https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94035
--- Comment #5 from Alexander Cherepanov <ch3root at openwall dot com> --- I see. But the problem with decimal floating-point formats remains... Based on bug 93806, comment 41, here is an example with equal but different values: ---------------------------------------------------------------------- #include <stdio.h> __attribute__((noipa)) // imagine it in a separate TU static _Decimal32 opaque(_Decimal32 d) { return d; } int main() { _Decimal32 x = opaque(1.0DF); unsigned char *p = (unsigned char *)&x; if (x == 1.00DF) printf("%d\n", p[0]); printf("%d\n", p[0]); } ---------------------------------------------------------------------- $ gcc -std=c2x -pedantic -Wall -Wextra test.c && ./a.out 10 10 $ gcc -std=c2x -pedantic -Wall -Wextra -O3 test.c && ./a.out 100 10 ---------------------------------------------------------------------- gcc x86-64 version: gcc (GCC) 10.0.1 20200305 (experimental) ---------------------------------------------------------------------- And then there are non-canonical representations for DFP values...