llvm-project

cfe1b46b - [DAGCombiner] Fold trunc(build_vector(ext(x), ext(x)) -> build_vector(x,x) (#179857)

[DAGCombiner] Fold trunc(build_vector(ext(x), ext(x)) -> build_vector(x,x) (#179857) The original implementation performed the transformation when isTruncateFree was true: truncate(build_vector(x, x)) -> build_vector(truncate(x), truncate(x)). In some cases, x comes from an ext, try to pre-truncate build_vectors source operands when the source operands of build_vectors comes from an ext. Testcase from: https://gcc.godbolt.org/z/bbxbYK7dh