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builder: build static binaries using musl on Linux
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This commit adds support for musl-libc and uses it by default on Linux.
The main benefit of it is that binaries are always statically linked
instead of depending on the host libc, even when using CGo.

Advantages:
  - The resulting binaries are always statically linked.
  - No need for any tools on the host OS, like a compiler, linker, or
    libc in a release build of TinyGo.
  - This also simplifies cross compilation as no cross compiler is
    needed (it's all built into the TinyGo release build).

Disadvantages:
  - Binary size increases by 5-6 kilobytes if -no-debug is used. Binary
    size increases by a much larger margin when debugging symbols are
    included (the default behavior) because musl is built with debugging
    symbols enabled.
  - Musl does things a bit differently than glibc, and some CGo code
    might rely on the glibc behavior.
  - The first build takes a bit longer because musl needs to be built.

As an additional bonus, time is now obtained from the system in a way
that fixes the Y2038 problem because musl has been a bit more agressive
in switching to 64-bit time_t.
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@aykevl
aykevl committed Oct 27, 2021
1 parent 9a55757 commit c8af12e
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Showing 12 changed files with 314 additions and 63 deletions.
19 changes: 3 additions & 16 deletions .circleci/config.yml
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Expand Up @@ -17,18 +17,15 @@ commands:
echo 'deb https://apt.llvm.org/buster/ llvm-toolchain-buster-<<parameters.llvm>> main' | sudo tee /etc/apt/sources.list.d/llvm.list
wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
sudo apt-get update
sudo apt-get install \
sudo apt-get install --no-install-recommends \
llvm-<<parameters.llvm>>-dev \
clang-<<parameters.llvm>> \
libclang-<<parameters.llvm>>-dev \
lld-<<parameters.llvm>> \
gcc-arm-linux-gnueabihf \
gcc-aarch64-linux-gnu \
qemu-system-arm \
qemu-user \
gcc-avr \
avr-libc
sudo apt-get install --no-install-recommends libc6-dev-i386 lib32gcc-8-dev
install-node:
steps:
- run:
Expand Down Expand Up @@ -136,17 +133,12 @@ commands:
name: "Install apt dependencies"
command: |
sudo apt-get update
sudo apt-get install \
sudo apt-get install --no-install-recommends \
libgnutls30 libssl1.0.2 \
gcc-arm-linux-gnueabihf \
libc6-dev-armel-cross \
gcc-aarch64-linux-gnu \
libc6-dev-arm64-cross \
qemu-system-arm \
qemu-user \
gcc-avr \
avr-libc
sudo apt-get install --no-install-recommends libc6-dev-i386 lib32gcc-6-dev
- install-node
- install-wasmtime
- install-xtensa-toolchain:
Expand Down Expand Up @@ -205,17 +197,12 @@ commands:
name: "Install apt dependencies"
command: |
sudo apt-get update
sudo apt-get install \
sudo apt-get install --no-install-recommends \
libgnutls30 libssl1.0.2 \
gcc-arm-linux-gnueabihf \
libc6-dev-armel-cross \
gcc-aarch64-linux-gnu \
libc6-dev-arm64-cross \
qemu-system-arm \
qemu-user \
gcc-avr \
avr-libc
sudo apt-get install --no-install-recommends libc6-dev-i386 lib32gcc-6-dev
- install-node
- install-wasmtime
- install-xtensa-toolchain:
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3 changes: 3 additions & 0 deletions .gitmodules
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Expand Up @@ -23,3 +23,6 @@
[submodule "lib/stm32-svd"]
path = lib/stm32-svd
url = https://github.com/tinygo-org/stm32-svd
[submodule "lib/musl"]
path = lib/musl
url = git://git.musl-libc.org/musl
25 changes: 25 additions & 0 deletions Makefile
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Expand Up @@ -465,6 +465,7 @@ endif
@$(MD5SUM) test.nro
$(TINYGO) build -size short -o test.hex -target=pca10040 -opt=0 ./testdata/stdlib.go
@$(MD5SUM) test.hex
GOOS=linux GOARCH=arm $(TINYGO) build -size short -o test.elf ./testdata/cgo
ifneq ($(OS),Windows_NT)
$(TINYGO) build -o test.elf -gc=leaking -scheduler=none examples/serial
endif
Expand All @@ -478,6 +479,9 @@ build/release: tinygo gen-device wasi-libc
@mkdir -p build/release/tinygo/lib/clang/include
@mkdir -p build/release/tinygo/lib/CMSIS/CMSIS
@mkdir -p build/release/tinygo/lib/compiler-rt/lib
@mkdir -p build/release/tinygo/lib/musl/arch
@mkdir -p build/release/tinygo/lib/musl/crt
@mkdir -p build/release/tinygo/lib/musl/src
@mkdir -p build/release/tinygo/lib/nrfx
