[llvm] [InstCombine] Fold negation of unsigned div of non-negatives (PR #84951)

[Yingwei Zheng via llvm-commits]

================
@@ -2062,6 +2062,25 @@ static Instruction *foldSubOfMinMax(BinaryOperator &I,
   return nullptr;
 }
 
+/// Fold `sub 0, (udiv nneg X, nneg C)` into `sdiv nneg X, -C`
+static Instruction *foldNegationOfUDivOfNonNegatives(BinaryOperator &I,
+                                                     InstCombinerImpl &IC) {
+  Value *RHS = I.getOperand(1);
+  Value *X;
+  Constant *C;
+
+  const auto &SQ = IC.getSimplifyQuery().getWithInstruction(&I);
+  if (match(RHS, m_OneUse(m_UDiv(m_Value(X), m_Constant(C)))) &&
+      isKnownNonNegative(X, SQ) && isKnownNonNegative(C, SQ)) {
+    bool HasNSW = I.hasNoSignedWrap();
+    auto *NegC = HasNSW ? IC.Builder.CreateNSWNeg(C, C->getName() + ".neg")
+                        : IC.Builder.CreateNeg(C, C->getName() + ".neg");
+    return BinaryOperator::CreateSDiv(X, NegC);
----------------
dtcxzyw wrote:

```suggestion
    return BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C));
```

https://github.com/llvm/llvm-project/pull/84951