llvm-gcc

Obsolete GCC-based C front-end for LLVM, superseded by clang

TLDR

Compile C program

$ llvm-gcc -o [program] [source.c]

Compile with optimization

$ llvm-gcc -O2 -o [program] [source.c]

Generate LLVM bitcode

$ llvm-gcc -emit-llvm -c [source.c] -o [source.bc]

Generate human-readable LLVM assembly

$ llvm-gcc -emit-llvm -S [source.c] -o [source.ll]

Modern equivalent using clang

$ clang -emit-llvm -c [source.c] -o [source.bc]

llvm-gcc was the LLVM C front-end: a modified version of GCC 4.2 whose parser fed LLVM's optimizer and code generator. By default it produced native object files like GCC; with -emit-llvm it wrote LLVM bitcode or LLVM assembly for use with tools such as opt, llc and lli. Since it was derived from GCC it accepted most GCC options and extensions, and also compiled Objective-C.

PARAMETERS

-o file

Output file name.

-O level

Optimization level (0-3, s).

-emit-llvm

Emit LLVM bitcode (with -c) or LLVM assembly (with -S) instead of native code.

-c

Compile only, no linking.

-S

Generate assembly output.

-I directory

Add a directory to the header search path.

-L directory

Add a directory to the library search path.

-lname

Link with library name.

-g

Include debug information.

--help

Print a summary of command line options.

CAVEATS

Obsolete and unmaintained. It is not part of any current LLVM release or distribution, and on macOS any remaining llvm-gcc name is just an alias for clang. Use clang instead.

HISTORY

llvm-gcc was the original front-end of the LLVM project, based on GCC 4.0 and later GCC 4.2. Apple shipped llvm-gcc-4.2 as a default compiler in Xcode 4. It was deprecated after LLVM 2.9 (2011), replaced by clang and the short-lived DragonEgg GCC plugin, and removed from Xcode in version 5 (2013).

RESOURCES

Homepage · Documentation