[PATCH] D116307: [RISCV] Teach VSETVLInsert to eliminate redundant vsetvli for vmv.s.x and vfmv.s.f.

[Jianjian Guan via Phabricator via llvm-commits]

jacquesguan added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp:470
+  case RISCV::PseudoVMV_S_X_MF8:
+  case RISCV::PseudoVFMV_F16_S_M1:
+  case RISCV::PseudoVFMV_F16_S_M2:
----------------
rogfer01 wrote:
> I'm confused by the commit title.
> 
> You mention `vmv.s.x` which seems OK with the cases above and you also mention `vfmv.s.f`. But IIUC the cases listed here are for `vfmv.f.s`, right?
> 
> This is my understanding after this exceprt from `RISCVInstrInfoVPseudos.td`
> 
> ```
> //===----------------------------------------------------------------------===//
> // 17.2. Floating-Point Scalar Move Instructions                                
> //===----------------------------------------------------------------------===//
>                                                                                 
> let Predicates = [HasVInstructionsAnyF] in {                                    
> foreach fvti = AllFloatVectors in {                                             
>   defvar instr = !cast<Instruction>("PseudoVFMV_"#fvti.ScalarSuffix#"_S_" #     
>                                     fvti.LMul.MX);                              
>   def : Pat<(fvti.Scalar (int_riscv_vfmv_f_s (fvti.Vector fvti.RegClass:$rs2))),
>                          (instr $rs2, fvti.Log2SEW)>;                           
>                                                                                 
>   def : Pat<(fvti.Vector (int_riscv_vfmv_s_f (fvti.Vector fvti.RegClass:$rs1),  
>                          (fvti.Scalar fvti.ScalarRegClass:$rs2), VLOpFrag)),    
>             (!cast<Instruction>("PseudoVFMV_S_"#fvti.ScalarSuffix#"_" #         
>                                 fvti.LMul.MX)                                   
>              (fvti.Vector $rs1),                                                
>              (fvti.Scalar fvti.ScalarRegClass:$rs2),                            
>              GPR:$vl, fvti.Log2SEW)>;                                           
> }                                                                               
> } // Predicates = [HasVInstructionsAnyF]                                        
> ```
Yes, you are right. I used wrong cases here; I will create a new revision to fix this and add more test cases for floating point. Thank you very much. 


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  https://reviews.llvm.org/D116307/new/

https://reviews.llvm.org/D116307