[gcc(refs/users/meissner/heads/work008-orig)] tree-optimization/96491 - avoid store commoning across abnormal edges

[gcc(refs/users/meissner/heads/work008-orig)] tree-optimization/96491 - avoid store commoning across abnormal edges

[Michael Meissner]

https://gcc.gnu.org/g:89b84cd794f984038984c10b03c3b0ab582f49cc

commit 89b84cd794f984038984c10b03c3b0ab582f49cc
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Aug 6 12:18:24 2020 +0200

    tree-optimization/96491 - avoid store commoning across abnormal edges
    
    This avoids store commoning across abnormal edges since that easily
    can disrupt abnormal coalescing because it might create overlapping
    lifetime of variables.
    
    2020-08-06  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/96491
            * tree-ssa-sink.c (sink_common_stores_to_bb): Avoid
            sinking across abnormal edges.
    
            * gcc.dg/torture/pr96491.c: New testcase.

Diff:
---
 gcc/testsuite/gcc.dg/torture/pr96491.c | 29 +++++++++++++++++++++++++++++
 gcc/tree-ssa-sink.c                    |  3 ++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/gcc/testsuite/gcc.dg/torture/pr96491.c b/gcc/testsuite/gcc.dg/torture/pr96491.c
new file mode 100644
index 00000000000..784559f4754
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr96491.c
@@ -0,0 +1,29 @@
+/* { dg-do compile }  */
+
+int rj;
+
+void __attribute__ ((returns_twice))
+da (void)
+{
+  rj = 1;
+}
+
+void
+c5 (void)
+{
+  for (;;)
+    ++rj;
+}
+
+void
+ls (int kz)
+{
+  if (kz == 0)
+    {
+      rj = 0;
+      c5 ();
+    }
+
+  da ();
+  c5 ();
+}
diff --git a/gcc/tree-ssa-sink.c b/gcc/tree-ssa-sink.c
index 962ad076968..4cc5195f2f8 100644
--- a/gcc/tree-ssa-sink.c
+++ b/gcc/tree-ssa-sink.c
@@ -503,7 +503,8 @@ sink_common_stores_to_bb (basic_block bb)
 	      tree arg = gimple_phi_arg_def (phi, i);
 	      gimple *def = SSA_NAME_DEF_STMT (arg);
 	      if (! is_gimple_assign (def)
-		  || stmt_can_throw_internal (cfun, def))
+		  || stmt_can_throw_internal (cfun, def)
+		  || (gimple_phi_arg_edge (phi, i)->flags & EDGE_ABNORMAL))
 		{
 		  /* ???  We could handle some cascading with the def being
 		     another PHI.  We'd have to insert multiple PHIs for