[crankshaft] Fragmentation-free allocation folding.

src/crankshaft/ia32/lithium-codegen-ia32.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.
 
 #if V8_TARGET_ARCH_IA32
 
 #include "src/crankshaft/ia32/lithium-codegen-ia32.h"
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 4852 matching lines @@
   // Allocate memory for the object.
   AllocationFlags flags = NO_ALLOCATION_FLAGS;
   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()->IsAllocationFolded()) {
+    flags = static_cast<AllocationFlags>(flags | ALLOCATION_FOLDED);
+  }
+
   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());
 
   if (instr->hydrogen()->MustPrefillWithFiller()) {
     if (instr->size()->IsConstantOperand()) {
       int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
       __ mov(temp, (size / kPointerSize) - 1);
     } else {
       temp = ToRegister(instr->size());
       __ shr(temp, kPointerSizeLog2);
       __ dec(temp);
     }
     Label loop;
     __ bind(&loop);
     __ mov(FieldOperand(result, temp, times_pointer_size, 0),
         isolate()->factory()->one_pointer_filler_map());
     __ dec(temp);
     __ j(not_zero, &loop);
   }
 }
 
+void LCodeGen::DoFastAllocate(LFastAllocate* instr) {
+  DCHECK(instr->hydrogen()->IsAllocationFolded());
+  Register result = ToRegister(instr->result());
+  Register temp = ToRegister(instr->temp());
+
+  AllocationFlags flags = NO_ALLOCATION_FLAGS;
+  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()) {
+    if (instr->size()->IsConstantOperand()) {
+      int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
+      CHECK(size <= Page::kMaxRegularHeapObjectSize);
+      __ FastAllocate(size, result, temp, flags);
+    } else {
+      Register size = ToRegister(instr->size());
+      __ FastAllocate(size, result, temp, flags);
+    }
+  }
+}
 
 void LCodeGen::DoDeferredAllocate(LAllocate* instr) {
   Register result = ToRegister(instr->result());
 
   // TODO(3095996): Get rid of this. For now, we need to make the
   // result register contain a valid pointer because it is already
   // contained in the register pointer map.
   __ Move(result, Immediate(Smi::FromInt(0)));
 
   PushSafepointRegistersScope scope(this);
@@ skipping 19 matching lines @@
     DCHECK(!instr->hydrogen()->IsNewSpaceAllocation());
     flags = AllocateTargetSpace::update(flags, OLD_SPACE);
   } else {
     flags = AllocateTargetSpace::update(flags, NEW_SPACE);
   }
   __ push(Immediate(Smi::FromInt(flags)));
 
   CallRuntimeFromDeferred(
       Runtime::kAllocateInTargetSpace, 2, instr, instr->context());
   __ StoreToSafepointRegisterSlot(result, eax);
+
+  if (instr->hydrogen()->IsAllocationFoldingDominator()) {
+    AllocationFlags allocation_flags = NO_ALLOCATION_FLAGS;
+    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.
+    ExternalReference allocation_top =
+        AllocationUtils::GetAllocationTopReference(isolate(), allocation_flags);
+    __ sub(eax, Immediate(kHeapObjectTag));
+    __ mov(Operand::StaticVariable(allocation_top), eax);

[Michael Lippautz, 2016/05/10 08:32:58]

***~~~ landmine detected ~~~***

+    __ add(eax, Immediate(kHeapObjectTag));
+  }
 }
 
 
 void LCodeGen::DoTypeof(LTypeof* instr) {
   DCHECK(ToRegister(instr->context()).is(esi));
   DCHECK(ToRegister(instr->value()).is(ebx));
   Label end, do_call;
   Register value_register = ToRegister(instr->value());
   __ JumpIfNotSmi(value_register, &do_call);
   __ mov(eax, Immediate(isolate()->factory()->number_string()));
@@ skipping 337 matching lines @@
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32