[MLIR][Affine] Mark affine.min and affine.max as NoSideffect.

[herhut]

Summary

The operation has no sideffects and it was probably just an oversight
that the trait is missing.

[herhut]

Noticed this because the loop.parallel transformation bailed out on these.

[herhut]

Commit message fixed.

[ftynse]

Weird, AffineMinOp and AffineMaxOp do have the trait, they are just below (I asked @OuHangKresnik to add them in one of recent commits). Can we explore more what's the problem with loop.parallel not seing the trait?

[herhut]

The answer is simple. I did not rebase :)

mlir/include/mlir/Dialect/AffineOps/AffineOps.td

OpBuilder getElseBodyBuilder() {
       return OpBuilder(&body, std::prev(body.end()));
     }
   }];
 
   let hasFolder = 1;
 }
 
 class AffineMinMaxOpBase<string mnemonic, list<OpTrait> traits = []> :
-    Op<Affine_Dialect, mnemonic, traits> {
+    Op<Affine_Dialect, mnemonic, !listconcat(traits, [NoSideEffect])> {
   let arguments = (ins AffineMapAttr:$map, Variadic<Index>:$operands);
   let results = (outs Index);
   let extraClassDeclaration = [{
     static StringRef getMapAttrName() { return "map"; }
   }];
   let verifier = [{ return ::verifyAffineMinMaxOp(*this); }];
   let printer = [{ return ::printAffineMinMaxOp(p, *this); }];
   let parser = [{ return ::parseAffineMinMaxOp<$cppClass>(parser, result); }];