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re PR tree-optimization/37242 (missed FRE opportunity because of signedness of addition)

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2019-08-20  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/37242
	* tree-ssa-sccvn.c (visit_nary_op): Also CSE (T)(a + b)
	to (T)a + (T)b if we know that a + b does not overflow.

	* gcc.dg/tree-ssa/ssa-fre-80.c: New testcase.

From-SVN: r274746
This commit is contained in:
Richard Biener 2019-08-20 12:02:56 +00:00 • committed by Richard Biener
parent a53aa4da8a
commit 3ed01d5408
4 changed files with 36 additions and 3 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2019-08-20 Richard Biener <rguenther@suse.de>
PR tree-optimization/37242
* tree-ssa-sccvn.c (visit_nary_op): Also CSE (T)(a + b)
to (T)a + (T)b if we know that a + b does not overflow.
2019-08-20 Eric Botcazou <ebotcazou@adacore.com>
PR rtl-optimization/91347

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2019-08-20 Richard Biener <rguenther@suse.de>
PR tree-optimization/37242
* gcc.dg/tree-ssa/ssa-fre-80.c: New testcase.
2019-08-20 Ed Schonberg <schonberg@adacore.com>
* gnat.dg/storage_size1.adb: New testcase.

16
gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-80.c Normal file
View file

@ -0,0 +1,16 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-fre1" } */
unsigned long a, b;
void foo (int m, int f)
{
unsigned long tem = (unsigned long)m;
a = tem + 1;
if (f)
{
int tem2 = m + 1;
b = (unsigned long)tem2; /* Eliminated to a. */
}
}
/* { dg-final { scan-tree-dump-times "\\(long unsigned int\\)" 1 "fre1" } } */

12
gcc/tree-ssa-sccvn.c
View file

@ -4312,8 +4312,12 @@ visit_nary_op (tree lhs, gassign *stmt)
operation. */
if (INTEGRAL_TYPE_P (type)
&& TREE_CODE (rhs1) == SSA_NAME
/* We only handle sign-changes or zero-extension -> & mask. */
&& ((TYPE_UNSIGNED (TREE_TYPE (rhs1))
/* We only handle sign-changes, zero-extension -> & mask or
sign-extension if we know the inner operation doesn't
overflow. */
&& (((TYPE_UNSIGNED (TREE_TYPE (rhs1))
|| (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
&& TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (rhs1))))
&& TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (rhs1)))
|| TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (rhs1))))
{
@ -4347,7 +4351,9 @@ visit_nary_op (tree lhs, gassign *stmt)
{
unsigned lhs_prec = TYPE_PRECISION (type);
unsigned rhs_prec = TYPE_PRECISION (TREE_TYPE (rhs1));
if (lhs_prec == rhs_prec)
if (lhs_prec == rhs_prec
|| (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
&& TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (rhs1))))
{
gimple_match_op match_op (gimple_match_cond::UNCOND,
NOP_EXPR, type, ops[0]);