[PATCH] tree-optimization/107447 - avoid hoisting returns-twice calls in LIM

[PATCH] tree-optimization/107447 - avoid hoisting returns-twice calls in LIM

[Richard Biener]

The following makes sure to not hoist returns-twice calls in LIM
since we have no way to move the abnormal edge associated with it
and we are prone having stray abnormal edges in the IL which will
then cause IL verification failures even when the actual call
does not return twice.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

	PR tree-optimization/107447
	* tree-ssa-loop-im.cc (determine_max_movement): Do not
	hoist returns-twice calls.

	* gcc.dg/torture/pr107447.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr107447.c | 23 +++++++++++++++++++++++
 gcc/tree-ssa-loop-im.cc                 | 13 +++++++++----
 2 files changed, 32 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr107447.c

diff --git a/gcc/testsuite/gcc.dg/torture/pr107447.c b/gcc/testsuite/gcc.dg/torture/pr107447.c
new file mode 100644
index 00000000000..06f7b7b15ae
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr107447.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+
+int n;
+
+void
+bar (int, int);
+
+__attribute__ ((noinline, returns_twice)) int
+zero (void)
+{
+  return 0;
+}
+
+void
+foo (void)
+{
+  (void) zero ();
+
+  n = 0;
+
+  for (;;)
+    bar (zero (), n);
+}
diff --git a/gcc/tree-ssa-loop-im.cc b/gcc/tree-ssa-loop-im.cc
index 2ea815050d1..2119d4072d3 100644
--- a/gcc/tree-ssa-loop-im.cc
+++ b/gcc/tree-ssa-loop-im.cc
@@ -835,10 +835,15 @@ determine_max_movement (gimple *stmt, bool must_preserve_exec)
 
       return true;
     }
-  else
-    FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter, SSA_OP_USE)
-      if (!add_dependency (val, lim_data, loop, true))
-	return false;
+
+  /* A stmt that receives abnormal edges cannot be hoisted.  */
+  if (is_a <gcall *> (stmt)
+      && (gimple_call_flags (stmt) & ECF_RETURNS_TWICE))
+    return false;
+
+  FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter, SSA_OP_USE)
+    if (!add_dependency (val, lim_data, loop, true))
+      return false;
 
   if (gimple_vuse (stmt))
     {
-- 
2.35.3