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stmt.c (optimize_tail_recursion): New function, extracted from ...

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* stmt.c (optimize_tail_recursion): New function, extracted from ...
        (expand_return): Use optimize_tail_recursion.
        * tree.h (optimize_tail_recursion): Declare.

From-SVN: r24574
This commit is contained in:
Jeffrey A Law 1999-01-08 05:05:20 -07:00 committed by Jeff Law
parent 5c280133c9
commit 642cac7ba0
3 changed files with 54 additions and 33 deletions
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14
gcc/ChangeLog
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@ -1,8 +1,3 @@
Thu Jan 7 19:52:53 1999 Gerald Pfeifer <pfeifer@dbai.tuwien.ac.at>
* system.h (abort): Supply more detailed information on how to
report an Internal Compiler Error.
Fri Jan 8 10:51:13 1999 Andreas Schwab <schwab@issan.cs.uni-dortmund.de>
* config/m68k/m68k.h: Declare output_function_epilogue.
@ -10,9 +5,18 @@ Fri Jan 8 10:51:13 1999 Andreas Schwab <schwab@issan.cs.uni-dortmund.de>
Fri Jan 8 01:43:53 1999 Jeffrey A Law (law@cygnus.com)
* stmt.c (optimize_tail_recursion): New function, extracted from ...
(expand_return): Use optimize_tail_recursion.
* tree.h (optimize_tail_recursion): Declare.
* toplev.c (compile_file): Move call to output_func_start_profiler
to after the loop to emit deferred functions.
Thu Jan 7 19:52:53 1999 Gerald Pfeifer <pfeifer@dbai.tuwien.ac.at>
* system.h (abort): Supply more detailed information on how to
report an Internal Compiler Error.
Thu Jan 7 11:26:17 1999 Mark Mitchell <mark@markmitchell.com>
* calls.c (store_unaligned_arguments_into_pseudos): Use xmalloc to

70
gcc/stmt.c
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@ -1,5 +1,5 @@
/* Expands front end tree to back end RTL for GNU C-Compiler
Copyright (C) 1987, 88, 89, 92-97, 1998 Free Software Foundation, Inc.
Copyright (C) 1987, 88, 89, 92-98, 1999 Free Software Foundation, Inc.
This file is part of GNU CC.
@ -2564,32 +2564,9 @@ expand_return (retval)
return;
}
/* For tail-recursive call to current function,
just jump back to the beginning.
It's unsafe if any auto variable in this function
has its address taken; for simplicity,
require stack frame to be empty. */
if (optimize && retval_rhs != 0
&& frame_offset == 0
&& TREE_CODE (retval_rhs) == CALL_EXPR
&& TREE_CODE (TREE_OPERAND (retval_rhs, 0)) == ADDR_EXPR
&& TREE_OPERAND (TREE_OPERAND (retval_rhs, 0), 0) == current_function_decl
/* Finish checking validity, and if valid emit code
to set the argument variables for the new call. */
&& tail_recursion_args (TREE_OPERAND (retval_rhs, 1),
DECL_ARGUMENTS (current_function_decl)))
{
if (tail_recursion_label == 0)
{
tail_recursion_label = gen_label_rtx ();
emit_label_after (tail_recursion_label,
tail_recursion_reentry);
}
emit_queue ();
expand_goto_internal (NULL_TREE, tail_recursion_label, last_insn);
emit_barrier ();
return;
}
/* Attempt to optimize the call if it is tail recursive. */
optimize_tail_recursion (retval_rhs, last_insn);
#ifdef HAVE_return
/* This optimization is safe if there are local cleanups
because expand_null_return takes care of them.
@ -2794,6 +2771,45 @@ drop_through_at_end_p ()
return insn && GET_CODE (insn) != BARRIER;
}
/* Test CALL_EXPR to determine if it is a potential tail recursion call
and emit code to optimize the tail recursion. LAST_INSN indicates where
to place the jump to the tail recursion label.
This is only used by expand_return, but expand_call is expected to
use it soon. */
void
optimize_tail_recursion (call_expr, last_insn)
tree call_expr;
rtx last_insn;
{
/* For tail-recursive call to current function,
just jump back to the beginning.
It's unsafe if any auto variable in this function
has its address taken; for simplicity,
require stack frame to be empty. */
if (optimize && call_expr != 0
&& frame_offset == 0
&& TREE_CODE (call_expr) == CALL_EXPR
&& TREE_CODE (TREE_OPERAND (call_expr, 0)) == ADDR_EXPR
&& TREE_OPERAND (TREE_OPERAND (call_expr, 0), 0) == current_function_decl
/* Finish checking validity, and if valid emit code
to set the argument variables for the new call. */
&& tail_recursion_args (TREE_OPERAND (call_expr, 1),
DECL_ARGUMENTS (current_function_decl)))
{
if (tail_recursion_label == 0)
{
tail_recursion_label = gen_label_rtx ();
emit_label_after (tail_recursion_label,
tail_recursion_reentry);
}
emit_queue ();
expand_goto_internal (NULL_TREE, tail_recursion_label, last_insn);
emit_barrier ();
}
}
/* Emit code to alter this function's formal parms for a tail-recursive call.
ACTUALS is a list of actual parameter expressions (chain of TREE_LISTs).
FORMALS is the chain of decls of formals.

3
gcc/tree.h
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@ -1,5 +1,5 @@
/* Front-end tree definitions for GNU compiler.
Copyright (C) 1989, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
Copyright (C) 1989, 93-98, 1999 Free Software Foundation, Inc.
This file is part of GNU CC.
@ -1930,6 +1930,7 @@ extern int expand_exit_something PROTO((void));
extern void expand_null_return PROTO((void));
extern void expand_return PROTO((tree));
extern void optimize_tail_recursion PROTO((tree, struct rtx_def *));
extern void expand_start_bindings PROTO((int));
extern void expand_end_bindings PROTO((tree, int, int));
extern void start_cleanup_deferral PROTO((void));