[crankshaft] Fragmentation-free allocation folding.

src/x64/macro-assembler-x64.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_X64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 4812 matching lines @@
     // Align the next allocation. Storing the filler map without checking top
     // is safe in new-space because the limit of the heap is aligned there.
     DCHECK(kPointerSize * 2 == kDoubleSize);
     DCHECK(kPointerAlignment * 2 == kDoubleAlignment);
     // Make sure scratch is not clobbered by this function as it might be
     // used in UpdateAllocationTopHelper later.
     DCHECK(!scratch.is(kScratchRegister));
     Label aligned;
     testl(result, Immediate(kDoubleAlignmentMask));
     j(zero, &aligned, Label::kNear);
-    if ((flags & PRETENURE) != 0) {
+    if (((flags & ALLOCATION_FOLDED) == 0) && ((flags & PRETENURE) != 0)) {
       ExternalReference allocation_limit =
           AllocationUtils::GetAllocationLimitReference(isolate(), flags);
       cmpp(result, ExternalOperand(allocation_limit));
       j(above_equal, gc_required);
     }
     LoadRoot(kScratchRegister, Heap::kOnePointerFillerMapRootIndex);
     movp(Operand(result, 0), kScratchRegister);
     addp(result, Immediate(kDoubleSize / 2));
     bind(&aligned);
   }
@@ skipping 22 matching lines @@
 
 
 void MacroAssembler::Allocate(int object_size,
                               Register result,
                               Register result_end,
                               Register scratch,
                               Label* gc_required,
                               AllocationFlags flags) {
   DCHECK((flags & (RESULT_CONTAINS_TOP | SIZE_IN_WORDS)) == 0);
   DCHECK(object_size <= Page::kMaxRegularHeapObjectSize);
+  DCHECK((flags & ALLOCATION_FOLDED) == 0);
   if (!FLAG_inline_new) {
     if (emit_debug_code()) {
       // Trash the registers to simulate an allocation failure.
       movl(result, Immediate(0x7091));
       if (result_end.is_valid()) {
         movl(result_end, Immediate(0x7191));
       }
       if (scratch.is_valid()) {
         movl(scratch, Immediate(0x7291));
       }
@@ skipping 17 matching lines @@
   Register top_reg = result_end.is_valid() ? result_end : result;
 
   if (!top_reg.is(result)) {
     movp(top_reg, result);
   }
   addp(top_reg, Immediate(object_size));
   Operand limit_operand = ExternalOperand(allocation_limit);
   cmpp(top_reg, limit_operand);
   j(above, gc_required);
 
-  // Update allocation top.
-  UpdateAllocationTopHelper(top_reg, scratch, flags);
+  if ((flags & ALLOCATION_FOLDING_DOMINATOR) == 0) {
+    // The top pointer is not updated for allocation folding dominators.
+    UpdateAllocationTopHelper(top_reg, scratch, flags);
+  }
 
   if (top_reg.is(result)) {
     subp(result, Immediate(object_size - kHeapObjectTag));
   } else {
     // Tag the result.
     DCHECK(kHeapObjectTag == 1);
     incp(result);
   }
 }
 
 
 void MacroAssembler::Allocate(int header_size,
                               ScaleFactor element_size,
                               Register element_count,
                               Register result,
                               Register result_end,
                               Register scratch,
                               Label* gc_required,
                               AllocationFlags flags) {
   DCHECK((flags & SIZE_IN_WORDS) == 0);
+  DCHECK((flags & ALLOCATION_FOLDING_DOMINATOR) == 0);
+  DCHECK((flags & ALLOCATION_FOLDED) == 0);
   leap(result_end, Operand(element_count, element_size, header_size));
   Allocate(result_end, result, result_end, scratch, gc_required, flags);
 }
 
 
 void MacroAssembler::Allocate(Register object_size,
                               Register result,
                               Register result_end,
                               Register scratch,
                               Label* gc_required,
                               AllocationFlags flags) {
   DCHECK((flags & SIZE_IN_WORDS) == 0);
+  DCHECK((flags & ALLOCATION_FOLDED) == 0);
   if (!FLAG_inline_new) {
     if (emit_debug_code()) {
       // Trash the registers to simulate an allocation failure.
       movl(result, Immediate(0x7091));
       movl(result_end, Immediate(0x7191));
       if (scratch.is_valid()) {
         movl(scratch, Immediate(0x7291));
       }
       // object_size is left unchanged by this function.
     }
     jmp(gc_required);
     return;
   }
   DCHECK(!result.is(result_end));
 
   // Load address of new object into result.
   LoadAllocationTopHelper(result, scratch, flags);
 
   if ((flags & DOUBLE_ALIGNMENT) != 0) {
     MakeSureDoubleAlignedHelper(result, scratch, gc_required, flags);
   }
 
-  // Calculate new top and bail out if new space is exhausted.
   ExternalReference allocation_limit =
       AllocationUtils::GetAllocationLimitReference(isolate(), flags);
   if (!object_size.is(result_end)) {
     movp(result_end, object_size);
   }
   addp(result_end, result);
-  j(carry, gc_required);
   Operand limit_operand = ExternalOperand(allocation_limit);
   cmpp(result_end, limit_operand);
   j(above, gc_required);
 
-  // Update allocation top.
-  UpdateAllocationTopHelper(result_end, scratch, flags);
+  if ((flags & ALLOCATION_FOLDING_DOMINATOR) == 0) {
+    // The top pointer is not updated for allocation folding dominators.
+    UpdateAllocationTopHelper(result_end, scratch, flags);
+  }
 
   // Tag the result.
   addp(result, Immediate(kHeapObjectTag));
 }
 
+void MacroAssembler::FastAllocate(int object_size, Register result,
+                                  Register result_end, AllocationFlags flags) {
+  DCHECK(!result.is(result_end));
+  // Load address of new object into result.
+  LoadAllocationTopHelper(result, no_reg, flags);
+
+  if ((flags & DOUBLE_ALIGNMENT) != 0) {
+    MakeSureDoubleAlignedHelper(result, no_reg, NULL, flags);
+  }
+
+  leap(result_end, Operand(result, object_size));
+
+  UpdateAllocationTopHelper(result_end, no_reg, flags);
+
+  addp(result, Immediate(kHeapObjectTag));
+}
+
+void MacroAssembler::FastAllocate(Register object_size, Register result,
+                                  Register result_end, AllocationFlags flags) {
+  DCHECK(!result.is(result_end));
+  // Load address of new object into result.
+  LoadAllocationTopHelper(result, no_reg, flags);
+
+  if ((flags & DOUBLE_ALIGNMENT) != 0) {
+    MakeSureDoubleAlignedHelper(result, no_reg, NULL, flags);
+  }
+
+  leap(result_end, Operand(result, object_size, times_1, 0));
+
+  UpdateAllocationTopHelper(result_end, no_reg, flags);
+
+  addp(result, Immediate(kHeapObjectTag));
+}
 
 void MacroAssembler::AllocateHeapNumber(Register result,
                                         Register scratch,
                                         Label* gc_required,
                                         MutableMode mode) {
   // Allocate heap number in new space.
   Allocate(HeapNumber::kSize, result, scratch, no_reg, gc_required,
            NO_ALLOCATION_FLAGS);
 
   Heap::RootListIndex map_index = mode == MUTABLE
@@ skipping 684 matching lines @@
   movl(rax, dividend);
   shrl(rax, Immediate(31));
   addl(rdx, rax);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64