https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103336
Bug ID: 103336
Summary: [arm64] operations on long double generate calls to
libgcc
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: sebpop at gmail dot com
Target Milestone: ---
On testsuite/gcc.target/i386/long-double-64-1.c, gcc produces a call to
__multf3 on arm64 and the test checks that such a call is not generated on
x86_64.
$ cat a.c
long double
foo (long double x)
{
return x * x;
}
On arm64:
$ gcc -O2 -S -o- a.c
foo:
stp x29, x30, [sp, -16]!
mov v1.16b, v0.16b
mov x29, sp
bl __multf3
ldp x29, x30, [sp], 16
ret
On x64:
$ gcc -O2 -S -o- a.c
foo:
endbr64
fldt 8(%rsp)
fmul %st(0), %st
ret
Why GCC does not generate an fmul on arm64 instead of calling libgcc?
There is a related performance issue in libGeos:
https://github.com/libgeos/geos/issues/509
