Add Float64Round operator.

src/compiler/machine-operator.h

Index: src/compiler/machine-operator.h
diff --git a/src/compiler/machine-operator.h b/src/compiler/machine-operator.h
index 568d3eb2b89acc163584aea605375772ccfed1f0..e4a06f28f3df28ade3520b380d05d6861a77a1c8 100644
--- a/src/compiler/machine-operator.h
+++ b/src/compiler/machine-operator.h
@@ -5,6 +5,7 @@
 #ifndef V8_COMPILER_MACHINE_OPERATOR_H_
 #define V8_COMPILER_MACHINE_OPERATOR_H_
 
+#include "src/base/flags.h"
 #include "src/compiler/machine-type.h"
 
 namespace v8 {
@@ -51,13 +52,38 @@ std::ostream& operator<<(std::ostream&, StoreRepresentation);
 
 StoreRepresentation const& StoreRepresentationOf(Operator const*);
 
+// Rounding mode for double rounding.
+enum Float64RoundMode {
+  kRoundDown,

[titzer, 2014/10/22 14:05:42]

A little confusing here.

These rounding modes map to operators, correct? Then why do we need the separate
enum if it is not a parameter to the operator?

[sigurds, 2014/10/22 14:24:50]

I thought it was cleaner to have one op + rounding mode instead of several ops
here. Changed it in the last upload. Please tell me which you think is better.

+  kRoundUp,
+  kRoundAway,    // Rounding, tie: away from zero.
+  kRoundTowards  // Rounding, tie: towards zero.
+};
+
+#define BACKEND_SPECIFIC_OPS(V) \

[titzer, 2014/10/22 14:05:42]

Can we try to avoid the higher order macro stuff here? It's really hard to tell
what methods are available on the MachineOperatorBuilder like this.

[sigurds, 2014/10/22 14:24:50]

Done.

+  V(Float64Floor, 0)            \
+  V(Float64Ceil, 1)             \
+  V(Float64RoundTiesAway, 2)    \
+  V(Float64RoundTiesTowards, 3)
+
+enum SupportedOperator {
+  kNoSupportedOperators = 0
+#define ENUMDEF(Name, Ordinal) , kSupports##Name = 1 << Ordinal
+  BACKEND_SPECIFIC_OPS(ENUMDEF)
+#undef ENUMDEF
+};
+
+typedef base::Flags<SupportedOperator, uint8_t> SupportedOperators;
+DEFINE_OPERATORS_FOR_FLAGS(SupportedOperators)
 
 // Interface for building machine-level operators. These operators are
 // machine-level but machine-independent and thus define a language suitable
 // for generating code to run on architectures such as ia32, x64, arm, etc.
 class MachineOperatorBuilder FINAL {
  public:
-  explicit MachineOperatorBuilder(MachineType word = kMachPtr);
+  explicit MachineOperatorBuilder(
+      MachineType word = kMachPtr,
+      SupportedOperators supportedOperators = kNoSupportedOperators);
 
   const Operator* Word32And();
   const Operator* Word32Or();
@@ -122,6 +148,9 @@ class MachineOperatorBuilder FINAL {
   const Operator* TruncateFloat64ToInt32();  // JavaScript semantics.
   const Operator* TruncateInt64ToInt32();
 
+  // Rounds a number depending on rounding mode.
+  const Operator* Float64Round(Float64RoundMode mode);
+
   // Floating point operators always operate with IEEE 754 round-to-nearest.
   const Operator* Float64Add();
   const Operator* Float64Sub();
@@ -149,6 +178,12 @@ class MachineOperatorBuilder FINAL {
   bool Is64() const { return word() == kRepWord64; }
   MachineType word() const { return word_; }
 
+// Getters to test if backend specific operation is available.
+#define GETTER(Name, Ordinal) \
+  bool Has##Name() { return supportedOperators_ & kSupports##Name; }
+  BACKEND_SPECIFIC_OPS(GETTER)
+#undef GETTER
+
 // Pseudo operators that translate to 32/64-bit operators depending on the
 // word-size of the target machine assumed by this builder.
 #define PSEUDO_OP_LIST(V) \
@@ -181,6 +216,7 @@ class MachineOperatorBuilder FINAL {
  private:
   const MachineOperatorBuilderImpl& impl_;
   const MachineType word_;
+  const SupportedOperators supportedOperators_;
 };
 
 }  // namespace compiler