[PATCH,testsuite] fortify vect-105.c against compiler optimizations

[Nathan Froyd]

This patch is intended to guard the testcase against compiler
optimizations for hoisting conditionals out of loops.  The test
currently passes on mainline for arm-none-{eabi,linux-gnueabi}, but
we've seen it fail on our 4.3 builds; the patch clearly moves things
closer to the original intent of the testcase.

Tested on arm-none-{eabi,linux-gnueabi}.  OK to commit?

-Nathan

2009-01-14  Mark Mitchell  <mark@codesourcery.com>

	* gcc.dg/vect/vect-105.c: Prevent compiler from hoisting abort
	out of loop.

Index: gcc.dg/vect/vect-105.c
===================================================================
--- gcc.dg/vect/vect-105.c	(revision 143372)
+++ gcc.dg/vect/vect-105.c	(working copy)
@@ -16,6 +16,8 @@ static int a[N][N] = {{1,2,3,11},{4,5,6,
 static int b[N][N] = {{17,28,15,23},{0,2,3,24},{4,31,82,25},{29,31,432,256}};
 static int c[N][N] = {{1,2,3,11},{4,9,13,34},{45,67,83,13},{34,45,67,83}};
 
+volatile int y;
+
 __attribute__ ((noinline))
 int main1 (int x) {
   int i,j;
@@ -28,7 +30,9 @@ int main1 (int x) {
      {
        p->a[i][j] = a[i][j];
        p->b[i][j] = b[i][j];
-       if (x == 135)
+       /* Because Y is volatile, the compiler cannot move this check out
+	  of the loop.  */
+       if (y)
 	 abort (); /* to avoid vectorization  */
      }
    }