MIPS: Introduce %_IsMinusZero.

Port r17639 (45b8a52)

BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/61203006

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17671 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/full-codegen-mips.cc

@@ -3133,6 +3133,36 @@ void FullCodeGenerator::EmitIsFunction(CallRuntime* expr) {
 }
 
 
+void FullCodeGenerator::EmitIsMinusZero(CallRuntime* expr) {
+  ZoneList<Expression*>* args = expr->arguments();
+  ASSERT(args->length() == 1);
+
+  VisitForAccumulatorValue(args->at(0));
+
+  Label materialize_true, materialize_false;
+  Label* if_true = NULL;
+  Label* if_false = NULL;
+  Label* fall_through = NULL;
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
+
+  __ CheckMap(v0, a1, Heap::kHeapNumberMapRootIndex, if_false, DO_SMI_CHECK);
+  __ lw(a2, FieldMemOperand(v0, HeapNumber::kExponentOffset));
+  __ lw(a1, FieldMemOperand(v0, HeapNumber::kMantissaOffset));
+  __ li(t0, 0x80000000);
+  Label not_nan;
+  __ Branch(&not_nan, ne, a2, Operand(t0));
+  __ mov(t0, zero_reg);
+  __ mov(a2, a1);
+  __ bind(&not_nan);
+
+  PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
+  Split(eq, a2, Operand(t0), if_true, if_false, fall_through);
+
+  context()->Plug(if_true, if_false);
+}
+
+
 void FullCodeGenerator::EmitIsArray(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT(args->length() == 1);

src/mips/lithium-codegen-mips.cc

@@ -2311,6 +2311,33 @@ void LCodeGen::DoCmpHoleAndBranch(LCmpHoleAndBranch* instr) {
 }
 
 
+void LCodeGen::DoCompareMinusZeroAndBranch(LCompareMinusZeroAndBranch* instr) {
+  Representation rep = instr->hydrogen()->value()->representation();
+  ASSERT(!rep.IsInteger32());
+  Label if_false;
+  Register scratch = ToRegister(instr->temp());
+
+  if (rep.IsDouble()) {
+    DoubleRegister value = ToDoubleRegister(instr->value());
+    __ BranchF(&if_false, NULL, ne, value, kDoubleRegZero);
+    __ FmoveHigh(scratch, value);
+    __ li(at, 0x80000000);
+  } else {
+    Register value = ToRegister(instr->value());
+    __ CheckMap(
+        value, scratch, Heap::kHeapNumberMapRootIndex, &if_false, DO_SMI_CHECK);
+    __ lw(scratch, FieldMemOperand(value, HeapNumber::kExponentOffset));
+    __ Branch(&if_false, ne, scratch, Operand(0x80000000));
+    __ lw(scratch, FieldMemOperand(value, HeapNumber::kMantissaOffset));
+    __ mov(at, zero_reg);
+  }
+  EmitBranch(instr, eq, scratch, Operand(at));
+
+  __ bind(&if_false);
+  EmitFalseBranchF(instr, al, kDoubleRegZero, kDoubleRegZero);
+}
+
+
 Condition LCodeGen::EmitIsObject(Register input,
                                  Register temp1,
                                  Register temp2,

src/mips/lithium-mips.cc

@@ -1703,6 +1703,16 @@ LInstruction* LChunkBuilder::DoCompareHoleAndBranch(
 }
 
 
+LInstruction* LChunkBuilder::DoCompareMinusZeroAndBranch(
+    HCompareMinusZeroAndBranch* instr) {
+  LInstruction* goto_instr = CheckElideControlInstruction(instr);
+  if (goto_instr != NULL) return goto_instr;
+  LOperand* value = UseRegister(instr->value());
+  LOperand* scratch = TempRegister();
+  return new(zone()) LCompareMinusZeroAndBranch(value, scratch);
+}
+
+
 LInstruction* LChunkBuilder::DoIsObjectAndBranch(HIsObjectAndBranch* instr) {
   ASSERT(instr->value()->representation().IsTagged());
   LOperand* temp = TempRegister();

src/mips/lithium-mips.h

@@ -72,6 +72,7 @@ class LCodeGen;
   V(ClampIToUint8)                              \
   V(ClampTToUint8)                              \
   V(ClassOfTestAndBranch)                       \
+  V(CompareMinusZeroAndBranch)                  \
   V(CompareNumericAndBranch)                    \
   V(CmpObjectEqAndBranch)                       \
   V(CmpHoleAndBranch)                           \
@@ -923,6 +924,22 @@ class LCmpHoleAndBranch V8_FINAL : public LControlInstruction<1, 0> {
 };
 
 
+class LCompareMinusZeroAndBranch V8_FINAL : public LControlInstruction<1, 1> {
+ public:
+  LCompareMinusZeroAndBranch(LOperand* value, LOperand* temp) {
+    inputs_[0] = value;
+    temps_[0] = temp;
+  }
+
+  LOperand* value() { return inputs_[0]; }
+  LOperand* temp() { return temps_[0]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(CompareMinusZeroAndBranch,
+                               "cmp-minus-zero-and-branch")
+  DECLARE_HYDROGEN_ACCESSOR(CompareMinusZeroAndBranch)
+};
+
+
 class LIsObjectAndBranch V8_FINAL : public LControlInstruction<1, 1> {
  public:
   LIsObjectAndBranch(LOperand* value, LOperand* temp) {