[PATCH] D123394: [CodeGen] Late cleanup of redundant address/immediate definitions.
Philip Reames via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Dec 1 10:36:09 PST 2022
reames added a comment.
This looks very interesting. I've been thinking about ways to improve stack addressing sequences on RISCV, and this nicely tackles many of the cases I was just thinking about.
Unfortunately, I think the patch as landed is wrong. See the inline comment on an example where we can't forward due to a clobber which doesn't appear to be respected.
================
Comment at: llvm/test/CodeGen/RISCV/rvv/rv64-spill-zvlsseg.ll:44
; SPILL-O2-NEXT: #NO_APP
-; SPILL-O2-NEXT: addi a0, sp, 16
-; SPILL-O2-NEXT: csrr a1, vlenb
----------------
This line looks to be wrong. a0 is clobbered on line 40 which is after the previous definition being forwarded from line 37.
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https://reviews.llvm.org/D123394/new/
https://reviews.llvm.org/D123394
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