[gcc r10-8747] tree-optimization/96514 - avoid if-converting control-altering calls

[Richard Biener]

https://gcc.gnu.org/g:a568a893f38a9cd32ddffd32bb9b6636deeeb5f1

commit r10-8747-ga568a893f38a9cd32ddffd32bb9b6636deeeb5f1
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Aug 7 10:16:05 2020 +0200

    tree-optimization/96514 - avoid if-converting control-altering calls
    
    This avoids if-converting when encountering control-altering calls.
    
    2020-08-07  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/96514
            * tree-if-conv.c (if_convertible_bb_p): If the last stmt
            is a call that is control-altering, fail.
    
            * gcc.dg/pr96514.c: New testcase.
    
    (cherry picked from commit c3f94f5786a014515c09c7852db228c74adf51e5)

Diff:
---
 gcc/testsuite/gcc.dg/pr96514.c | 27 +++++++++++++++++++++++++++
 gcc/tree-if-conv.c             |  5 +++++
 2 files changed, 32 insertions(+)

diff --git a/gcc/testsuite/gcc.dg/pr96514.c b/gcc/testsuite/gcc.dg/pr96514.c
new file mode 100644
index 00000000000..891b4da2b1e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr96514.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+
+int __attribute__ ((pure, returns_twice))
+r0 (void);
+
+void
+vy (int t7)
+{
+  while (t7 == 0)
+    r0 ();
+}
+
+void
+qw (int t7)
+{
+  vy (t7);
+
+  if (0)
+    r0 ();
+}
+
+void __attribute__ ((simd))
+un (int t7)
+{
+  qw (t7);
+  qw (t7);
+}
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index fc894eb94da..257759d01bf 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -1139,6 +1139,11 @@ if_convertible_bb_p (class loop *loop, basic_block bb, basic_block exit_bb)
   if (EDGE_COUNT (bb->succs) > 2)
     return false;
 
+  gimple *last = last_stmt (bb);
+  if (gcall *call = safe_dyn_cast <gcall *> (last))
+    if (gimple_call_ctrl_altering_p (call))
+      return false;
+
   if (exit_bb)
     {
       if (bb != loop->latch)