commit 2d35d9d7490ef3880ee366ccbf8f6e791f398c47
author Serban Constantinescu <serban.constantinescu@arm.com> Sun Feb 22 22:08:01 2015 +0000
committer Serban Constantinescu <serban.constantinescu@arm.com> Tue Mar 17 10:47:51 2015 +0000
tree 5e512b5da7d7c290d69e4437436feb15ccad5ffc
parent 8fff8c66738b35bafc5318e408afa21c34c57ff3

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: Ied8577c879845777e52867aced16b2b45e06ac6c
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>

compiler/optimizing/code_generator_arm64.cc

diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index c48cab4..8ee150b 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -63,6 +63,7 @@
 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;
@@ -1106,7 +1107,7 @@
     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;
 
@@ -1398,7 +1399,7 @@
   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;
     }
@@ -1468,7 +1469,7 @@
 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);
   }
@@ -2120,7 +2121,7 @@
   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;