[crankshaft] Fragmentation-free allocation folding.

src/x87/macro-assembler-x87.cc

Index: src/x87/macro-assembler-x87.cc
diff --git a/src/x87/macro-assembler-x87.cc b/src/x87/macro-assembler-x87.cc
index 068cc5f01e2f74bc07171f5d5f80258a07b3f2c8..3cee0eac5733b7fe8e24f31b8a5b5eb50a0584e7 100644
--- a/src/x87/macro-assembler-x87.cc
+++ b/src/x87/macro-assembler-x87.cc
@@ -1469,6 +1469,7 @@ void MacroAssembler::Allocate(int object_size,
                               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.
@@ -1510,6 +1511,7 @@ void MacroAssembler::Allocate(int object_size,
 
   // Calculate new top and bail out if space is exhausted.
   Register top_reg = result_end.is_valid() ? result_end : result;
+
   if (!top_reg.is(result)) {
     mov(top_reg, result);
   }
@@ -1517,8 +1519,10 @@ void MacroAssembler::Allocate(int object_size,
   cmp(top_reg, Operand::StaticVariable(allocation_limit));
   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)) {
     sub(result, Immediate(object_size - kHeapObjectTag));
@@ -1540,6 +1544,8 @@ void MacroAssembler::Allocate(int header_size,
                               Label* gc_required,
                               AllocationFlags flags) {
   DCHECK((flags & SIZE_IN_WORDS) == 0);
+  DCHECK((flags & ALLOCATION_FOLDING_DOMINATOR) == 0);
+  DCHECK((flags & ALLOCATION_FOLDED) == 0);
   if (!FLAG_inline_new) {
     if (emit_debug_code()) {
       // Trash the registers to simulate an allocation failure.
@@ -1605,7 +1611,6 @@ void MacroAssembler::Allocate(int header_size,
   UpdateAllocationTopHelper(result_end, scratch, flags);
 }
 
-
 void MacroAssembler::Allocate(Register object_size,
                               Register result,
                               Register result_end,
@@ -1613,6 +1618,7 @@ void MacroAssembler::Allocate(Register object_size,
                               Label* gc_required,
                               AllocationFlags flags) {
   DCHECK((flags & (RESULT_CONTAINS_TOP | 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.
@@ -1656,7 +1662,6 @@ void MacroAssembler::Allocate(Register object_size,
     mov(result_end, object_size);
   }
   add(result_end, result);
-  j(carry, gc_required);
   cmp(result_end, Operand::StaticVariable(allocation_limit));
   j(above, gc_required);
 
@@ -1664,10 +1669,59 @@ void MacroAssembler::Allocate(Register object_size,
   DCHECK(kHeapObjectTag == 1);
   inc(result);
 
-  // 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);
+  }
 }
 
+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) {
+    DCHECK(kPointerAlignment * 2 == kDoubleAlignment);
+    Label aligned;
+    test(result, Immediate(kDoubleAlignmentMask));
+    j(zero, &aligned, Label::kNear);
+    mov(Operand(result, 0),
+        Immediate(isolate()->factory()->one_pointer_filler_map()));
+    add(result, Immediate(kDoubleSize / 2));
+    bind(&aligned);
+  }
+
+  lea(result_end, Operand(result, object_size));
+  UpdateAllocationTopHelper(result_end, no_reg, flags);
+
+  DCHECK(kHeapObjectTag == 1);
+  inc(result);
+}
+
+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) {
+    DCHECK(kPointerAlignment * 2 == kDoubleAlignment);
+    Label aligned;
+    test(result, Immediate(kDoubleAlignmentMask));
+    j(zero, &aligned, Label::kNear);
+    mov(Operand(result, 0),
+        Immediate(isolate()->factory()->one_pointer_filler_map()));
+    add(result, Immediate(kDoubleSize / 2));
+    bind(&aligned);
+  }
+
+  lea(result_end, Operand(result, object_size, times_1, 0));
+  UpdateAllocationTopHelper(result_end, no_reg, flags);
+
+  DCHECK(kHeapObjectTag == 1);
+  inc(result);
+}
 
 void MacroAssembler::AllocateHeapNumber(Register result,
                                         Register scratch1,