ARM: Port instr simplification of array accesses.
After changing the addressing mode for array accesses (in
https://android-review.googlesource.com/248406) the 'add'
instruction that calculates the base address for the array can be
shared across accesses to the same array.
Before https://android-review.googlesource.com/248406:
add IP, r[Array], r[Index0], LSL #2
ldr r0, [IP, #12]
add IP, r[Array], r[Index1], LSL #2
ldr r0, [IP, #12]
Before this CL:
add IP. r[Array], #12
ldr r0, [IP, r[Index0], LSL #2]
add IP. r[Array], #12
ldr r0, [IP, r[Index1], LSL #2]
After this CL:
add IP. r[Array], #12
ldr r0, [IP, r[Index0], LSL #2]
ldr r0, [IP, r[Index1], LSL #2]
Link to the original optimization:
https://android-review.googlesource.com/#/c/127310/
Test: Run ART test suite on Nexus 6.
Change-Id: Iee26f9a0a7ca46abb90e3f60d19d22dc8dee4d8f
diff --git a/compiler/optimizing/instruction_simplifier_arm64.cc b/compiler/optimizing/instruction_simplifier_arm64.cc
index 983d31d..6d107d5 100644
--- a/compiler/optimizing/instruction_simplifier_arm64.cc
+++ b/compiler/optimizing/instruction_simplifier_arm64.cc
@@ -28,56 +28,6 @@
using helpers::HasShifterOperand;
using helpers::ShifterOperandSupportsExtension;
-void InstructionSimplifierArm64Visitor::TryExtractArrayAccessAddress(HInstruction* access,
- HInstruction* array,
- HInstruction* index,
- size_t data_offset) {
- if (kEmitCompilerReadBarrier) {
- // The read barrier instrumentation does not support the
- // HArm64IntermediateAddress instruction yet.
- //
- // TODO: Handle this case properly in the ARM64 code generator and
- // re-enable this optimization; otherwise, remove this TODO.
- // b/26601270
- return;
- }
- if (index->IsConstant() ||
- (index->IsBoundsCheck() && index->AsBoundsCheck()->GetIndex()->IsConstant())) {
- // When the index is a constant all the addressing can be fitted in the
- // memory access instruction, so do not split the access.
- return;
- }
- if (access->IsArraySet() &&
- access->AsArraySet()->GetValue()->GetType() == Primitive::kPrimNot) {
- // The access may require a runtime call or the original array pointer.
- return;
- }
-
- // Proceed to extract the base address computation.
- ArenaAllocator* arena = GetGraph()->GetArena();
-
- HIntConstant* offset = GetGraph()->GetIntConstant(data_offset);
- HArm64IntermediateAddress* address =
- new (arena) HArm64IntermediateAddress(array, offset, kNoDexPc);
- address->SetReferenceTypeInfo(array->GetReferenceTypeInfo());
- access->GetBlock()->InsertInstructionBefore(address, access);
- access->ReplaceInput(address, 0);
- // Both instructions must depend on GC to prevent any instruction that can
- // trigger GC to be inserted between the two.
- access->AddSideEffects(SideEffects::DependsOnGC());
- DCHECK(address->GetSideEffects().Includes(SideEffects::DependsOnGC()));
- DCHECK(access->GetSideEffects().Includes(SideEffects::DependsOnGC()));
- // TODO: Code generation for HArrayGet and HArraySet will check whether the input address
- // is an HArm64IntermediateAddress and generate appropriate code.
- // We would like to replace the `HArrayGet` and `HArraySet` with custom instructions (maybe
- // `HArm64Load` and `HArm64Store`). We defer these changes because these new instructions would
- // not bring any advantages yet.
- // Also see the comments in
- // `InstructionCodeGeneratorARM64::VisitArrayGet()` and
- // `InstructionCodeGeneratorARM64::VisitArraySet()`.
- RecordSimplification();
-}
-
bool InstructionSimplifierArm64Visitor::TryMergeIntoShifterOperand(HInstruction* use,
HInstruction* bitfield_op,
bool do_merge) {
@@ -190,19 +140,23 @@
void InstructionSimplifierArm64Visitor::VisitArrayGet(HArrayGet* instruction) {
size_t data_offset = CodeGenerator::GetArrayDataOffset(instruction);
- TryExtractArrayAccessAddress(instruction,
- instruction->GetArray(),
- instruction->GetIndex(),
- data_offset);
+ if (TryExtractArrayAccessAddress(instruction,
+ instruction->GetArray(),
+ instruction->GetIndex(),
+ data_offset)) {
+ RecordSimplification();
+ }
}
void InstructionSimplifierArm64Visitor::VisitArraySet(HArraySet* instruction) {
size_t access_size = Primitive::ComponentSize(instruction->GetComponentType());
size_t data_offset = mirror::Array::DataOffset(access_size).Uint32Value();
- TryExtractArrayAccessAddress(instruction,
- instruction->GetArray(),
- instruction->GetIndex(),
- data_offset);
+ if (TryExtractArrayAccessAddress(instruction,
+ instruction->GetArray(),
+ instruction->GetIndex(),
+ data_offset)) {
+ RecordSimplification();
+ }
}
void InstructionSimplifierArm64Visitor::VisitMul(HMul* instruction) {