Skip InductionVarAnalysis for a pathological case
Having a long chain of loop header phis hangs up the compiler.
Note that we can still compile the method if we skip the
InductionVarAnalysis phase.
Bug: 246249941
Fixes: 246249941
Bug: 32545907
Test: art/test/testrunner/testrunner.py --host --64 --optimizing -b
Test: dex2oat compile the app in 246249941
Change-Id: Id2d14b1c4d787f98d656055274c7cfcae6491686
diff --git a/compiler/optimizing/induction_var_analysis.h b/compiler/optimizing/induction_var_analysis.h
index 124c3b4..0509500 100644
--- a/compiler/optimizing/induction_var_analysis.h
+++ b/compiler/optimizing/induction_var_analysis.h
@@ -39,7 +39,9 @@
*/
class HInductionVarAnalysis : public HOptimization {
public:
- explicit HInductionVarAnalysis(HGraph* graph, const char* name = kInductionPassName);
+ explicit HInductionVarAnalysis(HGraph* graph,
+ OptimizingCompilerStats* stats = nullptr,
+ const char* name = kInductionPassName);
bool Run() override;
@@ -308,6 +310,15 @@
static std::string FetchToString(HInstruction* fetch);
static std::string InductionToString(InductionInfo* info);
+ // Returns true if we have a pathological case we don't want to analyze.
+ bool IsPathologicalCase();
+ // Starting with initial_phi, it calculates how many loop header phis in a row we have. To do
+ // this, we count the loop header phi which are used as an input of other loop header phis. It
+ // uses `cached_values` to avoid recomputing results.
+ void CalculateLoopHeaderPhisInARow(HPhi* initial_phi,
+ ScopedArenaSafeMap<HPhi*, int>& cached_values,
+ ScopedArenaAllocator& allocator);
+
/**
* Maintains the results of the analysis as a mapping from loops to a mapping from instructions
* to the induction information for that instruction in that loop.