[PATCH] D91753: [GlobalISel] Add an isExtendedTrueVal helper.

[Amara Emerson via Phabricator via llvm-commits]

aemerson added inline comments.


================
Comment at: llvm/lib/CodeGen/GlobalISel/Utils.cpp:746
+  if (ExtTy == S1)
+    return Val == 1;
+  switch (TLI.getBooleanContents(ExtTy.isVector(), IsFP)) {
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paquette wrote:
> aemerson wrote:
> > Not saying this is wrong, but what's the rationale here for Val needing to be exactly 1 for s1? If The type is s1 then isn't either -1 or 1 equivalently true?
> I think that's very philosophical, but I guess I'm fine either way?
> 
> I could believe that there's no meaningful distinction between 1 and -1 in 1-bit world.
I guess it depends on what the contract is for this function when the type size is < 64 bits. I know that if you get the constant value from a G_CONSTANT i1 true then it ends up as a -1 int64_t, so passing to this function would return false. Maybe we should mask off the upper bits on entry?


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  https://reviews.llvm.org/D91753/new/

https://reviews.llvm.org/D91753