Compiler Option: -gen
Sets the backend code emitter.
Syntax
`
-gen < backend >
`
Parameters
`backend`
`gas` for x86 GAS assembly, `gcc` for GNU C, `llvm` for LLVM IR.
Description
The `-gen` compiler option sets the backend code emitter and assembler.
-gen gas
The compiler will emit GAS assembler code to a `.asm` file which will then be compiled to an object file using '`as`'. This is fbc's original x86 code generation backend.
-gen gcc
The compiler will emit C code to a `.c` file which will then be compiled to an .asm file using '`gcc`' as a high level assembler. The C backend is intended to make FB portable to more platforms than just x86. This requires gcc to be installed so that fbc can invoke it to compile the C code, also see Installing gcc for -gen gcc.
-gen llvm
The compiler will emit LLVM IR code to a `.ll` file which will then be compiled to an .asm file using '`llc`'. The LLVM backend is still a work in progress. It is intended for the same purpose as the C backend, and could theoretically solve some of the C backend's problems, such as debugging meta data support.
See also

- Tools used by fbc
- Using the Command Line