middle-end/94206 fix memset folding to avoid types with padding

This makes sure that the store a memset is folded to uses a type
covering all bits.

2020-03-18   Richard Biener  <rguenther@suse.de>

	PR middle-end/94206
	* gimple-fold.c (gimple_fold_builtin_memset): Avoid using
	partial int modes or not mode-precision integer types for
	the store.

	* gcc.dg/torture/pr94206.c: New testcase.

gcc/ChangeLog

+2020-03-18   Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/94206
+	* gimple-fold.c (gimple_fold_builtin_memset): Avoid using
+	partial int modes or not mode-precision integer types for
+	the store.
+
 2020-03-18  Jakub Jelinek  <jakub@redhat.com>
 
 	* asan.c (get_mem_refs_of_builtin_call): Fix up duplicated word issue

gcc/gimple-fold.c

@@ -1235,12 +1235,18 @@ gimple_fold_builtin_memset (gimple_stmt_iterator *gsi, tree c, tree len)
 
   length = tree_to_uhwi (len);
   if (GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (etype)) != length
+      || (GET_MODE_PRECISION (SCALAR_INT_TYPE_MODE (etype))
+	  != GET_MODE_BITSIZE (SCALAR_INT_TYPE_MODE (etype)))
       || get_pointer_alignment (dest) / BITS_PER_UNIT < length)
     return NULL_TREE;
 
   if (length > HOST_BITS_PER_WIDE_INT / BITS_PER_UNIT)
     return NULL_TREE;
 
+  if (!type_has_mode_precision_p (etype))
+    etype = lang_hooks.types.type_for_mode (SCALAR_INT_TYPE_MODE (etype),
+					    TYPE_UNSIGNED (etype));
+
   if (integer_zerop (c))
     cval = 0;
   else

gcc/testsuite/ChangeLog

+2020-03-18   Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/94206
+	* gcc.dg/torture/pr94206.c: New testcase.
+
 2020-03-18  Duan bo  <duanbo3@huawei.com>
 
 	PR target/94201

gcc/testsuite/gcc.dg/torture/pr94206.c

+/* { dg-do run { target lp64 } } */
+
+struct {
+    unsigned long x:33;
+} s;
+typedef __typeof__(s.x + 0) uint33;
+
+int main()
+{
+  uint33 x;
+  __builtin_memset(&x, -1, sizeof x);
+  unsigned long u;
+  __builtin_memcpy(&u, &x, sizeof u);
+  if (u != -1ul)
+    __builtin_abort ();
+  return 0;
+}