Use the previous context link when checking context extension objects.

In generated code, when walking the context to inspect context extension
objects, use the previous context link directly.

R=ager@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/7044081

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8248 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index b0cc8fc..749d1f5 100644 (file)
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -1127,8 +1127,7 @@ void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
         __ b(ne, slow);
       }
       // Load next context in chain.
-      __ ldr(next, ContextOperand(current, Context::CLOSURE_INDEX));
-      __ ldr(next, FieldMemOperand(next, JSFunction::kContextOffset));
+      __ ldr(next, ContextOperand(current, Context::PREVIOUS_INDEX));
       // Walk the rest of the chain without clobbering cp.
       current = next;
     }
@@ -1154,8 +1153,7 @@ void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
     __ tst(temp, temp);
     __ b(ne, slow);
     // Load next context in chain.
-    __ ldr(next, ContextOperand(next, Context::CLOSURE_INDEX));
-    __ ldr(next, FieldMemOperand(next, JSFunction::kContextOffset));
+    __ ldr(next, ContextOperand(next, Context::PREVIOUS_INDEX));
     __ b(&loop);
     __ bind(&fast);
   }
@@ -1186,8 +1184,7 @@ MemOperand FullCodeGenerator::ContextSlotOperandCheckExtensions(
         __ tst(temp, temp);
         __ b(ne, slow);
       }
-      __ ldr(next, ContextOperand(context, Context::CLOSURE_INDEX));
-      __ ldr(next, FieldMemOperand(next, JSFunction::kContextOffset));
+      __ ldr(next, ContextOperand(context, Context::PREVIOUS_INDEX));
       // Walk the rest of the chain without clobbering cp.
       context = next;
     }

diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index fe29097..709d1ee 100644 (file)
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -2847,8 +2847,7 @@ void LCodeGen::DoOuterContext(LOuterContext* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
   __ ldr(result,
-         MemOperand(context, Context::SlotOffset(Context::CLOSURE_INDEX)));
-  __ ldr(result, FieldMemOperand(result, JSFunction::kContextOffset));
+         MemOperand(context, Context::SlotOffset(Context::PREVIOUS_INDEX)));
 }
 
 

diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index c727c03..8e8fcd2 100644 (file)
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -1078,8 +1078,7 @@ void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
         __ j(not_equal, slow);
       }
       // Load next context in chain.
-      __ mov(temp, ContextOperand(context, Context::CLOSURE_INDEX));
-      __ mov(temp, FieldOperand(temp, JSFunction::kContextOffset));
+      __ mov(temp, ContextOperand(context, Context::PREVIOUS_INDEX));
       // Walk the rest of the chain without clobbering esi.
       context = temp;
     }
@@ -1106,8 +1105,7 @@ void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
     __ cmp(ContextOperand(temp, Context::EXTENSION_INDEX), Immediate(0));
     __ j(not_equal, slow);
     // Load next context in chain.
-    __ mov(temp, ContextOperand(temp, Context::CLOSURE_INDEX));
-    __ mov(temp, FieldOperand(temp, JSFunction::kContextOffset));
+    __ mov(temp, ContextOperand(temp, Context::PREVIOUS_INDEX));
     __ jmp(&next);
     __ bind(&fast);
   }
@@ -1139,8 +1137,7 @@ MemOperand FullCodeGenerator::ContextSlotOperandCheckExtensions(
                Immediate(0));
         __ j(not_equal, slow);
       }
-      __ mov(temp, ContextOperand(context, Context::CLOSURE_INDEX));
-      __ mov(temp, FieldOperand(temp, JSFunction::kContextOffset));
+      __ mov(temp, ContextOperand(context, Context::PREVIOUS_INDEX));
       // Walk the rest of the chain without clobbering esi.
       context = temp;
     }

diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 851e130..7f6c5ad 100644 (file)
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -2678,8 +2678,8 @@ void LCodeGen::DoContext(LContext* instr) {
 void LCodeGen::DoOuterContext(LOuterContext* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
-  __ mov(result, Operand(context, Context::SlotOffset(Context::CLOSURE_INDEX)));
-  __ mov(result, FieldOperand(result, JSFunction::kContextOffset));
+  __ mov(result,
+         Operand(context, Context::SlotOffset(Context::PREVIOUS_INDEX)));
 }
 
 

diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index 8381eef..0978032 100644 (file)
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -1128,8 +1128,7 @@ void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
         __ Branch(slow, ne, temp, Operand(zero_reg));
       }
       // Load next context in chain.
-      __ lw(next, ContextOperand(current, Context::CLOSURE_INDEX));
-      __ lw(next, FieldMemOperand(next, JSFunction::kContextOffset));
+      __ lw(next, ContextOperand(current, Context::PREVIOUS_INDEX));
       // Walk the rest of the chain without clobbering cp.
       current = next;
     }
@@ -1153,8 +1152,7 @@ void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
     __ lw(temp, ContextOperand(next, Context::EXTENSION_INDEX));
     __ Branch(slow, ne, temp, Operand(zero_reg));
     // Load next context in chain.
-    __ lw(next, ContextOperand(next, Context::CLOSURE_INDEX));
-    __ lw(next, FieldMemOperand(next, JSFunction::kContextOffset));
+    __ lw(next, ContextOperand(next, Context::PREVIOUS_INDEX));
     __ Branch(&loop);
     __ bind(&fast);
   }
@@ -1184,8 +1182,7 @@ MemOperand FullCodeGenerator::ContextSlotOperandCheckExtensions(
         __ lw(temp, ContextOperand(context, Context::EXTENSION_INDEX));
         __ Branch(slow, ne, temp, Operand(zero_reg));
       }
-      __ lw(next, ContextOperand(context, Context::CLOSURE_INDEX));
-      __ lw(next, FieldMemOperand(next, JSFunction::kContextOffset));
+      __ lw(next, ContextOperand(context, Context::PREVIOUS_INDEX));
       // Walk the rest of the chain without clobbering cp.
       context = next;
     }

diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index 4704960..913bfa5 100644 (file)
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -3571,12 +3571,9 @@ 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.
-    lw(dst, MemOperand(cp, Context::SlotOffset(Context::CLOSURE_INDEX)));
-    // Load the function context (which is the incoming, outer context).
-    lw(dst, FieldMemOperand(dst, JSFunction::kContextOffset));
+    lw(dst, MemOperand(cp, Context::SlotOffset(Context::PREVIOUS_INDEX)));
     for (int i = 1; i < context_chain_length; i++) {
-      lw(dst, MemOperand(dst, Context::SlotOffset(Context::CLOSURE_INDEX)));
-      lw(dst, FieldMemOperand(dst, JSFunction::kContextOffset));
+      lw(dst, MemOperand(dst, Context::SlotOffset(Context::PREVIOUS_INDEX)));
     }
   } else {
     // Slot is in the current function context.  Move it into the

diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index f0297a6..746d18c 100644 (file)
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -1089,8 +1089,7 @@ void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
         __ j(not_equal, slow);
       }
       // Load next context in chain.
-      __ movq(temp, ContextOperand(context, Context::CLOSURE_INDEX));
-      __ movq(temp, FieldOperand(temp, JSFunction::kContextOffset));
+      __ movq(temp, ContextOperand(context, Context::PREVIOUS_INDEX));
       // Walk the rest of the chain without clobbering rsi.
       context = temp;
     }
@@ -1118,8 +1117,7 @@ void FullCodeGenerator::EmitLoadGlobalSlotCheckExtensions(
     __ cmpq(ContextOperand(temp, Context::EXTENSION_INDEX), Immediate(0));
     __ j(not_equal, slow);
     // Load next context in chain.
-    __ movq(temp, ContextOperand(temp, Context::CLOSURE_INDEX));
-    __ movq(temp, FieldOperand(temp, JSFunction::kContextOffset));
+    __ movq(temp, ContextOperand(temp, Context::PREVIOUS_INDEX));
     __ jmp(&next);
     __ bind(&fast);
   }
@@ -1151,8 +1149,7 @@ MemOperand FullCodeGenerator::ContextSlotOperandCheckExtensions(
                 Immediate(0));
         __ j(not_equal, slow);
       }
-      __ movq(temp, ContextOperand(context, Context::CLOSURE_INDEX));
-      __ movq(temp, FieldOperand(temp, JSFunction::kContextOffset));
+      __ movq(temp, ContextOperand(context, Context::PREVIOUS_INDEX));
       // Walk the rest of the chain without clobbering rsi.
       context = temp;
     }

diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index fb0520a..e7b66f2 100644 (file)
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -2682,8 +2682,7 @@ void LCodeGen::DoOuterContext(LOuterContext* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
   __ movq(result,
-          Operand(context, Context::SlotOffset(Context::CLOSURE_INDEX)));
-  __ movq(result, FieldOperand(result, JSFunction::kContextOffset));
+          Operand(context, Context::SlotOffset(Context::PREVIOUS_INDEX)));
 }