[patch] Re: trapv question

[Andrew MacLeod via Gcc-patches]

On 1/20/21 1:43 PM, Richard Biener wrote:

On January 20, 2021 6:52:11 PM GMT+01:00, Andrew MacLeod <amacl...@redhat.com> 
wrote:

diff --git a/gcc/testsuite/gcc.dg/torture/ftrapv-2.c
b/gcc/testsuite/gcc.dg/torture/ftrapv-2.c
index 75e464fe557..5824c2fdbb7 100644
--- a/gcc/testsuite/gcc.dg/torture/ftrapv-2.c
+++ b/gcc/testsuite/gcc.dg/torture/ftrapv-2.c
@@ -20,7 +20,7 @@ int main(void)
    int status = 0;
    if (child == 0)
      {
-      volatile int x = i + 1 < i;
+      i = i + 1;

But i should then be volatile which should make it LTO proof as well. Otherwise 
this looks OK.

Richard.

        exit (0);
      }
    else if (child == -1)


Is that the right thing to do?

THanks
Andrew

Done... pushed



commit 842afc4e289ed3fe69583672c1a180f268d73799
Author: Andrew MacLeod <amacl...@redhat.com>
Date:   Wed Jan 20 16:27:34 2021 -0500

    Re: trapv question
    
    Adjust testcase to so the ADD that is expected to overflow cannot
    be optimized.
    
            gcc/testsuite
            * gcc.dg/torture/ftrapv-2.c: Make overflow instruction unremovable.

diff --git a/gcc/testsuite/gcc.dg/torture/ftrapv-2.c 
b/gcc/testsuite/gcc.dg/torture/ftrapv-2.c
index 75e464fe557..4d746c9ce5c 100644
--- a/gcc/testsuite/gcc.dg/torture/ftrapv-2.c
+++ b/gcc/testsuite/gcc.dg/torture/ftrapv-2.c
@@ -12,7 +12,7 @@
 
 /* Verify SImode operations properly trap.  PR middle-end/68046 */
 
-int i = 0x7fffffff;
+volatile int i = 0x7fffffff;
 
 int main(void)
 {
@@ -20,7 +20,7 @@ int main(void)
   int status = 0;
   if (child == 0)
     {
-      volatile int x = i + 1 < i;
+      i = i + 1;
       exit (0);
     }
   else if (child == -1)