Harmony: optimize Math.clz32.

src/hydrogen-instructions.cc

 // Copyright 2012 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 1129 matching lines @@
 
 const char* HUnaryMathOperation::OpName() const {
   switch (op()) {
     case kMathFloor: return "floor";
     case kMathRound: return "round";
     case kMathAbs: return "abs";
     case kMathLog: return "log";
     case kMathExp: return "exp";
     case kMathSqrt: return "sqrt";
     case kMathPowHalf: return "pow-half";
+    case kMathClz32: return "clz32";
     default:
       UNREACHABLE();
       return NULL;
   }
 }
 
 
 Range* HUnaryMathOperation::InferRange(Zone* zone) {
   Representation r = representation();
+  if (op() == kMathClz32) return new(zone) Range(0, 32);
   if (r.IsSmiOrInteger32() && value()->HasRange()) {
     if (op() == kMathAbs) {
       int upper = value()->range()->upper();
       int lower = value()->range()->lower();
       bool spans_zero = value()->range()->CanBeZero();
       // Math.abs(kMinInt) overflows its representation, on which the
       // instruction deopts. Hence clamp it to kMaxInt.
       int abs_upper = upper == kMinInt ? kMaxInt : abs(upper);
       int abs_lower = lower == kMinInt ? kMaxInt : abs(lower);
       Range* result =
@@ skipping 2749 matching lines @@
           return H_CONSTANT_DOUBLE((d > 0.0) ? d : 0.0);
         case kMathLog:
         case kMathSqrt:
           return H_CONSTANT_DOUBLE((d > 0.0) ? d : OS::nan_value());
         case kMathPowHalf:
         case kMathAbs:
           return H_CONSTANT_DOUBLE((d > 0.0) ? d : -d);
         case kMathRound:
         case kMathFloor:
           return H_CONSTANT_DOUBLE(d);
+        case kMathClz32:
+          return H_CONSTANT_INT(32);
         default:
           UNREACHABLE();
           break;
       }
     }
     switch (op) {
       case kMathExp:
         return H_CONSTANT_DOUBLE(fast_exp(d));
       case kMathLog:
         return H_CONSTANT_DOUBLE(std::log(d));
       case kMathSqrt:
         return H_CONSTANT_DOUBLE(fast_sqrt(d));
       case kMathPowHalf:
         return H_CONSTANT_DOUBLE(power_double_double(d, 0.5));
       case kMathAbs:
         return H_CONSTANT_DOUBLE((d >= 0.0) ? d + 0.0 : -d);
       case kMathRound:
         // -0.5 .. -0.0 round to -0.0.
         if ((d >= -0.5 && Double(d).Sign() < 0)) return H_CONSTANT_DOUBLE(-0.0);
         // Doubles are represented as Significant * 2 ^ Exponent. If the
         // Exponent is not negative, the double value is already an integer.
         if (Double(d).Exponent() >= 0) return H_CONSTANT_DOUBLE(d);
         return H_CONSTANT_DOUBLE(std::floor(d + 0.5));
       case kMathFloor:
         return H_CONSTANT_DOUBLE(std::floor(d));
+      case kMathClz32: {
+        uint32_t i = static_cast<uint32_t>(constant->Integer32Value());
+        return H_CONSTANT_INT(
+            (i == 0) ? 32 : CompilerIntrinsics::CountLeadingZeros(i));
+      }
       default:
         UNREACHABLE();
         break;
     }
   } while (false);
   return new(zone) HUnaryMathOperation(context, value, op);
 }
 
 
 HInstruction* HPower::New(Zone* zone,
@@ skipping 551 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal