ARM: Implement DoPower in the lithium code generator.

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 2c916f6ad67b847376a3656a5189f25d1cb0c18c..02e22b22e6acac2570b3df9fa5fe8791b875747c 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -2861,6 +2861,70 @@ void LCodeGen::DoMathSqrt(LUnaryMathOperation* instr) {
 }
 
 
+void LCodeGen::DoPower(LPower* instr) {
+  LOperand* left = instr->InputAt(0);
+  LOperand* right = instr->InputAt(1);
+  Register scratch = scratch0();
+  DoubleRegister result_reg = ToDoubleRegister(instr->result());
+  Representation exponent_type = instr->hydrogen()->right()->representation();
+  if (exponent_type.IsDouble()) {
+    // Save r0-r3 on the stack, prepare arguments and call C function.
+    __ stm(db_w, sp, r0.bit() | r1.bit() | r2.bit() | r3.bit());

[Søren Thygesen Gjesse, 2011/02/17 09:59:56]

As discussed off-line this saving is not needed.

[Karl Klose, 2011/02/21 13:34:59]

Done.

+    __ PrepareCallCFunction(4, scratch);
+    __ vmov(r0, r1, ToDoubleRegister(left));
+    __ vmov(r2, r3, ToDoubleRegister(right));
+    __ CallCFunction(ExternalReference::power_double_double_function(), 4);
+  } else if (exponent_type.IsInteger32()) {
+    ASSERT(ToRegister(right).is(r0));
+    // Save r0-r3 on the stack, prepare arguments and call C function.
+    __ stm(db_w, sp, r0.bit() | r1.bit() | r2.bit() | r3.bit());

[Søren Thygesen Gjesse, 2011/02/17 09:59:56]

Ditto.

[Karl Klose, 2011/02/21 13:34:59]

Done.

+    __ PrepareCallCFunction(4, scratch);
+    __ mov(r2, ToRegister(right));
+    __ vmov(r0, r1, ToDoubleRegister(left));
+    __ CallCFunction(ExternalReference::power_double_int_function(), 4);
+  } else {
+    ASSERT(exponent_type.IsTagged());
+    ASSERT(instr->hydrogen()->left()->representation().IsDouble());
+    ASSERT(CpuFeatures::IsSupported(VFP3));

[Søren Thygesen Gjesse, 2011/02/17 09:59:56]

Crankshaft implies VFP3, and we are already in a VFP3 scope, so this ASSERT is
not necessary.

[Karl Klose, 2011/02/21 13:34:59]

Done.

+
+    Register right_reg = ToRegister(right);
+
+    // Check for smi on the right hand side.
+    Label non_smi, call;

[Søren Thygesen Gjesse, 2011/02/17 09:59:56]

Please use JumpIfNotSmi.

[Karl Klose, 2011/02/21 13:34:59]

Done.

+    __ tst(right_reg, Operand(kSmiTagMask));
+    __ b(ne, &non_smi);
+
+    // Untag smi and convert it to a double.
+    __ SmiUntag(right_reg);
+    SwVfpRegister single_scratch = double_scratch0().low();
+    __ vmov(single_scratch, right_reg);
+    __ vcvt_f64_s32(result_reg, single_scratch);
+    __ jmp(&call);
+
+    // Heap number map check.
+    __ bind(&non_smi);
+    __ ldr(scratch, FieldMemOperand(right_reg, HeapObject::kMapOffset));
+    __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
+    __ cmp(scratch, Operand(ip));
+    DeoptimizeIf(ne, instr->environment());
+    int32_t value_offset = HeapNumber::kValueOffset - kHeapObjectTag;
+    __ add(scratch, right_reg, Operand(value_offset), LeaveCC);

[Søren Thygesen Gjesse, 2011/02/17 09:59:56]

LeaveCC is default for add.

[Karl Klose, 2011/02/21 13:34:59]

Done.

+    __ vldr(result_reg, scratch, 0);
+
+    // Save r0-r3 on the stack, prepare arguments and call C function.
+    __ bind(&call);
+    __ stm(db_w, sp, r0.bit() | r1.bit() | r2.bit() | r3.bit());
+    __ PrepareCallCFunction(4, scratch);
+    __ vmov(r0, r1, ToDoubleRegister(left));
+    __ vmov(r2, r3, result_reg);
+    __ CallCFunction(ExternalReference::power_double_double_function(), 4);
+  }
+  // Store the result in the result register and restore r0-r3.

[Søren Thygesen Gjesse, 2011/02/17 09:59:56]

We need to support non USE_ARM_EABI, where fp result is returned in cr8, See
code-atubs-arm.cc.

Maybe we should abstract this to a macro assembler GetCFunctionDoubleResult
instruction to avoid the #ifdef/#endif spreading.

[Karl Klose, 2011/02/21 13:34:59]

Implemented MacroAssembler::GetCFunctionDoubleResult and used it here and in

+  __ vmov(result_reg, r0, r1);
+  __ ldm(ia_w, sp, r0.bit() | r1.bit() | r2.bit() | r3.bit());
+}
+
+
 void LCodeGen::DoUnaryMathOperation(LUnaryMathOperation* instr) {
   switch (instr->op()) {
     case kMathAbs: