Implement a simple register allocator that tries to keep instruction results in registers.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
diff --git a/runtime/vm/intermediate_language_x64.cc b/runtime/vm/intermediate_language_x64.cc
index b44d8a033f91bd3b4c552c2dfdd2dda6549c9931..b56000a2845ae7aae0d8bc80c66d828314f5e424 100644
--- a/runtime/vm/intermediate_language_x64.cc
+++ b/runtime/vm/intermediate_language_x64.cc
@@ -28,7 +28,7 @@ void BindInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
     // with branches.  Currrently IR does not provide an easy way to remove
     // instructions from the graph so we just leave fused comparison in it
     // but change its result location to be NoLocation.
-    __ pushq(locs()->out().reg());
+    compiler->frame_register_allocator()->Push(locs()->out().reg(), this);
   }
 }
 
@@ -105,7 +105,7 @@ void ReturnInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 // Generic summary for call instructions that have all arguments pushed
 // on the stack and return the result in a fixed register RAX.
 LocationSummary* Computation::MakeCallSummary() {
-  LocationSummary* result = new LocationSummary(0, 0);
+  LocationSummary* result = new LocationSummary(0, 0, LocationSummary::kCall);
   result->set_out(Location::RegisterLocation(RAX));
   return result;
 }
@@ -114,7 +114,9 @@ LocationSummary* Computation::MakeCallSummary() {
 LocationSummary* ClosureCallComp::MakeLocationSummary() const {
   const intptr_t kNumInputs = 0;
   const intptr_t kNumTemps = 1;
-  LocationSummary* result = new LocationSummary(kNumInputs, kNumTemps);
+  LocationSummary* result = new LocationSummary(kNumInputs,
+                                                kNumTemps,
+                                                LocationSummary::kCall);
   result->set_out(Location::RegisterLocation(RAX));
   result->set_temp(0, Location::RegisterLocation(R10));  // Arg. descriptor.
   return result;
@@ -198,10 +200,17 @@ void AssertBooleanComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 
 
 LocationSummary* EqualityCompareComp::MakeLocationSummary() const {
+  const LocationSummary::ContainsBranch contains_branch =
+      is_fused_with_branch() ? LocationSummary::kBranch
+                             : LocationSummary::kNoBranch;
+
   const intptr_t kNumInputs = 2;
   if ((NumTargets() == 1) && (ClassIdAt(0) == kSmi)) {
     const intptr_t kNumTemps = 1;
-    LocationSummary* locs = new LocationSummary(kNumInputs, kNumTemps);
+    LocationSummary* locs = new LocationSummary(kNumInputs,
+                                                kNumTemps,
+                                                LocationSummary::kNoCall,
+                                                contains_branch);
     locs->set_in(0, Location::RequiresRegister());
     locs->set_in(1, Location::RequiresRegister());
     locs->set_temp(0, Location::RequiresRegister());
@@ -212,7 +221,10 @@ LocationSummary* EqualityCompareComp::MakeLocationSummary() const {
   }
   if (NumTargets() > 0) {
     const intptr_t kNumTemps = 1;
-    LocationSummary* locs = new LocationSummary(kNumInputs, kNumTemps);
+    LocationSummary* locs = new LocationSummary(kNumInputs,
+                                                kNumTemps,
+                                                LocationSummary::kCall,
+                                                contains_branch);
     locs->set_in(0, Location::RequiresRegister());
     locs->set_in(1, Location::RequiresRegister());
     locs->set_temp(0, Location::RequiresRegister());
@@ -222,7 +234,10 @@ LocationSummary* EqualityCompareComp::MakeLocationSummary() const {
     return locs;
   }
   const intptr_t kNumTemps = 0;
-  LocationSummary* locs = new LocationSummary(kNumInputs, kNumTemps);
+  LocationSummary* locs = new LocationSummary(kNumInputs,
+                                              kNumTemps,
+                                              LocationSummary::kCall,
+                                              contains_branch);
   locs->set_in(0, Location::RequiresRegister());
   locs->set_in(1, Location::RequiresRegister());
   if (!is_fused_with_branch()) {
@@ -413,10 +428,17 @@ void EqualityCompareComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 
 