@mkdir -p build/release/tinygo/lib/picolibc/newlib/libc
@mkdir -p build/release/tinygo/lib/picolibc/newlib/libm
Expand All @@ -493,6 +497,27 @@ build/release: tinygo gen-device wasi-libc
@cp -rp lib/compiler-rt/lib/builtins build/release/tinygo/lib/compiler-rt/lib
@cp -rp lib/compiler-rt/LICENSE.TXT build/release/tinygo/lib/compiler-rt
@cp -rp lib/compiler-rt/README.txt build/release/tinygo/lib/compiler-rt
@cp -rp lib/musl/arch/aarch64 build/release/tinygo/lib/musl/arch
@cp -rp lib/musl/arch/arm build/release/tinygo/lib/musl/arch
@cp -rp lib/musl/arch/generic build/release/tinygo/lib/musl/arch
@cp -rp lib/musl/arch/i386 build/release/tinygo/lib/musl/arch
@cp -rp lib/musl/arch/x86_64 build/release/tinygo/lib/musl/arch
@cp -rp lib/musl/crt/crt1.c build/release/tinygo/lib/musl/crt
@cp -rp lib/musl/COPYRIGHT build/release/tinygo/lib/musl
@cp -rp lib/musl/include build/release/tinygo/lib/musl
@cp -rp lib/musl/src/env build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/errno build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/exit build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/include build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/internal build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/malloc build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/mman build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/signal build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/stdio build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/string build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/thread build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/time build/release/tinygo/lib/musl/src
@cp -rp lib/musl/src/unistd build/release/tinygo/lib/musl/src
@cp -rp lib/nrfx/* build/release/tinygo/lib/nrfx
@cp -rp lib/picolibc/newlib/libc/ctype build/release/tinygo/lib/picolibc/newlib/libc
@cp -rp lib/picolibc/newlib/libc/include build/release/tinygo/lib/picolibc/newlib/libc
Expand Down
12 changes: 11 additions & 1 deletion builder/build.go
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Expand Up @@ -92,6 +92,13 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
root := goenv.Get("TINYGOROOT")
var libcDependencies []*compileJob
switch config.Target.Libc {
case "musl":
job, err := Musl.load(config, dir)
if err != nil {
return err
}
libcDependencies = append(libcDependencies, dummyCompileJob(filepath.Join(filepath.Dir(job.result), "crt1.o")))
libcDependencies = append(libcDependencies, job)
case "picolibc":
libcJob, err := Picolibc.load(config, dir)
if err != nil {
Expand Down Expand Up @@ -586,12 +593,15 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
// while we're at it. Relocations can only be compressed when debug
// information is stripped.
ldflags = append(ldflags, "--strip-debug", "--compress-relocations")
} else if config.Target.Linker == "ld.lld" {
// ld.lld is also used on Linux.
ldflags = append(ldflags, "--strip-debug")
} else {
switch config.GOOS() {
case "linux":
// Either real linux or an embedded system (like AVR) that
// pretends to be Linux. It's a ELF linker wrapped by GCC in any
// case.
// case (not ld.lld - that case is handled above).
ldflags = append(ldflags, "-Wl,--strip-debug")
case "darwin":
// MacOS (darwin) doesn't have a linker flag to strip debug
Expand Down
4 changes: 2 additions & 2 deletions builder/builtins.go
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Original file line number Diff line number Diff line change
Expand Up @@ -158,11 +158,11 @@ var aeabiBuiltins = []string{
// For more information, see: https://compiler-rt.llvm.org/
var CompilerRT = Library{
name: "compiler-rt",
cflags: func(headerPath string) []string {
cflags: func(target, headerPath string) []string {
return []string{"-Werror", "-Wall", "-std=c11", "-nostdlibinc"}
},
sourceDir: "lib/compiler-rt/lib/builtins",
sources: func(target string) []string {
librarySources: func(target string) []string {
builtins := append([]string{}, genericBuiltins...) // copy genericBuiltins
if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {
builtins = append(builtins, aeabiBuiltins...)
Expand Down
69 changes: 45 additions & 24 deletions builder/library.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,31 +17,19 @@ type Library struct {
name string

// makeHeaders creates a header include dir for the library
makeHeaders func(includeDir string) error
makeHeaders func(target, includeDir string) error

