Refactor Math.min/max to be a single HInstruction.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index a0da25c2b1d561a4203556d46f02b5be4d8e933c..9243aed9e04828ed320504126d66cbc252a3c7fd 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -1649,6 +1649,63 @@ void LCodeGen::DoAddI(LAddI* instr) {
 }
 
 
+void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
+  LOperand* left = instr->InputAt(0);
+  LOperand* right = instr->InputAt(1);
+  HMathMinMax::Operation operation = instr->hydrogen()->operation();
+  Condition condition = (operation == HMathMinMax::kMathMin) ? le : ge;
+  if (instr->hydrogen()->representation().IsInteger32()) {
+    Register left_reg = ToRegister(left);
+    Operand right_op = (right->IsRegister() || right->IsConstantOperand())
+        ? ToOperand(right)
+        : Operand(EmitLoadRegister(right, ip));
+    Register result_reg = ToRegister(instr->result());
+    __ cmp(left_reg, right_op);
+    if (!result_reg.is(left_reg)) {
+      __ mov(result_reg, left_reg, LeaveCC, condition);
+    }
+    __ mov(result_reg, right_op, LeaveCC, NegateCondition(condition));
+  } else {
+    ASSERT(instr->hydrogen()->representation().IsDouble());
+    DoubleRegister left_reg = ToDoubleRegister(left);
+    DoubleRegister right_reg = ToDoubleRegister(right);
+    DoubleRegister result_reg = ToDoubleRegister(instr->result());
+    Label check_nan_left, check_zero, return_left, return_right, done;
+    __ VFPCompareAndSetFlags(left_reg, right_reg);
+    __ b(vs, &check_nan_left);
+    __ b(eq, &check_zero);
+    __ b(condition, &return_left);
+    __ b(al, &return_right);
+
+    __ bind(&check_zero);
+    __ VFPCompareAndSetFlags(left_reg, 0.0);
+    __ b(ne, &return_left);  // left == right != 0.
+    // At this point, both left and right are either 0 or -0.
+    if (operation == HMathMinMax::kMathMin) {
+      __ vorr(result_reg, left_reg, right_reg);
+    } else {
+      __ vadd(result_reg, left_reg, right_reg);

[Erik Corry, 2012/08/06 10:44:40]

Should this be vand?

[Yang, 2012/08/06 10:50:41]

I think vadd would work equally well here:
-0 + -0 = -0
-0 + 0 = 0
0 + -0 = 0
0 + 0 = 0

[Jakob Kummerow, 2012/08/06 14:08:43]

Added a comment explaining why "vadd" is not a typo.

+    }
+    __ b(al, &done);
+
+    __ bind(&check_nan_left);
+    __ VFPCompareAndSetFlags(left_reg, left_reg);
+    __ b(vs, &return_left);  // left == NaN.
+    __ bind(&return_right);
+    if (!right_reg.is(result_reg)) {
+      __ vmov(result_reg, right_reg);
+    }
+    __ b(al, &done);
+
+    __ bind(&return_left);
+    if (!left_reg.is(result_reg)) {
+      __ vmov(result_reg, left_reg);
+    }
+    __ bind(&done);
+  }
+}
+
+
 void LCodeGen::DoArithmeticD(LArithmeticD* instr) {
   DoubleRegister left = ToDoubleRegister(instr->InputAt(0));
   DoubleRegister right = ToDoubleRegister(instr->InputAt(1));