https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82677
Niels Möller <nisse at lysator dot liu.se> changed:
What |Removed |Added
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CC| |nisse at lysator dot liu.se
--- Comment #10 from Niels Möller <nisse at lysator dot liu.se> ---
Out of curiosity, how is this handled for division instructions generated by
gcc, with no __asm__ involved? E.g., consider
int foo(int d) {
int r = 1234567;
if (d != 0)
r = r / d;
return r;
}
On an architecture where the div instruction doesn't raise any exception on
divide by zero, this function could be compiled to a division instruction +
conditional move, without any branch instruction. Right?
But on most architectures, that optimization would be invalid, and the compiler
must somehow know that. Is that a property on the representation of division
expression? Or is it tied to some property of the instruction pattern for the
divide instruction?
My question really is: What would it take to mark an __asm__ expression so that
it's treated in the same way as a plain C division?
