https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94111
Bug ID: 94111
Summary: Wrong optimization: decimal floating-point infinity
casted to double -> zero
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: ch3root at openwall dot com
Target Milestone: ---
Cast to double of a decimal floating-point infinity gives zero:
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#include <math.h>
#include <string.h>
#include <stdio.h>
int main()
{
_Decimal32 d = (_Decimal32)INFINITY;
unsigned u;
memcpy(&u, &d, sizeof u);
printf("repr: %08x\n", u);
printf("cast: %g\n", (double)d);
}
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$ gcc -std=c2x -pedantic -Wall -Wextra test.c && ./a.out
repr: 78000000
cast: inf
$ gcc -std=c2x -pedantic -Wall -Wextra -O3 test.c && ./a.out
repr: 78000000
cast: 0
----------------------------------------------------------------------
gcc x86-64 version: gcc (GCC) 10.0.1 20200305 (experimental)
----------------------------------------------------------------------
The representation is right for infinity in _Decimal32.
