[RISCV][CodeGen] Add CodeGen support of Zibi experimental extension (#146858)

This adds the CodeGen support of Zibi v0.1 experimental extension, which
depends on #127463.

Author: BoyaoWang430

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -22494,6 +22494,7 @@ RISCVTargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
            "ReadCounterWide is only to be used on riscv32");
     return emitReadCounterWidePseudo(MI, BB);
   case RISCV::Select_GPR_Using_CC_GPR:
+  case RISCV::Select_GPR_Using_CC_Imm5_Zibi:
   case RISCV::Select_GPR_Using_CC_SImm5_CV:
   case RISCV::Select_GPRNoX0_Using_CC_SImm5NonZero_QC:
   case RISCV::Select_GPRNoX0_Using_CC_UImm5NonZero_QC:

llvm/lib/Target/RISCV/RISCVInstrInfo.cpp

@@ -955,13 +955,15 @@ RISCVCC::CondCode RISCVInstrInfo::getCondFromBranchOpc(unsigned Opc) {
   default:
     return RISCVCC::COND_INVALID;
   case RISCV::BEQ:
+  case RISCV::BEQI:
   case RISCV::CV_BEQIMM:
   case RISCV::QC_BEQI:
   case RISCV::QC_E_BEQI:
   case RISCV::NDS_BBC:
   case RISCV::NDS_BEQC:
     return RISCVCC::COND_EQ;
   case RISCV::BNE:
+  case RISCV::BNEI:
   case RISCV::QC_BNEI:
   case RISCV::QC_E_BNEI:
   case RISCV::CV_BNEIMM:
@@ -1041,6 +1043,16 @@ unsigned RISCVCC::getBrCond(RISCVCC::CondCode CC, unsigned SelectOpc) {
       return RISCV::BGEU;
     }
     break;
+  case RISCV::Select_GPR_Using_CC_Imm5_Zibi:
+    switch (CC) {
+    default:
+      llvm_unreachable("Unexpected condition code!");
+    case RISCVCC::COND_EQ:
+      return RISCV::BEQI;
+    case RISCVCC::COND_NE:
+      return RISCV::BNEI;
+    }
+    break;
   case RISCV::Select_GPR_Using_CC_SImm5_CV:
     switch (CC) {
     default:
@@ -1359,9 +1371,15 @@ bool RISCVInstrInfo::reverseBranchCondition(
   case RISCV::BEQ:
     Cond[0].setImm(RISCV::BNE);
     break;
+  case RISCV::BEQI:
+    Cond[0].setImm(RISCV::BNEI);
+    break;
   case RISCV::BNE:
     Cond[0].setImm(RISCV::BEQ);
     break;
+  case RISCV::BNEI:
+    Cond[0].setImm(RISCV::BEQI);
+    break;
   case RISCV::BLT:
     Cond[0].setImm(RISCV::BGE);
     break;
@@ -1611,6 +1629,8 @@ bool RISCVInstrInfo::isBranchOffsetInRange(unsigned BranchOp,
   case RISCV::BGE:
   case RISCV::BLTU:
   case RISCV::BGEU:
+  case RISCV::BEQI:
+  case RISCV::BNEI:
   case RISCV::CV_BEQIMM:
   case RISCV::CV_BNEIMM:
   case RISCV::QC_BEQI:
@@ -2859,6 +2879,9 @@ bool RISCVInstrInfo::verifyInstruction(const MachineInstr &MI,
         case RISCVOp::OPERAND_FOUR:
           Ok = Imm == 4;
           break;
+        case RISCVOp::OPERAND_IMM5_ZIBI:
+          Ok = (isUInt<5>(Imm) && Imm != 0) || Imm == -1;
+          break;
           // clang-format off
         CASE_OPERAND_SIMM(5)
         CASE_OPERAND_SIMM(6)

llvm/lib/Target/RISCV/RISCVInstrInfoZibi.td

@@ -42,3 +42,24 @@ let Predicates = [HasStdExtZibi] in {
   def BEQI : Branch_imm<0b010, "beqi">;
   def BNEI : Branch_imm<0b011, "bnei">;
 } // Predicates = [HasStdExtZibi]
+
+multiclass BccImmPat<CondCode Cond, Branch_imm Inst> {
+  def : Pat<(riscv_brcc (XLenVT GPR:$rs1), imm5_zibi:$cimm, Cond, bb:$imm12),
+            (Inst GPR:$rs1, imm5_zibi:$cimm, bare_simm13_lsb0_bb:$imm12)>;
+}
+
+defm CC_Imm5_Zibi : SelectCC_GPR_riirr<GPR, imm5_zibi>;
+
+class SelectZibi<CondCode Cond>
+    : Pat<(riscv_selectcc_frag:$cc (XLenVT GPR:$lhs), imm5_zibi:$cimm, Cond,
+              (XLenVT GPR:$truev), GPR:$falsev),
+          (Select_GPR_Using_CC_Imm5_Zibi GPR:$lhs, imm5_zibi:$cimm,
+              (IntCCtoRISCVCC $cc), GPR:$truev, GPR:$falsev)>;
+
+let Predicates = [HasStdExtZibi] in {
+  def : SelectZibi<SETEQ>;
+  def : SelectZibi<SETNE>;
+
+  defm : BccImmPat<SETEQ, BEQI>;
+  defm : BccImmPat<SETNE, BNEI>;
+} // Predicates = [HasStdExtZibi]

llvm/lib/Target/RISCV/RISCVInstrPredicates.td

@@ -49,6 +49,7 @@ def isSelectPseudo
                    MCReturnStatement<
                      CheckOpcode<[
                        Select_GPR_Using_CC_GPR,
+                       Select_GPR_Using_CC_Imm5_Zibi,
                        Select_GPR_Using_CC_SImm5_CV,
                        Select_GPRNoX0_Using_CC_SImm5NonZero_QC,
                        Select_GPRNoX0_Using_CC_UImm5NonZero_QC,