RE: [PATCH] Fix PR tree-optimization/77654

[Doug Gilmore <Doug dot Gilmore at imgtec dot com>]

It looks like the original message was dropped, resending.

Doug
________________________________________
From: Doug Gilmore
Sent: Tuesday, September 20, 2016 2:12 PM
To: gcc-patches@gcc.gnu.org; rguenth@gcc.gnu.org
Subject: [PATCH] Fix PR tree-optimization/77654

From:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77654

Richard Biener wrote:
> Looks good though addr_base should always be a pointer but it might
> not be an SSA name so better check that...

I took a look at other situations where duplicate_ssa_name_ptr_info()
is called and found that there are no checks for the SSA name since
that check is done in duplicate_ssa_name_ptr_info().  Do you still
want the additional check added?

Also does it make sense to make a test case for this?

I was thinking of making the following change to:

diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 8051a66..b799c43 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -296,7 +296,16 @@ ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
   pi1 = SSA_NAME_PTR_INFO (ptr1);
   pi2 = SSA_NAME_PTR_INFO (ptr2);
   if (!pi1 || !pi2)
-    return true;
+    {
+      if (dump_file)
+       {
+         if (! pi1)
+           fprintf (dump_file, "%s pi1 is NULL\n", __FUNCTION__);
+         if (! pi2)
+           fprintf (dump_file, "%s pi2 is NULL\n", __FUNCTION__);
+       }
+      return true;
+    }

Then when compiling the test case, we could scan for the RE
"pi. is NULL" in the dump file created by compiling with -fdump-rtl-sched2.

I attached the original patch.

Thanks,

Doug

gcc/
        PR tree-optimization/77654
        * tree-ssa-alias.c (issue_prefetch_ref): Add call
        to duplicate_ssa_name_ptr_info.