re PR target/82274 (__builtin_mul_overflow fails to detect overflow for int64_t…

re PR target/82274 (__builtin_mul_overflow fails to detect overflow for int64_t when compiled with -m32)

	PR target/82274
	* internal-fn.c (expand_mul_overflow): If both operands have
	the same highpart of -1 or 0 and the topmost bit of lowpart
	is different, overflow is if res <= 0 rather than res < 0.

	* libgcc2.c (__mulvDI3): If both operands have
	the same highpart of -1 and the topmost bit of lowpart is 0,
	multiplication overflows even if both lowparts are 0.

	* gcc.dg/pr82274-1.c: New test.
	* gcc.dg/pr82274-2.c: New test.

From-SVN: r253734

gcc/ChangeLog

+2017-10-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/82274
+	* internal-fn.c (expand_mul_overflow): If both operands have
+	the same highpart of -1 or 0 and the topmost bit of lowpart
+	is different, overflow is if res <= 0 rather than res < 0.
+
 2017-10-13  Pat Haugen  <pthaugen@us.ibm.com>
 
 	* config/rs6000/rs6000.c (rs6000_builtin_vectorization_cost): Remove

gcc/internal-fn.c

@@ -1770,8 +1770,8 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
 		}
 
 	      /* At this point hipart{0,1} are both in [-1, 0].  If they are
-		 the same, overflow happened if res is negative, if they are
-		 different, overflow happened if res is positive.  */
+		 the same, overflow happened if res is non-positive, if they
+		 are different, overflow happened if res is positive.  */
 	      if (op0_sign != 1 && op1_sign != 1 && op0_sign != op1_sign)
 		emit_jump (hipart_different);
 	      else if (op0_sign == 1 || op1_sign == 1)
@@ -1779,7 +1779,7 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
 					 NULL_RTX, NULL, hipart_different,
 					 profile_probability::even ());
 
-	      do_compare_rtx_and_jump (res, const0_rtx, LT, false, mode,
+	      do_compare_rtx_and_jump (res, const0_rtx, LE, false, mode,
 				       NULL_RTX, NULL, do_error,
 				       profile_probability::very_unlikely ());
 	      emit_jump (done_label);

gcc/testsuite/ChangeLog

+2017-10-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/82274
+	* gcc.dg/pr82274-1.c: New test.
+	* gcc.dg/pr82274-2.c: New test.
+
 2017-10-13  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/80873

gcc/testsuite/gcc.dg/pr82274-1.c

+/* PR target/82274 */
+/* { dg-do run } */
+/* { dg-shouldfail "trapv" } */
+/* { dg-options "-ftrapv" } */
+
+int
+main ()
+{
+#ifdef __SIZEOF_INT128__
+  volatile __int128 m = -(((__int128) 1) << (__CHAR_BIT__ * __SIZEOF_INT128__ / 2));
+#else
+  volatile long long m = -(1LL << (__CHAR_BIT__ * __SIZEOF_LONG_LONG__ / 2));
+#endif
+  m = m * m;
+  return 0;
+}

gcc/testsuite/gcc.dg/pr82274-2.c

+/* PR target/82274 */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+int
+main ()
+{
+#ifdef __SIZEOF_INT128__
+  __int128 m = -(((__int128) 1) << (__CHAR_BIT__ * __SIZEOF_INT128__ / 2));
+  volatile __int128 mv = m;
+  __int128 r;
+#else
+  long long m = -(1LL << (__CHAR_BIT__ * __SIZEOF_LONG_LONG__ / 2));
+  volatile long long mv = m;
+  long long r;
+#endif
+  if (!__builtin_mul_overflow (mv, mv, &r))
+    __builtin_abort ();
+  if (!__builtin_mul_overflow_p (mv, mv, r))
+    __builtin_abort ();
+  if (!__builtin_mul_overflow (m, m, &r))
+    __builtin_abort ();
+  if (!__builtin_mul_overflow_p (m, m, r))
+    __builtin_abort ();
+  return 0;
+}

libgcc/ChangeLog

+2017-10-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/82274
+	* libgcc2.c (__mulvDI3): If both operands have
+	the same highpart of -1 and the topmost bit of lowpart is 0,
+	multiplication overflows even if both lowparts are 0.
+
 2017-09-28  James Bowman  <james.bowman@ftdichip.com>
 
 	* config/ft32/crti-hw.S: Add watchdog vector, FT930 IRQ support.

libgcc/libgcc2.c

@@ -375,7 +375,8 @@ __mulvDI3 (DWtype u, DWtype v)
 		}
 	      else
 		{
-		  if (uu.s.high == (Wtype) -1 && vv.s.high == (Wtype) - 1)
+		  if ((uu.s.high & vv.s.high) == (Wtype) -1
+		      && (uu.s.low | vv.s.low) != 0)
 		    {
 		      DWunion ww = {.ll = (UDWtype) (UWtype) uu.s.low
 				    * (UDWtype) (UWtype) vv.s.low};