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re PR tree-optimization/81913 (wrong code at -O1)

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PR tree-optimization/81913
	* tree-ssa-loop-niter.c (number_of_iterations_cond): Skip niter
	analysis when either IVs in condition can wrap.

	gcc/testsuite
	* gcc.c-torture/execute/pr81913.c: New test.
	* gcc.dg/tree-ssa/loop-niter-1.c: New test.
	* gcc.dg/tree-ssa/loop-niter-2.c: New test.

From-SVN: r251337
This commit is contained in:
Bin Cheng 2017-08-24 15:38:39 +00:00 committed by Bin Cheng
parent 14e18d7100
commit 142ff60219
6 changed files with 106 additions and 2 deletions

6
gcc/ChangeLog

@ -1,3 +1,9 @@
2017-08-24 Bin Cheng <bin.cheng@arm.com>
PR tree-optimization/81913
* tree-ssa-loop-niter.c (number_of_iterations_cond): Skip niter
analysis when either IVs in condition can wrap.
2017-08-24 Uros Bizjak <ubizjak@gmail.com>
* dwarf2out.c (MAX_ARTIFICIAL_LABEL_BYTES): Increase to 40.

7
gcc/testsuite/ChangeLog

@ -1,3 +1,10 @@
2017-08-24 Bin Cheng <bin.cheng@arm.com>
PR tree-optimization/81913
* gcc.c-torture/execute/pr81913.c: New test.
* gcc.dg/tree-ssa/loop-niter-1.c: New test.
* gcc.dg/tree-ssa/loop-niter-2.c: New test.
2017-08-23 Richard Biener <rguenther@suse.de>
PR target/81921

27
gcc/testsuite/gcc.c-torture/execute/pr81913.c Normal file

@ -0,0 +1,27 @@
/* PR tree-optimization/81913 */
typedef unsigned char u8;
typedef unsigned int u32;
static u32
b (u8 d, u32 e, u32 g)
{
do
{
e += g + 1;
d--;
}
while (d >= (u8) e);
return e;
}
int
main (void)
{
u32 x = b (1, -0x378704, ~0xba64fc);
if (x != 0xd93190d0)
__builtin_abort ();
return 0;
}

31
gcc/testsuite/gcc.dg/tree-ssa/loop-niter-1.c Normal file

@ -0,0 +1,31 @@
/* { dg-do run } */
/* { dg-options "-O2 -fdump-tree-sccp-details" } */
typedef unsigned char u8;
typedef unsigned int u32;
static u32
b (u8 d, u32 e, u32 g)
{
do
{
e += g + 1;
d--;
}
while (d >= (u8) e);
return e;
}
int
main (void)
{
u32 x = b (200, -0x378704, ~0xba64fc);
if (x != 0xe1ee4ca0)
__builtin_abort ();
return 0;
}
/* Niter analyzer should be able to compute niters for the loop. */
/* { dg-final { scan-tree-dump "Replacing uses of: .* with: 3790490784" "sccp" { xfail *-*-* } } } */

31
gcc/testsuite/gcc.dg/tree-ssa/loop-niter-2.c Normal file

@ -0,0 +1,31 @@
/* { dg-do run } */
/* { dg-options "-O2 -fdump-tree-sccp-details" } */
typedef unsigned char u8;
typedef unsigned int u32;
static u32
b (u8 d, u32 e, u32 g)
{
do
{
e += g + 1;
d--;
}
while (d >= (u8) e);
return e;
}
int
main (void)
{
u32 x = b (1, -0x378704, ~0xba64fc);
if (x != 0xd93190d0)
__builtin_abort ();
return 0;
}
/* Niter analyzer should be able to compute niters for the loop even though
IV:d wraps. */
/* { dg-final { scan-tree-dump "Replacing uses of: .* with: 3643904208" "sccp" { xfail *-*-* } } } */

6
gcc/tree-ssa-loop-niter.c

@ -1728,7 +1728,7 @@ number_of_iterations_cond (struct loop *loop,
provided that either below condition is satisfied:
a) the test is NE_EXPR;
b) iv0.step - iv1.step is positive integer.
b) iv0.step - iv1.step is integer and iv0/iv1 don't overflow.
This rarely occurs in practice, but it is simple enough to manage. */
if (!integer_zerop (iv0->step) && !integer_zerop (iv1->step))
@ -1739,7 +1739,9 @@ number_of_iterations_cond (struct loop *loop,
/* No need to check sign of the new step since below code takes care
of this well. */
if (code != NE_EXPR && TREE_CODE (step) != INTEGER_CST)
if (code != NE_EXPR
&& (TREE_CODE (step) != INTEGER_CST
|| !iv0->no_overflow || !iv1->no_overflow))
return false;
iv0->step = step;