Code cleanup in GenerateRecordCallTarget.

src/mips/code-stubs-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 2497 matching lines @@
   // a0 : number of arguments to the construct function
   // a2 : Feedback vector
   // a3 : slot in feedback vector (Smi)
   // a1 : the function to call
   FrameScope scope(masm, StackFrame::INTERNAL);
   const RegList kSavedRegs = 1 << 4 |  // a0
                              1 << 5 |  // a1
                              1 << 6 |  // a2
                              1 << 7;   // a3
 
-  // Arguments register must be smi-tagged to call out.
+  // Number-of-arguments register must be smi-tagged to call out.
   __ SmiTag(a0);
   __ MultiPush(kSavedRegs);
 
   __ CallStub(stub);
 
   __ MultiPop(kSavedRegs);
   __ SmiUntag(a0);
 }
 
 
@@ skipping 12 matching lines @@
   DCHECK_EQ(*TypeFeedbackVector::UninitializedSentinel(masm->isolate()),
             masm->isolate()->heap()->uninitialized_symbol());
 
   // Load the cache state into t0.
   __ sll(t0, a3, kPointerSizeLog2 - kSmiTagSize);
   __ Addu(t0, a2, Operand(t0));
   __ lw(t0, FieldMemOperand(t0, FixedArray::kHeaderSize));
 
   // A monomorphic cache hit or an already megamorphic state: invoke the
   // function without changing the state.
+  // We don't know if t0 is a WeakCell or a Symbol, but it's harmless to read at
+  // this position in a symbol (see static asserts in type-feedback-vector.h).
   Label check_allocation_site;
   Register feedback_map = t1;
   Register weak_value = t4;
   __ lw(weak_value, FieldMemOperand(t0, WeakCell::kValueOffset));
   __ Branch(&done, eq, a1, Operand(weak_value));
   __ LoadRoot(at, Heap::kmegamorphic_symbolRootIndex);
   __ Branch(&done, eq, t0, Operand(at));
-  __ lw(feedback_map, FieldMemOperand(t0, 0));
+  __ lw(feedback_map, FieldMemOperand(t0, Heap::kMapOffset));
   __ LoadRoot(at, Heap::kWeakCellMapRootIndex);
   __ Branch(FLAG_pretenuring_call_new ? &miss : &check_allocation_site, ne,
             feedback_map, Operand(at));
 
-  // If a1 is not equal to the weak cell value, and the weak cell value is
-  // cleared, we have a new chance to become monomorphic.
+  // If the weak cell is cleared, we have a new chance to become monomorphic.
   __ JumpIfSmi(weak_value, &initialize);
   __ jmp(&megamorphic);
 
   if (!FLAG_pretenuring_call_new) {
     __ bind(&check_allocation_site);
     // If we came here, we need to see if we are the array function.
     // If we didn't have a matching function, and we didn't find the megamorph
     // sentinel, then we have in the slot either some other function or an
-    // AllocationSite. Do a map check on the object in a3.
+    // AllocationSite.
     __ LoadRoot(at, Heap::kAllocationSiteMapRootIndex);
     __ Branch(&miss, ne, feedback_map, Operand(at));
 
     // Make sure the function is the Array() function
     __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, t0);
     __ Branch(&megamorphic, ne, a1, Operand(t0));
     __ jmp(&done);
   }
 
   __ bind(&miss);
@@ skipping 2928 matching lines @@
                            kStackUnwindSpace, kInvalidStackOffset,
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS