Port inline swapping of elements for the sort function in array.js

from ia32 to arm.

Original change: http://codereview.chromium.org/1709008


Review URL: http://codereview.chromium.org/1944001

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4575 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/codegen-arm.cc

@@ -4507,6 +4507,28 @@ void CodeGenerator::GenerateNumberToString(ZoneList<Expression*>* args) {
 }
 
 
+class DeferredSwapElements: public DeferredCode {
+ public:
+  DeferredSwapElements(Register object, Register index1, Register index2)
+      : object_(object), index1_(index1), index2_(index2) {
+    set_comment("[ DeferredSwapElements");
+  }
+
+  virtual void Generate();
+
+ private:
+  Register object_, index1_, index2_;
+};
+
+
+void DeferredSwapElements::Generate() {
+  __ push(object_);
+  __ push(index1_);
+  __ push(index2_);
+  __ CallRuntime(Runtime::kSwapElements, 3);
+}
+
+
 void CodeGenerator::GenerateSwapElements(ZoneList<Expression*>* args) {
   Comment cmnt(masm_, "[ GenerateSwapElements");
 
@@ -4516,8 +4538,76 @@ void CodeGenerator::GenerateSwapElements(ZoneList<Expression*>* args) {
   Load(args->at(1));
   Load(args->at(2));
 
-  frame_->CallRuntime(Runtime::kSwapElements, 3);
-  frame_->EmitPush(r0);
+  Register index2 = r2;
+  Register index1 = r1;
+  Register object = r0;
+  Register tmp1 = r3;
+  Register tmp2 = r4;
+
+  frame_->EmitPop(index2);
+  frame_->EmitPop(index1);
+  frame_->EmitPop(object);
+
+  DeferredSwapElements* deferred =
+      new DeferredSwapElements(object, index1, index2);
+
+  // Fetch the map and check if array is in fast case.
+  // Check that object doesn't require security checks and
+  // has no indexed interceptor.
+  __ CompareObjectType(object, tmp1, tmp2, FIRST_JS_OBJECT_TYPE);
+  deferred->Branch(lt);
+  __ ldrb(tmp2, FieldMemOperand(tmp1, Map::kBitFieldOffset));
+  __ tst(tmp2, Operand(KeyedLoadIC::kSlowCaseBitFieldMask));
+  deferred->Branch(nz);
+
+  // Check the object's elements are in fast case.
+  __ ldr(tmp1, FieldMemOperand(object, JSObject::kElementsOffset));
+  __ ldr(tmp2, FieldMemOperand(tmp1, HeapObject::kMapOffset));
+  __ LoadRoot(ip, Heap::kFixedArrayMapRootIndex);
+  __ cmp(tmp2, ip);
+  deferred->Branch(ne);
+
+  // Smi-tagging is equivalent to multiplying by 2.
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize == 1);
+
+  // Check that both indices are smis.
+  __ mov(tmp2, index1);
+  __ orr(tmp2, tmp2, index2);
+  __ tst(tmp2, Operand(kSmiTagMask));
+  deferred->Branch(nz);
+
+  // Bring the offsets into the fixed array in tmp1 into index1 and
+  // index2.
+  __ mov(tmp2, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
+  __ add(index1, tmp2, Operand(index1, LSL, kPointerSizeLog2 - kSmiTagSize));
+  __ add(index2, tmp2, Operand(index2, LSL, kPointerSizeLog2 - kSmiTagSize));
+
+  // Swap elements.
+  Register tmp3 = object;
+  object = no_reg;
+  __ ldr(tmp3, MemOperand(tmp1, index1));
+  __ ldr(tmp2, MemOperand(tmp1, index2));
+  __ str(tmp3, MemOperand(tmp1, index2));
+  __ str(tmp2, MemOperand(tmp1, index1));
+
+  Label done;
+  __ InNewSpace(tmp1, tmp2, eq, &done);
+  // Possible optimization: do a check that both values are Smis
+  // (or them and test against Smi mask.)
+
+  __ mov(tmp2, tmp1);
+  RecordWriteStub recordWrite1(tmp1, index1, tmp3);
+  __ CallStub(&recordWrite1);
+
+  RecordWriteStub recordWrite2(tmp2, index2, tmp3);
+  __ CallStub(&recordWrite2);
+
+  __ bind(&done);
+
+  deferred->BindExit();
+  __ LoadRoot(tmp1, Heap::kUndefinedValueRootIndex);
+  frame_->EmitPush(tmp1);
 }
 
 
@@ -6503,6 +6593,12 @@ void NumberToStringStub::Generate(MacroAssembler* masm) {
 }
 
 
+void RecordWriteStub::Generate(MacroAssembler* masm) {
+  __ RecordWriteHelper(object_, offset_, scratch_);
+  __ Ret();
+}
+
+
 // On entry r0 (rhs) and r1 (lhs) are the values to be compared.
 // On exit r0 is 0, positive or negative to indicate the result of
 // the comparison.

src/arm/codegen-arm.h

@@ -904,6 +904,43 @@ class NumberToStringStub: public CodeStub {
 };
 
 
+class RecordWriteStub : public CodeStub {
+ public:
+  RecordWriteStub(Register object, Register offset, Register scratch)
+      : object_(object), offset_(offset), scratch_(scratch) { }
+
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Register object_;
+  Register offset_;
+  Register scratch_;
+
+#ifdef DEBUG
+  void Print() {
+    PrintF("RecordWriteStub (object reg %d), (offset reg %d),"
+           " (scratch reg %d)\n",
+           object_.code(), offset_.code(), scratch_.code());
+  }
+#endif
+
+  // Minor key encoding in 12 bits. 4 bits for each of the three
+  // registers (object, offset and scratch) OOOOAAAASSSS.
+  class ScratchBits: public BitField<uint32_t, 0, 4> {};
+  class OffsetBits: public BitField<uint32_t, 4, 4> {};
+  class ObjectBits: public BitField<uint32_t, 8, 4> {};
+
+  Major MajorKey() { return RecordWrite; }
+
+  int MinorKey() {
+    // Encode the registers.
+    return ObjectBits::encode(object_.code()) |
+           OffsetBits::encode(offset_.code()) |
+           ScratchBits::encode(scratch_.code());
+  }
+};
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_CODEGEN_ARM_H_

src/arm/macro-assembler-arm.cc

@@ -232,30 +232,23 @@ void MacroAssembler::LoadRoot(Register destination,
 }
 
 
-// Will clobber 4 registers: object, offset, scratch, ip.  The
-// register 'object' contains a heap object pointer.  The heap object
-// tag is shifted away.
-void MacroAssembler::RecordWrite(Register object, Register offset,
-                                 Register scratch) {
-  // The compiled code assumes that record write doesn't change the
-  // context register, so we check that none of the clobbered
-  // registers are cp.
-  ASSERT(!object.is(cp) && !offset.is(cp) && !scratch.is(cp));
+void MacroAssembler::RecordWriteHelper(Register object,
+                                       Register offset,
+                                       Register scratch) {
+  if (FLAG_debug_code) {
+    // Check that the object is not in new space.
+    Label not_in_new_space;
+    InNewSpace(object, scratch, ne, &not_in_new_space);
+    Abort("new-space object passed to RecordWriteHelper");
+    bind(&not_in_new_space);
+  }
 
   // This is how much we shift the remembered set bit offset to get the
   // offset of the word in the remembered set.  We divide by kBitsPerInt (32,
   // shift right 5) and then multiply by kIntSize (4, shift left 2).
   const int kRSetWordShift = 3;
 
-  Label fast, done;
-
-  // First, test that the object is not in the new space.  We cannot set
-  // remembered set bits in the new space.
-  // object: heap object pointer (with tag)
-  // offset: offset to store location from the object
-  and_(scratch, object, Operand(ExternalReference::new_space_mask()));
-  cmp(scratch, Operand(ExternalReference::new_space_start()));
-  b(eq, &done);
+  Label fast;
 
   // Compute the bit offset in the remembered set.
   // object: heap object pointer (with tag)
@@ -307,6 +300,38 @@ void MacroAssembler::RecordWrite(Register object, Register offset,
   mov(ip, Operand(1));
   orr(scratch, scratch, Operand(ip, LSL, offset));
   str(scratch, MemOperand(object));
+}
+
+
+void MacroAssembler::InNewSpace(Register object,
+                                Register scratch,
+                                Condition cc,
+                                Label* branch) {
+  ASSERT(cc == eq || cc == ne);
+  and_(scratch, object, Operand(ExternalReference::new_space_mask()));
+  cmp(scratch, Operand(ExternalReference::new_space_start()));
+  b(cc, branch);
+}
+
+
+// Will clobber 4 registers: object, offset, scratch, ip.  The
+// register 'object' contains a heap object pointer.  The heap object
+// tag is shifted away.
+void MacroAssembler::RecordWrite(Register object, Register offset,
+                                 Register scratch) {
+  // The compiled code assumes that record write doesn't change the
+  // context register, so we check that none of the clobbered
+  // registers are cp.
+  ASSERT(!object.is(cp) && !offset.is(cp) && !scratch.is(cp));
+
+  Label done;
+
+  // First, test that the object is not in the new space.  We cannot set
+  // remembered set bits in the new space.
+  InNewSpace(object, scratch, eq, &done);
+
+  // Record the actual write.
+  RecordWriteHelper(object, offset, scratch);
 
   bind(&done);
 

src/arm/macro-assembler-arm.h

@@ -86,6 +86,20 @@ class MacroAssembler: public Assembler {
                 Heap::RootListIndex index,
                 Condition cond = al);
 
