[crankshaft] Fragmentation-free allocation folding.

src/crankshaft/x64/lithium-codegen-x64.cc

 // Copyright 2013 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/crankshaft/x64/lithium-codegen-x64.h"
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 5152 matching lines @@
   // Allocate memory for the object.
   AllocationFlags flags = TAG_OBJECT;
   if (instr->hydrogen()->MustAllocateDoubleAligned()) {
     flags = static_cast<AllocationFlags>(flags | DOUBLE_ALIGNMENT);
   }
   if (instr->hydrogen()->IsOldSpaceAllocation()) {
     DCHECK(!instr->hydrogen()->IsNewSpaceAllocation());
     flags = static_cast<AllocationFlags>(flags | PRETENURE);
   }
 
+  if (instr->hydrogen()->IsAllocationFoldingDominator()) {
+    flags = static_cast<AllocationFlags>(flags | ALLOCATION_FOLDING_DOMINATOR);
+  }
+
+  if (instr->hydrogen()->IsAllocationFoldingDominated()) {
+    flags = static_cast<AllocationFlags>(flags | ALLOCATION_FOLDING_DOMINATED);
+  }
+
   if (instr->size()->IsConstantOperand()) {
     int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
     CHECK(size <= Page::kMaxRegularHeapObjectSize);
     __ Allocate(size, result, temp, no_reg, deferred->entry(), flags);
   } else {
     Register size = ToRegister(instr->size());
     __ Allocate(size, result, temp, no_reg, deferred->entry(), flags);
   }
 
   __ bind(deferred->exit());
@@ skipping 41 matching lines @@
     DCHECK(!instr->hydrogen()->IsNewSpaceAllocation());
     flags = AllocateTargetSpace::update(flags, OLD_SPACE);
   } else {
     flags = AllocateTargetSpace::update(flags, NEW_SPACE);
   }
   __ Push(Smi::FromInt(flags));
 
   CallRuntimeFromDeferred(
       Runtime::kAllocateInTargetSpace, 2, instr, instr->context());
   __ StoreToSafepointRegisterSlot(result, rax);
+
+  if (instr->hydrogen()->IsAllocationFoldingDominator()) {
+    AllocationFlags allocation_flags = TAG_OBJECT;
+    if (instr->hydrogen()->IsOldSpaceAllocation()) {
+      DCHECK(!instr->hydrogen()->IsNewSpaceAllocation());
+      allocation_flags = static_cast<AllocationFlags>(flags | PRETENURE);
+    }
+    // If the allocation folding dominator allocate triggered a GC, allocation
+    // happend in the runtime. We have to reset the top pointer to virtually
+    // undo the allocation.
+    __ SetTop(rax, allocation_flags);
+  }
 }
 
 
 void LCodeGen::DoTypeof(LTypeof* instr) {
   DCHECK(ToRegister(instr->context()).is(rsi));
   DCHECK(ToRegister(instr->value()).is(rbx));
   Label end, do_call;
   Register value_register = ToRegister(instr->value());
   __ JumpIfNotSmi(value_register, &do_call);
   __ Move(rax, isolate()->factory()->number_string());
@@ skipping 348 matching lines @@
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64