[PATCH] D33494: [mips] Fix multiprecision arithmetic.

[Simon Dardis via Phabricator via llvm-commits]

sdardis created this revision.
Herald added a subscriber: arichardson.

For multiprecision arithmetic on MIPS, rather than using ISD::ADDE / ISD::ADDC,
get SelectionDAG to break down the operation into ISD::ADDs and ISD::SETCC. Also
improve the generation code in such cases for targets with
TargetLoweringBase::ZeroOrOneBooleanContent by directly using the result of the
comparison node rather than using it in selects. Similarly for ISD::SUBE /
ISD::SUBC.

For MIPS, only the DSP ASE has a carry flag, so in the general case it is not
useful to directly support ISD::{ADDE, ADDC, SUBE, SUBC} nodes.

Address optimization breakage by moving the generation of MIPS specific integer
multiply-accumulate nodes to before operation legalization.

This revolves PR32713.

Thanks to Simonas Kazlauskas for reporting the issue!


Repository:
  rL LLVM

https://reviews.llvm.org/D33494

Files:
  lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
  lib/Target/Mips/MipsISelLowering.cpp
  lib/Target/Mips/MipsSEISelDAGToDAG.cpp
  lib/Target/Mips/MipsSEISelDAGToDAG.h
  lib/Target/Mips/MipsSEISelLowering.cpp
  test/CodeGen/Mips/2008-06-05-Carry.ll
  test/CodeGen/Mips/dsp-patterns.ll
  test/CodeGen/Mips/llcarry.ll
  test/CodeGen/Mips/llvm-ir/add.ll
  test/CodeGen/Mips/llvm-ir/sub.ll
  test/CodeGen/Mips/madd-msub.ll

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