[PATCH] D148558: [CodeGen] Improve handling -Ofast generated code by ComplexDeinterleaving pass

[Igor Kirillov via Phabricator via llvm-commits]

igor.kirillov created this revision.
Herald added subscribers: hiraditya, kristof.beyls.
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Code generated with -Ofast and -O3 -ffp-contract=fast (add
-ffinite-math-only to enable vectorization) can differ significantly.
Code compiled with -O3 can be deinterleaved using patterns as the
instruction order is preserved. However, with the -Ofast flag, there
can be multiple changes in the computation sequence, and even the real
and imaginary parts may not be calculated in parallel.
For more details, refer to
llvm/test/CodeGen/AArch64/complex-deinterleaving-*-fast.ll and
llvm/test/CodeGen/AArch64/complex-deinterleaving-*-fast.ll tests.
This patch implements a more general approach and enables handling most
-Ofast cases.

Depends on D148550 <https://reviews.llvm.org/D148550>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D148558

Files:
  llvm/include/llvm/CodeGen/TargetLowering.h
  llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
  llvm/lib/Target/AArch64/AArch64ISelLowering.h
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/lib/Target/ARM/ARMISelLowering.h
  llvm/test/CodeGen/AArch64/complex-deinterleaving-add-mull-fixed-fast.ll
  llvm/test/CodeGen/AArch64/complex-deinterleaving-add-mull-scalable-fast.ll
  llvm/test/CodeGen/AArch64/complex-deinterleaving-mixed-cases.ll
  llvm/test/CodeGen/AArch64/complex-deinterleaving-uniform-cases.ll

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