[LLVMdev] tablegen for fast isel

[Daniel Sanders]

The error stems from DSUB and DSUBu having the same pattern and predicates (to find this out, I printed SimplePatterns[Operands][OpcodeName][VT][RetVT][PredicateCheck].Name just before the error). If you remove the last argument ('sub') from the DSUB definition then it will generate the file successfully.

It's probably a bug that DSUB has 'sub' instead of the default 'null_frag'. The 'dsub' instruction it defines will trap on overflow which doesn't agree with the codegen pattern. Most likely, this bug has been concealed by the DSUBu instruction (the non-trapping version) being defined first which has prevented SelectionDAG from even trying to match DSUB.

> -----Original Message-----
> From: reed kotler [mailto:rkotler at mips.com]
> Sent: 24 April 2014 01:21
> To: LLVMdev at cs.uiuc.edu
> Cc: Rafael Espíndola; Daniel Sanders
> Subject: tablegen for fast isel
> 
> What is the purpose of tablegen created files for fast-isel?
> 
> If I make the following change to Makefile in lib/Target/Mips
> 
>   BUILT_SOURCES = MipsGenRegisterInfo.inc MipsGenInstrInfo.inc \
>                   MipsGenAsmWriter.inc MipsGenCodeEmitter.inc \
>                   MipsGenDAGISel.inc MipsGenCallingConv.inc \
> -                MipsGenSubtargetInfo.inc MipsGenMCCodeEmitter.inc \
> +               MipsGenSubtargetInfo.inc MipsGenFastISel.inc
> MipsGenMCCodeEmitter.inc \
>                   MipsGenDisassemblerTables.inc \
>                   MipsGenMCPseudoLowering.inc MipsGenAsmMatcher.inc
> 
> 
> I get an error.
> 
> Included from
> /home/rkotler/workspace/llvm/lib/Target/Mips/MipsInstrInfo.td:1474:
> /home/rkotler/workspace/llvm/lib/Target/Mips/Mips64InstrInfo.td:89:1:
> error: Duplicate record in FastISel table!
> def DSUB   : ArithLogicR<"dsub", GPR64Opnd, 0, II_DSUB, sub>, ADD_FM<0,
> 0x2e>;
> ^
> make[3]: ***
> [/home/rkotler/llvmw/build/lib/Target/Mips/Debug+Asserts/MipsGenFastIS
> el.inc.tmp]
> Error 1
> 
> 
> Then it creates a blank file for MipsGenFastISel.inc and after that I get no
> build errors.
> 
> I'm not sure what this is about .
> 
> Any ideas?
> 
> Tia.
> 
> Reed