Fix failure in merge_block.c testcase

[Jan Hubicka via Gcc-patches]

Hi,
this testcase needs -fno-ipa-modref becuase otherwise it hits the issue
that complete loop unrolling leaves somewhat mismatched profile.

Bootstrapped/regtested x86_64-linux, comitted.

gcc/testsuite/ChangeLog:

2021-11-21  Jan Hubicka  <hubi...@ucw.cz>

        PR ipa/103264
        * gcc.dg/tree-prof/merge_block.c: Add -fno-ipa-modref

diff --git a/gcc/testsuite/gcc.dg/tree-prof/merge_block.c 
b/gcc/testsuite/gcc.dg/tree-prof/merge_block.c
index 5da5ddff6a0..e8a8873f152 100644
--- a/gcc/testsuite/gcc.dg/tree-prof/merge_block.c
+++ b/gcc/testsuite/gcc.dg/tree-prof/merge_block.c
@@ -1,5 +1,5 @@
 
-/* { dg-options "-O2 -fno-ipa-pure-const -fdump-tree-optimized-blocks-details 
-fno-early-inlining" } */
+/* { dg-options "-O2 -fno-ipa-pure-const -fdump-tree-optimized-blocks-details 
-fno-early-inlining -fno-ipa-modref" } */
 int a[8];
 int t()
 {