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|
// Package builder is the compiler driver of TinyGo. It takes in a package name
// and an output path, and outputs an executable. It manages the entire
// compilation pipeline in between.
package builder
import (
"crypto/sha512"
"debug/elf"
"encoding/binary"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"go/types"
"hash/crc32"
"io/ioutil"
"math/bits"
"os"
"path/filepath"
"runtime"
"sort"
"strings"
"github.com/tinygo-org/tinygo/compileopts"
"github.com/tinygo-org/tinygo/compiler"
"github.com/tinygo-org/tinygo/goenv"
"github.com/tinygo-org/tinygo/interp"
"github.com/tinygo-org/tinygo/loader"
"github.com/tinygo-org/tinygo/stacksize"
"github.com/tinygo-org/tinygo/transform"
"tinygo.org/x/go-llvm"
)
// BuildResult is the output of a build. This includes the binary itself and
// some other metadata that is obtained while building the binary.
type BuildResult struct {
// A path to the output binary. It will be removed after Build returns, so
// if it should be kept it must be copied or moved away.
Binary string
// The directory of the main package. This is useful for testing as the test
// binary must be run in the directory of the tested package.
MainDir string
// ImportPath is the import path of the main package. This is useful for
// correctly printing test results: the import path isn't always the same as
// the path listed on the command line.
ImportPath string
}
// packageAction is the struct that is serialized to JSON and hashed, to work as
// a cache key of compiled packages. It should contain all the information that
// goes into a compiled package to avoid using stale data.
//
// Right now it's still important to include a hash of every import, because a
// dependency might have a public constant that this package uses and thus this
// package will need to be recompiled if that constant changes. In the future,
// the type data should be serialized to disk which can then be used as cache
// key, avoiding the need for recompiling all dependencies when only the
// implementation of an imported package changes.
type packageAction struct {
ImportPath string
CompilerVersion int // compiler.Version
InterpVersion int // interp.Version
LLVMVersion string
Config *compiler.Config
CFlags []string
FileHashes map[string]string // hash of every file that's part of the package
Imports map[string]string // map from imported package to action ID hash
OptLevel int // LLVM optimization level (0-3)
SizeLevel int // LLVM optimization for size level (0-2)
UndefinedGlobals []string // globals that are left as external globals (no initializer)
}
// Build performs a single package to executable Go build. It takes in a package
// name, an output path, and set of compile options and from that it manages the
// whole compilation process.
//
// The error value may be of type *MultiError. Callers will likely want to check
// for this case and print such errors individually.
func Build(pkgName, outpath string, config *compileopts.Config, action func(BuildResult) error) error {
// Create a temporary directory for intermediary files.
dir, err := ioutil.TempDir("", "tinygo")
if err != nil {
return err
}
defer os.RemoveAll(dir)
compilerConfig := &compiler.Config{
Triple: config.Triple(),
CPU: config.CPU(),
Features: config.Features(),
GOOS: config.GOOS(),
GOARCH: config.GOARCH(),
CodeModel: config.CodeModel(),
RelocationModel: config.RelocationModel(),
Scheduler: config.Scheduler(),
FuncImplementation: config.FuncImplementation(),
AutomaticStackSize: config.AutomaticStackSize(),
DefaultStackSize: config.Target.DefaultStackSize,
NeedsStackObjects: config.NeedsStackObjects(),
Debug: true,
LLVMFeatures: config.LLVMFeatures(),
}
// Load the target machine, which is the LLVM object that contains all
// details of a target (alignment restrictions, pointer size, default
// address spaces, etc).
machine, err := compiler.NewTargetMachine(compilerConfig)
if err != nil {
return err
}
// Load entire program AST into memory.
lprogram, err := loader.Load(config, []string{pkgName}, config.ClangHeaders, types.Config{
Sizes: compiler.Sizes(machine),
})
if err != nil {
return err
}
err = lprogram.Parse()
if err != nil {
return err
}
// Create the *ssa.Program. This does not yet build the entire SSA of the
// program so it's pretty fast and doesn't need to be parallelized.
program := lprogram.LoadSSA()
// Add jobs to compile each package.