 LocationSummary* RelationalOpComp::MakeLocationSummary() const {
+  const LocationSummary::ContainsBranch contains_branch =
+      is_fused_with_branch() ? LocationSummary::kBranch
+                             : LocationSummary::kNoBranch;
+
   if (operands_class_id() == kSmi || operands_class_id() == kDouble) {
     const intptr_t kNumInputs = 2;
     const intptr_t kNumTemps = 1;
-    LocationSummary* summary = new LocationSummary(kNumInputs, kNumTemps);
+    LocationSummary* summary = new LocationSummary(kNumInputs,
+                                                   kNumTemps,
+                                                   LocationSummary::kCall,
+                                                   contains_branch);
     summary->set_in(0, Location::RequiresRegister());
     summary->set_in(1, Location::RequiresRegister());
     if (!is_fused_with_branch()) {
@@ -560,7 +582,11 @@ void RelationalOpComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 
 
 LocationSummary* NativeCallComp::MakeLocationSummary() const {
-  LocationSummary* locs = new LocationSummary(0, 3);
+  const intptr_t kNumInputs = 0;
+  const intptr_t kNumTemps = 3;
+  LocationSummary* locs = new LocationSummary(kNumInputs,
+                                              kNumTemps,
+                                              LocationSummary::kCall);
   locs->set_temp(0, Location::RegisterLocation(RAX));
   locs->set_temp(1, Location::RegisterLocation(RBX));
   locs->set_temp(2, Location::RegisterLocation(R10));
@@ -779,23 +805,14 @@ void StoreIndexedComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 
 
 LocationSummary* InstanceSetterComp::MakeLocationSummary() const {
-  const intptr_t kNumInputs = 2;
-  return LocationSummary::Make(kNumInputs, Location::NoLocation());
-  return NULL;
+  return MakeCallSummary();
 }
 
 
 void InstanceSetterComp::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Register receiver = locs()->in(0).reg();
-  Register value = locs()->in(1).reg();
-
-  // Preserve the value (second argument) under the arguments as the result
-  // of the computation, then call the setter.
   const String& function_name =
       String::ZoneHandle(Field::SetterSymbol(field_name()));
 
-  __ pushq(receiver);
-  __ pushq(value);
   compiler->AddCurrentDescriptor(PcDescriptors::kDeopt,
                                  cid(),
                                  token_index(),
@@ -911,7 +928,9 @@ LocationSummary* CreateArrayComp::MakeLocationSummary() const {
   // ArgumentCount getter and an ArgumentAt getter.
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 1;
-  LocationSummary* locs = new LocationSummary(kNumInputs, kNumTemps);
+  LocationSummary* locs = new LocationSummary(kNumInputs,
+                                              kNumTemps,
+                                              LocationSummary::kCall);
   locs->set_in(0, Location::RegisterLocation(RBX));
   locs->set_temp(0, Location::RegisterLocation(R10));
   locs->set_out(Location::RegisterLocation(RAX));
@@ -943,7 +962,9 @@ void CreateArrayComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 
 LocationSummary* AllocateObjectWithBoundsCheckComp::
     MakeLocationSummary() const {
-  return LocationSummary::Make(2, Location::RequiresRegister());
+  return LocationSummary::Make(2,
+                               Location::RequiresRegister(),
+                               LocationSummary::kCall);
 }
 
 
@@ -999,7 +1020,9 @@ void LoadVMFieldComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 LocationSummary* InstantiateTypeArgumentsComp::MakeLocationSummary() const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 0;
-  LocationSummary* locs = new LocationSummary(kNumInputs, kNumTemps);
+  LocationSummary* locs = new LocationSummary(kNumInputs,
+                                              kNumTemps,
+                                              LocationSummary::kCall);
   locs->set_in(0, Location::RequiresRegister());
   locs->set_out(Location::SameAsFirstInput());
   return locs;
@@ -1178,7 +1201,9 @@ void ExtractConstructorInstantiatorComp::EmitNativeCode(
 LocationSummary* AllocateContextComp::MakeLocationSummary() const {
   const intptr_t kNumInputs = 0;
   const intptr_t kNumTemps = 1;
-  LocationSummary* locs = new LocationSummary(kNumInputs, kNumTemps);
+  LocationSummary* locs = new LocationSummary(kNumInputs,
+                                              kNumTemps,
+                                              LocationSummary::kCall);
   locs->set_temp(0, Location::RegisterLocation(R10));
   locs->set_out(Location::RegisterLocation(RAX));
   return locs;
@@ -1199,7 +1224,9 @@ void AllocateContextComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 
 
 LocationSummary* CloneContextComp::MakeLocationSummary() const {
-  return LocationSummary::Make(1, Location::RequiresRegister());
+  return LocationSummary::Make(1,
+                               Location::RequiresRegister(),
+                               LocationSummary::kCall);
 }
 
 
@@ -1246,7 +1273,10 @@ void CatchEntryComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 LocationSummary* CheckStackOverflowComp::MakeLocationSummary() const {
   const intptr_t kNumInputs = 0;
   const intptr_t kNumTemps = 1;
-  LocationSummary* summary = new LocationSummary(kNumInputs, kNumTemps);
+  // TODO(vegorov): spilling is required only on infrequently executed path.

