_array_type (value_type, arr_index_type);
|
||
if (default_type != value_type)
|
||
{
|
||
unsigned int i;
|
||
constructor_elt *elt;
|
||
|
||
FOR_EACH_VEC_SAFE_ELT (info->constructors[num], i, elt)
|
||
elt->value = fold_convert (value_type, elt->value);
|
||
}
|
||
ctor = build_constructor (array_type, info->constructors[num]);
|
||
TREE_CONSTANT (ctor) = true;
|
||
TREE_STATIC (ctor) = true;
|
||
|
||
decl = build_decl (loc, VAR_DECL, NULL_TREE, array_type);
|
||
TREE_STATIC (decl) = 1;
|
||
DECL_INITIAL (decl) = ctor;
|
||
|
||
DECL_NAME (decl) = create_tmp_var_name ("CSWTCH");
|
||
DECL_ARTIFICIAL (decl) = 1;
|
||
DECL_IGNORED_P (decl) = 1;
|
||
TREE_CONSTANT (decl) = 1;
|
||
TREE_READONLY (decl) = 1;
|
||
DECL_IGNORED_P (decl) = 1;
|
||
varpool_node::finalize_decl (decl);
|
||
|
||
fetch = build4 (ARRAY_REF, value_type, decl, tidx, NULL_TREE,
|
||
NULL_TREE);
|
||
if (default_type != value_type)
|
||
{
|
||
fetch = fold_convert (default_type, fetch);
|
||
fetch = force_gimple_operand_gsi (&gsi, fetch, true, NULL_TREE,
|
||
true, GSI_SAME_STMT);
|
||
}
|
||
load = gimple_build_assign (name, fetch);
|
||
}
|
||
|
||
gsi_insert_before (&gsi, load, GSI_SAME_STMT);
|
||
update_stmt (load);
|
||
info->arr_ref_last = load;
|
||
}
|
||
|
||
/* Builds and initializes static arrays initialized with values gathered from
|
||
the SWTCH switch statement. Also creates statements that load values from
|
||
them. */
|
||
|
||
static void
|
||
build_arrays (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
tree arr_index_type;
|
||
tree tidx, sub, utype;
|
||
gimple *stmt;
|
||
gimple_stmt_iterator gsi;
|
||
gphi_iterator gpi;
|
||
int i;
|
||
location_t loc = gimple_location (swtch);
|
||
|
||
gsi = gsi_for_stmt (swtch);
|
||
|
||
/* Make sure we do not generate arithmetics in a subrange. */
|
||
utype = TREE_TYPE (info->index_expr);
|
||
if (TREE_TYPE (utype))
|
||
utype = lang_hooks.types.type_for_mode (TYPE_MODE (TREE_TYPE (utype)), 1);
|
||
else
|
||
utype = lang_hooks.types.type_for_mode (TYPE_MODE (utype), 1);
|
||
|
||
arr_index_type = build_index_type (info->range_size);
|
||
tidx = make_ssa_name (utype);
|
||
sub = fold_build2_loc (loc, MINUS_EXPR, utype,
|
||
fold_convert_loc (loc, utype, info->index_expr),
|
||
fold_convert_loc (loc, utype, info->range_min));
|
||
sub = force_gimple_operand_gsi (&gsi, sub,
|
||
false, NULL, true, GSI_SAME_STMT);
|
||
stmt = gimple_build_assign (tidx, sub);
|
||
|
||
gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
|
||
update_stmt (stmt);
|
||
info->arr_ref_first = stmt;
|
||
|
||
for (gpi = gsi_start_phis (info->final_bb), i = 0;
|
||
!gsi_end_p (gpi); gsi_next (&gpi), i++)
|
||
build_one_array (swtch, i, arr_index_type, gpi.phi (), tidx, info);
|
||
}
|
||
|
||
/* Generates and appropriately inserts loads of default values at the position
|
||
given by BSI. Returns the last inserted statement. */
|
||
|
||
static gassign *
|
||
gen_def_assigns (gimple_stmt_iterator *gsi, struct switch_conv_info *info)
|
||
{
|
||
int i;
|
||
gassign *assign = NULL;
|
||
|
||
for (i = 0; i < info->phi_count; i++)
|
||
{
|
||
tree name = copy_ssa_name (info->target_inbound_names[i]);
|
||
info->target_outbound_names[i] = name;
|
||
assign = gimple_build_assign (name, info->default_values[i]);
|
||
gsi_insert_before (gsi, assign, GSI_SAME_STMT);
|
||
update_stmt (assign);
|
||
}
|
||
return assign;
|
||
}
|
||
|
||
/* Deletes the unused bbs and edges that now contain the switch statement and
|
||
its empty branch bbs. BBD is the now dead BB containing the original switch
|
||
statement, FINAL is the last BB of the converted switch statement (in terms
|
||
of succession). */
|
||
|
||
static void
|
||
prune_bbs (basic_block bbd, basic_block final)
|
||
{
|
||
edge_iterator ei;
|
||
edge e;
|
||
|
||
for (ei = ei_start (bbd->succs); (e = ei_safe_edge (ei)); )
|
||
{
|
||
basic_block bb;
|
||
bb = e->dest;
|
||
remove_edge (e);
|
||
if (bb != final)
|
||
delete_basic_block (bb);
|
||
}
|
||
delete_basic_block (bbd);
|
||
}
|
||
|
||
/* Add values to phi nodes in final_bb for the two new edges. E1F is the edge
|
||
from the basic block loading values from an array and E2F from the basic
|
||
block loading default values. BBF is the last switch basic block (see the
|
||
bbf description in the comment below). */
|
||
|
||
static void
|
||
fix_phi_nodes (edge e1f, edge e2f, basic_block bbf,
|
||
struct switch_conv_info *info)
|
||
{
|
||
gphi_iterator gsi;
|
||
int i;
|
||
|
||
for (gsi = gsi_start_phis (bbf), i = 0;
|
||
!gsi_end_p (gsi); gsi_next (&gsi), i++)
|
||
{
|
||
gphi *phi = gsi.phi ();
|
||
add_phi_arg (phi, info->target_inbound_names[i], e1f, UNKNOWN_LOCATION);
|
||
add_phi_arg (phi, info->target_outbound_names[i], e2f, UNKNOWN_LOCATION);
|
||
}
|
||
}
|
||
|
||
/* Creates a check whether the switch expression value actually falls into the
|
||
range given by all the cases. If it does not, the temporaries are loaded
|
||
with default values instead. SWTCH is the switch statement being converted.
|
||
|
||
bb0 is the bb with the switch statement, however, we'll end it with a
|
||
condition instead.
|
||
|
||
bb1 is the bb to be used when the range check went ok. It is derived from
|
||
the switch BB
|
||
|
||
bb2 is the bb taken when the expression evaluated outside of the range
|
||
covered by the created arrays. It is populated by loads of default
|
||
values.
|
||
|
||
bbF is a fall through for both bb1 and bb2 and contains exactly what
|
||
originally followed the switch statement.
|
||
|
||
bbD contains the switch statement (in the end). It is unreachable but we
|
||
still need to strip off its edges.
|
||
*/
|
||
|
||
static void
|
||
gen_inbound_check (gswitch *swtch, struct switch_conv_info *info)
|
||
{
|
||
tree label_decl1 = create_artificial_label (UNKNOWN_LOCATION);
|
||
tree label_decl2 = create_artificial_label (UNKNOWN_LOCATION);
|
||
tree label_decl3 = create_artificial_label (UNKNOWN_LOCATION);
|
||
glabel *label1, *label2, *label3;
|
||
tree utype, tidx;
|
||
tree bound;
|
||
|
||
gcond *cond_stmt;
|
||
|
||
gassign *last_assign;
|
||
gimple_stmt_iterator gsi;
|
||
basic_block bb0, bb1, bb2, bbf, bbd;
|
||
edge e01, e02, e21, e1d, e1f, e2f;
|
||
location_t loc = gimple_location (swtch);
|
||
|
||
gcc_assert (info->default_values);
|
||
|
||
bb0 = gimple_bb (swtch);
|
||
|
||
tidx = gimple_assign_lhs (info->arr_ref_first);
|
||
utype = TREE_TYPE (tidx);
|
||
|
||
/* (end of) block 0 */
|
||
gsi = gsi_for_stmt (info->arr_ref_first);
|
||
gsi_next (&gsi);
|
||
|
||
bound = fold_convert_loc (loc, utype, info->range_size);
|
||
cond_stmt = gimple_build_cond (LE_EXPR, tidx, bound, NULL_TREE, NULL_TREE);
|
||
gsi_insert_before (&gsi, cond_stmt, GSI_SAME_STMT);
|
||
update_stmt (cond_stmt);
|
||
|
||
/* block 2 */
|
||
label2 = gimple_build_label (label_decl2);
|
||
gsi_insert_before (&gsi, label2, GSI_SAME_STMT);
|
||
last_assign = gen_def_assigns (&gsi, info);
|
||
|
||
/* block 1 */
|
||
label1 = gimple_build_label (label_decl1);
|
||
gsi_insert_before (&gsi, label1, GSI_SAME_STMT);
|
||
|
||
/* block F */
|
||
gsi = gsi_start_bb (info->final_bb);
|
||
label3 = gimple_build_label (label_decl3);
|
||
gsi_insert_before (&gsi, label3, GSI_SAME_STMT);
|
||
|
||
/* cfg fix */
|
||
e02 = split_block (bb0, cond_stmt);
|
||
bb2 = e02->dest;
|
||
|
||
e21 = split_block (bb2, last_assign);
|
||
bb1 = e21->dest;
|
||
remove_edge (e21);
|
||
|
||
e1d = split_block (bb1, info->arr_ref_last);
|
||
bbd = e1d->dest;
|
||
remove_edge (e1d);
|
||
|
||
/* flags and profiles of the edge for in-range values */
|
||
e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE);
|
||
e01->probability = REG_BR_PROB_BASE - info->default_prob;
|
||
e01->count = info->other_count;
|
||
|
||
/* flags and profiles of the edge taking care of out-of-range values */
|
||
e02->flags &= ~EDGE_FALLTHRU;
|
||
e02->flags |= EDGE_FALSE_VALUE;
|
||
e02->probability = info->default_prob;
|
||
e02->count = info->default_count;
|
||
|
||
bbf = info->final_bb;
|
||
|
||
e1f = make_edge (bb1, bbf, EDGE_FALLTHRU);
|
||
e1f->probability = REG_BR_PROB_BASE;
|
||
e1f->count = info->other_count;
|
||
|
||
e2f = make_edge (bb2, bbf, EDGE_FALLTHRU);
|
||
e2f->probability = REG_BR_PROB_BASE;
|
||
e2f->count = info->default_count;
|
||
|
||
/* frequencies of the new BBs */
|
||
bb1->frequency = EDGE_FREQUENCY (e01);
|
||
bb2->frequency = EDGE_FREQUENCY (e02);
|
||
bbf->frequency = EDGE_FREQUENCY (e1f) + EDGE_FREQUENCY (e2f);
|
||
|
||
/* Tidy blocks that have become unreachable. */
|
||
prune_bbs (bbd, info->final_bb);
|
||
|
||
/* Fixup the PHI nodes in bbF. */
|
||
fix_phi_nodes (e1f, e2f, bbf, info);
|
||
|
||
/* Fix the dominator tree, if it is available. */
|
||
if (dom_info_available_p (CDI_DOMINATORS))
|
||
{
|
||
vec<basic_block> bbs_to_fix_dom;
|
||
|
||
set_immediate_dominator (CDI_DOMINATORS, bb1, bb0);
|
||
set_immediate_dominator (CDI_DOMINATORS, bb2, bb0);
|
||
if (! get_immediate_dominator (CDI_DOMINATORS, bbf))
|
||
/* If bbD was the immediate dominator ... */
|
||
set_immediate_dominator (CDI_DOMINATORS, bbf, bb0);
|
||
|
||
bbs_to_fix_dom.create (4);
|
||
bbs_to_fix_dom.quick_push (bb0);
|
||
bbs_to_fix_dom.quick_push (bb1);
|
||
bbs_to_fix_dom.quick_push (bb2);
|
||
bbs_to_fix_dom.quick_push (bbf);
|
||
|
||
iterate_fix_dominators (CDI_DOMINATORS, bbs_to_fix_dom, true);
|
||
bbs_to_fix_dom.release ();
|
||
}
|
||
}
|
||
|
||
/* The following function is invoked on every switch statement (the current one
|
||
is given in SWTCH) and runs the individual phases of switch conversion on it
|
||
one after another until one fails or the conversion is completed.
|
||
Returns NULL on success, or a pointer to a string with the reason why the
|
||
conversion failed. */
|
||
|
||
static const char *
|
||
process_switch (gswitch *swtch)
|
||
{
|
||
struct switch_conv_info info;
|
||
|
||
/* Group case labels so that we get the right results from the heuristics
|
||
that decide on the code generation approach for this switch. */
|
||
group_case_labels_stmt (swtch);
|
||
|
||
/* If this switch is now a degenerate case with only a default label,
|
||
there is nothing left for us to do. */
|
||
if (gimple_switch_num_labels (swtch) < 2)
|
||
return "switch is a degenerate case";
|
||
|
||
collect_switch_conv_info (swtch, &info);
|
||
|
||
/* No error markers should reach here (they should be filtered out
|
||
during gimplification). */
|
||
gcc_checking_assert (TREE_TYPE (info.index_expr) != error_mark_node);
|
||
|
||
/* A switch on a constant should have been optimized in tree-cfg-cleanup. */
|
||
gcc_checking_assert (! TREE_CONSTANT (info.index_expr));
|
||
|
||
if (info.uniq <= MAX_CASE_BIT_TESTS)
|
||
{
|
||
if (expand_switch_using_bit_tests_p (info.range_size,
|
||
info.uniq, info.count,
|
||
optimize_bb_for_speed_p
|
||
(gimple_bb (swtch))))
|
||
{
|
||
if (dump_file)
|
||
fputs (" expanding as bit test is preferable\n", dump_file);
|
||
emit_case_bit_tests (swtch, info.index_expr, info.range_min,
|
||
info.range_size, info.range_max);
|
||
loops_state_set (LOOPS_NEED_FIXUP);
|
||
return NULL;
|
||
}
|
||
|
||
if (info.uniq <= 2)
|
||
/* This will be expanded as a decision tree in stmt.c:expand_case. */
