[llvm] [SCEV] Use APInt for DividesBy when collecting loop guard info (NFC). (PR #163017)

[Nikita Popov via llvm-commits]

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@@ -15633,47 +15633,34 @@ void ScalarEvolution::LoopGuards::collectFromBlock(
           return false;
         };
 
-    // Checks whether Expr is a non-negative constant, and Divisor is a positive
-    // constant, and returns their APInt in ExprVal and in DivisorVal.
-    auto GetNonNegExprAndPosDivisor = [&](const SCEV *Expr, const SCEV *Divisor,
-                                          APInt &ExprVal, APInt &DivisorVal) {
-      auto *ConstExpr = dyn_cast<SCEVConstant>(Expr);
-      auto *ConstDivisor = dyn_cast<SCEVConstant>(Divisor);
-      if (!ConstExpr || !ConstDivisor)
-        return false;
-      ExprVal = ConstExpr->getAPInt();
-      DivisorVal = ConstDivisor->getAPInt();
-      return ExprVal.isNonNegative() && !DivisorVal.isNonPositive();
-    };
-
     // Return a new SCEV that modifies \p Expr to the closest number divides by
     // \p Divisor and greater or equal than Expr.
-    // For now, only handle constant Expr and Divisor.
+    // For now, only handle constant Expr.
     auto GetNextSCEVDividesByDivisor = [&](const SCEV *Expr,
-                                           const SCEV *Divisor) {
-      APInt ExprVal;
-      APInt DivisorVal;
-      if (!GetNonNegExprAndPosDivisor(Expr, Divisor, ExprVal, DivisorVal))
+                                           const APInt &DivisorVal) {
+      const APInt *ExprVal;
+      if (!match(Expr, m_scev_APInt(ExprVal)) ||
+          DivisorVal.isNonPositive())
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nikic wrote:

This drops the `ExprVal.isNonNegative()` check. Is that intentional? (I haven't checked this carefully, but presumably negative values would need special handling for signed min/max?)

https://github.com/llvm/llvm-project/pull/163017