Issue 6576030: X64 Crankshaft: Implement Math.abs on x64 lithium.

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Issue 6576030: X64 Crankshaft: Implement Math.abs on x64 lithium. (Closed)

Created:
9 years, 10 months ago by William Hesse

Modified:
9 years, 7 months ago

Reviewers:
Lasse Reichstein

CC:
v8-dev

Base URL:
http://v8.googlecode.com/svn/branches/bleeding_edge/

Visibility:
Public.

Description

X64 Crankshaft: Implement Math.abs on x64 lithium. Committed: http://code.google.com/p/v8/source/detail?r=6936

Patch Set 1 #

Total comments: 4

Created: 9 years, 10 months ago

Download [raw] [tar.bz2]

	Unified diffs	Side-by-side diffs	Stats (+134 lines, -6 lines)			Patch
M	src/x64/assembler-x64.h	View	1 chunk	+2 lines, -0 lines	0 comments	Download
M	src/x64/assembler-x64.cc	View	1 chunk	+22 lines, -0 lines	0 comments	Download
M	src/x64/disasm-x64.cc	View	1 chunk	+7 lines, -3 lines	0 comments	Download
M	src/x64/lithium-codegen-x64.h	View	1 chunk	+1 line, -0 lines	0 comments	Download
M	src/x64/lithium-codegen-x64.cc	View	1 chunk	+96 lines, -2 lines	4 comments	Download
M	src/x64/macro-assembler-x64.h	View	1 chunk	+1 line, -1 line	0 comments	Download
M	src/x64/macro-assembler-x64.cc	View	1 chunk	+5 lines, -0 lines	0 comments	Download

Messages

Total messages: 2 (0 generated)

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Lasse Reichstein

9 years, 10 months ago (2011-02-24 13:57:02 UTC) #2

LGTM

http://codereview.chromium.org/6576030/diff/1/src/x64/lithium-codegen-x64.cc
File src/x64/lithium-codegen-x64.cc (right):

http://codereview.chromium.org/6576030/diff/1/src/x64/lithium-codegen-x64.cc#...
src/x64/lithium-codegen-x64.cc:2333: __ negl(input_reg);
If you want to avoid the jumps, you can do:

movl(kScratchRegister, input_reg);
asrl(kScratchRegister, 31);
xorl(input_reg, kScratchRegister);
subl(inpt_reg, kScratchRegister);
DeoptimizeIf(negative, ...).

On the other hand, it's probably not any faster than using negl.

http://codereview.chromium.org/6576030/diff/1/src/x64/lithium-codegen-x64.cc#...
src/x64/lithium-codegen-x64.cc:2334: __ testl(input_reg, input_reg);
The negl instruction sets the sign flag, so you can omit the testl.

http://codereview.chromium.org/6576030/diff/1/src/x64/lithium-codegen-x64.cc#...
src/x64/lithium-codegen-x64.cc:2358: XMMRegister  scratch = xmm0;
Extra space before "scratch".

http://codereview.chromium.org/6576030/diff/1/src/x64/lithium-codegen-x64.cc#...
src/x64/lithium-codegen-x64.cc:2362: __ andpd(input_reg, scratch);
Neat.

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