[PATCH] D150670: [WebAssembly] Disable generation of fshl/fshr for rotates
Paulo Matos via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu May 18 00:07:35 PDT 2023
pmatos added a comment.
In D150670#4351147 <https://reviews.llvm.org/D150670#4351147>, @nikic wrote:
> Lowering to a rotate intrinsic only "solves" this for wasm and will at the same time make these rotates completely opaque to optimization -- heck, it looks like we don't even support constant folding for these intrinsics (https://llvm.godbolt.org/z/hMWG16b9W).
Another thing wrt this optimization regard is that Wasm is slightly different from other targets in that it's not natively executed but instead executed through a VM or passed through binaryen for further optimization. I just tested this and emcc which passes the resulting file through binaryen performs this optimization. I imagine V8 won't have problems with this code either, therefore the missing optimization in llvm is not problematic for the target.
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https://reviews.llvm.org/D150670/new/
https://reviews.llvm.org/D150670
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