[PATCH] D120009: [RISCV][NFC] Add sched for some instructions in Zb extension

Fri Feb 18 22:24:42 PST 2022

craig.topper added inline comments.

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Comment at: llvm/lib/Target/RISCV/RISCVInstrInfoZb.td:860

+let Predicates = [HasStdExtZbpOrZbkb, IsRV32] in {
 // We treat zip and unzip as separate instructions, so match it directly.
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Jimerlife wrote:
> craig.topper wrote:
> > Jimerlife wrote:
> > > craig.topper wrote:
> > > > Is this not a functional change for RV64 because ZIP_RV32 will put 0b01111 in bits 24:20 which matches the 15 that was requested in the pattern?
> > > This change will not affect RV64. where defined ZIP_RV32 and UNZIP_RV32 also add "IsRV32" constrain.
> > Without this patch isel will pick these instructions on rv64. The IsRV32 on the instructions only affects the assembler or disassembler.
> > 
> > We need to understand what really happens on RV64 so I know if this needs to be bacported to LLVM 14
> OK, I will remove this change and keep adding only sched in this patch.
I investigated this, the use of `i32` in the pattern prevents it from matching on RV64. So there was no issue. Still a good idea to use IsRV32. I'll go ahead and commit that. Thanks for spotting it.

Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D120009/new/

https://reviews.llvm.org/D120009