re PR middle-end/91450 (__builtin_mul_overflow(A,B,R) wrong code if product < 0, *R is unsigned, and !(A&B))

	PR middle-end/91450
	* internal-fn.c (expand_mul_overflow): For s1 * s2 -> ur, if one
	operand is negative and one non-negative, compare the non-negative
	one against 0 rather than comparing s1 & s2 against 0.  Otherwise,
	don't compare (s1 & s2) == 0, but compare separately both s1 == 0
	and s2 == 0, unless one of them is known to be negative.  Remove
	tem2 variable, use tem where tem2 has been used before.

	* gcc.c-torture/execute/pr91450-1.c: New test.
	* gcc.c-torture/execute/pr91450-2.c: New test.

From-SVN: r278437

5 files changed, 194 insertions, 11 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 030d71b..6560a39 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2019-11-19  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/91450
+	* internal-fn.c (expand_mul_overflow): For s1 * s2 -> ur, if one
+	operand is negative and one non-negative, compare the non-negative
+	one against 0 rather than comparing s1 & s2 against 0.  Otherwise,
+	don't compare (s1 & s2) == 0, but compare separately both s1 == 0
+	and s2 == 0, unless one of them is known to be negative.  Remove
+	tem2 variable, use tem where tem2 has been used before.
+
 2019-11-19  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* doc/invoke.texi (-gno-internal-reset-location-views): Fix typo.
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index 88d52d2..6bbbc9e 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -1409,7 +1409,7 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
   /* s1 * s2 -> ur  */
   if (!uns0_p && !uns1_p && unsr_p)
     {
-      rtx tem, tem2;
+      rtx tem;
       switch (pos_neg0 | pos_neg1)
 	{
 	case 1: /* Both operands known to be non-negative.  */
@@ -1439,10 +1439,8 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
 	      ops.op2 = NULL_TREE;
 	      ops.location = loc;
 	      res = expand_expr_real_2 (&ops, NULL_RTX, mode, EXPAND_NORMAL);
-	      tem = expand_binop (mode, and_optab, op0, op1, NULL_RTX, false,
-				  OPTAB_LIB_WIDEN);
-	      do_compare_rtx_and_jump (tem, const0_rtx, EQ, true, mode,
-				       NULL_RTX, NULL, done_label,
+	      do_compare_rtx_and_jump (pos_neg0 == 1 ? op0 : op1, const0_rtx, EQ,
+				       true, mode, NULL_RTX, NULL, done_label,
 				       profile_probability::very_likely ());
 	      goto do_error_label;
 	    }
@@ -1473,16 +1471,23 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
 	  arg1 = error_mark_node;
 	  emit_jump (do_main_label);
 	  emit_label (after_negate_label);
-	  tem2 = expand_binop (mode, xor_optab, op0, op1, NULL_RTX, false,
-			       OPTAB_LIB_WIDEN);
-	  do_compare_rtx_and_jump (tem2, const0_rtx, GE, false, mode, NULL_RTX,
-				   NULL, do_main_label, profile_probability::very_likely ());
+	  tem = expand_binop (mode, xor_optab, op0, op1, NULL_RTX, false,
+			      OPTAB_LIB_WIDEN);
+	  do_compare_rtx_and_jump (tem, const0_rtx, GE, false, mode, NULL_RTX,
+				   NULL, do_main_label,
+				   profile_probability::very_likely ());
 	  /* One argument is negative here, the other positive.  This
 	     overflows always, unless one of the arguments is 0.  But
 	     if e.g. s2 is 0, (U) s1 * 0 doesn't overflow, whatever s1
 	     is, thus we can keep do_main code oring in overflow as is.  */
-	  do_compare_rtx_and_jump (tem, const0_rtx, EQ, true, mode, NULL_RTX,
-				   NULL, do_main_label, profile_probability::very_likely ());
+	  if (pos_neg0 != 2)
+	    do_compare_rtx_and_jump (op0, const0_rtx, EQ, true, mode, NULL_RTX,
+				     NULL, do_main_label,
+				     profile_probability::very_unlikely ());
+	  if (pos_neg1 != 2)
+	    do_compare_rtx_and_jump (op1, const0_rtx, EQ, true, mode, NULL_RTX,
+				     NULL, do_main_label,
+				     profile_probability::very_unlikely ());
 	  expand_arith_set_overflow (lhs, target);
 	  emit_label (do_main_label);
 	  goto do_main;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b569888..16a4106 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 2019-11-19  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/91450
+	* gcc.c-torture/execute/pr91450-1.c: New test.
+	* gcc.c-torture/execute/pr91450-2.c: New test.
+
 	PR c++/92504
 	* g++.dg/gomp/pr92504.C: New test.
 
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr91450-1.c b/gcc/testsuite/gcc.c-torture/execute/pr91450-1.c
new file mode 100644
index 0000000..9aafc5f
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr91450-1.c
@@ -0,0 +1,88 @@
+/* PR middle-end/91450 */
+
+__attribute__((noipa)) unsigned long long
+foo (int a, int b)
+{
+  unsigned long long r;
+  if (!__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  return r;
+}
+
+__attribute__((noipa)) unsigned long long
+bar (int a, int b)
+{
+  unsigned long long r;
+  if (a >= 0)
+    return 0;
+  if (!__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  return r;
+}
+
+__attribute__((noipa)) unsigned long long
+baz (int a, int b)
+{
+  unsigned long long r;
+  if (b >= 0)
+    return 0;
+  if (!__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  return r;
+}
+
+__attribute__((noipa)) unsigned long long
+qux (int a, int b)
+{
+  unsigned long long r;
+  if (a >= 0)
+    return 0;
+  if (b < 0)
+    return 0;
+  if (!__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  return r;
+}
+
+__attribute__((noipa)) unsigned long long
+quux (int a, int b)
+{
+  unsigned long long r;
+  if (a < 0)
+    return 0;
+  if (b >= 0)
+    return 0;
+  if (!__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  return r;
+}
+
+int
+main ()
+{
+  if (foo (-4, 2) != -8ULL)
+    __builtin_abort ();
+  if (foo (2, -4) != -8ULL)
+    __builtin_abort ();
+  if (bar (-4, 2) != -8ULL)
+    __builtin_abort ();
+  if (baz (2, -4) != -8ULL)
+    __builtin_abort ();
+  if (qux (-4, 2) != -8ULL)
+    __builtin_abort ();
+  if (quux (2, -4) != -8ULL)
+    __builtin_abort ();
+  if (foo (-2, 1) != -2ULL)
+    __builtin_abort ();
+  if (foo (1, -2) != -2ULL)
+    __builtin_abort ();
+  if (bar (-2, 1) != -2ULL)
+    __builtin_abort ();
+  if (baz (1, -2) != -2ULL)
+    __builtin_abort ();
+  if (qux (-2, 1) != -2ULL)
+    __builtin_abort ();
+  if (quux (1, -2) != -2ULL)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr91450-2.c b/gcc/testsuite/gcc.c-torture/execute/pr91450-2.c
new file mode 100644
index 0000000..bfaabbb
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr91450-2.c
@@ -0,0 +1,76 @@
+/* PR middle-end/91450 */
+
+__attribute__((noipa)) void
+foo (int a, int b)
+{
+  unsigned long long r;
+  if (__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  if (r != 0)
+    __builtin_abort ();
+}
+
+__attribute__((noipa)) void
+bar (int a, int b)
+{
+  unsigned long long r;
+  if (a >= 0)
+    return;
+  if (__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  if (r != 0)
+    __builtin_abort ();
+}
+
+__attribute__((noipa)) void
+baz (int a, int b)
+{
+  unsigned long long r;
+  if (b >= 0)
+    return;
+  if (__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  if (r != 0)
+    __builtin_abort ();
+}
+
+__attribute__((noipa)) void
+qux (int a, int b)
+{
+  unsigned long long r;
+  if (a >= 0)
+    return;
+  if (b < 0)
+    return;
+  if (__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  if (r != 0)
+    __builtin_abort ();
+}
+
+__attribute__((noipa)) void
+quux (int a, int b)
+{
+  unsigned long long r;
+  if (a < 0)
+    return;
+  if (b >= 0)
+    return;
+  if (__builtin_mul_overflow (a, b, &r))
+    __builtin_abort ();
+  if (r != 0)
+    __builtin_abort ();
+}
+
+int
+main ()
+{
+  foo (-4, 0);
+  foo (0, -4);
+  foo (0, 0);
+  bar (-4, 0);
+  baz (0, -4);
+  qux (-4, 0);
+  quux (0, -4);
+  return 0;
+}