diff options
Diffstat (limited to 'compiler/optimizing')
| -rw-r--r-- | compiler/optimizing/instruction_simplifier.cc | 59 |
1 files changed, 58 insertions, 1 deletions
diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc index a75639f3c5..6ff71f2d3e 100644 --- a/compiler/optimizing/instruction_simplifier.cc +++ b/compiler/optimizing/instruction_simplifier.cc @@ -24,6 +24,7 @@ #include "intrinsics.h" #include "intrinsics_utils.h" #include "mirror/class-inl.h" +#include "optimizing/data_type.h" #include "optimizing/nodes.h" #include "scoped_thread_state_change-inl.h" #include "sharpening.h" @@ -112,7 +113,6 @@ class InstructionSimplifierVisitor : public HGraphDelegateVisitor { void VisitDeoptimize(HDeoptimize* deoptimize) override; void VisitVecMul(HVecMul* instruction) override; void VisitPredicatedInstanceFieldGet(HPredicatedInstanceFieldGet* instruction) override; - void SimplifySystemArrayCopy(HInvoke* invoke); void SimplifyStringEquals(HInvoke* invoke); void SimplifyFP2Int(HInvoke* invoke); @@ -1185,6 +1185,33 @@ static bool IsTypeConversionLossless(DataType::Type input_type, DataType::Type r !(result_type == DataType::Type::kInt64 && input_type == DataType::Type::kFloat32); } +static bool CanRemoveRedundantAnd(HConstant* and_right, + HConstant* shr_right, + DataType::Type result_type) { + int64_t and_cst = Int64FromConstant(and_right); + int64_t shr_cst = Int64FromConstant(shr_right); + + // In the following sequence A is the input value, D is the result: + // B := A & x + // C := B >> r + // D := TypeConv(n-bit type) C + + // The value of D is entirely dependent on the bits [n-1:0] of C, which in turn are dependent + // on bits [r+n-1:r] of B. + // Therefore, if the AND does not change bits [r+n-1:r] of A then it will not affect D. + // This can be checked by ensuring that bits [r+n-1:r] of the AND Constant are 1. + + // For example: return (byte) ((value & 0xff00) >> 8) + // return (byte) ((value & 0xff000000) >> 31) + + // The mask sets bits [r+n-1:r] to 1, and all others to 0. + int64_t mask = DataType::MaxValueOfIntegralType(DataType::ToUnsigned(result_type)) << shr_cst; + + // If the result of a bitwise AND between the mask and the AND constant is the original mask, then + // the AND does not change bits [r+n-1:r], meaning that it is redundant and can be removed. + return ((and_cst & mask) == mask); +} + static inline bool TryReplaceFieldOrArrayGetType(HInstruction* maybe_get, DataType::Type new_type) { if (maybe_get->IsInstanceFieldGet()) { maybe_get->AsInstanceFieldGet()->SetType(new_type); @@ -1305,6 +1332,36 @@ void InstructionSimplifierVisitor::VisitTypeConversion(HTypeConversion* instruct return; } } + } else if (input->IsShr() && DataType::IsIntegralType(result_type) && + // Optimization only applies to lossy Type Conversions. + !IsTypeConversionLossless(input_type, result_type)) { + DCHECK(DataType::IsIntegralType(input_type)); + HShr* shr_op = input->AsShr(); + HConstant* shr_right = shr_op->GetConstantRight(); + HInstruction* shr_left = shr_op->GetLeastConstantLeft(); + if (shr_right != nullptr && shr_left->IsAnd()) { + // Optimization needs AND -> SHR -> TypeConversion pattern. + HAnd* and_op = shr_left->AsAnd(); + HConstant* and_right = and_op->GetConstantRight(); + HInstruction* and_left = and_op->GetLeastConstantLeft(); + DataType::Type and_left_type = and_left->GetType(); + if (!DataType::IsUnsignedType(and_left_type) && + !DataType::IsUnsignedType(result_type) && + !DataType::IsUnsignedType(and_right->GetType()) && + (DataType::Size(and_left_type) < 8) && + (DataType::Size(result_type) == 1)) { + // TODO: Support Unsigned Types. + // TODO: Support Long Types. + // TODO: Support result types other than byte. + if (and_right != nullptr && and_op->HasOnlyOneNonEnvironmentUse() && + CanRemoveRedundantAnd(and_right, shr_right, result_type)) { + and_op->ReplaceWith(and_left); + and_op->GetBlock()->RemoveInstruction(and_op); + RecordSimplification(); + return; + } + } + } } else if (input->IsAnd() && DataType::IsIntegralType(result_type)) { DCHECK(DataType::IsIntegralType(input_type)); HAnd* input_and = input->AsAnd(); |