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

[Roger Ferrer Ibanez via Phabricator via llvm-commits]

rogfer01 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:
----------------
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]                                        
```


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

https://reviews.llvm.org/D116307