Split ToDouble into two IL instruction to make it work with SSA.

vm/intermediate_language_ia32.cc

Index: vm/intermediate_language_ia32.cc
===================================================================
--- vm/intermediate_language_ia32.cc	(revision 10648)
+++ vm/intermediate_language_ia32.cc	(working copy)
@@ -1983,47 +1983,48 @@
 }
 
 
-LocationSummary* ToDoubleComp::MakeLocationSummary() const {
+LocationSummary* DoubleToDoubleComp::MakeLocationSummary() const {
   const intptr_t kNumInputs = 1;
-  if (from() == kDoubleCid) {
-    const intptr_t kNumTemps = 1;
-    LocationSummary* locs =
-        new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
-    locs->set_in(0, Location::RequiresRegister());
-    locs->set_temp(0, Location::RequiresRegister());
-    locs->set_out(Location::SameAsFirstInput());
-    locs->set_temp(0, Location::RequiresRegister());
-    return locs;
-  } else {
-    ASSERT(from() == kSmiCid);
-    return MakeCallSummary();  // Calls a stub to allocate result.
-  }
+  const intptr_t kNumTemps = 1;
+  LocationSummary* locs =
+      new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
+  locs->set_in(0, Location::RequiresRegister());
+  locs->set_temp(0, Location::RequiresRegister());
+  locs->set_out(Location::SameAsFirstInput());
+  locs->set_temp(0, Location::RequiresRegister());

[srdjan, 2012/08/14 21:21:26]

Remove both set_temp(0, ...), kNumTemps = 0.

[Florian Schneider, 2012/08/15 10:27:23]

ia32 needs a temp register for the CompareClassId.

+  return locs;
 }
 
 
-void ToDoubleComp::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Register value = (from() == kDoubleCid) ? locs()->in(0).reg() : EBX;
+void DoubleToDoubleComp::EmitNativeCode(FlowGraphCompiler* compiler) {
+  Register value = locs()->in(0).reg();
   Register result = locs()->out().reg();
 
-  const DeoptReasonId deopt_reason = (from() == kDoubleCid) ?
-      kDeoptDoubleToDouble : kDeoptIntegerToDouble;
   Label* deopt = compiler->AddDeoptStub(instance_call()->deopt_id(),
                                         instance_call()->try_index(),
-                                        deopt_reason,
+                                        kDeoptDoubleToDouble,
                                         value);
+  Register temp = locs()->temp(0).reg();
+  __ testl(value, Immediate(kSmiTagMask));
+  __ j(ZERO, deopt);  // Deoptimize if Smi.
+  __ CompareClassId(value, kDoubleCid, temp);
+  __ j(NOT_EQUAL, deopt);  // Deoptimize if not Double.
+  ASSERT(value == result);
+}
 
-  if (from() == kDoubleCid) {
-    Register temp = locs()->temp(0).reg();
-    __ testl(value, Immediate(kSmiTagMask));
-    __ j(ZERO, deopt);  // Deoptimize if Smi.
-    __ CompareClassId(value, kDoubleCid, temp);
-    __ j(NOT_EQUAL, deopt);  // Deoptimize if not Double.
-    ASSERT(value == result);
-    return;
-  }
 
-  ASSERT(from() == kSmiCid);
+LocationSummary* SmiToDoubleComp::MakeLocationSummary() const {
+  return MakeCallSummary();  // Calls a stub to allocate result.
+}
 
+
+void SmiToDoubleComp::EmitNativeCode(FlowGraphCompiler* compiler) {
+  Register result = locs()->out().reg();
+
+  Label* deopt = compiler->AddDeoptStub(instance_call()->deopt_id(),
+                                        instance_call()->try_index(),
+                                        kDeoptIntegerToDouble);
+
   const Class& double_class = compiler->double_class();
   const Code& stub =
     Code::Handle(StubCode::GetAllocationStubForClass(double_class));
@@ -2036,13 +2037,15 @@
                          PcDescriptors::kOther,
                          locs()->stack_bitmap());
   ASSERT(result == EAX);
-  __ popl(value);
+  Register value = EBX;

[srdjan, 2012/08/14 21:21:26]

Allocate temp for EBX and use it here.

[Florian Schneider, 2012/08/15 10:27:23]

Since this instruction is a call, we can freely use all registers as temps.

+  __ movl(value, Address(ESP, 0));

[srdjan, 2012/08/14 21:21:26]

Why not popl(value) and add value to AddDeoptStub?

[Florian Schneider, 2012/08/15 10:27:23]

This is because of a subtle problem with deoptimiation. Maybe I should add a
comment: We need to preserve the arguemt until after the deoptimization point
because the deopt info assumes that the value is on the stack.

This instruction should probably be redesigned in a future CL, once we have
deferred code for the allocation call and can inline new-space allocation of
doubles.

 
   __ testl(value, Immediate(kSmiTagMask));
   __ j(NOT_ZERO, deopt);  // Deoptimize if not Smi.
   __ SmiUntag(value);
   __ cvtsi2sd(XMM0, value);
   __ movsd(FieldAddress(result, Double::value_offset()), XMM0);
+  __ Drop(1);
 }