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 <serguei.i.katkov@intel.com>
diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
index d391145..931a1c3 100644
--- a/compiler/optimizing/instruction_simplifier.cc
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -438,9 +438,14 @@
// 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 @@
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();