[PATCH] D104793: [ARM] Transform a floating-point to fixed-point conversion to a VCVT_fix

[Sam Tebbs via Phabricator via llvm-commits]

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Much like fixed-point to floating-point conversion, the converse can also be transformed into a fixed-point VCVT. This patch transforms multiplications of floating point numbers by 2^n into a VCVT_fix. The exception is that a conversion with 1 fractional bit ends up being an FADD (FADD(x, x) emulates FMUL(x, 2)) rather than an FMUL so there is a special case for that. This patch also moves the code from https://reviews.llvm.org/D103903 into a separate function as fixed to float and float to fixed are very similar.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D104793

Files:
  llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
  llvm/test/CodeGen/Thumb2/mve-vcvt-fixed-to-float.ll
  llvm/test/CodeGen/Thumb2/mve-vcvt-fixed.ll
  llvm/test/CodeGen/Thumb2/mve-vcvt-float-to-fixed.ll

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