Bug 42182 – Change how numeric compare functions are detected

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Gavin Barraclough]

There are three problems with the current mechanism:

* It requires that a function executable be bytecode compiled without being JIT generated (in order to copy the bytecode from the numeric compare function).  This is a problem since we have an invariant when running with the JIT that functions are never bytecode compiled without also being JIT generated (after checking the codeblock we assume the function has JIT code).  To help maintain this invariant 
* This implementation will prevent us from experimenting with alternate compilation paths which do not compile via bytecode.
* It doesn't work.  Functions passing more than two arguments will match if they are comparing their last two arguments, not the first two.  Generally the mapping back from bytecode to semantics may be more complex then initially expected.

(bug can be triggered by following test: "javascript: alert([3,1,5,2,4].sort(function(w, x, y){ return x - y; }));")

[Gavin Barraclough]

Created attachment 61401 [details]
Initial patch, new copy with changelog & test case to follow.

[Gavin Barraclough]

Created attachment 61407 [details]
The patch

[WebKit Review Bot]

Attachment 61407 [details] did not pass style-queue:

Failed to run "['WebKitTools/Scripts/check-webkit-style']" exit_code: 1
JavaScriptCore/parser/Nodes.h:810:  More than one command on the same line  [whitespace/newline] [4]
JavaScriptCore/parser/Nodes.h:811:  More than one command on the same line  [whitespace/newline] [4]
Total errors found: 2 in 5 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Eric Seidel (no email)]

Attachment 61407 [details] did not build on mac:
Build output: http://webkit-commit-queue.appspot.com/results/3528112

[Gavin Barraclough]

Created attachment 61408 [details]
Ooops, submitted patch had issues !DEBUG.

[WebKit Review Bot]

Attachment 61408 [details] did not pass style-queue:

Failed to run "['WebKitTools/Scripts/check-webkit-style']" exit_code: 1
JavaScriptCore/parser/Nodes.h:810:  More than one command on the same line  [whitespace/newline] [4]
JavaScriptCore/parser/Nodes.h:811:  More than one command on the same line  [whitespace/newline] [4]
Total errors found: 2 in 6 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Gavin Barraclough]

committed r63244.