LLVM: gccld tool


NAME

gccld

SYNOPSIS

gccld [options] < filename> [ filename ...]

DESCRIPTION

The gccld utility takes a set of LLVM bytecode files and links them together into a single LLVM bytecode file. The output bytecode file can be another bytecode library or an executable bytecode program. Using additional options, gccld is able to produce native code executables.

The gccld utility is primarily used by the C and C++ front-ends, and as such, attempts to mimic the interface provided by the default system linker so that it can act as a "drop-in" replacement.

The gccld tool performs a small set of interprocedural, post-link, optimizations on the program.

Search Order

When looking for objects specified on the command line, gccld will search for the object first in the current directory and then in the directory specified by the LLVM_LIB_SEARCH_PATH environment variable. If it cannot find the object, it fails.

When looking for a library specified with the -l option, gccld first attempts to load a file with that name from the current directory. If that fails, it looks for lib<library>.bc, lib<library>.a, or lib<library>.<shared library extension>, in that order, in each directory added to the library search path with the -L option. These directories are searched in the order they were specified. If the library cannot be located, then gccld looks in the directory specified by the LLVM_LIB_SEARCH_PATH environment variable. If it does not find a library there, it fails.

The shared library extension is usually .so, but it may differ depending upon the system.

The -L option is global. It does not matter where it is specified in the list of command line arguments; the directory is simply added to the search path and is applied to all libraries, preceding or succeeding, in the command line.

Link order

All object files are linked first in the order they were specified on the command line. All library files are linked next. Some libraries may not be linked into the object program; see below.

Library Linkage

Object files and static bytecode objects are always linked into the output file. Library archives (.a files) load only the objects within the archive that define symbols needed by the output file. Hence, libraries should be listed after the object files and libraries which need them; otherwise, the library may not be linked in, and the dependent library will not have its undefined symbols defined.

Native code generation

The gccld program has limited support for native code generation, when using the -native option.

OPTIONS

EXIT STATUS

If gccld succeeds, it will exit with 0. Otherwise, if an error occurs, it will exit with a non-zero value.

SEE ALSO

llvm-link gccas

BUGS

The -L option cannot be used for find native code libraries when using the -native option.
Maintained by the LLVM Team.