On Thu, 19 Oct 2023, Georg-Johann Lay wrote:
> Just came across the following test case
>
> #include <stdio.h>
>
> int main (void)
> {
> float a = -248.75;
> printf ("%f\n", a);
>
> unsigned char* ptr = (unsigned char*) &a;
> for (size_t i = 0; i < sizeof (a); i++)
> {
> printf ("%.2X ", ptr[i]);
> }
> }
>
> Compiled with gcc v13.2 (or master) and -O3 -std=c2x.
>
> The for loop prints "00 00 00 00" which is because "a"
> is not written to the frame, but read in the loop thus garbage.
>
> With -fno-strict-aliasing, output is "00 C0 78 C3" as expected.
>
> https://godbolt.org/z/GMcez7M95
>
> What am I missing?
Nice catch, I've filed https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111884
Alexander
