llvm-g++

Obsolete G++-based C++ front-end for LLVM, superseded by clang++

TLDR

Compile C++ program

$ llvm-g++ -o [program] [source.cpp]

Compile with optimization

$ llvm-g++ -O2 -o [program] [source.cpp]

Generate LLVM bitcode

$ llvm-g++ -emit-llvm -c [source.cpp] -o [source.bc]

Generate human-readable LLVM assembly

$ llvm-g++ -emit-llvm -S [source.cpp] -o [source.ll]

Modern equivalent using clang++

$ clang++ -std=c++20 -O2 -o [program] [source.cpp]

llvm-g++ was the LLVM C++ front-end: a modified version of g++ from GCC 4.2 that compiled C++ and Objective-C++ into native code, LLVM bitcode or LLVM assembly. By default it produced native objects like g++; with -emit-llvm it wrote LLVM IR instead. It accepted most g++ options and extensions.

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.

-std= standard

C++ standard version (at most c++98 / gnu++98 and partial c++0x, as in GCC 4.2).

-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, with no support for modern C++ standards. It is not part of any current LLVM release, and on macOS any remaining llvm-g++ name is just an alias for clang++. Use clang++ instead.

HISTORY

llvm-g++ shipped alongside llvm-gcc as part of the original LLVM GCC-based front-end. Apple bundled it in Xcode 4. It was deprecated after LLVM 2.9 (2011) in favor of clang++ and removed from Xcode in version 5 (2013).

RESOURCES

Homepage · Documentation