Hi!
To represent 128-bit unsigned multiplication results of 64-bit unsigned
operands one sometimes needs 3 HWIs instead of 2.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk?
2015-02-23 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/65170
* wide-int.cc (wi::mul_internal): For the umul_ppmm optimization,
if val[1] < 0, clear also val[2] and return 3.
* gcc.c-torture/execute/pr65170.c: New test.
* gcc.dg/tree-ssa/vrp96.c: New test.
--- gcc/wide-int.cc.jj 2015-01-27 09:25:38.000000000 +0100
+++ gcc/wide-int.cc 2015-02-23 15:43:20.303280261 +0100
@@ -1297,6 +1297,11 @@ wi::mul_internal (HOST_WIDE_INT *val, co
return 1;
}
umul_ppmm (val[1], val[0], op1.ulow (), op2.ulow ());
+ if (val[1] < 0)
+ {
+ val[2] = 0;
+ return 3;
+ }
return 1 + (val[1] != 0 || val[0] < 0);
}
/* Likewise if the output is a full single HWI, except that the
--- gcc/testsuite/gcc.c-torture/execute/pr65170.c.jj 2015-02-23
15:55:10.678713455 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr65170.c 2015-02-23
15:57:40.851272695 +0100
@@ -0,0 +1,27 @@
+/* PR tree-optimization/65170 */
+
+#ifdef __SIZEOF_INT128__
+typedef unsigned __int128 V;
+typedef unsigned long long int H;
+#else
+typedef unsigned long long int V;
+typedef unsigned int H;
+#endif
+
+__attribute__((noinline, noclone)) void
+foo (V b, V c)
+{
+ V a;
+ b &= (H) -1;
+ c &= (H) -1;
+ a = b * c;
+ if (a != 1)
+ __builtin_abort ();
+}
+
+int
+main ()
+{
+ foo (1, 1);
+ return 0;
+}
--- gcc/testsuite/gcc.dg/tree-ssa/vrp96.c.jj 2015-02-23 16:33:45.157112406
+0100
+++ gcc/testsuite/gcc.dg/tree-ssa/vrp96.c 2015-02-23 16:35:22.861527289
+0100
@@ -0,0 +1,53 @@
+/* PR tree-optimization/65170 */
+/* { dg-do compile { target int128 } } */
+/* { dg-options "-O2 -fdump-tree-vrp1" } */
+
+typedef unsigned __int128 T;
+extern void link_error (void);
+extern void required_check (void);
+
+T
+foo (T b, T c)
+{
+ T a;
+ b &= 0xffffffffffffffffULL;
+ c &= 0xffffffffffffffffULL;
+ if (b < 7 || c < 7)
+ return 0;
+ a = b * c;
+ if (a < 49 || a > (((T) 0xfffffffffffffffeULL << 64) | 1))
+ link_error ();
+ return a;
+}
+
+T
+bar (T b, T c)
+{
+ T a;
+ b &= 0xffffffffffffffffULL;
+ c &= 0xffffffffffffffffULL;
+ if (b < 7 || c < 7)
+ return 0;
+ a = b * c;
+ if (a == 49)
+ required_check ();
+ return a;
+}
+
+T
+baz (T b, T c)
+{
+ T a;
+ b &= 0xffffffffffffffffULL;
+ c &= 0xffffffffffffffffULL;
+ if (b < 7 || c < 7)
+ return 0;
+ a = b * c;
+ if (a == (((T) 0xfffffffffffffffeULL << 64) | 1))
+ required_check ();
+ return a;
+}
+
+/* { dg-final { scan-tree-dump-not "link_error" "vrp1" } } */
+/* { dg-final { scan-tree-dump-times "required_check" 2 "vrp1" } } */
+/* { dg-final { cleanup-tree-dump "vrp1" } } */
Jakub
