//===-- X86InstrControl.td - Control Flow Instructions -----*- tablegen -*-===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file describes the X86 jump, return, call, and related instructions. // //===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===// // Control Flow Instructions. // // Return instructions. // // The X86retflag return instructions are variadic because we may add ST0 and // ST1 arguments when returning values on the x87 stack. let isTerminator = 1, isReturn = 1, isBarrier = 1, hasCtrlDep = 1, FPForm = SpecialFP, SchedRW = [WriteJumpLd] in { def RET32 : I <0xC3, RawFrm, (outs), (ins variable_ops), "ret{l}", []>, OpSize32, Requires<[Not64BitMode]>; def RET64 : I <0xC3, RawFrm, (outs), (ins variable_ops), "ret{q}", []>, OpSize32, Requires<[In64BitMode]>; def RET16 : I <0xC3, RawFrm, (outs), (ins), "ret{w}", []>, OpSize16; def RETI32 : Ii16<0xC2, RawFrm, (outs), (ins i16imm:$amt, variable_ops), "ret{l}\t$amt", []>, OpSize32, Requires<[Not64BitMode]>; def RETI64 : Ii16<0xC2, RawFrm, (outs), (ins i16imm:$amt, variable_ops), "ret{q}\t$amt", []>, OpSize32, Requires<[In64BitMode]>; def RETI16 : Ii16<0xC2, RawFrm, (outs), (ins i16imm:$amt), "ret{w}\t$amt", []>, OpSize16; def LRET32 : I <0xCB, RawFrm, (outs), (ins), "{l}ret{l|f}", []>, OpSize32; def LRET64 : RI <0xCB, RawFrm, (outs), (ins), "{l}ret{|f}q", []>, Requires<[In64BitMode]>; def LRET16 : I <0xCB, RawFrm, (outs), (ins), "{l}ret{w|f}", []>, OpSize16; def LRETI32 : Ii16<0xCA, RawFrm, (outs), (ins i16imm:$amt), "{l}ret{l|f}\t$amt", []>, OpSize32; def LRETI64 : RIi16<0xCA, RawFrm, (outs), (ins i16imm:$amt), "{l}ret{|f}q\t$amt", []>, Requires<[In64BitMode]>; def LRETI16 : Ii16<0xCA, RawFrm, (outs), (ins i16imm:$amt), "{l}ret{w|f}\t$amt", []>, OpSize16; // The machine return from interrupt instruction, but sometimes we need to // perform a post-epilogue stack adjustment. Codegen emits the pseudo form // which expands to include an SP adjustment if necessary. def IRET16 : I <0xcf, RawFrm, (outs), (ins), "iret{w}", []>, OpSize16; def IRET32 : I <0xcf, RawFrm, (outs), (ins), "iret{l|d}", []>, OpSize32; def IRET64 : RI <0xcf, RawFrm, (outs), (ins), "iretq", []>, Requires<[In64BitMode]>; let isCodeGenOnly = 1 in def IRET : PseudoI<(outs), (ins i32imm:$adj), [(X86iret timm:$adj)]>; def RET : PseudoI<(outs), (ins i32imm:$adj, variable_ops), [(X86retflag timm:$adj)]>; } // Unconditional branches. let isBarrier = 1, isBranch = 1, isTerminator = 1, SchedRW = [WriteJump] in { def JMP_1 : Ii8PCRel<0xEB, RawFrm, (outs), (ins brtarget8:$dst), "jmp\t$dst", [(br bb:$dst)]>; let hasSideEffects = 0, isCodeGenOnly = 1, ForceDisassemble = 1 in { def JMP_2 : Ii16PCRel<0xE9, RawFrm, (outs), (ins brtarget16:$dst), "jmp\t$dst", []>, OpSize16; def JMP_4 : Ii32PCRel<0xE9, RawFrm, (outs), (ins brtarget32:$dst), "jmp\t$dst", []>, OpSize32; } } // Conditional Branches. let