// Packages that have a cache hit will not be compiled again.
var packageJobs []*compileJob
packageBitcodePaths := make(map[string]string)
packageActionIDs := make(map[string]string)
optLevel, sizeLevel, _ := config.OptLevels()
for _, pkg := range lprogram.Sorted() {
pkg := pkg // necessary to avoid a race condition
var undefinedGlobals []string
for name := range config.Options.GlobalValues[pkg.Pkg.Path()] {
undefinedGlobals = append(undefinedGlobals, name)
}
sort.Strings(undefinedGlobals)
// Create a cache key: a hash from the action ID below that contains all
// the parameters for the build.
actionID := packageAction{
ImportPath: pkg.ImportPath,
CompilerVersion: compiler.Version,
InterpVersion: interp.Version,
LLVMVersion: llvm.Version,
Config: compilerConfig,
CFlags: pkg.CFlags,
FileHashes: make(map[string]string, len(pkg.FileHashes)),
Imports: make(map[string]string, len(pkg.Pkg.Imports())),
OptLevel: optLevel,
SizeLevel: sizeLevel,
UndefinedGlobals: undefinedGlobals,
}
for filePath, hash := range pkg.FileHashes {
actionID.FileHashes[filePath] = hex.EncodeToString(hash)
}
for _, imported := range pkg.Pkg.Imports() {
hash, ok := packageActionIDs[imported.Path()]
if !ok {
return fmt.Errorf("package %s imports %s but couldn't find dependency", pkg.ImportPath, imported.Path())
}
actionID.Imports[imported.Path()] = hash
}
buf, err := json.Marshal(actionID)
if err != nil {
panic(err) // shouldn't happen
}
hash := sha512.Sum512_224(buf)
packageActionIDs[pkg.ImportPath] = hex.EncodeToString(hash[:])
// Determine the path of the bitcode file (which is a serialized version
// of a LLVM module).
cacheDir := goenv.Get("GOCACHE")
if cacheDir == "off" {
// Use temporary build directory instead, effectively disabling the
// build cache.
cacheDir = dir
}
bitcodePath := filepath.Join(cacheDir, "pkg-"+hex.EncodeToString(hash[:])+".bc")
packageBitcodePaths[pkg.ImportPath] = bitcodePath
// Check whether this package has been compiled before, and if so don't
// compile it again.
if _, err := os.Stat(bitcodePath); err == nil {
// Already cached, don't recreate this package.
continue
}
// The package has not yet been compiled, so create a job to do so.
job := &compileJob{
description: "compile package " + pkg.ImportPath,
run: func(*compileJob) error {
// Compile AST to IR. The compiler.CompilePackage function will
// build the SSA as needed.
mod, errs := compiler.CompilePackage(pkg.ImportPath, pkg, program.Package(pkg.Pkg), machine, compilerConfig, config.DumpSSA())
if errs != nil {
return newMultiError(errs)
}
if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
return errors.New("verification error after compiling package " + pkg.ImportPath)
}
// Erase all globals that are part of the undefinedGlobals list.
// This list comes from the -ldflags="-X pkg.foo=val" option.
// Instead of setting the value directly in the AST (which would
// mean the value, which may be a secret, is stored in the build
// cache), the global itself is left external (undefined) and is
// only set at the end of the compilation.
for _, name := range undefinedGlobals {
globalName := pkg.Pkg.Path() + "." + name
global := mod.NamedGlobal(globalName)
if global.IsNil() {
return errors.New("global not found: " + globalName)
}
name := global.Name()
newGlobal := llvm.AddGlobal(mod, global.Type().ElementType(), name+".tmp")
global.ReplaceAllUsesWith(newGlobal)
global.EraseFromParentAsGlobal()
newGlobal.SetName(name)
}
// Try to interpret package initializers at compile time.
// It may only be possible to do this partially, in which case
// it is completed after all IR files are linked.
pkgInit := mod.NamedFunction(pkg.Pkg.Path() + ".init")
if pkgInit.IsNil() {
panic("init not found for " + pkg.Pkg.Path())
}
err := interp.RunFunc(pkgInit, config.DumpSSA())
if err != nil {
return err
}
if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
return errors.New("verification error after interpreting " + pkgInit.Name())
}
if sizeLevel >= 2 {
// Set the "optsize" attribute to make slightly smaller
// binaries at the cost of some performance.
kind := llvm.AttributeKindID("optsize")
attr := mod.Context().CreateEnumAttribute(kind, 0)
for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
fn.AddFunctionAttr(attr)
}
}
// Run function passes for each function in the module.
// These passes are intended to be run on each function right
// after they're created to reduce IR size (and maybe also for
// cache locality to improve performance), but for now they're
// run here for each function in turn. Maybe this can be
// improved in the future.
builder := llvm.NewPassManagerBuilder()
defer builder.Dispose()
builder.SetOptLevel(optLevel)
builder.SetSizeLevel(sizeLevel)
funcPasses := llvm.NewFunctionPassManagerForModule(mod)
defer funcPasses.Dispose()
builder.PopulateFunc(funcPasses)
funcPasses.InitializeFunc()
for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
if fn.IsDeclaration() {
continue
}
funcPasses.RunFunc(fn)
}
funcPasses.FinalizeFunc()
// Serialize the LLVM module as a bitcode file.
// Write to a temporary path that is renamed to the destination
// file to avoid race conditions with other TinyGo invocatiosn
// that might also be compiling this package at the same time.
f, err := ioutil.TempFile(filepath.Dir(bitcodePath), filepath.Base(bitcodePath))
if err != nil {
return err
}
if runtime.GOOS == "windows" {
// Work around a problem on Windows.
