diff options
Diffstat (limited to 'llvm/docs/CodeGenerator.rst')
| -rw-r--r-- | llvm/docs/CodeGenerator.rst | 27 |
1 files changed, 11 insertions, 16 deletions
diff --git a/llvm/docs/CodeGenerator.rst b/llvm/docs/CodeGenerator.rst index fc537a7f6c0..6a54343dfba 100644 --- a/llvm/docs/CodeGenerator.rst +++ b/llvm/docs/CodeGenerator.rst @@ -386,32 +386,27 @@ functions make it easy to build arbitrary machine instructions. Usage of the .. code-block:: c++ // Create a 'DestReg = mov 42' (rendered in X86 assembly as 'mov DestReg, 42') - // instruction. The '1' specifies how many operands will be added. - MachineInstr *MI = BuildMI(X86::MOV32ri, 1, DestReg).addImm(42); - - // Create the same instr, but insert it at the end of a basic block. + // instruction and insert it at the end of the given MachineBasicBlock. + const TargetInstrInfo &TII = ... MachineBasicBlock &MBB = ... - BuildMI(MBB, X86::MOV32ri, 1, DestReg).addImm(42); + DebugLoc DL; + MachineInstr *MI = BuildMI(MBB, DL, TII.get(X86::MOV32ri), DestReg).addImm(42); // Create the same instr, but insert it before a specified iterator point. MachineBasicBlock::iterator MBBI = ... - BuildMI(MBB, MBBI, X86::MOV32ri, 1, DestReg).addImm(42); + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), DestReg).addImm(42); // Create a 'cmp Reg, 0' instruction, no destination reg. - MI = BuildMI(X86::CMP32ri, 2).addReg(Reg).addImm(0); + MI = BuildMI(MBB, DL, TII.get(X86::CMP32ri8)).addReg(Reg).addImm(42); // Create an 'sahf' instruction which takes no operands and stores nothing. - MI = BuildMI(X86::SAHF, 0); + MI = BuildMI(MBB, DL, TII.get(X86::SAHF)); // Create a self looping branch instruction. - BuildMI(MBB, X86::JNE, 1).addMBB(&MBB); - -The key thing to remember with the ``BuildMI`` functions is that you have to -specify the number of operands that the machine instruction will take. This -allows for efficient memory allocation. You also need to specify if operands -default to be uses of values, not definitions. If you need to add a definition -operand (other than the optional destination register), you must explicitly mark -it as such: + BuildMI(MBB, DL, TII.get(X86::JNE)).addMBB(&MBB); + +If you need to add a definition operand (other than the optional destination +register), you must explicitly mark it as such: .. code-block:: c++ |
