Reid Kleckner
821afb2ed8
Tracking issue: https://github.com/llvm/llvm-project/issues/201242 Migration guide docs: https://llvm.org/docs/SphinxQuickstartTemplate.html#markdown-migration-guidelines RFC: https://discourse.llvm.org/t/rfc-make-myst-markdown-the-llvm-docs-format-rip-rest/90840 This was prepared with rst2myst plus LLM-assisted cleanup. I paged through all the generated HTML looking for migration artifacts, and all of the differences I could find appear to be formatting error corrections. Please spot check my work and approve if it looks good.
2.3 KiB
(getting_started)=
Getting Started
This guide provides a single, robust path for new users and contributors to
build, test, and verify LLVM-libc. We use the runtimes build (see
{ref}build_concepts for more information) because it is faster and sufficient
for most development tasks.
1. Install Dependencies
To build LLVM-libc, you will need a recent version of Clang (v15+) and basic
build tools. On a Debian/Ubuntu-based system, you can install these using
apt-get:
sudo apt-get update
sudo apt-get install git cmake ninja-build clang gcc-multilib
2. Clone and Configure
The following command clones the complete LLVM project and configures the
build for LLVM-libc. We include compiler-rt to enable the Scudo memory
allocator.
git clone --depth=1 https://github.com/llvm/llvm-project.git
cd llvm-project
cmake -G Ninja -S runtimes -B build \
-DLLVM_ENABLE_RUNTIMES="libc;compiler-rt" \
-DLLVM_LIBC_FULL_BUILD=ON \
-DCMAKE_BUILD_TYPE=Debug \
-DCMAKE_C_COMPILER=clang \
-DCMAKE_CXX_COMPILER=clang++ \
-DLLVM_LIBC_INCLUDE_SCUDO=ON \
-DCOMPILER_RT_BUILD_SCUDO_STANDALONE_WITH_LLVM_LIBC=ON \
-DCOMPILER_RT_BUILD_GWP_ASAN=OFF \
-DCOMPILER_RT_SCUDO_STANDALONE_BUILD_SHARED=OFF \
-DCMAKE_EXPORT_COMPILE_COMMANDS=ON
3. Build and Test
After configuring, you can build the library, the math library (libm), and run all unit tests:
ninja -C build libc libm check-libc
To run a specific test, such as isalpha in ctype.h:
ninja -C build libc.test.src.ctype.isalpha_test.__unit__
4. Verify with Hello World
To verify your build, create a simple hello.c file:
#include <stdio.h>
int main() {
printf("Hello world from LLVM-libc!\n");
return 0;
}
Compile it using the build artifacts:
clang -nostdinc -nostdlib hello.c -o hello \
-I build/libc/include \
-I $(clang -print-resource-dir)/include \
build/libc/startup/linux/crt1.o \
build/libc/lib/libc.a \
build/libc/lib/libm.a
Finally, run the executable:
./hello
# Output: Hello world from LLVM-libc!
This setup builds LLVM-libc as a standalone library using the
recommended set of flags. From here, you can visit {ref}full_host_build
for advanced sysroot setup, {ref}overlay_mode to learn about using
LLVM-libc to augment your system's C library, or {ref}build_concepts
to understand other build scenarios.