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Link function contexts directly to the previous context.

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Instead of NULL in the previous field of function contexts, put the previous
context.  This saves the indirection of fetching the previous through the
context's closure.

R=ager@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/7134042

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8238 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
kmillikin@chromium.org 2011-06-09 12:45:26 +00:00
parent c40aa827bf
commit 4b96218589
10 changed files with 23 additions and 49 deletions
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4
src/arm/code-stubs-arm.cc
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@ -167,10 +167,10 @@ void FastNewContextStub::Generate(MacroAssembler* masm) {
__ mov(r1, Operand(Smi::FromInt(0)));
__ str(r3, MemOperand(r0, Context::SlotOffset(Context::CLOSURE_INDEX)));
__ str(r0, MemOperand(r0, Context::SlotOffset(Context::FCONTEXT_INDEX)));
__ str(r1, MemOperand(r0, Context::SlotOffset(Context::PREVIOUS_INDEX)));
__ str(cp, MemOperand(r0, Context::SlotOffset(Context::PREVIOUS_INDEX)));
__ str(r1, MemOperand(r0, Context::SlotOffset(Context::EXTENSION_INDEX)));
// Copy the global object from the surrounding context.
// Copy the global object from the previous context.
__ ldr(r1, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
__ str(r1, MemOperand(r0, Context::SlotOffset(Context::GLOBAL_INDEX)));

7
src/arm/macro-assembler-arm.cc
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@ -2538,12 +2538,9 @@ void MacroAssembler::Abort(const char* msg) {
void MacroAssembler::LoadContext(Register dst, int context_chain_length) {
if (context_chain_length > 0) {
// Move up the chain of contexts to the context containing the slot.
ldr(dst, MemOperand(cp, Context::SlotOffset(Context::CLOSURE_INDEX)));
// Load the function context (which is the incoming, outer context).
ldr(dst, FieldMemOperand(dst, JSFunction::kContextOffset));
ldr(dst, MemOperand(cp, Context::SlotOffset(Context::PREVIOUS_INDEX)));
for (int i = 1; i < context_chain_length; i++) {
ldr(dst, MemOperand(dst, Context::SlotOffset(Context::CLOSURE_INDEX)));
ldr(dst, FieldMemOperand(dst, JSFunction::kContextOffset));
ldr(dst, MemOperand(dst, Context::SlotOffset(Context::PREVIOUS_INDEX)));
}
} else {
// Slot is in the current function context. Move it into the

15
src/contexts.cc
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@ -187,11 +187,9 @@ Handle<Object> Context::Lookup(Handle<String> name, ContextLookupFlags flags,
}
}
// proceed with enclosing context
// Proceed with the previous context.
if (context->IsGlobalContext()) {
follow_context_chain = false;
} else if (context->IsFunctionContext()) {
context = Handle<Context>(context->closure()->context(), isolate);
} else {
context = Handle<Context>(context->previous(), isolate);
}
@ -234,7 +232,7 @@ bool Context::GlobalIfNotShadowedByEval(Handle<String> name) {
// Check context only holding the function name variable.
index = scope_info->FunctionContextSlotIndex(*name);
if (index >= 0) return false;
context = Context::cast(context->closure()->context());
context = context->previous();
}
// No local or potential with statement found so the variable is
@ -245,8 +243,10 @@ bool Context::GlobalIfNotShadowedByEval(Handle<String> name) {
void Context::ComputeEvalScopeInfo(bool* outer_scope_calls_eval,
bool* outer_scope_calls_non_strict_eval) {
Context* context = this;
while (true) {
// Skip up the context chain checking all the function contexts to see
// whether they call eval.
Context* context = fcontext();
while (!context->IsGlobalContext()) {
Handle<SerializedScopeInfo> scope_info(
context->closure()->shared()->scope_info());
if (scope_info->CallsEval()) {
@ -258,8 +258,7 @@ void Context::ComputeEvalScopeInfo(bool* outer_scope_calls_eval,
return;
}
}
if (context->IsGlobalContext()) break;
context = Context::cast(context->closure()->context());
context = context->previous()->fcontext();
}
}

3
src/contexts.h
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@ -166,9 +166,6 @@ enum ContextLookupFlags {
// the moment we also use it in generated code for context slot accesses -
// and there we don't want a loop because of code bloat - but we may not
// need it there after all (see comment in codegen_*.cc).
//
// - If we cannot get rid of fcontext, consider making 'previous' never NULL
// except for the global context. This could simplify Context::Lookup.
class Context: public FixedArray {
public:

2
src/heap.cc
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@ -3928,7 +3928,7 @@ MaybeObject* Heap::AllocateFunctionContext(int length, JSFunction* function) {
context->set_map(function_context_map());
context->set_closure(function);
context->set_fcontext(context);
context->set_previous(NULL);
context->set_previous(function->context());
context->set_extension(NULL);
context->set_global(function->context()->global());
return context;

9
src/ia32/code-stubs-ia32.cc
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@ -138,14 +138,11 @@ void FastNewContextStub::Generate(MacroAssembler* masm) {
__ Set(ebx, Immediate(0)); // Set to NULL.
__ mov(Operand(eax, Context::SlotOffset(Context::CLOSURE_INDEX)), ecx);
__ mov(Operand(eax, Context::SlotOffset(Context::FCONTEXT_INDEX)), eax);
__ mov(Operand(eax, Context::SlotOffset(Context::PREVIOUS_INDEX)), ebx);
__ mov(Operand(eax, Context::SlotOffset(Context::PREVIOUS_INDEX)), esi);
__ mov(Operand(eax, Context::SlotOffset(Context::EXTENSION_INDEX)), ebx);
// Copy the global object from the surrounding context. We go through the
// context in the function (ecx) to match the allocation behavior we have
// in the runtime system (see Heap::AllocateFunctionContext).
__ mov(ebx, FieldOperand(ecx, JSFunction::kContextOffset));
__ mov(ebx, Operand(ebx, Context::SlotOffset(Context::GLOBAL_INDEX)));
// Copy the global object from the previous context.
__ mov(ebx, Operand(esi, Context::SlotOffset(Context::GLOBAL_INDEX)));
__ mov(Operand(eax, Context::SlotOffset(Context::GLOBAL_INDEX)), ebx);
// Initialize the rest of the slots to undefined.

7
src/ia32/macro-assembler-ia32.cc
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@ -1759,12 +1759,9 @@ void MacroAssembler::GetBuiltinEntry(Register target, Builtins::JavaScript id) {
void MacroAssembler::LoadContext(Register dst, int context_chain_length) {
if (context_chain_length > 0) {
// Move up the chain of contexts to the context containing the slot.
mov(dst, Operand(esi, Context::SlotOffset(Context::CLOSURE_INDEX)));
// Load the function context (which is the incoming, outer context).
mov(dst, FieldOperand(dst, JSFunction::kContextOffset));
mov(dst, Operand(esi, Context::SlotOffset(Context::PREVIOUS_INDEX)));
for (int i = 1; i < context_chain_length; i++) {
mov(dst, Operand(dst, Context::SlotOffset(Context::CLOSURE_INDEX)));
mov(dst, FieldOperand(dst, JSFunction::kContextOffset));
mov(dst, Operand(dst, Context::SlotOffset(Context::PREVIOUS_INDEX)));
}
} else {
// Slot is in the current function context. Move it into the

12
src/runtime.cc
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@ -8607,11 +8607,7 @@ RUNTIME_FUNCTION(ObjectPair, Runtime_ResolvePossiblyDirectEval) {
// Stop search when eval is found or when the global context is
// reached.
if (attributes != ABSENT || context->IsGlobalContext()) break;
if (context->IsFunctionContext()) {
context = Handle<Context>(context->closure()->context(), isolate);
} else {
context = Handle<Context>(context->previous(), isolate);
}
context = Handle<Context>(context->previous(), isolate);
}
// If eval could not be resolved, it has been deleted and we need to
@ -10268,11 +10264,7 @@ class ScopeIterator {
}
// Move to the next context.
if (context_->IsFunctionContext()) {
context_ = Handle<Context>(context_->closure()->context());
} else {
context_ = Handle<Context>(context_->previous());
}
context_ = Handle<Context>(context_->previous(), isolate_);
// If passing the local scope indicate that the current scope is now the
// local scope.

4
src/x64/code-stubs-x64.cc
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@ -133,10 +133,10 @@ void FastNewContextStub::Generate(MacroAssembler* masm) {
__ Set(rbx, 0); // Set to NULL.
__ movq(Operand(rax, Context::SlotOffset(Context::CLOSURE_INDEX)), rcx);
__ movq(Operand(rax, Context::SlotOffset(Context::FCONTEXT_INDEX)), rax);
__ movq(Operand(rax, Context::SlotOffset(Context::PREVIOUS_INDEX)), rbx);
__ movq(Operand(rax, Context::SlotOffset(Context::PREVIOUS_INDEX)), rsi);
__ movq(Operand(rax, Context::SlotOffset(Context::EXTENSION_INDEX)), rbx);
// Copy the global object from the surrounding context.
// Copy the global object from the previous context.
__ movq(rbx, Operand(rsi, Context::SlotOffset(Context::GLOBAL_INDEX)));
__ movq(Operand(rax, Context::SlotOffset(Context::GLOBAL_INDEX)), rbx);

9
src/x64/macro-assembler-x64.cc
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@ -3617,15 +3617,10 @@ void MacroAssembler::CopyBytes(Register destination,
void MacroAssembler::LoadContext(Register dst, int context_chain_length) {
if (context_chain_length > 0) {
// Move up the chain of contexts to the context containing the slot.
movq(dst, Operand(rsi, Context::SlotOffset(Context::CLOSURE_INDEX)));
// Load the function context (which is the incoming, outer context).
movq(dst, FieldOperand(dst, JSFunction::kContextOffset));
movq(dst, Operand(rsi, Context::SlotOffset(Context::PREVIOUS_INDEX)));
for (int i = 1; i < context_chain_length; i++) {
movq(dst, Operand(dst, Context::SlotOffset(Context::CLOSURE_INDEX)));
movq(dst, FieldOperand(dst, JSFunction::kContextOffset));
movq(dst, Operand(dst, Context::SlotOffset(Context::PREVIOUS_INDEX)));
}
// The context may be an intermediate context, not a function context.
movq(dst, Operand(dst, Context::SlotOffset(Context::FCONTEXT_INDEX)));
} else {
// Slot is in the current function context. Move it into the
// destination register in case we store into it (the write barrier