From 1add3635563b39e3c0e9bed4930d11b3f605fdd3 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Fri, 28 Oct 2022 14:20:36 +0200
Subject: [PATCH] tree-optimization/107447 - avoid hoisting returns-twice calls
in LIM
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.
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 000000000000..06f7b7b15ae7
--- /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 2ea815050d18..2119d4072d3a 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))
{
--
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