[llvm-branch-commits] [llvm] [DA] Check nsw when extracting a constant operand of SCEVMul (PR #164408)

[Michael Kruse via llvm-branch-commits]

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@@ -2828,8 +2828,9 @@ static std::optional<APInt> getConstantPart(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())
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Meinersbur wrote:

Could you update the function comment, maybe even the function name? This returns the (constant) coefficent/slope of a linear function. Without NSW, it is still a "constant part", just not the slope of a linear function. 
Suggestion: `getConstCoefficent`, like at those places where it is called.

https://github.com/llvm/llvm-project/pull/164408