[HashRecognize] Make it a non-PM analysis (#144742)

Make HashRecognize a non-PassManager analysis that can be called to get
the result on-demand, creating a new getResult() entry-point. The issue
was discovered when attempting to use the analysis to perform a
transform in LoopIdiomRecognize.

Author: artagnon

llvm/include/llvm/Analysis/HashRecognize.h

@@ -84,12 +84,13 @@ class HashRecognize {
 public:
   HashRecognize(const Loop &L, ScalarEvolution &SE);
 
-  // The main analysis entry point.
+  // The main analysis entry points.
   std::variant<PolynomialInfo, ErrBits, StringRef> recognizeCRC() const;
+  std::optional<PolynomialInfo> getResult() const;
 
   // Auxilary entry point after analysis to interleave the generating polynomial
   // and return a 256-entry CRC table.
-  CRCTable genSarwateTable(const APInt &GenPoly, bool ByteOrderSwapped) const;
+  static CRCTable genSarwateTable(const APInt &GenPoly, bool ByteOrderSwapped);
 
   void print(raw_ostream &OS) const;
 
@@ -107,15 +108,6 @@ class HashRecognizePrinterPass
   PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
                         LoopStandardAnalysisResults &AR, LPMUpdater &);
 };
-
-class HashRecognizeAnalysis : public AnalysisInfoMixin<HashRecognizeAnalysis> {
-  friend AnalysisInfoMixin<HashRecognizeAnalysis>;
-  static AnalysisKey Key;
-
-public:
-  using Result = HashRecognize;
-  Result run(Loop &L, LoopAnalysisManager &AM, LoopStandardAnalysisResults &AR);
-};
 } // namespace llvm
 
 #endif

llvm/lib/Analysis/HashRecognize.cpp

@@ -472,7 +472,7 @@ static bool checkExtractBits(const KnownBits &Known, unsigned N,
 /// polynomial. The optimization technique of table-lookup for CRC is also
 /// called the Sarwate algorithm.
 CRCTable HashRecognize::genSarwateTable(const APInt &GenPoly,
-                                        bool ByteOrderSwapped) const {
+                                        bool ByteOrderSwapped) {
   unsigned BW = GenPoly.getBitWidth();
   CRCTable Table;
   Table[0] = APInt::getZero(BW);
@@ -686,20 +686,20 @@ void HashRecognize::print(raw_ostream &OS) const {
 void HashRecognize::dump() const { print(dbgs()); }
 #endif
 
+std::optional<PolynomialInfo> HashRecognize::getResult() const {
+  auto Res = HashRecognize(L, SE).recognizeCRC();
+  if (std::holds_alternative<PolynomialInfo>(Res))
+    return std::get<PolynomialInfo>(Res);
+  return std::nullopt;
+}
+
 HashRecognize::HashRecognize(const Loop &L, ScalarEvolution &SE)
     : L(L), SE(SE) {}
 
 PreservedAnalyses HashRecognizePrinterPass::run(Loop &L,
                                                 LoopAnalysisManager &AM,
                                                 LoopStandardAnalysisResults &AR,
                                                 LPMUpdater &) {
-  AM.getResult<HashRecognizeAnalysis>(L, AR).print(OS);
+  HashRecognize(L, AR.SE).print(OS);
   return PreservedAnalyses::all();
 }
-
-HashRecognize HashRecognizeAnalysis::run(Loop &L, LoopAnalysisManager &AM,
-                                         LoopStandardAnalysisResults &AR) {
-  return {L, AR.SE};
-}
-
-AnalysisKey HashRecognizeAnalysis::Key;

llvm/lib/Passes/PassRegistry.def

@@ -672,7 +672,6 @@ LOOPNEST_PASS("no-op-loopnest", NoOpLoopNestPass())
 #define LOOP_ANALYSIS(NAME, CREATE_PASS)
 #endif
 LOOP_ANALYSIS("ddg", DDGAnalysis())
-LOOP_ANALYSIS("hash-recognize", HashRecognizeAnalysis())
 LOOP_ANALYSIS("iv-users", IVUsersAnalysis())
 LOOP_ANALYSIS("no-op-loop", NoOpLoopAnalysis())
 LOOP_ANALYSIS("pass-instrumentation", PassInstrumentationAnalysis(PIC))