https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93301
--- Comment #4 from Alexander Cherepanov <ch3root at openwall dot com> ---
(In reply to Richard Biener from comment #1)
> guess DOM would also happily propagate equivalences
Yeah, this gives a simpler testcase:
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#include <stdio.h>
__attribute__((noipa)) // imagine it in a separate TU
static int opaque(int i) { return i; }
int main()
{
unsigned char x = opaque(1);
unsigned char y;
(void)&y;
if (x - 1 == y) {
printf("x = %d; x - 1 = %d\n", x, opaque(1) ? x - 1 : 5);
opaque(y);
}
}
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$ gcc -std=c11 test.c && ./a.out
x = 1; x - 1 = 0
$ gcc -std=c11 -O3 test.c && ./a.out
x = 1; x - 1 = 5
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gcc x86-64 version: gcc (GCC) 10.0.1 20200126 (experimental)
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