diff options
Diffstat (limited to 'compiler/optimizing')
| -rw-r--r-- | compiler/optimizing/induction_var_range.cc | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/compiler/optimizing/induction_var_range.cc b/compiler/optimizing/induction_var_range.cc index b1f33abdf8..b54507a03c 100644 --- a/compiler/optimizing/induction_var_range.cc +++ b/compiler/optimizing/induction_var_range.cc @@ -1359,6 +1359,15 @@ bool InductionVarRange::GenerateLastValuePeriodic(const HBasicBlock* context, HInstruction* x = nullptr; HInstruction* y = nullptr; HInstruction* t = nullptr; + + // Overflows when the stride is equal to `1` are fine since the periodicity is + // `2` and the lowest bit is the same. Similar with `-1`. + auto allow_potential_overflow = [&]() { + int64_t stride_value = 0; + return IsConstant(context, loop, trip->op_a->op_b, kExact, &stride_value) && + (stride_value == 1 || stride_value == -1); + }; + if (period == 2 && GenerateCode(context, loop, @@ -1383,7 +1392,8 @@ bool InductionVarRange::GenerateLastValuePeriodic(const HBasicBlock* context, graph, block, /*is_min=*/ false, - graph ? &t : nullptr)) { + graph ? &t : nullptr, + allow_potential_overflow())) { // During actual code generation (graph != nullptr), generate is_even ? x : y. if (graph != nullptr) { DataType::Type type = trip->type; |