re PR tree-optimization/81162 (UBSAN switch triggers incorrect optimization in SLSR)

[gcc]

2016-07-14  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/81162
	* gimple-ssa-strength-reduction.c (replace_mult_candidate): Don't
	replace a negate with an add.

[gcc/testsuite]

2016-07-14  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/81162
	* gcc.dg/pr81162.c: New file.

From-SVN: r250212

gcc/ChangeLog

+2016-07-14  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
+
+	PR tree-optimization/81162
+	* gimple-ssa-strength-reduction.c (replace_mult_candidate): Don't
+	replace a negate with an add.
+
 2017-07-14  James Greenhalgh  <james.greenhalgh@arm.com>
 
 	* doc/invoke.texi (arm/-mcpu): Document +crypto.

gcc/gimple-ssa-strength-reduction.c

@@ -2082,13 +2082,14 @@ replace_mult_candidate (slsr_cand_t c, tree basis_name, widest_int bump)
      types but allows for safe negation without twisted logic.  */
   if (wi::fits_shwi_p (bump)
       && bump.to_shwi () != HOST_WIDE_INT_MIN
-      /* It is not useful to replace casts, copies, or adds of
+      /* It is not useful to replace casts, copies, negates, or adds of
 	 an SSA name and a constant.  */
       && cand_code != SSA_NAME
       && !CONVERT_EXPR_CODE_P (cand_code)
       && cand_code != PLUS_EXPR
       && cand_code != POINTER_PLUS_EXPR
-      && cand_code != MINUS_EXPR)
+      && cand_code != MINUS_EXPR
+      && cand_code != NEGATE_EXPR)
     {
       enum tree_code code = PLUS_EXPR;
       tree bump_tree;

gcc/testsuite/ChangeLog

+2016-07-14  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
+
+	PR tree-optimization/81162
+	* gcc.dg/pr81162.c: New file.
+
 2017-07-14  Martin Sebor  <msebor@redhat.com>
 
 	* gcc.dg/tree-ssa/ssa-dse-30.c: Correct test to look for memmove

gcc/testsuite/gcc.dg/pr81162.c

+/* PR tree-optimization/81162 */
+/* { dg-do run } */
+/* { dg-options "-fsanitize=undefined -O2" } */
+
+short s;
+int i1 = 1;
+int i2 = 1;
+unsigned char uc = 147;
+
+int main() {
+  s = (-uc + 2147483647) << 0;
+  if (9031239389974324562ULL >= (-((i1 && i2) + uc) ^ -21096) ) {
+    return 0;
+  } else {
+    return -1;
+  }
+}