// cflags returns the C flags specific to this library
cflags func(headerPath string) []string
cflags func(target, headerPath string) []string

// The source directory, relative to TINYGOROOT.
sourceDir string

// The source files, relative to sourceDir.
sources func(target string) []string
}

// fullPath returns the full path to the source directory.
func (l *Library) fullPath() string {
return filepath.Join(goenv.Get("TINYGOROOT"), l.sourceDir)
}
librarySources func(target string) []string

// sourcePaths returns a slice with the full paths to the source files.
func (l *Library) sourcePaths(target string) []string {
sources := l.sources(target)
paths := make([]string, len(sources))
for i, name := range sources {
paths[i] = filepath.Join(l.fullPath(), name)
}
return paths
// The source code for the crt1.o file, relative to sourceDir.
crt1Source string
}

// Load the library archive, possibly generating and caching it if needed.
Expand Down Expand Up @@ -90,14 +78,15 @@ func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJ

// Make headers if needed.
headerPath := filepath.Join(outdir, "include")
target := config.Triple()
if l.makeHeaders != nil {
if _, err = os.Stat(headerPath); err != nil {
temporaryHeaderPath, err := ioutil.TempDir(outdir, "include.tmp*")
if err != nil {
return nil, err
}
defer os.RemoveAll(temporaryHeaderPath)
err = l.makeHeaders(temporaryHeaderPath)
err = l.makeHeaders(target, temporaryHeaderPath)
if err != nil {
return nil, err
}
Expand All @@ -119,11 +108,16 @@ func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJ
// Note: -fdebug-prefix-map is necessary to make the output archive
// reproducible. Otherwise the temporary directory is stored in the archive
// itself, which varies each run.
target := config.Triple()
args := append(l.cflags(headerPath), "-c", "-Oz", "-g", "-ffunction-sections", "-fdata-sections", "-Wno-macro-redefined", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir)
args := append(l.cflags(target, headerPath), "-c", "-Oz", "-g", "-ffunction-sections", "-fdata-sections", "-Wno-macro-redefined", "--target="+target, "-fdebug-prefix-map="+dir+"="+remapDir)
cpu := config.CPU()
if cpu != "" {
args = append(args, "-mcpu="+cpu)
// X86 has deprecated the -mcpu flag, so we need to use -march instead.
// However, ARM has not done this.
if strings.HasPrefix(target, "i386") || strings.HasPrefix(target, "x86_64") {
args = append(args, "-march="+cpu)
} else {
args = append(args, "-mcpu="+cpu)
}
}
if strings.HasPrefix(target, "arm") || strings.HasPrefix(target, "thumb") {
args = append(args, "-fshort-enums", "-fomit-frame-pointer", "-mfloat-abi=soft")
Expand Down Expand Up @@ -162,9 +156,10 @@ func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJ

// Create jobs to compile all sources. These jobs are depended upon by the
// archive job above, so must be run first.
for _, srcpath := range l.sourcePaths(target) {
srcpath := srcpath // avoid concurrency issues by redefining inside the loop
objpath := filepath.Join(dir, filepath.Base(srcpath)+".o")
for _, path := range l.librarySources(target) {
srcpath := filepath.Join(goenv.Get("TINYGOROOT"), l.sourceDir, path)
objpath := filepath.Join(dir, path+".o")
os.MkdirAll(filepath.Dir(objpath), 0o777)
objs = append(objs, objpath)
job.dependencies = append(job.dependencies, &compileJob{
description: "compile " + srcpath,
Expand All @@ -181,5 +176,31 @@ func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJ
})
}

// Create crt1.o job, if needed.
// Add this as a (fake) dependency to the ar file so it gets compiled.
// (It could be done in parallel with creating the ar file, but it probably
// won't make much of a difference in speed).
if l.crt1Source != "" {
srcpath := filepath.Join(goenv.Get("TINYGOROOT"), l.sourceDir, l.crt1Source)
job.dependencies = append(job.dependencies, &compileJob{
description: "compile " + srcpath,
run: func(*compileJob) error {
var compileArgs []string
compileArgs = append(compileArgs, args...)
tmpfile, err := ioutil.TempFile(outdir, "crt1.o.tmp*")
if err != nil {
return err
}
tmpfile.Close()
compileArgs = append(compileArgs, "-o", tmpfile.Name(), srcpath)
err = runCCompiler(compileArgs...)
if err != nil {
return &commandError{"failed to build", srcpath, err}
}
return os.Rename(tmpfile.Name(), filepath.Join(outdir, "crt1.o"))
},
})
}

return job, nil
}
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