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Minor sk_memset{16|32}_SSE2 optimization.

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Using explicitly indexed references allows some compilers to generate more efficient loops. For gcc 4.6.3:

613c18: 83 ea 10 sub $0x10,%edx
613c1b: 66 0f 7f 07 movdqa %xmm0,(%rdi)
613c1f: 66 0f 7f 47 10 movdqa %xmm0,0x10(%rdi)
613c24: 66 0f 7f 47 20 movdqa %xmm0,0x20(%rdi)
613c29: 66 0f 7f 47 30 movdqa %xmm0,0x30(%rdi)
613c2e: 48 83 c7 40 add $0x40,%rdi
613c32: 83 fa 0f cmp $0xf,%edx
613c35: 7f e1 jg 613c18 <_Z16sk_memset32_SSE2Pjji+0x38>

vs. previous:

613c18: 83 ea 10 sub $0x10,%edx
613c1b: 66 0f 7f 07 movdqa %xmm0,(%rdi)
613c1f: 66 0f 7f 47 10 movdqa %xmm0,0x10(%rdi)
613c24: 66 0f 7f 47 20 movdqa %xmm0,0x20(%rdi)
613c29: 48 83 c7 40 add $0x40,%rdi
613c2d: 83 fa 0f cmp $0xf,%edx
613c30: 66 0f 7f 47 f0 movdqa %xmm0,-0x10(%rdi)
613c35: 7f e1 jg 613c18 <_Z16sk_memset32_SSE2Pjji+0x38>


This yields a 0.2% - 1% improvement with the memset micro benchmarks, presumably due to avoiding a stall on the next store after the %rdi increment.

R=reed@google.com, senorblanco@chromium.org

Author: fmalita@chromium.org

Review URL: https://chromiumcodereview.appspot.com/21703003

git-svn-id: http://skia.googlecode.com/svn/trunk@10545 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
commit-bot@chromium.org 2013-08-05 20:25:57 +00:00
parent 67ed64e9aa
commit 9772a52f0d
1 changed files with 10 additions and 8 deletions
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18
src/opts/SkUtils_opts_SSE2.cpp
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@ -25,10 +25,11 @@ void sk_memset16_SSE2(uint16_t *dst, uint16_t value, int count)
__m128i *d = reinterpret_cast<__m128i*>(dst);
__m128i value_wide = _mm_set1_epi16(value);
while (count >= 32) {
_mm_store_si128(d++, value_wide);
_mm_store_si128(d++, value_wide);
_mm_store_si128(d++, value_wide);
_mm_store_si128(d++, value_wide);
_mm_store_si128(d , value_wide);
_mm_store_si128(d + 1, value_wide);
_mm_store_si128(d + 2, value_wide);
_mm_store_si128(d + 3, value_wide);
d += 4;
count -= 32;
}
dst = reinterpret_cast<uint16_t*>(d);
@ -54,10 +55,11 @@ void sk_memset32_SSE2(uint32_t *dst, uint32_t value, int count)
__m128i *d = reinterpret_cast<__m128i*>(dst);
__m128i value_wide = _mm_set1_epi32(value);
while (count >= 16) {
_mm_store_si128(d++, value_wide);
_mm_store_si128(d++, value_wide);
_mm_store_si128(d++, value_wide);
_mm_store_si128(d++, value_wide);
_mm_store_si128(d , value_wide);
_mm_store_si128(d + 1, value_wide);
_mm_store_si128(d + 2, value_wide);
_mm_store_si128(d + 3, value_wide);
d += 4;
count -= 16;
}
dst = reinterpret_cast<uint32_t*>(d);