Recognize XOR-based periodic induction.
Rationale:
This is a commonly used construct (e.g. x = !x for booleans
and x ^= 1 for integers). This CL prepares some upcoming
optimizations that exploit such inductions.
Change-Id: I46edffb9de1075a836995daf5c2dfff7891f3034
Test: 530-checker-loops2 and induction_var_analysis_test
diff --git a/compiler/optimizing/induction_var_range.cc b/compiler/optimizing/induction_var_range.cc
index cd8b7c7..140c7f0 100644
--- a/compiler/optimizing/induction_var_range.cc
+++ b/compiler/optimizing/induction_var_range.cc
@@ -525,6 +525,8 @@
return GetMul(info->op_a, info->op_b, trip, in_body, is_min);
case HInductionVarAnalysis::kDiv:
return GetDiv(info->op_a, info->op_b, trip, in_body, is_min);
+ case HInductionVarAnalysis::kXor:
+ return GetXor(info->op_a, info->op_b);
case HInductionVarAnalysis::kFetch:
return GetFetch(info->fetch, trip, in_body, is_min);
case HInductionVarAnalysis::kTripCountInLoop:
@@ -626,6 +628,21 @@
return Value();
}
+InductionVarRange::Value InductionVarRange::GetXor(
+ HInductionVarAnalysis::InductionInfo* info1,
+ HInductionVarAnalysis::InductionInfo* info2) const {
+ int64_t v1 = 0;
+ int64_t v2 = 0;
+ // Only accept exact values.
+ if (IsConstant(info1, kExact, &v1) && IsConstant(info2, kExact, &v2)) {
+ int64_t value = v1 ^ v2;
+ if (CanLongValueFitIntoInt(value)) {
+ return Value(static_cast<int32_t>(value));
+ }
+ }
+ return Value();
+}
+
InductionVarRange::Value InductionVarRange::MulRangeAndConstant(
int64_t value,
HInductionVarAnalysis::InductionInfo* info,