Issue 6304001: Support StringCharCodeAt in hydrogen/lithium.

Keyboard Shortcuts

	File
u :	up to issue
j / k :	jump to file after / before current file
J / K :	jump to next file with a comment after / before current file
	Side-by-side diff
i :	toggle intra-line diffs
e :	expand all comments
c :	collapse all comments
s :	toggle showing all comments
n / p :	next / previous diff chunk or comment
N / P :	next / previous comment
<Up> / <Down> :	next / previous line

	Issue
u :	up to list of issues
j / k :	jump to patch after / before current patch
o / <Enter> :	open current patch in side-by-side view
i :	open current patch in unified diff view

	Issue List
j / k :	jump to issue after / before current issue
o / <Enter> :	open current issue

Issue 6304001: Support StringCharCodeAt in hydrogen/lithium. (Closed)

Created:
9 years, 11 months ago by Vitaly Repeshko

Modified:
9 years, 7 months ago

Reviewers:
fschneider

CC:
v8-dev

Visibility:
Public.

Description

Support StringCharCodeAt in hydrogen/lithium.

Patch Set 1 #

Total comments: 4

Created: 9 years, 11 months ago

Download [raw] [tar.bz2]

	Unified diffs	Side-by-side diffs	Stats (+319 lines, -57 lines)			Patch
M	src/ast.cc	View	4 chunks	+9 lines, -17 lines	0 comments	Download
M	src/hydrogen.h	View	1 chunk	+4 lines, -1 line	0 comments	Download
M	src/hydrogen.cc	View	8 chunks	+77 lines, -36 lines	0 comments	Download
M	src/hydrogen-instructions.h	View	4 chunks	+44 lines, -0 lines	2 comments	Download
M	src/ia32/lithium-codegen-ia32.h	View	1 chunk	+1 line, -0 lines	0 comments	Download
M	src/ia32/lithium-codegen-ia32.cc	View	2 chunks	+138 lines, -3 lines	0 comments	Download
M	src/ia32/lithium-ia32.h	View	4 chunks	+28 lines, -0 lines	0 comments	Download
M	src/ia32/lithium-ia32.cc	View	1 chunk	+13 lines, -0 lines	2 comments	Download
M	src/objects.h	View	3 chunks	+4 lines, -0 lines	0 comments	Download
M	src/objects-printer.cc	View	1 chunk	+1 line, -0 lines	0 comments	Download

Messages

Total messages: 2 (0 generated)

Expand Messages | Collapse Messages

fschneider

9 years, 11 months ago (2011-01-14 12:06:11 UTC) #2

I'm with Kevin in that we should avoid adding too many special cases to the
hydrogen-builder.

Maybe we can achieve almost the same performance by implementing
%_StringCharCodeAt in hydrogen and making sure that we inline the builtin
functions that call it with the standard inlining mechanism.

For the out-of-bounds access you need to return NaN which would make the output
representation a double number. This does not seem ideal. - How about returning
a tagged value (smi or heap number) instead?

http://codereview.chromium.org/6304001/diff/1/src/hydrogen-instructions.h
File src/hydrogen-instructions.h (right):

http://codereview.chromium.org/6304001/diff/1/src/hydrogen-instructions.h#new...
src/hydrogen-instructions.h:84: //       HStringChartCodeAt
->HStringCharCodeAt

http://codereview.chromium.org/6304001/diff/1/src/hydrogen-instructions.h#new...
src/hydrogen-instructions.h:2914: class HStringLength: public HUnaryOperation {
Could you use HStringLength to optimize access like s.length (similar to the way
we do for ArrayLength)?

http://codereview.chromium.org/6304001/diff/1/src/ia32/lithium-ia32.cc
File src/ia32/lithium-ia32.cc (right):

http://codereview.chromium.org/6304001/diff/1/src/ia32/lithium-ia32.cc#newcod...
src/ia32/lithium-ia32.cc:1746: return
AssignEnvironment(AssignPointerMap(DefineAsRegister(
I'd rather split this into multiple statements to improve readability.

LOperand* object = UseRegister(instr->string());
LOperand* index = UseRegisterOrConstant(instr->index());
...

http://codereview.chromium.org/6304001/diff/1/src/ia32/lithium-ia32.cc#newcod...
src/ia32/lithium-ia32.cc:1753: return DefineAsRegister(
I'd also split this into 2 statement here.

Expand Messages | Collapse Messages