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cse.c (find_comparison_args): Check for cycles of any length.

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2012-07-26  Andrew Jenner  <andrew@codesourcery.com>
	    Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* cse.c (find_comparison_args): Check for cycles of any length.

	gcc/testsuite/
	* gcc.c-torture/compile/pr50380.c: Add code to cause cycle of length 2.

Co-Authored-By: Sandra Loosemore <sandra@codesourcery.com>

From-SVN: r189896
This commit is contained in:
Andrew Jenner 2012-07-26 20:51:24 +00:00 • committed by Sandra Loosemore
parent 18a8e9ef96
commit 27ec0502c8
4 changed files with 40 additions and 9 deletions
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5
gcc/ChangeLog
View file

@ -1,3 +1,8 @@
2012-07-26 Andrew Jenner <andrew@codesourcery.com>
Sandra Loosemore <sandra@codesourcery.com>
* cse.c (find_comparison_args): Check for cycles of any length.
2012-07-26 Nick Clifton <nickc@redhat.com>
* config/mn10300/mn10300.c (REG_SAVE_BYTES): Delete.

23
gcc/cse.c
View file

@ -43,6 +43,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-pass.h"
#include "df.h"
#include "dbgcnt.h"
#include "pointer-set.h"
/* The basic idea of common subexpression elimination is to go
through the code, keeping a record of expressions that would
@ -2897,6 +2898,9 @@ find_comparison_args (enum rtx_code code, rtx *parg1, rtx *parg2,
enum machine_mode *pmode1, enum machine_mode *pmode2)
{
rtx arg1, arg2;
struct pointer_set_t *visited = NULL;
/* Set nonzero when we find something of interest. */
rtx x = NULL;
arg1 = *parg1, arg2 = *parg2;
@ -2904,11 +2908,18 @@ find_comparison_args (enum rtx_code code, rtx *parg1, rtx *parg2,
while (arg2 == CONST0_RTX (GET_MODE (arg1)))
{
/* Set nonzero when we find something of interest. */
rtx x = 0;
int reverse_code = 0;
struct table_elt *p = 0;
/* Remember state from previous iteration. */
if (x)
{
if (!visited)
visited = pointer_set_create ();
pointer_set_insert (visited, x);
x = 0;
}
/* If arg1 is a COMPARE, extract the comparison arguments from it.
On machines with CC0, this is the only case that can occur, since
fold_rtx will return the COMPARE or item being compared with zero
@ -2985,10 +2996,8 @@ find_comparison_args (enum rtx_code code, rtx *parg1, rtx *parg2,
if (! exp_equiv_p (p->exp, p->exp, 1, false))
continue;
/* If it's the same comparison we're already looking at, skip it. */
if (COMPARISON_P (p->exp)
&& XEXP (p->exp, 0) == arg1
&& XEXP (p->exp, 1) == arg2)
/* If it's a comparison we've used before, skip it. */
if (visited && pointer_set_contains (visited, p->exp))
continue;
if (GET_CODE (p->exp) == COMPARE
@ -3069,6 +3078,8 @@ find_comparison_args (enum rtx_code code, rtx *parg1, rtx *parg2,
*pmode1 = GET_MODE (arg1), *pmode2 = GET_MODE (arg2);
*parg1 = fold_rtx (arg1, 0), *parg2 = fold_rtx (arg2, 0);
if (visited)
pointer_set_destroy (visited);
return code;
}

5
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,8 @@
2012-07-26 Andrew Jenner <andrew@codesourcery.com>
Sandra Loosemore <sandra@codesourcery.com>
* gcc.c-torture/compile/pr50380.c: Add code to cause cycle of length 2.
2012-07-26 Tobias Burnus <burnus@net-b.de>
* gfortran.dg/contiguous_1.f90: Update dg-error.

16
gcc/testsuite/gcc.c-torture/compile/pr50380.c
View file

@ -1,12 +1,22 @@
/* This test used to get stuck in an infinite loop in find_comparison_args
when compiling for MIPS at -O2. */
__attribute__ ((__noreturn__)) extern void fail (void);
char x;
/* This used to get stuck in an infinite loop in find_comparison_args
when compiling this function for MIPS at -O2. */
void foo (const unsigned char y)
{
((void) (__builtin_expect((!! y == y), 1) ? 0 : (fail (), 0)));
x = ! y;
}
/* This used to similarly get stuck when compiling for PowerPC at -O2. */
int foo2 (int arg)
{
if (arg != !arg)
fail ();
if (arg)
fail ();
}