|
||
return " expanding as jumps is preferable";
|
||
}
|
||
|
||
/* If there is no common successor, we cannot do the transformation. */
|
||
if (! info.final_bb)
|
||
return "no common successor to all case label target blocks found";
|
||
|
||
/* Check the case label values are within reasonable range: */
|
||
if (!check_range (&info))
|
||
{
|
||
gcc_assert (info.reason);
|
||
return info.reason;
|
||
}
|
||
|
||
/* For all the cases, see whether they are empty, the assignments they
|
||
represent constant and so on... */
|
||
if (! check_all_empty_except_final (&info))
|
||
{
|
||
gcc_assert (info.reason);
|
||
return info.reason;
|
||
}
|
||
if (!check_final_bb (&info))
|
||
{
|
||
gcc_assert (info.reason);
|
||
return info.reason;
|
||
}
|
||
|
||
/* At this point all checks have passed and we can proceed with the
|
||
transformation. */
|
||
|
||
create_temp_arrays (&info);
|
||
gather_default_values (gimple_switch_default_label (swtch), &info);
|
||
build_constructors (swtch, &info);
|
||
|
||
build_arrays (swtch, &info); /* Build the static arrays and assignments. */
|
||
gen_inbound_check (swtch, &info); /* Build the bounds check. */
|
||
|
||
/* Cleanup: */
|
||
free_temp_arrays (&info);
|
||
return NULL;
|
||
}
|
||
|
||
/* The main function of the pass scans statements for switches and invokes
|
||
process_switch on them. */
|
||
|
||
namespace {
|
||
|
||
const pass_data pass_data_convert_switch =
|
||
{
|
||
GIMPLE_PASS, /* type */
|
||
"switchconv", /* name */
|
||
OPTGROUP_NONE, /* optinfo_flags */
|
||
TV_TREE_SWITCH_CONVERSION, /* tv_id */
|
||
( PROP_cfg | PROP_ssa ), /* properties_required */
|
||
0, /* properties_provided */
|
||
0, /* properties_destroyed */
|
||
0, /* todo_flags_start */
|
||
TODO_update_ssa, /* todo_flags_finish */
|
||
};
|
||
|
||
class pass_convert_switch : public gimple_opt_pass
|
||
{
|
||
public:
|
||
pass_convert_switch (gcc::context *ctxt)
|
||
: gimple_opt_pass (pass_data_convert_switch, ctxt)
|
||
{}
|
||
|
||
/* opt_pass methods: */
|
||
virtual bool gate (function *) { return flag_tree_switch_conversion != 0; }
|
||
virtual unsigned int execute (function *);
|
||
|
||
}; // class pass_convert_switch
|
||
|
||
unsigned int
|
||
pass_convert_switch::execute (function *fun)
|
||
{
|
||
basic_block bb;
|
||
|
||
FOR_EACH_BB_FN (bb, fun)
|
||
{
|
||
const char *failure_reason;
|
||
gimple *stmt = last_stmt (bb);
|
||
if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
|
||
{
|
||
if (dump_file)
|
||
{
|
||
expanded_location loc = expand_location (gimple_location (stmt));
|
||
|
||
fprintf (dump_file, "beginning to process the following "
|
||
"SWITCH statement (%s:%d) : ------- \n",
|
||
loc.file, loc.line);
|
||
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
|
||
putc ('\n', dump_file);
|
||
}
|
||
|
||
failure_reason = process_switch (as_a <gswitch *> (stmt));
|
||
if (! failure_reason)
|
||
{
|
||
if (dump_file)
|
||
{
|
||
fputs ("Switch converted\n", dump_file);
|
||
fputs ("--------------------------------\n", dump_file);
|
||
}
|
||
|
||
/* Make no effort to update the post-dominator tree. It is actually not
|
||
that hard for the transformations we have performed, but it is not
|
||
supported by iterate_fix_dominators. */
|
||
free_dominance_info (CDI_POST_DOMINATORS);
|
||
}
|
||
else
|
||
{
|
||
if (dump_file)
|
||
{
|
||
fputs ("Bailing out - ", dump_file);
|
||
fputs (failure_reason, dump_file);
|
||
fputs ("\n--------------------------------\n", dump_file);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
} // anon namespace
|
||
|
||
gimple_opt_pass *
|
||
make_pass_convert_switch (gcc::context *ctxt)
|
||
{
|
||
return new pass_convert_switch (ctxt);
|
||
}
|