https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19347
Phosit <phosit at autistici dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |phosit at autistici dot org
--- Comment #9 from Phosit <phosit at autistici dot org> ---
When there are few iterations (likely when it is unroled) there is no
alias-check:
void fill(int* data, int& value)
{
for(unsigned long i{0}; i != 4; ++i)
data[i] = value;
}
--- at -O2 results in:
fill(int*, int&):
movd xmm1, DWORD PTR [rsi]
pshufd xmm0, xmm1, 0xe0
movq QWORD PTR [rdi], xmm0
movd xmm0, DWORD PTR [rsi]
pshufd xmm0, xmm0, 0xe0
movq QWORD PTR [rdi+8], xmm0
ret
---
At -O3 the loop isn't removed and (thus) there is an alias-check.
