From f9d741e32c6f1629ce70eefc68d3363fa1cfd696 Mon Sep 17 00:00:00 2001 From: Vladimir Marko Date: Fri, 20 Nov 2015 15:08:11 +0000 Subject: Optimizing/ARM: Improve long shifts by 1. Implement long Shl(x,1) as LSLS+ADC, Shr(x,1) as ASR+RRX and UShr(x,1) as LSR+RRX. Remove the simplification substituting Shl(x,1) with ADD(x,x) as it interferes with some other optimizations instead of helping them. And since it didn't help 64-bit architectures anyway, codegen is the correct place for it. This is now implemented for ARM and x86, so only mips32 can be improved. Change-Id: Idd14f23292198b2260189e1497ca5411b21743b3 --- compiler/optimizing/code_generator_arm.cc | 14 +++++++++++++- compiler/optimizing/instruction_simplifier.cc | 10 ---------- 2 files changed, 13 insertions(+), 11 deletions(-) (limited to 'compiler/optimizing') diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc index 12ab68e8cd..c7e412c8e3 100644 --- a/compiler/optimizing/code_generator_arm.cc +++ b/compiler/optimizing/code_generator_arm.cc @@ -3361,7 +3361,19 @@ void InstructionCodeGeneratorARM::HandleShift(HBinaryOperation* op) { __ mov(o_l, ShifterOperand(high)); __ LoadImmediate(o_h, 0); } - } else { // shift_value < 32 + } else if (shift_value == 1) { + if (op->IsShl()) { + __ Lsls(o_l, low, 1); + __ adc(o_h, high, ShifterOperand(high)); + } else if (op->IsShr()) { + __ Asrs(o_h, high, 1); + __ Rrx(o_l, low); + } else { + __ Lsrs(o_h, high, 1); + __ Rrx(o_l, low); + } + } else { + DCHECK(2 <= shift_value && shift_value < 32) << shift_value; if (op->IsShl()) { __ Lsl(o_h, high, shift_value); __ orr(o_h, o_h, ShifterOperand(low, LSR, 32 - shift_value)); diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc index b97dc1a511..b36870cf59 100644 --- a/compiler/optimizing/instruction_simplifier.cc +++ b/compiler/optimizing/instruction_simplifier.cc @@ -169,16 +169,6 @@ void InstructionSimplifierVisitor::VisitShift(HBinaryOperation* instruction) { // src instruction->ReplaceWith(input_other); instruction->GetBlock()->RemoveInstruction(instruction); - } else if (instruction->IsShl() && input_cst->IsOne()) { - // Replace Shl looking like - // SHL dst, src, 1 - // with - // ADD dst, src, src - HAdd *add = new(GetGraph()->GetArena()) HAdd(instruction->GetType(), - input_other, - input_other); - instruction->GetBlock()->ReplaceAndRemoveInstructionWith(instruction, add); - RecordSimplification(); } } } -- cgit v1.2.3-59-g8ed1b