+
+  // Check if object is in new space.
+  // scratch can be object itself, but it will be clobbered.
+  void InNewSpace(Register object,
+                  Register scratch,
+                  Condition cc,  // eq for new space, ne otherwise
+                  Label* branch);
+
+
+  // Set the remebered set bit for an offset into an
+  // object. RecordWriteHelper only works if the object is not in new
+  // space.
+  void RecordWriteHelper(Register object, Register offset, Register scracth);
+
   // Sets the remembered set bit for [address+offset], where address is the
   // address of the heap object 'object'.  The address must be in the first 8K
   // of an allocated page. The 'scratch' register is used in the

src/ia32/codegen-ia32.h

@@ -1082,8 +1082,8 @@ class RecordWriteStub : public CodeStub {
   }
 #endif
 
-  // Minor key encoding in 12 bits of three registers (object, address and
-  // scratch) OOOOAAAASSSS.
+  // Minor key encoding in 12 bits. 4 bits for each of the three
+  // registers (object, address and scratch) OOOOAAAASSSS.
   class ScratchBits: public BitField<uint32_t, 0, 4> {};
   class AddressBits: public BitField<uint32_t, 4, 4> {};
   class ObjectBits: public BitField<uint32_t, 8, 4> {};

src/ia32/macro-assembler-ia32.cc

@@ -50,6 +50,14 @@ MacroAssembler::MacroAssembler(void* buffer, int size)
 void MacroAssembler::RecordWriteHelper(Register object,
                                        Register addr,
                                        Register scratch) {
+  if (FLAG_debug_code) {
+    // Check that the object is not in new space.
+    Label not_in_new_space;
+    InNewSpace(object, scratch, not_equal, &not_in_new_space);
+    Abort("new-space object passed to RecordWriteHelper");
+    bind(&not_in_new_space);
+  }
+
   Label fast;
 
   // Compute the page start address from the heap object pointer, and reuse
@@ -134,7 +142,7 @@ void MacroAssembler::RecordWrite(Register object, int offset,
 
   // First, check if a remembered set write is even needed. The tests below
   // catch stores of Smis and stores into young gen (which does not have space
-  // for the remembered set bits.
+  // for the remembered set bits).
   Label done;
 
   // Skip barrier if writing a smi.

src/ia32/macro-assembler-ia32.h

@@ -48,7 +48,9 @@ class MacroAssembler: public Assembler {
   // ---------------------------------------------------------------------------
   // GC Support
 
-
+  // Set the remebered set bit for an address which points into an
+  // object. RecordWriteHelper only works if the object is not in new
+  // space.
   void RecordWriteHelper(Register object,
                          Register addr,
                          Register scratch);

src/x64/codegen-x64.h

@@ -1033,8 +1033,8 @@ class RecordWriteStub : public CodeStub {
   }
 #endif
 
-  // Minor key encoding in 12 bits of three registers (object, address and
-  // scratch) OOOOAAAASSSS.
+  // Minor key encoding in 12 bits. 4 bits for each of the three
+  // registers (object, address and scratch) OOOOAAAASSSS.
   class ScratchBits : public BitField<uint32_t, 0, 4> {};
   class AddressBits : public BitField<uint32_t, 4, 4> {};
   class ObjectBits : public BitField<uint32_t, 8, 4> {};

src/x64/macro-assembler-x64.cc

@@ -75,6 +75,14 @@ void MacroAssembler::StackLimitCheck(Label* on_stack_overflow) {
 void MacroAssembler::RecordWriteHelper(Register object,
                                        Register addr,
                                        Register scratch) {
+  if (FLAG_debug_code) {
+    // Check that the object is not in new space.
+    Label not_in_new_space;
+    InNewSpace(object, scratch, not_equal, &not_in_new_space);
+    Abort("new-space object passed to RecordWriteHelper");
+    bind(&not_in_new_space);
+  }
+
   Label fast;
 
   // Compute the page start address from the heap object pointer, and reuse
@@ -157,7 +165,7 @@ void MacroAssembler::RecordWrite(Register object,
 
   // First, check if a remembered set write is even needed. The tests below
   // catch stores of Smis and stores into young gen (which does not have space
-  // for the remembered set bits.
+  // for the remembered set bits).
   Label done;
   JumpIfSmi(value, &done);
 

src/x64/macro-assembler-x64.h

@@ -66,6 +66,9 @@ class MacroAssembler: public Assembler {
   // ---------------------------------------------------------------------------
   // GC Support
 
+  // Set the remebered set bit for an address which points into an
+  // object. RecordWriteHelper only works if the object is not in new
+  // space.
   void RecordWriteHelper(Register object,
                          Register addr,
                          Register scratch);