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 5f36e461958d1113b16004a69ec8a08ed26764ba..62f656d1646523979e47ca725999233df554a751 100644 (file)
--- 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 c8e819b8952326e45809a9dacbec18a2ec846d01..47c5b77a16bb0c9feb7ef5d7259df79b41a81ddd 100644 (file)
--- 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 (file)
index 0000000..96eb967
--- /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 a51b1b81740d018d05a4a77fc11f69b6b94efe92..57ae47420e3617fba8b6ec2477a01546899eaf59 100644 (file)
--- 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);