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On loongarch64 with lsx extension, we select `VBITREV_W` for `v4i32 (xor X, (shl splat(1), Y))`:8e66303916/llvm/lib/Target/LoongArch/LoongArchLSXInstrInfo.td (L1583-L1584)And `vsplat_imm_eq_1` is defined as:8e66303916/llvm/lib/Target/LoongArch/LoongArchLSXInstrInfo.td (L77-L87)For the `(bitconvert (v4i32 (build_vector)))` case, the pattern is expected to be: ``` PATTERN: (xor:{ *:[v4i32] } v4i32:{ *:[v4i32] }:$vj, (shl:{ *:[v4i32] } (bitconvert:{ *:[v4i32] } (build_vector:{ *:[v4i32] }))<<P:Predicate_vsplat_imm_eq_1>>, v4i32:{ *:[v4i32] }:$vk)) RESULT: (VBITREV_W:{ *:[v4i32] } v4i32:{ *:[v4i32] }:$vj, v4i32:{ *:[v4i32] }:$vk) ``` However, `simplifyTree` drops the `bitconvert` node and its predicates:8e66303916/llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp (L3036-L3062)Then llvm will match `vsplat_imm_eq_1` for any v4i32 splats and cause a miscompilation: ``` PATTERN: (xor:{ *:[v4i32] } v4i32:{ *:[v4i32] }:$vj, (shl:{ *:[v4i32] } (build_vector:{ *:[v4i32] }), v4i32:{ *:[v4i32] }:$vk)) RESULT: (VBITREV_W:{ *:[v4i32] } v4i32:{ *:[v4i32] }:$vj, v4i32:{ *:[v4i32] }:$vk) ``` This patch adds additional checks for predicates associated with the trivial bitconvert node. Unused patterns in the LoongArch target are also removed. Fixes https://github.com/llvm/llvm-project/issues/116008.
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