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With LLVM 20 the SIMD intrinsic wasm32::u8x16_sub_sat is compiled to a function call #137419

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With LLVM 20 the SIMD intrinsic wasm32::u8x16_sub_sat is compiled to a function call#137419
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A-LLVMArea: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues.A-SIMDArea: SIMD (Single Instruction Multiple Data)C-bugCategory: This is a bug.O-wasmTarget: WASM (WebAssembly), http://webassembly.org/

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@hkratz
hkratz
opened on Feb 22, 2025

The WASM SIMD intrinsic std::arch::wasm32::u8x16_sub_sat used to be compiled to the WASM instruction i8x16.sub_sat_u. Since the switch LLVM 20 (bisected) it is compiled to call llvm.wasm.sub.sat.unsigned.v16i8

Other intrinsics (e.g. saturated integer addition) do not seem to be affected.

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    A-LLVMArea: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues.A-SIMDArea: SIMD (Single Instruction Multiple Data)C-bugCategory: This is a bug.O-wasmTarget: WASM (WebAssembly), http://webassembly.org/

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