--- Comment #4 from rguenth at gcc dot gnu dot org 2010-07-06 13:38 ---
Subject: Bug 44828
Author: rguenth
Date: Tue Jul 6 13:37:58 2010
New Revision: 161869
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=161869
Log:
2010-07-06 Richard Guenther
PR middle-end/44828
--- Comment #3 from rguenth at gcc dot gnu dot org 2010-07-06 10:35 ---
The bug is that we have in .original
{
return si1 * si2;
}
while it should have been
{
return (char)((unsigned char) si1 * (unsigned char) si2);
}
which is premature optimization by convert_to_integer, short-
--- Comment #2 from jakub at gcc dot gnu dot org 2010-07-06 09:33 ---
Not sure whether the testcase is valid or not. The multiplication using char
variables on both sides (and likewise for result) is: -54 * -56 (= 3024),
but (char) 3024 is -48. For int that would be clear undefined beh
--- Comment #1 from jakub at gcc dot gnu dot org 2010-07-06 09:25 ---
Shorter testcase:
extern void abort (void);
static char
foo (char si1, char si2)
{
return si1 * si2;
}
int a = 0x105F61CA;
int
main (void)
{
int b = 0x0332F5C8;
if (foo (b, a) > 0)
abort ();
return 0;
}
