From: Tom de Vries <tdevries@suse.de>
Date: Mon, 3 Sep 2018 10:14:52 +0000 (+0000)
Subject: backport "[tail-merge] Fix side-effect test in stmt_local_def"
X-Git-Tag: releases/gcc-6.5.0~86
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8026cd4783640171c0bbdbc23c8e275dddfc315d;p=thirdparty%2Fgcc.git

backport "[tail-merge] Fix side-effect test in stmt_local_def"

2018-09-03  Tom de Vries  <tdevries@suse.de>

	backport from trunk:
	2018-06-21  Tom de Vries  <tdevries@suse.de>

	PR tree-optimization/85859
	* tree-ssa-tail-merge.c (stmt_local_def): Copy gimple_is_call
	test with comment from bb_no_side_effects_p.

	* gcc.dg/pr85859.c: New test.

From-SVN: r264055
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5f36e461958d..62f656d16465 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2018-09-03  Tom de Vries  <tdevries@suse.de>
+
+	backport from trunk:
+	2018-06-21  Tom de Vries  <tdevries@suse.de>
+
+	PR tree-optimization/85859
+	* tree-ssa-tail-merge.c (stmt_local_def): Copy gimple_is_call
+	test with comment from bb_no_side_effects_p.
+
 2018-08-21  H.J. Lu  <hongjiu.lu@intel.com>
 
 	Backport from mainline
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c8e819b89523..47c5b77a16bb 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2018-09-03  Tom de Vries  <tdevries@suse.de>
+
+	backport from trunk:
+	2018-06-21  Tom de Vries  <tdevries@suse.de>
+
+	PR tree-optimization/85859
+	* gcc.dg/pr85859.c: New test.
+
 2018-08-21  H.J. Lu  <hongjiu.lu@intel.com>
 
 	Backport from mainline
diff --git a/gcc/testsuite/gcc.dg/pr85859.c b/gcc/testsuite/gcc.dg/pr85859.c
new file mode 100644
index 000000000000..96eb96711371
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr85859.c
@@ -0,0 +1,19 @@
+/* { dg-do run } */
+/* { dg-options "-ftree-tail-merge -Wno-div-by-zero -O2 -fno-dce -fno-isolate-erroneous-paths-dereference -fno-tree-dce -fno-tree-vrp" } */
+
+int b, c, d, e;
+
+__attribute__ ((noinline, noclone))
+int foo (short f)
+{
+  f %= 0;
+  return f;
+}
+
+int
+main (void)
+{
+  b = (unsigned char) __builtin_parity (d);
+  e ? foo (0) : (long) &c;
+  return 0;
+}
diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c
index a51b1b81740d..57ae47420e36 100644
--- a/gcc/tree-ssa-tail-merge.c
+++ b/gcc/tree-ssa-tail-merge.c
@@ -298,7 +298,15 @@ stmt_local_def (gimple *stmt)
   if (gimple_vdef (stmt) != NULL_TREE
       || gimple_has_side_effects (stmt)
       || gimple_could_trap_p_1 (stmt, false, false)
-      || gimple_vuse (stmt) != NULL_TREE)
+      || gimple_vuse (stmt) != NULL_TREE
+      /* Copied from tree-ssa-ifcombine.c:bb_no_side_effects_p():
+	 const calls don't match any of the above, yet they could
+	 still have some side-effects - they could contain
+	 gimple_could_trap_p statements, like floating point
+	 exceptions or integer division by zero.  See PR70586.
+	 FIXME: perhaps gimple_has_side_effects or gimple_could_trap_p
+	 should handle this.  */
+      || is_gimple_call (stmt))
     return false;
 
   def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_DEF);