isBranch = 1, isTerminator = 1, Uses = [EFLAGS], SchedRW = [WriteJump], isCodeGenOnly = 1, ForceDisassemble = 1 in { def JCC_1 : Ii8PCRel <0x70, AddCCFrm, (outs), (ins brtarget8:$dst, ccode:$cond), "j${cond}\t$dst", [(X86brcond bb:$dst, timm:$cond, EFLAGS)]>; let hasSideEffects = 0 in { def JCC_2 : Ii16PCRel<0x80, AddCCFrm, (outs), (ins brtarget16:$dst, ccode:$cond), "j${cond}\t$dst", []>, OpSize16, TB; def JCC_4 : Ii32PCRel<0x80, AddCCFrm, (outs), (ins brtarget32:$dst, ccode:$cond), "j${cond}\t$dst", []>, TB, OpSize32; } } def : InstAlias<"jo\t$dst", (JCC_1 brtarget8:$dst, 0), 0>; def : InstAlias<"jno\t$dst", (JCC_1 brtarget8:$dst, 1), 0>; def : InstAlias<"jb\t$dst", (JCC_1 brtarget8:$dst, 2), 0>; def : InstAlias<"jae\t$dst", (JCC_1 brtarget8:$dst, 3), 0>; def : InstAlias<"je\t$dst", (JCC_1 brtarget8:$dst, 4), 0>; def : InstAlias<"jne\t$dst", (JCC_1 brtarget8:$dst, 5), 0>; def : InstAlias<"jbe\t$dst", (JCC_1 brtarget8:$dst, 6), 0>; def : InstAlias<"ja\t$dst", (JCC_1 brtarget8:$dst, 7), 0>; def : InstAlias<"js\t$dst", (JCC_1 brtarget8:$dst, 8), 0>; def : InstAlias<"jns\t$dst", (JCC_1 brtarget8:$dst, 9), 0>; def : InstAlias<"jp\t$dst", (JCC_1 brtarget8:$dst, 10), 0>; def : InstAlias<"jnp\t$dst", (JCC_1 brtarget8:$dst, 11), 0>; def : InstAlias<"jl\t$dst", (JCC_1 brtarget8:$dst, 12), 0>; def : InstAlias<"jge\t$dst", (JCC_1 brtarget8:$dst, 13), 0>; def : InstAlias<"jle\t$dst", (JCC_1 brtarget8:$dst, 14), 0>; def : InstAlias<"jg\t$dst", (JCC_1 brtarget8:$dst, 15), 0>; // jcx/jecx/jrcx instructions. let isBranch = 1, isTerminator = 1, hasSideEffects = 0, SchedRW = [WriteJump] in { // These are the 32-bit versions of this instruction for the asmparser. In // 32-bit mode, the address size prefix is jcxz and the unprefixed version is // jecxz. let Uses = [CX] in def JCXZ : Ii8PCRel<0xE3, RawFrm, (outs), (ins brtarget8:$dst), "jcxz\t$dst", []>, AdSize16, Requires<[Not64BitMode]>; let Uses = [ECX] in def JECXZ : Ii8PCRel<0xE3, RawFrm, (outs), (ins brtarget8:$dst), "jecxz\t$dst", []>, AdSize32; let Uses = [RCX] in def JRCXZ : Ii8PCRel<0xE3, RawFrm, (outs), (ins brtarget8:$dst), "jrcxz\t$dst", []>, AdSize64, Requires<[In64BitMode]>; } // Indirect branches let isBranch = 1, isTerminator = 1, isBarrier = 1, isIndirectBranch = 1 in { def JMP16r : I<0xFF, MRM4r, (outs), (ins GR16:$dst), "jmp{w}\t{*}$dst", [(brind GR16:$dst)]>, Requires<[Not64BitMode]>, OpSize16, Sched<[WriteJump]>; def JMP16m : I<0xFF, MRM4m, (outs), (ins i16mem:$dst), "jmp{w}\t{*}$dst", [(brind (loadi16 addr:$dst))]>, Requires<[Not64BitMode]>, OpSize16, Sched<[WriteJumpLd]>; def JMP32r : I<0xFF, MRM4r, (outs), (ins GR32:$dst), "jmp{l}\t{*}$dst", [(brind GR32:$dst)]>, Requires<[Not64BitMode]>, OpSize32, Sched<[WriteJump]>; def JMP32m : I<0xFF, MRM4m, (outs), (ins i32mem:$dst), "jmp{l}\t{*}$dst", [(brind (loadi32 addr:$dst))]>, Requires<[Not64BitMode]>, OpSize32, Sched<[WriteJumpLd]>; def JMP64r : I<0xFF, MRM4r, (outs), (ins GR64:$dst), "jmp{q}\t{*}$dst", [(brind GR64:$dst)]>, Requires<[In64BitMode]>, Sched<[WriteJump]>; def JMP64m : I<0xFF, MRM4m, (outs), (ins i64mem:$dst), "jmp{q}\t{*}$dst", [(brind (loadi64 addr:$dst))]>, Requires<[In64BitMode]>, Sched<[WriteJumpLd]>; // Win64 wants indirect jumps leaving the function to have a REX_W prefix. // These are switched from TAILJMPr/m64_REX in MCInstLower. let isCodeGenOnly = 1, hasREX_WPrefix = 1 in { def JMP64r_REX : I<0xFF, MRM4r, (outs), (ins GR64:$dst), "rex64 jmp{q}\t{*}$dst", []>, Sched<[WriteJump]>; let mayLoad = 1 in def JMP64m_REX : I<0xFF, MRM4m, (outs), (ins i64mem:$dst), "rex64 jmp{q}\t{*}$dst", []>, Sched<[WriteJumpLd]>; } // Non-tracking jumps for IBT, use with caution. let isCodeGenOnly = 1 in { def JMP16r_NT : I<0xFF, MRM4r, (outs), (ins GR16 : $dst), "jmp{w}\t{*}$dst", [(X86NoTrackBrind GR16 : $dst)]>, Requires<[Not64BitMode]>, OpSize16, Sched<[WriteJump]>, NOTRACK; def JMP16m_NT : I<0xFF, MRM4m, (outs), (ins i16mem : $dst), "jmp{w}\t{*}$dst", [(X86NoTrackBrind (loadi16 addr : $dst))]>, Requires<[Not64BitMode]>, OpSize16, Sched<[WriteJumpLd]>, NOTRACK; def JMP32r_NT : I<0xFF, MRM4r, (outs), (ins GR32 : $dst), "jmp{l}\t{*}$dst", [(X86NoTrackBrind GR32 : $dst)]>, Requires<[Not64BitMode]>, OpSize32, Sched<[WriteJump]>, NOTRACK; def JMP32m_NT : I<0xFF, MRM4m, (outs), (ins i32mem : $dst), "jmp{l}\t{*}$dst", [(X86NoTrackBrind (loadi32 addr : $dst))]>, Requires<[Not64BitMode]>, OpSize32, Sched<[WriteJumpLd]>, NOTRACK; def JMP64r_NT : I<0xFF, MRM4r, (outs), (ins GR64 : $dst), "jmp{q}\t{*}$dst", [(X86NoTrackBrind GR64 : $dst)]>, Requires<[In64BitMode]>, Sched<[WriteJump]>, NOTRACK; def JMP64m_NT : I<0xFF, MRM4m, (outs), (ins i64mem : $dst), "jmp{q}\t{*}$dst", [(X86NoTrackBrind(loadi64 addr : $dst))]>, Requires<[In64BitMode]>, Sched<[WriteJumpLd]>, NOTRACK; } let Predicates = [Not64BitMode], AsmVariantName = "att" in { def FARJMP16i : Iseg16<0xEA, RawFrmImm16, (outs), (ins i16imm:$off, i16imm:$seg), "ljmp{w}\t$seg, $off", []>, OpSize16, Sched<[WriteJump]>; def FARJMP32i : Iseg32<0xEA, RawFrmImm16, (outs), (ins i32imm:$off, i16imm:$seg), "ljmp{l}\t$seg, $off", []>, OpSize32, Sched<[WriteJump]>; } let mayLoad = 1 in { def FARJMP64m : RI<0xFF, MRM5m, (outs), (ins opaquemem:$dst), "ljmp{q}\t{*}$dst", []>, Sched<[WriteJump]>, Requires<[In64BitMode]>; let AsmVariantName = "att" in def FARJMP16m : I<0xFF, MRM5m, (outs), (ins opaquemem:$dst), "ljmp{w}\t{*}$dst", []>, OpSize16, Sched<[WriteJumpLd]>; def FARJMP32m : I<0xFF, MRM5m, (outs), (ins opaquemem:$dst), "{l}jmp{l}\t{*}$dst", []>, OpSize32, Sched<[WriteJumpLd]>; } } // Loop instructions let isBranch = 1, isTerminator = 1, SchedRW = [WriteJump] in { def LOOP : Ii8PCRel<0xE2, RawFrm, (outs), (ins brtarget8:$dst), "loop\t$dst", []>; def LOOPE : Ii8PCRel<0xE1, RawFrm, (outs), (ins brtarget8:$dst), "loope\t$dst", []>; def LOOPNE : Ii8PCRel<0xE0, RawFrm, (outs), (ins brtarget8:$dst), "loopne\t$dst", []>; } //===----------------------------------------------------------------------===// // Call Instructions... // let isCall = 1 in // All calls clobber the non-callee saved registers. ESP is marked as // a use to prevent stack-pointer assignments that appear immediately // before calls from potentially appearing dead. Uses for argument // registers are added manually. let Uses = [ESP, SSP] in { def CALLpcrel32 : Ii32PCRel<0xE8, RawFrm, (outs), (ins i32imm_brtarget:$dst), "call{l}\t$dst", []>, OpSize32, Requires<[Not64BitMode]>, Sched<[WriteJump]>; let hasSideEffects = 0 in def CALLpcrel16 : Ii16PCRel<0xE8, RawFrm, (outs), (ins i16imm_brtarget:$dst), "call{w}\t$dst", []>, OpSize16, Sched<[WriteJump]>; def CALL16r : I<0xFF, MRM2r, (outs), (ins GR16:$dst), "call{w}\t{*}$dst", [(X86call GR16:$dst)]>, OpSize16, Requires<[Not64BitMode]>, Sched<[WriteJump]>; def CALL16m : I<0xFF, MRM2m, (outs), (ins i16mem:$dst), "call{w}\t{*}$dst", [(X86call (loadi16 addr:$dst))]>, OpSize16, Requires<[Not64BitMode,FavorMemIndirectCall]>, Sched<[WriteJumpLd]>; def CALL32r : I<0xFF, MRM2r, (outs), (ins GR32:$dst), "call{l}\t{*}$dst", [(X86call GR32:$dst)]>, OpSize32, Requires<[Not64BitMode,NotUseIndirectThunkCalls]>, Sched<[WriteJump]>; def CALL32m : I<0xFF, MRM2m, (outs), (ins i32mem:$dst), "call{l}\t{*}$dst", [(X86call (loadi32 addr:$dst))]>, OpSize32, Requires<[Not64BitMode,FavorMemIndirectCall, NotUseIndirectThunkCalls]>, Sched<[WriteJumpLd]>; // Non-tracking calls for IBT, use with caution. let isCodeGenOnly = 1 in { def CALL16r_NT : I<0xFF, MRM2r, (outs), (ins GR16 : $dst), "call{w}\t{*}$dst",[(X86NoTrackCall GR16 : $dst)]>, OpSize16, Requires<[Not64BitMode]>, Sched<[WriteJump]>, NOTRACK; def CALL16m_NT : I<0xFF, MRM2m, (outs), (ins i16mem : $dst), "call{w}\t{*}$dst",[(X86NoTrackCall(loadi16 addr : $dst))]>, OpSize16, Requires<[Not64BitMode,FavorMemIndirectCall]>, Sched<[WriteJumpLd]>, NOTRACK; def CALL32r_NT : I<0xFF, MRM2r, (outs), (ins GR32 : $dst), "call{l}\t{*}$dst",[(X86NoTrackCall GR32 : $dst)]>, OpSize32, Requires<[Not64BitMode]>, Sched<[WriteJump]>, NOTRACK; def CALL32m_NT : I<0xFF, MRM2m, (outs), (ins i32mem : $dst), "call{l}\t{*}$dst",[(X86NoTrackCall(loadi32 addr : $dst))]>, OpSize32, Requires<[Not64BitMode,FavorMemIndirectCall]>, Sched<[WriteJumpLd]>, NOTRACK; } let Predicates = [Not64BitMode], AsmVariantName = "att" in { def FARCALL16i : Iseg16<0x9A, RawFrmImm16, (outs), (ins i16imm:$off, i16imm:$seg), "lcall{w}\t$seg, $off", []>, OpSize16, Sched<[WriteJump]>; def FARCALL32i : Iseg32<0x9A, RawFrmImm16, (outs), (ins i32imm:$off, i16imm:$seg), "lcall{l}\t$seg, $off", []>, OpSize32, Sched<[WriteJump]>; } let mayLoad = 1 in { def FARCALL16m : I<0xFF, MRM3m, (outs), (ins opaquemem:$dst), "lcall{w}\t{*}$dst", []>, OpSize16, Sched<[WriteJumpLd]>; def FARCALL32m : I<0xFF, MRM3m, (outs), (ins opaquemem:$dst), "{l}call{l}\t{*}$dst", []>, OpSize32, Sched<[WriteJumpLd]>; } } // Tail call stuff. let isCall = 1, isTerminator = 1, isReturn = 1, isBarrier = 1, isCodeGenOnly = 1, Uses = [ESP, SSP] in { def TCRETURNdi : PseudoI<(outs), (ins i32imm_brtarget:$dst, i32imm:$offset), []>, Sched<[WriteJump]>, NotMemoryFoldable; def TCRETURNri : PseudoI<(outs), (ins ptr_rc_tailcall:$dst, i32imm:$offset), []>, Sched<[WriteJump]>, NotMemoryFoldable; let mayLoad = 1 in def TCRETURNmi : PseudoI<(outs), (ins i32mem_TC:$dst, i32imm:$offset), []>, Sched<[WriteJumpLd]>; def TAILJMPd : PseudoI<(outs), (ins i32imm_brtarget:$dst), []>, Sched<[WriteJump]>; def TAILJMPr : PseudoI<(outs), (ins ptr_rc_tailcall:$dst), []>, Sched<[WriteJump]>; let mayLoad = 1 in def TAILJMPm : PseudoI<(outs), (ins i32mem_TC:$dst), []>, Sched<[WriteJumpLd]>; } // Conditional tail calls are similar to the above, but they are branches // rather than barriers, and they use EFLAGS. let isCall = 1, isTerminator = 1, isReturn = 1, isBranch = 1, isCodeGenOnly = 1, SchedRW = [WriteJump] in let Uses = [ESP, EFLAGS, SSP] in { def TCRETURNdicc : PseudoI<(outs), (ins i32imm_brtarget:$dst, i32imm:$offset, i32imm:$cond), []>; // This gets substituted to a conditional jump instruction in MC lowering. def TAILJMPd_CC : PseudoI<(outs), (ins i32imm_brtarget:$dst, i32imm:$cond), []>; } //===----------------------------------------------------------------------===// // Call Instructions... // // RSP is marked as a use to prevent stack-pointer assignments that appear // immediately before calls from potentially appearing dead. Uses for argument // registers are added manually. let isCall = 1, Uses = [RSP, SSP], SchedRW = [WriteJump] in { // NOTE: this pattern doesn't match "X86call imm", because we do not know // that the offset between an arbitrary immediate and the call will fit in // the 32-bit pcrel field that we have. def CALL64pcrel32 : Ii32PCRel<0xE8, RawFrm, (outs), (ins i64i32imm_brtarget:$dst), "call{q}\t$dst", []>, OpSize32, Requires<[In64BitMode]>; def CALL64r : I<0xFF, MRM2r, (outs), (ins GR64:$dst), "call{q}\t{*}$dst", [(X86call GR64:$dst)]>, Requires<[In64BitMode,NotUseIndirectThunkCalls]>; def CALL64m : I<0xFF, MRM2m, (outs), (ins i64mem:$dst), "call{q}\t{*}$dst", [(X86call (loadi64 addr:$dst))]>, Requires<[In64BitMode,FavorMemIndirectCall, NotUseIndirectThunkCalls]>; // Non-tracking calls for IBT, use with caution. let isCodeGenOnly = 1 in { def CALL64r_NT : I<0xFF, MRM2r, (outs), (ins GR64 : $dst), "call{q}\t{*}$dst",[(X86NoTrackCall GR64 : $dst)]>, Requires<[In64BitMode]>, NOTRACK; def CALL64m_NT : I<0xFF, MRM2m, (outs), (ins i64mem : $dst), "call{q}\t{*}$dst", [(X86NoTrackCall(loadi64 addr : $dst))]>, Requires<[In64BitMode,FavorMemIndirectCall]>, NOTRACK; } let mayLoad = 1 in def FARCALL64m : RI<0xFF, MRM3m, (outs), (ins opaquemem:$dst), "lcall{q}\t{*}$dst", []>; } let isCall = 1, isTerminator = 1, isReturn = 1, isBarrier = 1, isCodeGenOnly = 1, Uses = [RSP, SSP] in { def TCRETURNdi64 : PseudoI<(outs), (ins i64i32imm_brtarget:$dst, i32imm:$offset), []>, Sched<[WriteJump]>; def TCRETURNri64 : PseudoI<(outs), (ins ptr_rc_tailcall:$dst, i32imm:$offset), []>, Sched<[WriteJump]>, NotMemoryFoldable; let mayLoad = 1 in def TCRETURNmi64 : PseudoI<(outs), (ins i64mem_TC:$dst, i32imm:$offset), []>, Sched<[WriteJumpLd]>, NotMemoryFoldable; def TAILJMPd64 : PseudoI<(outs), (ins i64i32imm_brtarget:$dst), []>, Sched<[WriteJump]>; def TAILJMPr64 : PseudoI<(outs), (ins ptr_rc_tailcall:$dst), []>, Sched<[WriteJump]>; let mayLoad = 1 in def TAILJMPm64 : PseudoI<(outs), (ins i64mem_TC:$dst), []>, Sched<[WriteJumpLd]>; // Win64 wants indirect jumps leaving the function to have a REX_W prefix. let hasREX_WPrefix = 1 in { def TAILJMPr64_REX : PseudoI<(outs), (ins ptr_rc_tailcall:$dst), []>, Sched<[WriteJump]>; let mayLoad = 1 in def TAILJMPm64_REX : PseudoI<(outs), (ins i64mem_TC:$dst), []>, Sched<[WriteJumpLd]>; } } let isPseudo = 1, isCall = 1, isCodeGenOnly = 1, Uses = [RSP, SSP], usesCustomInserter = 1, SchedRW = [WriteJump] in { def INDIRECT_THUNK_CALL32 : PseudoI<(outs), (ins GR32:$dst), [(X86call GR32:$dst)]>, Requires<[Not64BitMode,UseIndirectThunkCalls]>; def INDIRECT_THUNK_CALL64 : PseudoI<(outs), (ins GR64:$dst), [(X86call GR64:$dst)]>, Requires<[In64BitMode,UseIndirectThunkCalls]>; // Indirect thunk variant of indirect tail calls. let isTerminator = 1, isReturn = 1, isBarrier = 1 in { def INDIRECT_THUNK_TCRETURN64 : PseudoI<(outs), (ins GR64:$dst, i32imm:$offset), []>; def INDIRECT_THUNK_TCRETURN32 : PseudoI<(outs), (ins GR32:$dst, i32imm:$offset), []>; } } let isPseudo = 1, isCall = 1, isCodeGenOnly = 1, Uses = [RSP, SSP], SchedRW = [WriteJump] in { def CALL64m_RVMARKER : PseudoI<(outs), (ins i64imm:$rvfunc, i64mem:$dst), [(X86call_rvmarker tglobaladdr:$rvfunc, (loadi64 addr:$dst))]>, Requires<[In64BitMode]>; def CALL64r_RVMARKER : PseudoI<(outs), (ins i64imm:$rvfunc, GR64:$dst), [(X86call_rvmarker tglobaladdr:$rvfunc, GR64:$dst)]>, Requires<[In64BitMode]>; def CALL64pcrel32_RVMARKER : PseudoI<(outs), (ins i64imm:$rvfunc, i64i32imm_brtarget:$dst), []>, Requires<[In64BitMode]>; } // Conditional tail calls are similar to the above, but they are branches // rather than barriers, and they use EFLAGS. let isCall = 1, isTerminator = 1, isReturn = 1, isBranch = 1, isCodeGenOnly = 1, SchedRW = [WriteJump] in let Uses = [RSP, EFLAGS, SSP] in { def TCRETURNdi64cc : PseudoI<(outs), (ins i64i32imm_brtarget:$dst, i32imm:$offset, i32imm:$cond), []>; // This gets substituted to a conditional jump instruction in MC lowering. def TAILJMPd64_CC : PseudoI<(outs), (ins i64i32imm_brtarget:$dst, i32imm:$cond), []>; }