Compiler Option Gen

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Compiler Option: -gen

Sets the backend code emitter.

Syntax

-gen < backend >

Parameters

backend

gas for x86 GAS assembly, gcc for GNU C, gas64 for x86_64 GAS assembly, clang for clang, llvm for LLVM IR.

Description

The -gen compiler option sets the backend code emitter and assembler. If this option is not specified, the default is -gen gas for x86 and -gen gcc for x86_64.

-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 the compiler's original x86 code generation backend.

-gen gas64

The compiler will emit GAS assembler code (64-bit) to a .asm file which will then be compiled to an object file using 'as'.

-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 the compiler can invoke it to compile the C code, also see Installing gcc for -gen gcc.

-gen clang

The compiler will emit C code to a .c file which will then be compiled to an .asm file using 'clang' as a high level assembler.

-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

• Using the Command Line

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