Improve bce so that more bounds checks can be eliminated.
For pattern like "int[] array = new int[size+1]", we record this range
for size:
[-1, array.length-1]
This can eliminate more bounds checks.
Also simplify overflow/underflow handling and make it more solid.
Enhance instruction simplifier such that if array is a result of
NewArray with a constant size, replace array.length with that constant.
Plan to move all bce gtests to checker in another change.
Change-Id: Ibe7cc7940b68fb6465dc3e0ff3ebdb0fd6487aa9
diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
index 17c8f33..44dbb9d 100644
--- a/compiler/optimizing/instruction_simplifier.cc
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -28,6 +28,7 @@
void VisitArraySet(HArraySet* equal) OVERRIDE;
void VisitTypeConversion(HTypeConversion* instruction) OVERRIDE;
void VisitNullCheck(HNullCheck* instruction) OVERRIDE;
+ void VisitArrayLength(HArrayLength* instruction) OVERRIDE;
};
void InstructionSimplifier::Run() {
@@ -75,6 +76,18 @@
}
}
+void InstructionSimplifierVisitor::VisitArrayLength(HArrayLength* instruction) {
+ HInstruction* input = instruction->InputAt(0);
+ // If the array is a NewArray with constant size, replace the array length
+ // with the constant instruction. This helps the bounds check elimination phase.
+ if (input->IsNewArray()) {
+ input = input->InputAt(0);
+ if (input->IsIntConstant()) {
+ instruction->ReplaceWith(input);
+ }
+ }
+}
+
void InstructionSimplifierVisitor::VisitArraySet(HArraySet* instruction) {
HInstruction* value = instruction->GetValue();
if (value->GetType() != Primitive::kPrimNot) return;