[all-commits] [llvm/llvm-project] bd46e2: [X86] Re-enable lowerUINT_TO_FP_vXi32 under fast-m...

[topperc via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: bd46e29742759dd0d57feb0f33affa9adc7d2fbf
      https://github.com/llvm/llvm-project/commit/bd46e29742759dd0d57feb0f33affa9adc7d2fbf
  Author: Craig Topper <craig.topper at gmail.com>
  Date:   2020-01-02 (Thu, 02 Jan 2020)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/ftrunc.ll
    M llvm/test/CodeGen/X86/known-bits-vector.ll
    M llvm/test/CodeGen/X86/vec-strict-inttofp-128.ll
    M llvm/test/CodeGen/X86/vec-strict-inttofp-256.ll
    M llvm/test/CodeGen/X86/vec_int_to_fp.ll
    M llvm/test/CodeGen/X86/vec_uint_to_fp-fastmath.ll
    M llvm/test/CodeGen/X86/vec_uint_to_fp.ll
    M llvm/test/CodeGen/X86/vector-constrained-fp-intrinsics.ll

  Log Message:
  -----------
  [X86] Re-enable lowerUINT_TO_FP_vXi32 under fast-math by using an FSUB instead of an FADD.

Summary:
We previously disabled this under fast math due to aggressive
reassociation by the machine combiner. But I think we can work
around this by using a FSUB instead of FADD for the first
operation.

This matches the similar algorithm we do for uint_to_fp i64->f64
in TargetLowering::expandUINT_TO_FP. If reassociation hasn't
been a problem for that, hopefully its not a problem here.

Reviewers: RKSimon, spatel, scanon

Reviewed By: spatel

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71968