[PowerPC][Power10] Exploit the xxspltiw and xxspltidp instructions.

[lei]

Summary

This patch exploits the VSX Vector Splat Immediate Word and VSX Vector Splat Immediate Double Precision Instructions:

xxspltiw XT,IMM32
xxspltidp XT,IMM32

Depends on D82896.

[lei]

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

1477

Any reason why we are not following the format used for the other case statements?
If it fit within 1 line, it would be good to match the formate of this switch stmt.

llvm/lib/Target/PowerPC/PPCInstrPrefix.td

708

nit: indentation is off.

llvm/test/CodeGen/PowerPC/power10-immediate-moves-and-splats.ll

4 ↗

(On Diff #274602)

Do we need BE run line here?

[amyk]

Updated the patch:

• to include BE RUN line in the test
• adjust indentation
• add functions to the llvm namespace.

[amyk]

llvm/lib/Target/PowerPC/PPCInstrPrefix.td

708

I'm not entirely sure why the indentation appears like that, as the indentation is correct in the patch... (under v2f64).

llvm/test/CodeGen/PowerPC/power10-immediate-moves-and-splats.ll

4 ↗

(On Diff #274602)

I've added the BE line for now as different code is generated for tests similar to testDoubleToDoubleFail. If there is a preference to remove the BE line, I can remove it.

[amyk]

Updated the patch:

• to include proper test case to account for PC Rel.
• add BE run line to the test case.

[amyk]

FYI @lei regarding the test case.

llvm/test/CodeGen/PowerPC/power10-immediate-moves-and-splats.ll

4 ↗

(On Diff #274602)

I realized that the correct test case has checks to account for PC Rel. I have updated the revision and kept the BE run lines for now.

[amyk]

Make changes to adhere to clang-format.

[amyk]

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

1477

This line is actually due to clang-format.

[lei]

llvm/test/CodeGen/PowerPC/power10-immediate-moves-and-splats.ll

11 ↗

(On Diff #274668)

Was thinking maybe we can break this test file into 2 different ones:

1. p10-splatsImm.ll
   • contain tests that produces the same code for both LE/BE (not dependent of PCRel).
   • both run lines can use default for check prefix.
2. p10-splatsImm-pcrel.ll
   • contain tests that produce code dependent on whether PCRel is supported or not
   • Use default for PCRel enabled (LE tests) and CHECK-TOC for when it's not (ie BE and when PCRel is disabled).

[lei]

llvm/test/CodeGen/PowerPC/power10-immediate-moves-and-splats.ll

11 ↗

(On Diff #274668)

I meant p10-splatImm.ll and p10-splatImm-no-pcrel.ll

[lei]

Taking over ownership to address review comments.

[lei]

• clean up condition code in isFPImmLegal()
• split test file into pcrel and non-pcrel related, clean up checks
• add test for BE elfv2

[anil9]

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

9338–9351

This fixme comment is no longer relevant as the fix has already been applied.

[NeHuang]

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

9342

Is it better to combine these two conditions? Seems only the first argument of getCanonicalConstSplat depends on SplatSize.

if (Subtarget.hasPrefixInstrs() && (SplatSize == 2 || SplatSize == 4))
  return getCanonicalConstSplat ((SplatSize == 2) ? (SplatBits |= SplatBits << 16) : SplatBits, 4, Op.getValueType(), DAG, dl)

16324

Undo this change.

[anil9]

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

9342

The current code is more readable than the suggested one, and was decided on after a discussion. I prefer the way it is now.

[lei]

Remove unnecessary FIXME message, accidental formating, and simplify if-condition as suggested by Victor.

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

9342

I can do that, don't feel strongly about it either way.

[nemanjai]

LGTM other than the minor nit.

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

9342

+1

llvm/test/CodeGen/PowerPC/p10-splatImm-pcrel.ll

1 ↗

(On Diff #274890)

Seems that this test case should have something in its name to indicate that none of the splats can use the new splat instructions.

[lei]

revert changes to the if condition

[anil9]

LGTM

[nemanjai]

LGTM.

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

16303

Maybe add a comment to state that this includes positive zero.

[lei]

rename test file and add additional ccomments to code.

[lei]

llvm/test/CodeGen/PowerPC/p10-splatImm-pcrel.ll

1 ↗

(On Diff #274890)

Will rename to test/CodeGen/PowerPC/p10-splatImm-CPload-pcrel.ll on commit.