[RISCV] Add new CondCode COND_CV_BEQIMM/COND_CV_BNEIMM for CV immediate branch

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

@@ -789,7 +789,7 @@ bool RISCVInstructionSelector::select(MachineInstr &MI) {
     RISCVCC::CondCode CC;
     getOperandsForBranch(MI.getOperand(0).getReg(), CC, LHS, RHS, *MRI);
 
-    auto Bcc = MIB.buildInstr(RISCVCC::getBrCond(STI, CC), {}, {LHS, RHS})
+    auto Bcc = MIB.buildInstr(RISCVCC::getBrCond(CC), {}, {LHS, RHS})
                    .addMBB(MI.getOperand(1).getMBB());
     MI.eraseFromParent();
     return constrainSelectedInstRegOperands(*Bcc, TII, TRI, RBI);

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -20640,7 +20640,7 @@ static MachineBasicBlock *emitSelectPseudo(MachineInstr &MI,
 
   // Insert appropriate branch.
   if (MI.getOperand(2).isImm())
-    BuildMI(HeadMBB, DL, TII.getBrCond(CC, MI.getOperand(2).isImm()))
+    BuildMI(HeadMBB, DL, TII.getBrCond(CC))
         .addReg(LHS)
         .addImm(MI.getOperand(2).getImm())
         .addMBB(TailMBB);

llvm/lib/Target/RISCV/RISCVInstrInfo.cpp

@@ -974,10 +974,6 @@ static RISCVCC::CondCode getCondFromBranchOpc(unsigned Opc) {
   switch (Opc) {
   default:
     return RISCVCC::COND_INVALID;
-  case RISCV::CV_BEQIMM:
-    return RISCVCC::COND_EQ;
-  case RISCV::CV_BNEIMM:
-    return RISCVCC::COND_NE;
   case RISCV::BEQ:
     return RISCVCC::COND_EQ;
   case RISCV::BNE:
@@ -990,6 +986,10 @@ static RISCVCC::CondCode getCondFromBranchOpc(unsigned Opc) {
     return RISCVCC::COND_LTU;
   case RISCV::BGEU:
     return RISCVCC::COND_GEU;
+  case RISCV::CV_BEQIMM:
+    return RISCVCC::COND_CV_BEQIMM;
+  case RISCV::CV_BNEIMM:
+    return RISCVCC::COND_CV_BNEIMM;
   }
 }
 
@@ -1027,23 +1027,14 @@ static void parseCondBranch(MachineInstr &LastInst, MachineBasicBlock *&Target,
   Cond.push_back(LastInst.getOperand(1));
 }
 
-unsigned RISCVCC::getBrCond(const RISCVSubtarget &STI, RISCVCC::CondCode CC,
-                            bool Imm) {
+unsigned RISCVCC::getBrCond(RISCVCC::CondCode CC) {
   switch (CC) {
   default:
     llvm_unreachable("Unknown condition code!");
   case RISCVCC::COND_EQ:
-    if (!Imm)
-      return RISCV::BEQ;
-    if (STI.hasVendorXCVbi())
-      return RISCV::CV_BEQIMM;
-    llvm_unreachable("Unknown branch immediate!");
+    return RISCV::BEQ;
   case RISCVCC::COND_NE:
-    if (!Imm)
-      return RISCV::BNE;
-    if (STI.hasVendorXCVbi())
-      return RISCV::CV_BNEIMM;
-    llvm_unreachable("Unknown branch immediate!");
+    return RISCV::BNE;
   case RISCVCC::COND_LT:
     return RISCV::BLT;
   case RISCVCC::COND_GE:
@@ -1052,12 +1043,15 @@ unsigned RISCVCC::getBrCond(const RISCVSubtarget &STI, RISCVCC::CondCode CC,
     return RISCV::BLTU;
   case RISCVCC::COND_GEU:
     return RISCV::BGEU;
+  case RISCVCC::COND_CV_BEQIMM:
+    return RISCV::CV_BEQIMM;
+  case RISCVCC::COND_CV_BNEIMM:
+    return RISCV::CV_BNEIMM;
   }
 }
 
-const MCInstrDesc &RISCVInstrInfo::getBrCond(RISCVCC::CondCode CC,
-                                             bool Imm) const {
-  return get(RISCVCC::getBrCond(STI, CC, Imm));
+const MCInstrDesc &RISCVInstrInfo::getBrCond(RISCVCC::CondCode CC) const {
+  return get(RISCVCC::getBrCond(CC));
 }
 
