On Tue, Dec 17, 2013 at 06:50:24PM +0100, Jakub Jelinek wrote:
> Isn't this undefined behavior in C? I mean, shouldn't you
> shift up (unsigned __int128) 1 and only cast to (__int128) at the end?
Oh my, how could I.
Yeah, (__int128) 1 << 127 is UB. Fixed below, ok now?
2013-12-17 Marek Polacek <pola...@redhat.com>
testsuite/:
* c-c++-common/ubsan/overflow-int128.c: New test.
--- gcc/testsuite/c-c++-common/ubsan/overflow-int128.c.mp 2013-12-17
16:54:28.123468111 +0100
+++ gcc/testsuite/c-c++-common/ubsan/overflow-int128.c 2013-12-17
18:54:19.000000000 +0100
@@ -0,0 +1,40 @@
+/* { dg-do run } */
+/* { dg-require-effective-target int128 } */
+/* { dg-options "-fsanitize=signed-integer-overflow" } */
+/* { dg-skip-if "" { *-*-* } { "-flto" } { "" } } */
+
+/* 2^127 - 1 */
+#define INT128_MAX (__int128) (((unsigned __int128) 1 << ((__SIZEOF_INT128__ *
__CHAR_BIT__) - 1)) - 1)
+#define INT128_MIN (-INT128_MAX - 1)
+
+int
+main (void)
+{
+ volatile __int128 i = INT128_MAX;
+ volatile __int128 j = 1;
+ volatile __int128 k = i + j;
+ k = j + i;
+ i++;
+ j = INT128_MAX - 100;
+ j += (1 << 10);
+
+ j = INT128_MIN;
+ i = -1;
+ k = i + j;
+ k = j + i;
+ j--;
+ j = INT128_MIN + 100;
+ j += -(1 << 10);
+
+ i = INT128_MAX;
+ j = 2;
+ k = i * j;
+
+ i = INT128_MIN;
+ i = -i;
+
+ return 0;
+}
+
+/* { dg-output "signed integer overflow: 0x7fffffffffffffffffffffffffffffff
\\+ 1 cannot be represented in type '__int128'(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: 1 \\+
0x7fffffffffffffffffffffffffffffff cannot be represented in type
'__int128'(\n|\r\n|\r)" } */
Marek
