Opt Compiler: Materialise constants that cannot be encoded

The VIXL MacroAssembler deals gracefully with any immediate. However
when the constant has multiple uses and cannot be encoded in the
instruction's immediate field we are better off using a register for
the constant and thus sharing the constant generation between multiple
uses.

Eg:
  var += #Const;    // #Const cannot be encoded.
  var += #Const;

Before:                 After:
  mov wip0, #Const        mov w4, #Const
  add w0, w0, wip0        add w0, w0, w4
  mov wip0, #Const        add w0, w0, w4
  add w0, w0, wip0

Change-Id: I8d1f620872d1241cf582fb4f3b45b5091b790146
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index c21084a6fe..6b4c2f0656 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -63,6 +63,7 @@ using helpers::StackOperandFrom;
 using helpers::VIXLRegCodeFromART;
 using helpers::WRegisterFrom;
 using helpers::XRegisterFrom;
+using helpers::ARM64EncodableConstantOrRegister;
 
 static constexpr size_t kHeapRefSize = sizeof(mirror::HeapReference<mirror::Object>);
 static constexpr int kCurrentMethodStackOffset = 0;
@@ -1104,7 +1105,7 @@ void LocationsBuilderARM64::HandleBinaryOp(HBinaryOperation* instr) {
     case Primitive::kPrimInt:
     case Primitive::kPrimLong:
       locations->SetInAt(0, Location::RequiresRegister());
-      locations->SetInAt(1, Location::RegisterOrConstant(instr->InputAt(1)));
+      locations->SetInAt(1, ARM64EncodableConstantOrRegister(instr->InputAt(1), instr));
       locations->SetOut(Location::RequiresRegister(), Location::kNoOutputOverlap);
       break;
 
@@ -1395,7 +1396,7 @@ void LocationsBuilderARM64::VisitCompare(HCompare* compare) {
   switch (in_type) {
     case Primitive::kPrimLong: {
       locations->SetInAt(0, Location::RequiresRegister());
-      locations->SetInAt(1, Location::RegisterOrConstant(compare->InputAt(1)));
+      locations->SetInAt(1, ARM64EncodableConstantOrRegister(compare->InputAt(1), compare));
       locations->SetOut(Location::RequiresRegister(), Location::kNoOutputOverlap);
       break;
     }
@@ -1465,7 +1466,7 @@ void InstructionCodeGeneratorARM64::VisitCompare(HCompare* compare) {
 void LocationsBuilderARM64::VisitCondition(HCondition* instruction) {
   LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction);
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RegisterOrConstant(instruction->InputAt(1)));
+  locations->SetInAt(1, ARM64EncodableConstantOrRegister(instruction->InputAt(1), instruction));
   if (instruction->NeedsMaterialization()) {
     locations->SetOut(Location::RequiresRegister(), Location::kNoOutputOverlap);
   }
@@ -2116,7 +2117,7 @@ void LocationsBuilderARM64::VisitNeg(HNeg* neg) {
   switch (neg->GetResultType()) {
     case Primitive::kPrimInt:
     case Primitive::kPrimLong:
-      locations->SetInAt(0, Location::RegisterOrConstant(neg->InputAt(0)));
+      locations->SetInAt(0, ARM64EncodableConstantOrRegister(neg->InputAt(0), neg));
       locations->SetOut(Location::RequiresRegister(), Location::kNoOutputOverlap);
       break;