Source:
#include <string.h>
void dequant_lsps(double *lsps, int num,
const unsigned short *values,
int n_stages, const unsigned char * __restrict table,
const double * __restrict mul_q, const double * __restrict
base_q)
{
const unsigned char *t_off = &table[values[0] * num];
int m;
memset(lsps, 0, num * sizeof(*lsps));
for (m = 0; m < num; m++)
lsps[m] += base_q[0] + mul_q[0] * t_off[m];
}
> /usr/local/gcc45/bin/gcc -O3 -S base_lsp.c
The inner loop:
L3:
movzbl (%r15), %edx
incq %r15
cvtsi2sd %edx, %xmm0
mulsd 0(%r13), %xmm0 <- constant (and "0" prefix)
addsd (%r14), %xmm0 <- constant
addsd (%rbx,%rax), %xmm0
movsd %xmm0, (%rbx,%rax)
addq $8, %rax
cmpq %rcx, %rax
jne L3
Rest of the output attached.
base_q and mul_q should be loaded outside of the loop but aren't. I added
__restrict to base_q/mul_q/table, but it didn't affect it.
Code is reduced from FFmpeg WMA Voice decoder.
--
Summary: Constant load not raised out of loop
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: astrange at ithinksw dot com
GCC host triplet: x86_64-apple-darwin10.2.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43224
