decompress: refine data depdency #140
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danlark1
reviewed
Aug 24, 2021
snappy.cc
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| ip += next_literal_tag + 1; | ||
| } else { | ||
| *tag = ip[tag_type]; | ||
| ip += tag_type +1; |
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Please, separate +1 with space like + 1
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Good catch. Updated in new version.
|
LGTM |
pwnall
requested changes
Aug 26, 2021
snappy.cc
Outdated
| *tag = is_literal ? ip[literal_tag_offset] : ip[tag_type]; | ||
| ip += is_literal ? literal_tag_offset : tag_type; | ||
| ip++; | ||
| if (0 == tag_type) { |
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Can we add the is_literal constant back?
const bool is_literal = (tag_type == 0);
if (is_literal) {This would make it easier for me to read the code. I hope it doesn't throw off Clang's codegen?
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Updated to reflect the comment. Thanks.
The final ip advance value doesn't have to wait for the result of offset to load *tag. It can be computed along with the offset, so the codegen will use one csinc in parallel with ldrb. This will improve the throughput. With this change it is observed ~4.2% uplift in UFlat/10 and ~3.7% in UFlatMedley Signed-off-by: Jun He <jun.he@arm.com> Change-Id: I20ab211235bbf578c6c978f2bbd9160a49e920da
pwnall
approved these changes
Aug 31, 2021
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The final ip advance value doesn't have to wait for
the result of offset to load *tag. It can be computed
along with the offset, so the codegen will use one
csinc in parallel with ldrb. This will improve the
throughput.
With this change it is observed ~4.2% uplift in UFlat/10
and ~3.7% in UFlatMedley
Signed-off-by: Jun He jun.he@arm.com
Change-Id: I20ab211235bbf578c6c978f2bbd9160a49e920da