Ciao,
Il 2020-02-11 14:56 Marc Glisse ha scritto:
On Tue, 11 Feb 2020, Niels Möller wrote:
if (usize != vsize)
return (usize > vsize) ? 1 : -1;
On x86_64, both gcc and clang optimize (usize > vsize) ? 1 : -1 to 2 *
(usize > vsize) - 1 (as a single LEA for gcc, 2 ADD for llvm). So the
generated code may be just as good with the simple code.
We know, optimising is a complex task, and we are not writing a compiler
here. But it is funnier to observe how the compilers translate the last
line of mpz/cmp.c:
return (usize >= 0 ? cmp : -cmp);
in the branches where the compiler "knows" that cmp is zero :-)
Ĝis,
m
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