[RISCV] Don't allow i64 vector div by constant to use mulh with Zve64x

[eopXD]

Summary

EEW=64 of mulh and its vairants requires V extension.

Authored by: Craig Topper <[e-mail]> @craig.topper

[craig.topper]

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

919–924

This one should say vXi64. This is the fixed vector section.

llvm/test/CodeGen/RISCV/rvv/vdiv-sdnode-rv32.ll

1 ↗

(On Diff #402189)

Can we do this without splitting the tests back into rv32/rv64 versions?

Why do we need need UTC_ARGS: --force-update

[eopXD]

llvm/test/CodeGen/RISCV/rvv/vdiv-sdnode-rv32.ll

1 ↗

(On Diff #402189)

Can we do this without splitting the tests back into rv32/rv64 versions?

I looked into the test case. Looks like under rv64 and V it loads the argument using two instructions (one to load %hi and one to load %lo). I tried specifying TargetABI lp64 for it but it didn't change.

https://pastebin.com/vrkajMSN

What argument should I add to eliminate this situation? My understanding is that the differences are in XLEN (rv32 vs rv64) and extensions (zve vs v). The machine instruction generated should only differ between different XLEN.

[craig.topper]

llvm/test/CodeGen/RISCV/rvv/vdiv-sdnode-rv32.ll

1 ↗

(On Diff #402189)

It can't be fixed. There aren't enough bits in the GPR for RV32. We'll just need to have multiple check-prefixes. Something like

CHECK,RV32,RV32-ZVE32
CHECK,RV32,RV32-V
CHECK,RV64,RV64-ZVE32
CHECK,RV64,RV64-V

[eopXD]

llvm/test/CodeGen/RISCV/rvv/vdiv-sdnode-rv32.ll

1 ↗

(On Diff #402189)

Okay. I will do that and have a single file for an instruction.

[eopXD]

Update test case.

[craig.topper]

llvm/test/CodeGen/RISCV/rvv/vdiv-sdnode.ll

3

Did you run the make check-llvm after running the script? FileCheck doesn't like prefixes to appear in check-prefixes if it doesn't appear in the test file. RV32-ZVE64X does not appear on any lines.

[eopXD]

Update comment.

[eopXD]

Update test case.

[eopXD]

Concluding the test case change:

• For eew < 64, check lines should be the same between all 4 lines of RUN:
• For eew = 64
  • Since this patch rules out vmulh from Zve64*, ZVE64X lines don't use them.
  • GPR length for rv32 and rv64 differ, so ways to load from function arguments differ between RV32-V and RV64-V

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

919–924

Updated.

llvm/test/CodeGen/RISCV/rvv/vdiv-sdnode.ll

3

Updated. Thank you.

[frasercrmck]

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

615

Do we need to move this comment down? It still applies at its previous location, doesn't it?

[eopXD]

Undo comment moved and follow clang-format.

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

615

Yes you are correct. Change reverted.

[craig.topper]

LGTM

[eopXD]

Rebase with no change, the buildbot halted.