re PR tree-optimization/86017 (multiple consecutive calls to bzero/memset not merged)

2018-06-01  Richard Biener  <rguenther@suse.de>

	PR middle-end/86017
	* gimple-fold.c (var_decl_component_p): Also allow offsetted
	vars wrapped in MEM_REFs.

	* gcc.dg/tree-ssa/pr86017.c: New testcase.

From-SVN: r261061

gcc/ChangeLog

+2018-06-01  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/86017
+	* gimple-fold.c (var_decl_component_p): Also allow offsetted
+	vars wrapped in MEM_REFs.
+
 2018-06-01  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	* config/aarch64/aarch64.c (aarch64_ira_change_pseudo_allocno_class):

gcc/gimple-fold.c

@@ -632,7 +632,9 @@ var_decl_component_p (tree var)
   tree inner = var;
   while (handled_component_p (inner))
     inner = TREE_OPERAND (inner, 0);
-  return SSA_VAR_P (inner);
+  return (DECL_P (inner)
+	  || (TREE_CODE (inner) == MEM_REF
+	      && TREE_CODE (TREE_OPERAND (inner, 0)) == ADDR_EXPR));
 }
 
 /* If the SIZE argument representing the size of an object is in a range

gcc/testsuite/ChangeLog

 2018-06-01  Richard Biener  <rguenther@suse.de>
 
+	PR middle-end/86017
+	* gcc.dg/tree-ssa/pr86017.c: New testcase.
+
+2018-06-01  Richard Biener  <rguenther@suse.de>
+
 	PR ipa/85960
 	* gcc.dg/ipa/ipa-pta-19.c: New testcase.
 

gcc/testsuite/gcc.dg/tree-ssa/pr86017.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-store-merging" } */
+
+void f (void*);
+
+void g (void)
+{
+  char a[8];
+  __builtin_memset (a, 0, 8);
+
+  f (a);
+}
+
+void h (void)
+{
+  char a[8];
+  __builtin_memset (a, 0, 1);
+  __builtin_memset (a + 1, 0, 1);
+  __builtin_memset (a + 2, 0, 1);
+  __builtin_memset (a + 3, 0, 1);
+  __builtin_memset (a + 4, 0, 1);
+  __builtin_memset (a + 5, 0, 1);
+  __builtin_memset (a + 6, 0, 1);
+  __builtin_memset (a + 7, 0, 1);
+
+  f (a);
+}
+
+/* { dg-final { scan-tree-dump "Merged into 1 stores" "store-merging" } } */