[srdjan, 2012/06/18 16:33:20]

A quick fix could be to use the deoptimization stub for the this kind of "stack
checks"

[Vyacheslav Egorov (Google), 2012/06/18 17:51:16]

Yes, I agree. 

In V8 we have a generic "deferred code facility for this kind of stuff (calls to
runtime from deferred code are surrounded by register spilling). Call to the
stack overflow runtime routine is done from this deferred code. 

+  LocationSummary* summary = new LocationSummary(kNumInputs,
+                                                 kNumTemps,
+                                                 LocationSummary::kCall);
   summary->set_temp(0, Location::RequiresRegister());
   return summary;
 }
@@ -1271,13 +1301,7 @@ LocationSummary* BinaryOpComp::MakeLocationSummary() const {
   const intptr_t kNumInputs = 2;
 
   if (operands_type() == kDoubleOperands) {
-    const intptr_t kNumTemps = 1;
-    LocationSummary* summary = new LocationSummary(kNumInputs, kNumTemps);
-    summary->set_in(0, Location::RequiresRegister());
-    summary->set_in(1, Location::RequiresRegister());
-    summary->set_out(Location::RegisterLocation(RAX));
-    summary->set_temp(0, Location::RequiresRegister());
-    return summary;
+    return MakeCallSummary();  // Calls into a stub for allocation.
   }
 
   ASSERT(operands_type() == kSmiOperands);
@@ -1456,17 +1480,15 @@ static void EmitSmiBinaryOp(FlowGraphCompiler* compiler, BinaryOpComp* comp) {
 
 static void EmitDoubleBinaryOp(FlowGraphCompiler* compiler,
                                BinaryOpComp* comp) {
-  Register left = comp->locs()->in(0).reg();
-  Register right = comp->locs()->in(1).reg();
-  Register temp = comp->locs()->temp(0).reg();
+  Register left = RBX;
+  Register right = RCX;
+  Register temp = RDX;
   Register result = comp->locs()->out().reg();
 
   const Class& double_class = compiler->double_class();
   const Code& stub =
     Code::Handle(StubCode::GetAllocationStubForClass(double_class));
   const ExternalLabel label(double_class.ToCString(), stub.EntryPoint());
-  __ pushq(left);
-  __ pushq(right);
   compiler->GenerateCall(comp->instance_call()->token_index(),
                          comp->instance_call()->try_index(),
                          &label,
@@ -1566,7 +1588,9 @@ void UnarySmiOpComp::EmitNativeCode(FlowGraphCompiler* compiler) {
 LocationSummary* NumberNegateComp::MakeLocationSummary() const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 1;  // Needed for doubles.
-  LocationSummary* summary = new LocationSummary(kNumInputs, kNumTemps);
+  LocationSummary* summary = new LocationSummary(kNumInputs,
+                                                 kNumTemps,
+                                                 LocationSummary::kCall);
   summary->set_in(0, Location::RequiresRegister());
   summary->set_out(Location::SameAsFirstInput());
   summary->set_temp(0, Location::RequiresRegister());
@@ -1632,13 +1656,13 @@ LocationSummary* ToDoubleComp::MakeLocationSummary() const {
     return locs;
   } else {
     ASSERT(from() == kSmi);
-    return LocationSummary::Make(kNumInputs, Location::RegisterLocation(RAX));
+    return MakeCallSummary();
   }
 }
 
 
 void ToDoubleComp::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Register value = locs()->in(0).reg();
+  Register value = (from() == kDouble) ? locs()->in(0).reg() : RBX;
   Register result = locs()->out().reg();
 
   const DeoptReasonId deopt_reason = (from() == kDouble) ?
@@ -1666,7 +1690,6 @@ void ToDoubleComp::EmitNativeCode(FlowGraphCompiler* compiler) {
   const ExternalLabel label(double_class.ToCString(), stub.EntryPoint());
 
   // TODO(vegorov): allocate box in the driver loop to avoid pushing and poping.
-  __ pushq(value);
   compiler->GenerateCall(instance_call()->token_index(),
                          instance_call()->try_index(),
                          &label,