MIPS: Retry "Use a WeakCell in the CallIC type vector."

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 983 matching lines @@
   return true;
 }
 
 
 void CodeStub::GenerateStubsAheadOfTime(Isolate* isolate) {
   CEntryStub::GenerateAheadOfTime(isolate);
   StoreBufferOverflowStub::GenerateFixedRegStubsAheadOfTime(isolate);
   StubFailureTrampolineStub::GenerateAheadOfTime(isolate);
   ArrayConstructorStubBase::GenerateStubsAheadOfTime(isolate);
   CreateAllocationSiteStub::GenerateAheadOfTime(isolate);
+  CreateWeakCellStub::GenerateAheadOfTime(isolate);
   BinaryOpICStub::GenerateAheadOfTime(isolate);
   StoreRegistersStateStub::GenerateAheadOfTime(isolate);
   RestoreRegistersStateStub::GenerateAheadOfTime(isolate);
   BinaryOpICWithAllocationSiteStub::GenerateAheadOfTime(isolate);
 }
 
 
 void StoreRegistersStateStub::GenerateAheadOfTime(Isolate* isolate) {
   StoreRegistersStateStub stub(isolate);
   stub.GetCode();
@@ skipping 1776 matching lines @@
   Label extra_checks_or_miss, slow_start;
   Label slow, non_function, wrap, cont;
   Label have_js_function;
   int argc = arg_count();
   ParameterCount actual(argc);
 
   // The checks. First, does r1 match the recorded monomorphic target?
   __ sll(t0, a3, kPointerSizeLog2 - kSmiTagSize);
   __ Addu(t0, a2, Operand(t0));
   __ lw(t0, FieldMemOperand(t0, FixedArray::kHeaderSize));
-  __ Branch(&extra_checks_or_miss, ne, a1, Operand(t0));
+
+  // We don't know that we have a weak cell. We might have a private symbol
+  // or an AllocationSite, but the memory is safe to examine.
+  // AllocationSite::kTransitionInfoOffset - contains a Smi or pointer to
+  // FixedArray.
+  // WeakCell::kValueOffset - contains a JSFunction or Smi(0)
+  // Symbol::kHashFieldSlot - if the low bit is 1, then the hash is not
+  // computed, meaning that it can't appear to be a pointer. If the low bit is
+  // 0, then hash is computed, but the 0 bit prevents the field from appearing
+  // to be a pointer.
+  STATIC_ASSERT(WeakCell::kSize >= kPointerSize);
+  STATIC_ASSERT(AllocationSite::kTransitionInfoOffset ==
+                    WeakCell::kValueOffset &&
+                WeakCell::kValueOffset == Symbol::kHashFieldSlot);
+
+  __ lw(t1, FieldMemOperand(t0, WeakCell::kValueOffset));
+  __ Branch(&extra_checks_or_miss, ne, a1, Operand(t1));
+
+  // The compare above could have been a SMI/SMI comparison. Guard against this
+  // convincing us that we have a monomorphic JSFunction.
+  __ JumpIfSmi(a1, &extra_checks_or_miss);
 
   __ bind(&have_js_function);
   if (CallAsMethod()) {
     EmitContinueIfStrictOrNative(masm, &cont);
     // Compute the receiver in sloppy mode.
     __ lw(a3, MemOperand(sp, argc * kPointerSize));
 
     __ JumpIfSmi(a3, &wrap);
     __ GetObjectType(a3, t0, t0);
     __ Branch(&wrap, lt, t0, Operand(FIRST_SPEC_OBJECT_TYPE));
@@ skipping 56 matching lines @@
   // Make sure the function is not the Array() function, which requires special
   // behavior on MISS.
   __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, t0);
   __ Branch(&miss, eq, a1, Operand(t0));
 
   // Update stats.
   __ lw(t0, FieldMemOperand(a2, with_types_offset));
   __ Addu(t0, t0, Operand(Smi::FromInt(1)));
   __ sw(t0, FieldMemOperand(a2, with_types_offset));
 
-  // Store the function.
-  __ sll(t0, a3, kPointerSizeLog2 - kSmiTagSize);
-  __ Addu(t0, a2, Operand(t0));
-  __ Addu(t0, t0, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
-  __ sw(a1, MemOperand(t0, 0));
+  // Store the function. Use a stub since we need a frame for allocation.
+  // a2 - vector
+  // a3 - slot
+  // a1 - function
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    CreateWeakCellStub create_stub(masm->isolate());
+    __ Push(a1);
+    __ CallStub(&create_stub);
+    __ Pop(a1);
+  }
 
-  // Update the write barrier.
-  __ mov(t1, a1);
-  __ RecordWrite(a2, t0, t1, kRAHasNotBeenSaved, kDontSaveFPRegs,
-                 EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
   __ Branch(&have_js_function);
 
   // We are here because tracing is on or we encountered a MISS case we can't
   // handle here.
   __ bind(&miss);
   GenerateMiss(masm);
 
   // the slow case
   __ bind(&slow_start);
   // Check that the function is really a JavaScript function.
@@ skipping 2255 matching lines @@
                            kStackUnwindSpace, kInvalidStackOffset,
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS