X87: implement MathPow stub for X87.

src/x87/code-stubs-x87.cc

Index: src/x87/code-stubs-x87.cc
diff --git a/src/x87/code-stubs-x87.cc b/src/x87/code-stubs-x87.cc
index c3903f99ecb04694fabc425f62f3cc0f71275a4b..0fe2cd93c5b47f14d387160f27418fc9232f8a72 100644
--- a/src/x87/code-stubs-x87.cc
+++ b/src/x87/code-stubs-x87.cc
@@ -325,8 +325,28 @@ void FloatingPointHelper::CheckFloatOperands(MacroAssembler* masm,
 
 
 void MathPowStub::Generate(MacroAssembler* masm) {
-  // No SSE2 support
-  UNREACHABLE();
+  const Register base = edx;
+  const Register scratch = ecx;
+  Counters* counters = isolate()->counters();
+  Label call_runtime;
+
+  // We will call runtime helper function directly.
+  if (exponent_type() == ON_STACK) {
+    // The arguments are still on the stack.
+    __ bind(&call_runtime);
+    __ TailCallRuntime(Runtime::kMathPowRT, 2, 1);
+
+    // The stub is called from non-optimized code, which expects the result
+    // as heap number in exponent.
+    __ AllocateHeapNumber(eax, scratch, base, &call_runtime);
+    __ fstp_d(FieldOperand(eax, HeapNumber::kValueOffset));
+    __ IncrementCounter(counters->math_pow(), 1);
+    __ ret(2 * kPointerSize);
+  } else {
+    // Currently it's only called from full-compiler and exponent type is
+    // ON_STACK.
+    UNIMPLEMENTED();
+  }
 }