[PATCH] D118316: [PowerPC] Materialize special ConstantFP using instructions instead of load from TOC

[Ting Wang via Phabricator via llvm-commits]

tingwang created this revision.
tingwang added reviewers: nemanjai, jsji, shchenz, qiucf, PowerPC.
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ConstantFP in the range of [-16, 15] (excluding 0.0, which is done by XXLXOR) that can be exactly converted to integer can be materialized into register using VSPLTISW and XVCVSXWDP. This will reduce TOC usage, get rid of memory reference, and maybe save some TOC pointer calculations.

ConstantFP is expanded into load from TOC during ExpandNode. This patch identifies the opportunity before expansion, and does the manual instruction selection later. LIT test shows this patch exposes some other issues, please see my comments on the test scripts.

Since Power10 use prefixed instructions to materialize ConstantFP, maybe target Power9 for this change.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118316

Files:
  llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
  llvm/lib/Target/PowerPC/PPCISelLowering.cpp
  llvm/test/CodeGen/PowerPC/handle-f16-storage-type.ll
  llvm/test/CodeGen/PowerPC/recipest.ll
  llvm/test/CodeGen/PowerPC/scalar_cmp.ll
  llvm/test/CodeGen/PowerPC/toc-float.ll
  llvm/test/CodeGen/PowerPC/vec_extract_p9.ll

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