[llvm] fix for Issue #139786 - Missed Optimization: max(max(x, c1) << c2, c3) —> max(x << c2, c3) when c3 >= c1 * 2 ^ c2 (PR #140526)

[Yingwei Zheng via llvm-commits]

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@@ -1171,6 +1171,84 @@ static Instruction *moveAddAfterMinMax(IntrinsicInst *II,
   return IsSigned ? BinaryOperator::CreateNSWAdd(NewMinMax, Add->getOperand(1))
                   : BinaryOperator::CreateNUWAdd(NewMinMax, Add->getOperand(1));
 }
+
+//Try canonicalize min/max(x << shamt, c<<shamt) into max(x, c) << shamt
+static Instruction *moveShiftAfterMinMax(IntrinsicInst *II, InstCombiner::BuilderTy &Builder) {
+  Intrinsic::ID MinMaxID = II->getIntrinsicID();
+  assert((MinMaxID == Intrinsic::smax || MinMaxID == Intrinsic::smin ||
+    MinMaxID == Intrinsic::umax || MinMaxID == Intrinsic::umin) &&
----------------
dtcxzyw wrote:

```suggestion
  assert(isa<MinMaxIntrinsic>(II) &&
```

https://github.com/llvm/llvm-project/pull/140526