Changeset 240864 in webkit for trunk/Source/JavaScriptCore/bytecode/ModuleProgramCodeBlock.h

Timestamp:

Feb 1, 2019, 1:14:19 PM (7 years ago)

Author:

[email protected]

Message:

[JSC] Unify CodeBlock IsoSubspaces
​https://bugs.webkit.org/show_bug.cgi?id=194167

Reviewed by Saam Barati.

When we move CodeBlock into its IsoSubspace, we create IsoSubspaces for each subclass of CodeBlock.
But this is not necessary since,

1. They do not override the classInfo methods.
2. sizeof(ProgramCodeBlock etc.) == sizeof(CodeBlock) since subclasses adds no additional fields.

Creating IsoSubspace for each subclass is costly in terms of memory. Especially, IsoSubspace for
ProgramCodeBlock is. We typically create only one ProgramCodeBlock, and it means the rest of the
MarkedBlock (16KB - sizeof(footer) - sizeof(ProgramCodeBlock)) is just wasted.

This patch unifies these IsoSubspaces into one.

• bytecode/CodeBlock.cpp:

(JSC::CodeBlock::destroy):

• bytecode/CodeBlock.h:
• bytecode/EvalCodeBlock.cpp:

(JSC::EvalCodeBlock::destroy): Deleted.

• bytecode/EvalCodeBlock.h: We drop some utility functions in EvalCodeBlock and use UnlinkedEvalCodeBlock's one directly.
• bytecode/FunctionCodeBlock.cpp:

(JSC::FunctionCodeBlock::destroy): Deleted.

• bytecode/FunctionCodeBlock.h:
• bytecode/GlobalCodeBlock.h:
• bytecode/ModuleProgramCodeBlock.cpp:

(JSC::ModuleProgramCodeBlock::destroy): Deleted.

• bytecode/ModuleProgramCodeBlock.h:
• bytecode/ProgramCodeBlock.cpp:

(JSC::ProgramCodeBlock::destroy): Deleted.

• bytecode/ProgramCodeBlock.h:
• interpreter/Interpreter.cpp:

(JSC::Interpreter::execute):

• runtime/VM.cpp:

(JSC::VM::VM):

• runtime/VM.h:

(JSC::VM::forEachCodeBlockSpace):

File:

• trunk/Source/JavaScriptCore/bytecode/ModuleProgramCodeBlock.h (modified) (2 diffs)

trunk/Source/JavaScriptCore/bytecode/ModuleProgramCodeBlock.h

@@ -43 +43 @@
     static IsoSubspace* subspaceFor(VM& vm)
     {
-        return &vm.moduleProgramCodeBlockSpace.space;
+        return &vm.codeBlockSpace.space;
     }
 
@@ -80 +80 @@
     {
     }
-
-    static void destroy(JSCell*);
 };
+static_assert(sizeof(ModuleProgramCodeBlock) == sizeof(CodeBlock), "Subclasses of CodeBlock should be the same size to share IsoSubspace");
 
 } // namespace JSC