[RISCV][GISel] Support fcmp and fclass for Zfh. (#96696)

Author: topperc

llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp

@@ -1148,16 +1148,16 @@ bool RISCVInstructionSelector::selectSelect(MachineInstr &MI,
 
 // Convert an FCMP predicate to one of the supported F or D instructions.
 static unsigned getFCmpOpcode(CmpInst::Predicate Pred, unsigned Size) {
-  assert((Size == 32 || Size == 64) && "Unsupported size");
+  assert((Size == 16 || Size == 32 || Size == 64) && "Unsupported size");
   switch (Pred) {
   default:
     llvm_unreachable("Unsupported predicate");
   case CmpInst::FCMP_OLT:
-    return Size == 32 ? RISCV::FLT_S : RISCV::FLT_D;
+    return Size == 16 ? RISCV::FLT_H : Size == 32 ? RISCV::FLT_S : RISCV::FLT_D;
   case CmpInst::FCMP_OLE:
-    return Size == 32 ? RISCV::FLE_S : RISCV::FLE_D;
+    return Size == 16 ? RISCV::FLE_H : Size == 32 ? RISCV::FLE_S : RISCV::FLE_D;
   case CmpInst::FCMP_OEQ:
-    return Size == 32 ? RISCV::FEQ_S : RISCV::FEQ_D;
+    return Size == 16 ? RISCV::FEQ_H : Size == 32 ? RISCV::FEQ_S : RISCV::FEQ_D;
   }
 }
 
@@ -1209,7 +1209,7 @@ bool RISCVInstructionSelector::selectFPCompare(MachineInstr &MI,
   Register RHS = CmpMI.getRHSReg();
 
   unsigned Size = MRI.getType(LHS).getSizeInBits();
-  assert((Size == 32 || Size == 64) && "Unexpected size");
+  assert((Size == 16 || Size == 32 || Size == 64) && "Unexpected size");
 
   Register TmpReg = DstReg;
 

llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp

@@ -402,13 +402,20 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST)
                 typeIs(1, s32)(Query));
       });
 
-  getActionDefinitionsBuilder(G_FCMP)
-      .legalIf(all(typeIs(0, sXLen), typeIsScalarFPArith(1, ST)))
-      .clampScalar(0, sXLen, sXLen);
+  auto &FCmpActions = getActionDefinitionsBuilder(G_FCMP).legalIf(
+      all(typeIs(0, sXLen), typeIsScalarFPArith(1, ST)));
+  // TODO: Fold this into typeIsScalarFPArith.
+  if (ST.hasStdExtZfh())
+    FCmpActions.legalFor({sXLen, s16});
+  FCmpActions.clampScalar(0, sXLen, sXLen);
 
   // TODO: Support vector version of G_IS_FPCLASS.
-  getActionDefinitionsBuilder(G_IS_FPCLASS)
-      .customIf(all(typeIs(0, s1), typeIsScalarFPArith(1, ST)));
+  auto &FClassActions =
+      getActionDefinitionsBuilder(G_IS_FPCLASS)
+          .customIf(all(typeIs(0, s1), typeIsScalarFPArith(1, ST)));
+  // TODO: Fold this into typeIsScalarFPArith.
+  if (ST.hasStdExtZfh())
+    FClassActions.customFor({s1, s16});
 
   auto &FConstantActions = getActionDefinitionsBuilder(G_FCONSTANT)
                                .legalIf(typeIsScalarFPArith(0, ST));

llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.cpp

@@ -478,7 +478,6 @@ RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
     LLT Ty = MRI.getType(MI.getOperand(2).getReg());
 
     unsigned Size = Ty.getSizeInBits();
-    assert((Size == 32 || Size == 64) && "Unsupported size for G_FCMP");
 
     OpdsMapping[0] = GPRValueMapping;
     OpdsMapping[2] = OpdsMapping[3] = getFPValueMapping(Size);