[PATCH] D109481: [WebAssembly] Custom optimization for truncate

[Thomas Lively via Phabricator via llvm-commits]

tlively added a comment.

Nice, these tests give me a good sense of what this optimization is doing. The transformation looks good.



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Comment at: llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp:2439
 
+static SDValue extractSubVector(SDValue Vec, unsigned IdxVal, SelectionDAG &DAG,
+                                const SDLoc &DL, unsigned VectorWidth) {
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For both this and `truncateVectorWithNARROW`, it would be good to add comments about what the parameters are for and what will be returned.


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  https://reviews.llvm.org/D109481/new/

https://reviews.llvm.org/D109481