[PATCH] D73892: [SelectionDAG] Optimize build_vector of truncates and shifts
Sebastian Neubauer via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 3 07:24:56 PST 2020
sebastian-ne created this revision.
sebastian-ne added a reviewer: bogner.
Herald added subscribers: llvm-commits, kerbowa, hiraditya, jvesely.
Herald added a project: LLVM.
Add a simplification to fuse a manual vector extract with shifts and
truncate into a bitcast.
Unpacking and packing values into vectors is only optimized with
extractelement instructions, not when manually unpacked using shifts
and truncates.
This patch simplifies shifts and truncates into a bitcast if possible.
Simplify (build_vec (trunc $1)
(trunc (srl $1 width))
(trunc (srl $1 (2 * width))) ...)
to (bitcast $1)
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D73892
Files:
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
llvm/test/CodeGen/AMDGPU/scalar_to_vector.ll
llvm/test/CodeGen/AMDGPU/vector_shuffle.packed.ll
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