Allow the optimizing code generator to call Math.pow with untagged doubles.

src/hydrogen.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4075 matching lines @@
     case kMathSqrt:
       if (argument_count == 2) {
         HValue* argument = Pop();
         // Pop receiver.
         Pop();
         HUnaryMathOperation* op = new HUnaryMathOperation(argument, id);
         PushAndAdd(op, expr->position());
         return true;
       }
       break;
+    case kMathPow:
+      if (argument_count == 3) {
+        HValue* right = Pop();
+        HValue* left = Pop();
+        Pop();  // Pop receiver.
+        // Use sqrt() if exponent is 0.5 or -0.5.
+        if (right->IsConstant() && HConstant::cast(right)->HasDoubleValue()) {
+          double exponent = HConstant::cast(right)->DoubleValue();
+          if (exponent == 0.5) {
+            PushAndAdd(new HUnaryMathOperation(left, kMathPowHalf));
+            return true;
+          } else if (exponent == -0.5) {
+            HConstant* double_one =
+                new HConstant(Handle<Object>(Smi::FromInt(1)),
+                              Representation::Double());
+            AddInstruction(double_one);
+            HUnaryMathOperation* square_root =
+                new HUnaryMathOperation(left, kMathPowHalf);
+            AddInstruction(square_root);
+            PushAndAdd(new HDiv(double_one, square_root));
+            return true;
+          } else if (exponent == 2.0) {
+            PushAndAdd(new HMul(left, left));
+            return true;
+          }
+        } else if (right->IsConstant() &&
+            HConstant::cast(right)->HasInteger32Value() &&
+            HConstant::cast(right)->Integer32Value() == 2) {
+          PushAndAdd(new HMul(left, left));
+          return true;
+        }
+
+        PushAndAdd(new HPower(left, right));
+        return true;
+      }
+      break;
     default:
       // Either not a special math function or not yet supported for inlining.
       break;
   }
   return false;
 }
 
 
 bool HGraphBuilder::TryCallApply(Call* expr) {
   Expression* callee = expr->expression();
@@ skipping 907 matching lines @@
 
 // Fast call for custom callbacks.
 void HGraphBuilder::GenerateCallFunction(int argument_count) {
   BAILOUT("inlined runtime function: CallFunction");
 }
 
 
 // Fast call to math functions.
 void HGraphBuilder::GenerateMathPow(int argument_count) {
   ASSERT_EQ(2, argument_count);
-  PushArgumentsForStubCall(argument_count);
-  PushAndAdd(new HCallStub(CodeStub::MathPow, argument_count),
-             RelocInfo::kNoPosition);
+  HValue* right = Pop();
+  HValue* left = Pop();
+  PushAndAdd(new HPower(left, right));
 }
 
 
 void HGraphBuilder::GenerateMathSin(int argument_count) {
   ASSERT_EQ(1, argument_count);
   PushArgumentsForStubCall(argument_count);
   HCallStub* instr =
       new HCallStub(CodeStub::TranscendentalCache, argument_count);
   instr->set_transcendental_type(TranscendentalCache::SIN);
   PushAndAdd(instr, RelocInfo::kNoPosition);
@@ skipping 505 matching lines @@
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (chunk_ != NULL) chunk_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal