Using BuildMI to build X86_64 instructions

salsouaf · October 13, 2022, 9:17am

Hello all,

I am trying to create and insert a set of instructions using BuildMI, I was able to find the syntax to create mov, add , cmp…
But I was wondering if there is a way to create/insert a label. The latter will be my jump destination.

Thank you in advance.

phoebe · October 13, 2022, 9:56am

github.com

llvm/llvm-project/blob/main/llvm/lib/Target/X86/X86IndirectThunks.cpp#L251


      
            CallTarget->setMachineBlockAddressTaken();
            CallTarget->setAlignment(Align(16));
          
          
  // Insert return address clobber
            const unsigned MovOpc = Is64Bit ? X86::MOV64mr : X86::MOV32mr;
            const Register SPReg = Is64Bit ? X86::RSP : X86::ESP;
            addRegOffset(BuildMI(CallTarget, DebugLoc(), TII->get(MovOpc)), SPReg, false,
                         0)
                .addReg(ThunkReg);
          
          
  CallTarget->back().setPreInstrSymbol(MF, TargetSym);
            BuildMI(CallTarget, DebugLoc(), TII->get(RetOpc));
          }
          
          
FunctionPass *llvm::createX86IndirectThunksPass() {
            return new X86IndirectThunks();
          }
          
          
char X86IndirectThunks::ID = 0;
          
          
bool X86IndirectThunks::doInitialization(Module &M) {

salsouaf · October 13, 2022, 9:59am

Thank you so much for your quick reply I’ll take a look !!

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Using BuildMI to build X86_64 instructions

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