From 115b53f609e74672fa93eea1845bb17340d5112a Mon Sep 17 00:00:00 2001 From: Serguei Katkov Date: Wed, 5 Aug 2015 17:03:30 +0600 Subject: ART: Fix the simplifier for add/sub Instruction simplifier for add/sub should not proceed with floats because that might cause the incorrect behavior with signed zero. Change-Id: If0c9bf3931bcbf96b0814f8605a86997aea37145 Signed-off-by: Serguei Katkov --- compiler/optimizing/instruction_simplifier.cc | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) (limited to 'compiler/optimizing/instruction_simplifier.cc') diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc index d3911456fb..931a1c3cb7 100644 --- a/compiler/optimizing/instruction_simplifier.cc +++ b/compiler/optimizing/instruction_simplifier.cc @@ -438,9 +438,14 @@ void InstructionSimplifierVisitor::VisitAdd(HAdd* instruction) { // ADD dst, src, 0 // with // src - instruction->ReplaceWith(input_other); - instruction->GetBlock()->RemoveInstruction(instruction); - return; + // Note that we cannot optimize `x + 0.0` to `x` for floating-point. When + // `x` is `-0.0`, the former expression yields `0.0`, while the later + // yields `-0.0`. + if (Primitive::IsIntegralType(instruction->GetType())) { + instruction->ReplaceWith(input_other); + instruction->GetBlock()->RemoveInstruction(instruction); + return; + } } HInstruction* left = instruction->GetLeft(); @@ -800,21 +805,24 @@ void InstructionSimplifierVisitor::VisitSub(HSub* instruction) { HConstant* input_cst = instruction->GetConstantRight(); HInstruction* input_other = instruction->GetLeastConstantLeft(); + Primitive::Type type = instruction->GetType(); + if (Primitive::IsFloatingPointType(type)) { + return; + } + if ((input_cst != nullptr) && input_cst->IsZero()) { // Replace code looking like // SUB dst, src, 0 // with // src + // Note that we cannot optimize `x - 0.0` to `x` for floating-point. When + // `x` is `-0.0`, the former expression yields `0.0`, while the later + // yields `-0.0`. instruction->ReplaceWith(input_other); instruction->GetBlock()->RemoveInstruction(instruction); return; } - Primitive::Type type = instruction->GetType(); - if (!Primitive::IsIntegralType(type)) { - return; - } - HBasicBlock* block = instruction->GetBlock(); ArenaAllocator* allocator = GetGraph()->GetArena(); -- cgit v1.2.3-59-g8ed1b