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

	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: r253743

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f67bef557bd3ff11d8276ef6fe6d7fa8254689ce..e55d99a9b972d44cb62ef7a2f2a22585d06d88b3 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+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.
+
 2017-10-10  Andreas Tobler  <andreast@gcc.gnu.org>
 
        * config.gcc: (armv7*-*-freebsd*): New target.

diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index 736012a139fcf9459dd50d981b164529a1d65860..2af0b45413f6acd8688dde4f533f1804cd79dceb 100644 (file)
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -1565,8 +1565,8 @@ 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)
@@ -1574,7 +1574,7 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
                                         NULL_RTX, NULL, hipart_different,
                                         PROB_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,
                                       PROB_VERY_UNLIKELY);
              emit_jump (done_label);

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c53d6b168f8378ebbbdcad9241e7d8d7462a517e..332d709643e94959bbc3706e41fe9501c6658871 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+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.
+
 2017-10-06  Thomas Koenig  <tkoenig@gcc.gnu.org>
             Steven G. Kargl  <kargl@gcc.gnu.org>
 

diff --git a/gcc/testsuite/gcc.dg/pr82274-1.c b/gcc/testsuite/gcc.dg/pr82274-1.c
new file mode 100644 (file)
index 0000000..f96b733
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr82274-1.c
@@ -0,0 +1,16 @@
+/* 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;
+}

diff --git a/gcc/testsuite/gcc.dg/pr82274-2.c b/gcc/testsuite/gcc.dg/pr82274-2.c
new file mode 100644 (file)
index 0000000..ccc55b5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr82274-2.c
@@ -0,0 +1,22 @@
+/* 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 (m, m, &r))
+    __builtin_abort ();
+  return 0;
+}

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index d04836f070df149a77c2c1f1954d143bd921cf0e..8b1238e907c7345a759c65ae245887e2fd4b7cfa 100644 (file)
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,10 @@
+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.
+
 2017-07-20  Peter Bergner  <bergner@vnet.ibm.com>
 
        Backport from mainline

diff --git a/libgcc/libgcc2.c b/libgcc/libgcc2.c
index 3797e046f9249710067fac5513b08f3dc5696172..0024a5756cb3ce98fa23ef23d804966f36f8d4bc 100644 (file)
--- a/libgcc/libgcc2.c
+++ b/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};