41 lines
1.1 KiB
Diff
41 lines
1.1 KiB
Diff
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2017-10-13 Jakub Jelinek <jakub@redhat.com>
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PR target/82274
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* libgcc2.c (__mulvDI3): If both operands have
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the same highpart of -1 and the topmost bit of lowpart is 0,
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multiplication overflows even if both lowparts are 0.
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* gcc.dg/pr82274-1.c: New test.
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--- libgcc/libgcc2.c 2017/10/13 16:50:13 253733
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+++ libgcc/libgcc2.c 2017/10/13 17:19:12 253734
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@@ -375,7 +375,8 @@
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}
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else
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{
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- if (uu.s.high == (Wtype) -1 && vv.s.high == (Wtype) - 1)
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+ if ((uu.s.high & vv.s.high) == (Wtype) -1
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+ && (uu.s.low | vv.s.low) != 0)
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{
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DWunion ww = {.ll = (UDWtype) (UWtype) uu.s.low
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* (UDWtype) (UWtype) vv.s.low};
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--- /dev/null
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+++ gcc/testsuite/gcc.dg/pr82274-1.c
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@@ -0,0 +1,16 @@
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+/* PR target/82274 */
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+/* { dg-do run } */
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+/* { dg-shouldfail "trapv" } */
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+/* { dg-options "-ftrapv" } */
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+
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+int
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+main ()
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+{
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+#ifdef __SIZEOF_INT128__
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+ volatile __int128 m = -(((__int128) 1) << (__CHAR_BIT__ * __SIZEOF_INT128__ / 2));
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+#else
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+ volatile long long m = -(1LL << (__CHAR_BIT__ * __SIZEOF_LONG_LONG__ / 2));
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+#endif
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+ m = m * m;
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+ return 0;
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+}
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