[PATCH] D65094: [PowerPC] Combine address computation to favour selecting DForm instructions

[Nemanja Ivanovic via Phabricator via llvm-commits]

nemanjai created this revision.
nemanjai added reviewers: hfinkel, echristo, jsji, stefanp.
Herald added subscribers: shchenz, wuzish, mgrang, MaskRay, kbarton.
Herald added a project: LLVM.

When selecting a memory operation for which the only available D-Form instructions have alignment requirements for the displacement immediate, we end up having to select X-Form instructions if the immediate isn't a required multiple. However, if the base register is used for multiple memory operations, we don't need to be so pessimistic.

For example,

  vector int test(char *Ptr) {
    vector int a = *(vector int *)(Ptr+7);
    vector int b = *(vector int *)(Ptr+23);
    vector int c = *(vector int *)(Ptr+39);
    vector int d = *(vector int *)(Ptr+55);
    return a + b + c + d;
  }

We currently materialize the constants `3, 7, 23, 39` in registers and use those as index registers with `R3` as the base. However, if we computed the value `r3 + 55`, we can use DQ-Form instructions with displacements (48, 23, 16, 0).

This patch performs these adjustments and fixes up some of the addressing computation functions so as to avoid redundant code.


Repository:
  rL LLVM

https://reviews.llvm.org/D65094

Files:
  lib/Target/PowerPC/PPCISelDAGToDAG.cpp
  lib/Target/PowerPC/PPCISelLowering.cpp
  lib/Target/PowerPC/PPCISelLowering.h
  lib/Target/PowerPC/PPCInstr64Bit.td
  lib/Target/PowerPC/PPCInstrInfo.td
  test/CodeGen/PowerPC/dform-adjust.ll
  test/CodeGen/PowerPC/float-load-store-pair.ll
  test/CodeGen/PowerPC/peephole-align.ll
  test/CodeGen/PowerPC/pre-inc-disable.ll
  test/CodeGen/PowerPC/qpx-unal-cons-lds.ll
  test/CodeGen/PowerPC/unal-altivec-wint.ll
  test/CodeGen/PowerPC/unal-altivec.ll
  test/CodeGen/PowerPC/unal-vec-ldst.ll

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D65094.211075.patch
Type: text/x-patch
Size: 38587 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190722/f851f348/attachment.bin>