3 files changed, 18 insertions, 14 deletions

diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index 84ee8c0..11d8294 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -2854,14 +2854,18 @@ bool DependenceInfo::testMIV(const SCEV *Src, const SCEV *Dst,
          banerjeeMIVtest(Src, Dst, Loops, Result);
 }
 
-// Given a product, e.g., 10*X*Y, returns the first constant operand,
-// in this case 10. If there is no constant part, returns std::nullopt.
-static std::optional<APInt> getConstantPart(const SCEV *Expr) {
+/// Given a SCEVMulExpr, returns its first operand if its first operand is a
+/// constant and the product doesn't overflow in a signed sense. Otherwise,
+/// returns std::nullopt. For example, given (10 * X * Y)<nsw>, it returns 10.
+/// Notably, if it doesn't have nsw, the multiplication may overflow, and if
+/// so, it may not a multiple of 10.
+static std::optional<APInt> getConstanCoefficient(const SCEV *Expr) {
   if (const auto *Constant = dyn_cast<SCEVConstant>(Expr))
     return Constant->getAPInt();
   if (const auto *Product = dyn_cast<SCEVMulExpr>(Expr))
     if (const auto *Constant = dyn_cast<SCEVConstant>(Product->getOperand(0)))
-      return Constant->getAPInt();
+      if (Product->hasNoSignedWrap())
+        return Constant->getAPInt();
   return std::nullopt;
 }
 
@@ -2887,7 +2891,7 @@ bool DependenceInfo::accumulateCoefficientsGCD(const SCEV *Expr,
   if (AddRec->getLoop() == CurLoop) {
     CurLoopCoeff = Step;
   } else {
-    std::optional<APInt> ConstCoeff = getConstantPart(Step);
+    std::optional<APInt> ConstCoeff = getConstanCoefficient(Step);
 
     // If the coefficient is the product of a constant and other stuff, we can
     // use the constant in the GCD computation.
@@ -2940,7 +2944,7 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
     const SCEV *Coeff = AddRec->getStepRecurrence(*SE);
     // If the coefficient is the product of a constant and other stuff,
     // we can use the constant in the GCD computation.
-    std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
+    std::optional<APInt> ConstCoeff = getConstanCoefficient(Coeff);
     if (!ConstCoeff)
       return false;
     RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
@@ -2958,7 +2962,7 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
     const SCEV *Coeff = AddRec->getStepRecurrence(*SE);
     // If the coefficient is the product of a constant and other stuff,
     // we can use the constant in the GCD computation.
-    std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
+    std::optional<APInt> ConstCoeff = getConstanCoefficient(Coeff);
     if (!ConstCoeff)
       return false;
     RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
@@ -2979,7 +2983,7 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
       } else if (const SCEVMulExpr *Product = dyn_cast<SCEVMulExpr>(Operand)) {
         // Search for constant operand to participate in GCD;
         // If none found; return false.
-        std::optional<APInt> ConstOp = getConstantPart(Product);
+        std::optional<APInt> ConstOp = getConstanCoefficient(Product);
         if (!ConstOp)
           return false;
         ExtraGCD = APIntOps::GreatestCommonDivisor(ExtraGCD, ConstOp->abs());
@@ -3032,7 +3036,7 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
     Delta = SE->getMinusSCEV(SrcCoeff, DstCoeff);
     // If the coefficient is the product of a constant and other stuff,
     // we can use the constant in the GCD computation.
-    std::optional<APInt> ConstCoeff = getConstantPart(Delta);
+    std::optional<APInt> ConstCoeff = getConstanCoefficient(Delta);
     if (!ConstCoeff)
       // The difference of the two coefficients might not be a product
       // or constant, in which case we give up on this direction.
diff --git a/llvm/lib/Analysis/HashRecognize.cpp b/llvm/lib/Analysis/HashRecognize.cpp
index 4529123..8974ce5 100644
--- a/llvm/lib/Analysis/HashRecognize.cpp
+++ b/llvm/lib/Analysis/HashRecognize.cpp
@@ -468,8 +468,11 @@ std::variant<PolynomialInfo, StringRef> HashRecognize::recognizeCRC() const {
 
     // Ensure that the PHIs have exactly two uses:
     // the bit-shift, and the XOR (or a cast feeding into the XOR).
+    // Also ensure that the SimpleRecurrence's evolution doesn't have stray
+    // users.
     if (!ConditionalRecurrence.Phi->hasNUses(2) ||
-        !SimpleRecurrence.Phi->hasNUses(2))
+        !SimpleRecurrence.Phi->hasNUses(2) ||
+        SimpleRecurrence.BO->getUniqueUndroppableUser() != SimpleRecurrence.Phi)
       return "Recurrences have stray uses";
 
     // Check that the SelectInst ConditionalRecurrence.Step is conditional on
diff --git a/llvm/lib/Analysis/HeatUtils.cpp b/llvm/lib/Analysis/HeatUtils.cpp
index a1cc707..08e9428 100644
--- a/llvm/lib/Analysis/HeatUtils.cpp
+++ b/llvm/lib/Analysis/HeatUtils.cpp
@@ -64,10 +64,7 @@ std::string llvm::getHeatColor(uint64_t Freq, uint64_t MaxFreq) {
 }
 
 std::string llvm::getHeatColor(double Percent) {
-  if (Percent > 1.0)
-    Percent = 1.0;
-  if (Percent < 0.0)
-    Percent = 0.0;
+  Percent = std::clamp(Percent, 0.0, 1.0);
   unsigned ColorID = unsigned(round(Percent * (HeatSize - 1.0)));
   return HeatPalette[ColorID];
 }