[PATCH] D71389: [ConstantFold][SVE] Fix constant folding for bitcast.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


================
Comment at: llvm/lib/IR/ConstantFold.cpp:52
+  // compile-time.
+  if (DstTy->isScalable())
+    return nullptr;
----------------
huihuiz wrote:
> sdesmalen wrote:
> > Do we want to add support for a special case here for splat operations (like the one in the test)?
> Actually we can not, we will end up in scalable vector constant. 
> Instead of <4 x i32> <i32 1, i32 1, i32 1, i32 1>, we will need a form like "<vscale x 4 x i32> [?]"
> 
> I don't know how to express scalable vector constant in current upstream, please let me know if I get anything wrong?
I think the suggestion is to special-case the specific sequence of insertelement+splatvector+bitcast, and bitcast the operand of the insertelement.  Not sure how useful that would be in general, though.


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https://reviews.llvm.org/D71389