 RISCVCC::CondCode RISCVCC::getOppositeBranchCondition(RISCVCC::CondCode CC) {
@@ -1076,6 +1070,10 @@ RISCVCC::CondCode RISCVCC::getOppositeBranchCondition(RISCVCC::CondCode CC) {
     return RISCVCC::COND_GEU;
   case RISCVCC::COND_GEU:
     return RISCVCC::COND_LTU;
+  case RISCVCC::COND_CV_BEQIMM:
+    return RISCVCC::COND_CV_BNEIMM;
+  case RISCVCC::COND_CV_BNEIMM:
+    return RISCVCC::COND_CV_BEQIMM;
   }
 }
 
@@ -1206,7 +1204,7 @@ unsigned RISCVInstrInfo::insertBranch(
 
   // Either a one or two-way conditional branch.
   auto CC = static_cast<RISCVCC::CondCode>(Cond[0].getImm());
-  MachineInstr &CondMI = *BuildMI(&MBB, DL, getBrCond(CC, Cond[2].isImm()))
+  MachineInstr &CondMI = *BuildMI(&MBB, DL, getBrCond(CC))
                               .add(Cond[1])
                               .add(Cond[2])
                               .addMBB(TBB);

llvm/lib/Target/RISCV/RISCVInstrInfo.h

@@ -41,11 +41,13 @@ enum CondCode {
   COND_GE,
   COND_LTU,
   COND_GEU,
+  COND_CV_BEQIMM,
+  COND_CV_BNEIMM,
   COND_INVALID
 };
 
 CondCode getOppositeBranchCondition(CondCode);
-unsigned getBrCond(const RISCVSubtarget &STI, CondCode CC, bool Imm = false);
+unsigned getBrCond(CondCode CC);
 
 } // end of namespace RISCVCC
 
@@ -65,7 +67,7 @@ class RISCVInstrInfo : public RISCVGenInstrInfo {
   explicit RISCVInstrInfo(RISCVSubtarget &STI);
 
   MCInst getNop() const override;
-  const MCInstrDesc &getBrCond(RISCVCC::CondCode CC, bool Imm = false) const;
+  const MCInstrDesc &getBrCond(RISCVCC::CondCode CC) const;
 
   Register isLoadFromStackSlot(const MachineInstr &MI,
                                int &FrameIndex) const override;

llvm/lib/Target/RISCV/RISCVInstrInfoXCV.td

@@ -791,6 +791,13 @@ let Predicates = [HasVendorXCValu, IsRV32], AddedComplexity = 1 in {
 // Patterns for immediate branching operations
 //===----------------------------------------------------------------------===//
 
+def IntCCtoRISCVCCCV : SDNodeXForm<riscv_selectcc, [{
+  ISD::CondCode CC = cast<CondCodeSDNode>(N->getOperand(2))->get();
+  assert(CC == ISD::SETEQ || CC == ISD::SETNE);
+  RISCVCC::CondCode BrCC = CC == ISD::SETEQ ? RISCVCC::COND_CV_BEQIMM : RISCVCC::COND_CV_BNEIMM;
+  return CurDAG->getTargetConstant(BrCC, SDLoc(N), Subtarget->getXLenVT());
+}]>;
+
 let Predicates = [HasVendorXCVbi, IsRV32], AddedComplexity = 2 in {
   def : Pat<(riscv_brcc GPR:$rs1, simm5:$imm5, SETEQ, bb:$imm12),
             (CV_BEQIMM GPR:$rs1, simm5:$imm5, bare_simm13_lsb0:$imm12)>;
@@ -807,7 +814,7 @@ let Predicates = [HasVendorXCVbi, IsRV32], AddedComplexity = 2 in {
       : Pat<(riscv_selectcc_frag:$cc (i32 GPR:$lhs), simm5:$Constant, Cond,
                                      (i32 GPR:$truev), GPR:$falsev),
             (Select_GPR_Using_CC_Imm GPR:$lhs, simm5:$Constant,
-             (IntCCtoRISCVCC $cc), GPR:$truev, GPR:$falsev)>;
+             (IntCCtoRISCVCCCV $cc), GPR:$truev, GPR:$falsev)>;
 
   def : Selectbi<SETEQ>;
   def : Selectbi<SETNE>;