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re PR tree-optimization/43491 (Unnecessary temporary for global register variable) 

2011-12-22  Bin Cheng  <bin.cheng@arm.com>
	Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/43491
	* tree-ssa-pre.c (eliminate): Don't replace global register
	variable when it is the RHS of a single assign.

	testsuite:
	* gcc.dg/tree-ssa/pr43491.c: New test.


Co-Authored-By: Richard Guenther <rguenther@suse.de>

From-SVN: r182650
This commit is contained in:
Bin Cheng 2011-12-23 05:43:09 +00:00 committed by Joey Ye
parent 994182df27
commit 2b9ed3bc10
4 changed files with 77 additions and 12 deletions
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7
gcc/ChangeLog
View File

@ -1,3 +1,10 @@
2011-12-22 Bin Cheng <bin.cheng@arm.com>
Richard Guenther <rguenther@suse.de>
PR tree-optimization/43491
* tree-ssa-pre.c (eliminate): Don't replace global register
variable when it is the RHS of a single assign.
2011-12-22 Joey Ye <joey.ye@arm.com>
* toplev.c (process_options): Fix typo.

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2011-12-22 Bin Cheng <bin.cheng@arm.com>
PR tree-optimization/43491
* gcc.dg/tree-ssa/pr43491.c: New test.
2011-12-22 John David Anglin <dave.anglin@nrc-cnrc.gc.ca>
PR testsuite/50722

42
gcc/testsuite/gcc.dg/tree-ssa/pr43491.c Normal file
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@ -0,0 +1,42 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-pre-stats" } */
#define REGISTER register
#if defined __arm__
# define REG1 asm("r4")
#elif defined __i386__
# define REG1 asm("ebx")
#elif defined __mips__
# define REG1 asm("s0")
#elif defined __x86_64__
# define REG1 asm("rbp")
#else
# undef REGISTER
# define REGISTER
# define REG1
#endif
REGISTER long data_0 REG1;
long data_3;
long foo(long data, long v)
{
long i;
long t, u;
if (data)
i = data_0 + data_3;
else {
v = 2;
i = 5;
}
t = data_0 + data_3;
u = i;
return v * t * u;
}
/* We should not eliminate global register variable when it is the RHS of
a single assignment. */
/* { dg-final { scan-tree-dump-times "Eliminated: 2" 1 "pre" { target { arm-*-* i?86-*-* mips*-*-* x86_64-*-* } } } } */
/* { dg-final { scan-tree-dump-times "Eliminated: 3" 1 "pre" { target { ! { arm-*-* i?86-*-* mips*-*-* x86_64-*-* } } } } } */
/* { dg-final { cleanup-tree-dump "pre" } } */

35
gcc/tree-ssa-pre.c
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@ -4161,28 +4161,40 @@ eliminate (void)
{
for (gsi = gsi_start_bb (b); !gsi_end_p (gsi); gsi_next (&gsi))
{
tree lhs = NULL_TREE;
tree rhs = NULL_TREE;
stmt = gsi_stmt (gsi);
if (gimple_has_lhs (stmt))
lhs = gimple_get_lhs (stmt);
if (gimple_assign_single_p (stmt))
rhs = gimple_assign_rhs1 (stmt);
/* Lookup the RHS of the expression, see if we have an
available computation for it. If so, replace the RHS with
the available computation. */
the available computation.
See PR43491.
We don't replace global register variable when it is a the RHS of
a single assign. We do replace local register variable since gcc
does not guarantee local variable will be allocated in register. */
if (gimple_has_lhs (stmt)
&& TREE_CODE (gimple_get_lhs (stmt)) == SSA_NAME
&& TREE_CODE (lhs) == SSA_NAME
&& !gimple_assign_ssa_name_copy_p (stmt)
&& (!gimple_assign_single_p (stmt)
|| !is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))
|| (!is_gimple_min_invariant (rhs)
&& (gimple_assign_rhs_code (stmt) != VAR_DECL
|| !is_global_var (rhs)
|| !DECL_HARD_REGISTER (rhs))))
&& !gimple_has_volatile_ops (stmt)
&& !has_zero_uses (gimple_get_lhs (stmt)))
&& !has_zero_uses (lhs))
{
tree lhs = gimple_get_lhs (stmt);
tree rhs = NULL_TREE;
tree sprime = NULL;
pre_expr lhsexpr = get_or_alloc_expr_for_name (lhs);
pre_expr sprimeexpr;
if (gimple_assign_single_p (stmt))
rhs = gimple_assign_rhs1 (stmt);
sprimeexpr = bitmap_find_leader (AVAIL_OUT (b),
get_expr_value_id (lhsexpr),
NULL);
@ -4298,10 +4310,9 @@ eliminate (void)
dead. */
else if (gimple_assign_single_p (stmt)
&& !is_gimple_reg (gimple_assign_lhs (stmt))
&& (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
|| is_gimple_min_invariant (gimple_assign_rhs1 (stmt))))
&& (TREE_CODE (rhs) == SSA_NAME
|| is_gimple_min_invariant (rhs)))
{
tree rhs = gimple_assign_rhs1 (stmt);
tree val;
val = vn_reference_lookup (gimple_assign_lhs (stmt),
gimple_vuse (stmt), VN_WALK, NULL);