tree-optimization/95268 - fix commoning of clobbers

This fixes handling of clobbers when commoning stores.

2020-05-22  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/95268
	* tree-ssa-sink.c (sink_common_stores_to_bb): Handle clobbers
	properly.

	* g++.dg/torture/pr95268.C: New testcase.

4 files changed, 71 insertions, 11 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d22e9aa..b0ba14b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-22  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/95268
+	* tree-ssa-sink.c (sink_common_stores_to_bb): Handle clobbers
+	properly.
+
 2020-05-22  Jan Hubicka  <hubicka@ucw.cz>
 
 	* tree-streamer.c (record_common_node): Fix hash value of pre-streamed
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1e8ad06..5a62826 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2020-05-22  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/95268
+	* g++.dg/torture/pr95268.C: New testcase.
+
+2020-05-22  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/95248
 	* gcc.dg/torture/pr95248.c: New testcase.
 
diff --git a/gcc/testsuite/g++.dg/torture/pr95268.C b/gcc/testsuite/g++.dg/torture/pr95268.C
new file mode 100644
index 0000000..8385b86
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr95268.C
@@ -0,0 +1,46 @@
+// { dg-do compile }
+// { dg-require-effective-target lp64 }
+// { dg-additional-options "-Wno-overflow" }
+
+#include <algorithm>
+
+extern short var_0, var_2, var_3, var_9, var_11, var_13, var_14, var_19, var_22,
+    var_32, var_37, var_44, var_57, var_59, var_63, var_70;
+extern unsigned var_5;
+extern char var_6, var_12, var_18, var_38, var_39, var_43, var_55, var_64,
+    arr_35;
+extern long var_7, var_8, var_10, var_15, var_25, var_56;
+extern int var_21, var_36, var_51, var_65, var_68, arr_7;
+extern bool var_46, var_58, var_67;
+
+void test() {
+  var_12 = 0 >= 0;
+  var_13 = arr_7;
+  var_14 = (unsigned long)var_7 >> -564810131 + 564810189;
+  var_15 = var_5;
+  var_18 = -602739307623583391;
+  var_19 = -~0;
+  var_21 = var_10 >> var_8 - 17101301574577641170ULL;
+  var_22 = var_5;
+  var_25 = var_9;
+  var_32 = std::max((unsigned)var_2, var_5);
+  var_36 = 9557;
+  var_37 = 394545925;
+  var_38 = 0 >= 0;
+  var_39 = var_5;
+  var_43 = 0;
+  var_44 = arr_35;
+  var_46 = var_7;
+  for (short a = 0; a < 9; a = 021)
+    for (short b = 0; b < 024; b += 4)
+      var_51 = std::min((long long)(var_2 ?: var_9), (long long)var_9);
+  var_55 = var_0;
+  var_56 = 3896150587;
+  var_57 = var_11;
+  var_58 = var_59 = var_11;
+  var_63 = 73;
+  var_64 = 10393232284806619711ULL;
+  var_65 = var_3;
+  var_67 = var_6;
+  var_68 = var_70 = 0;
+}
diff --git a/gcc/tree-ssa-sink.c b/gcc/tree-ssa-sink.c
index c5b535be..b61ecf1 100644
--- a/gcc/tree-ssa-sink.c
+++ b/gcc/tree-ssa-sink.c
@@ -534,7 +534,9 @@ sink_common_stores_to_bb (basic_block bb)
 	      /* ??? We could handle differing SSA uses in the LHS by inserting
 		 PHIs for them.  */
 	      else if (! operand_equal_p (gimple_assign_lhs (first_store),
-					  gimple_assign_lhs (def), 0))
+					  gimple_assign_lhs (def), 0)
+		       || (gimple_clobber_p (first_store)
+			   && !gimple_clobber_p (def)))
 		{
 		  first_store = NULL;
 		  break;
@@ -546,16 +548,17 @@ sink_common_stores_to_bb (basic_block bb)
 
 	  /* Check if we need a PHI node to merge the stored values.  */
 	  bool allsame = true;
-	  for (unsigned i = 1; i < vdefs.length (); ++i)
-	    {
-	      gimple *def = SSA_NAME_DEF_STMT (vdefs[i]);
-	      if (! operand_equal_p (gimple_assign_rhs1 (first_store),
-				     gimple_assign_rhs1 (def), 0))
-		{
-		  allsame = false;
-		  break;
-		}
-	    }
+	  if (!gimple_clobber_p (first_store))
+	    for (unsigned i = 1; i < vdefs.length (); ++i)
+	      {
+		gimple *def = SSA_NAME_DEF_STMT (vdefs[i]);
+		if (! operand_equal_p (gimple_assign_rhs1 (first_store),
+				       gimple_assign_rhs1 (def), 0))
+		  {
+		    allsame = false;
+		    break;
+		  }
+	      }
 
 	  /* We cannot handle aggregate values if we need to merge them.  */
 	  tree type = TREE_TYPE (gimple_assign_lhs (first_store));