[PATCH] D156129: Attributor: Try to propagate concrete denormal-fp-math{-f32}

[Sameer Sahasrabuddhe via Phabricator via llvm-commits]

sameerds added inline comments.


================
Comment at: llvm/include/llvm/Transforms/IPO/Attributor.h:5114
+
+  ChangeStatus indicateOptimisticFixpoint() override {
+    return ChangeStatus::UNCHANGED;
----------------
arsenm wrote:
> sameerds wrote:
> > Is it correct to say that an optimistic fix point is when all the "dynamic" components are set to default (`ieee`)? This attribute is reinventing what a fixed point means. Does this function need to set the optimistic fixed point? Or I would guess this function is actually never called, in which case it should be marked with `llvm_unreachable()`?
> No. You cannot say IEEE is more optimistic than preserve-sign or positive-zero. They're just different. The only thing you can infer is known or unknown
I understand what you want it to do. I am trying to understand what the code actually means. The manifest function replaces "dynamic" with "default/ieee". Both the optimistic and pessimistic fixed points leave dynamic alone. What is a fixed point here? When a client calls either of the fixed point functions, what should the interpretation of "dynamic" be? Should it be the same as the manifest method, which means setting it to default/ieee? Clearly, the client intended that no more changes should be possible, but the manifest will change it.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D156129/new/

https://reviews.llvm.org/D156129