Bug 75595 – Default HashTraits for Opcode don't work for Opcode = 0

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

[Michael Saboff]

Opcode is defined as a void* and the value '0' is used in a HaspMap when COMPUTED_GOTO_INTERPRETER is enabled.

An Opcode specific HashTraits needs to be created to account for this.

[Michael Saboff]

Created attachment 121202 [details]
Proposed patch

[WebKit Review Bot]

Attachment 121202 [details] did not pass style-queue:

Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'Source/JavaScriptCore/ChangeLog', u'Source..." exit_code: 1

Source/JavaScriptCore/interpreter/Interpreter.h:45:  Code inside a namespace should not be indented.  [whitespace/indent] [4]
Total errors found: 1 in 2 files


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

[Michael Saboff]

Created attachment 121203 [details]
Patch with indent change for stylebot

[Geoffrey Garen]

Comment on attachment 121203 [details]
Patch with indent change for stylebot

A few comments:

1. I believe you can just use WTF::UnsignedWithZeroKeyHashTraits. You can do this by putting UnsignedWithZeroKeyHashTraits in the declaration of any hash table using Opcode as key, or by declaring HashTraits<Opcode> to inherit from UnsignedWithZeroKeyHashTraits. This is better than duplicating UnsignedWithZeroKeyHashTraits.

2. This code should not be conditional on #if ENABLE(COMPUTED_GOTO_INTERPRETER). That feature define does not have any bearing on whether the Opcode type has 0 in its domain.

3. The best place to put HashTraits for Opcode is Opcode.h. That way, it's impossible to put Opcode into a hash table inocrrectly.

[Geoffrey Garen]

Even better solution: fix up Interpreter::initialize, as we discussed.

[Michael Saboff]

Created attachment 121379 [details]
Updated patch as discussed

[David Harrison]

rdar://10649745

[Geoffrey Garen]

I think you can remove the whole "if (canUseJIT)" case from Interpreter::initialize. m_opcodeTable isn't used at all if Opcodes are not pointers.

[Michael Saboff]

Committed r104338: <http://trac.webkit.org/changeset/104338>