// For some reason, WriteBitcodeToFile causes TinyGo to
// exit with the following message:
// LLVM ERROR: IO failure on output stream: Bad file descriptor
buf := llvm.WriteBitcodeToMemoryBuffer(mod)
defer buf.Dispose()
_, err = f.Write(buf.Bytes())
} else {
// Otherwise, write bitcode directly to the file (probably
// faster).
err = llvm.WriteBitcodeToFile(mod, f)
}
if err != nil {
// WriteBitcodeToFile doesn't produce a useful error on its
// own, so create a somewhat useful error message here.
return fmt.Errorf("failed to write bitcode for package %s to file %s", pkg.ImportPath, bitcodePath)
}
err = f.Close()
if err != nil {
return err
}
return os.Rename(f.Name(), bitcodePath)
},
}
packageJobs = append(packageJobs, job)
}
// Add job that links and optimizes all packages together.
var mod llvm.Module
var stackSizeLoads []string
programJob := &compileJob{
description: "link+optimize packages (LTO)",
dependencies: packageJobs,
run: func(*compileJob) error {
// Load and link all the bitcode files. This does not yet optimize
// anything, it only links the bitcode files together.
ctx := llvm.NewContext()
mod = ctx.NewModule("")
for _, pkg := range lprogram.Sorted() {
pkgMod, err := ctx.ParseBitcodeFile(packageBitcodePaths[pkg.ImportPath])
if err != nil {
return fmt.Errorf("failed to load bitcode file: %w", err)
}
err = llvm.LinkModules(mod, pkgMod)
if err != nil {
return fmt.Errorf("failed to link module: %w", err)
}
}
// Create runtime.initAll function that calls the runtime
// initializer of each package.
llvmInitFn := mod.NamedFunction("runtime.initAll")
llvmInitFn.SetLinkage(llvm.InternalLinkage)
llvmInitFn.SetUnnamedAddr(true)
llvmInitFn.Param(0).SetName("context")
llvmInitFn.Param(1).SetName("parentHandle")
block := mod.Context().AddBasicBlock(llvmInitFn, "entry")
irbuilder := mod.Context().NewBuilder()
defer irbuilder.Dispose()
irbuilder.SetInsertPointAtEnd(block)
i8ptrType := llvm.PointerType(mod.Context().Int8Type(), 0)
for _, pkg := range lprogram.Sorted() {
pkgInit := mod.NamedFunction(pkg.Pkg.Path() + ".init")
if pkgInit.IsNil() {
panic("init not found for " + pkg.Pkg.Path())
}
irbuilder.CreateCall(pkgInit, []llvm.Value{llvm.Undef(i8ptrType), llvm.Undef(i8ptrType)}, "")
}
irbuilder.CreateRetVoid()
// After linking, functions should (as far as possible) be set to
// private linkage or internal linkage. The compiler package marks
// non-exported functions by setting the visibility to hidden or
// (for thunks) to linkonce_odr linkage. Change the linkage here to
// internal to benefit much more from interprocedural optimizations.
for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
if fn.Visibility() == llvm.HiddenVisibility {
fn.SetVisibility(llvm.DefaultVisibility)
fn.SetLinkage(llvm.InternalLinkage)
} else if fn.Linkage() == llvm.LinkOnceODRLinkage {
fn.SetLinkage(llvm.InternalLinkage)
}
}
// Do the same for globals.
for global := mod.FirstGlobal(); !global.IsNil(); global = llvm.NextGlobal(global) {
if global.Visibility() == llvm.HiddenVisibility {
global.SetVisibility(llvm.DefaultVisibility)
global.SetLinkage(llvm.InternalLinkage)
} else if global.Linkage() == llvm.LinkOnceODRLinkage {
global.SetLinkage(llvm.InternalLinkage)
}
}
if config.Options.PrintIR {
fmt.Println("; Generated LLVM IR:")
fmt.Println(mod.String())
}
// Run all optimization passes, which are much more effective now
// that the optimizer can see the whole program at once.
err := optimizeProgram(mod, config)
if err != nil {
return err
}
// Make sure stack sizes are loaded from a separate section so they can be
// modified after linking.
if config.AutomaticStackSize() {
stackSizeLoads = transform.CreateStackSizeLoads(mod, config)
}
return nil
},
}
// Check whether we only need to create an object file.
// If so, we don't need to link anything and will be finished quickly.
outext := filepath.Ext(outpath)
if outext == ".o" || outext == ".bc" || outext == ".ll" {
// Run jobs to produce the LLVM module.
err := runJobs(programJob)
if err != nil {
return err
}
// Generate output.
switch outext {
case ".o":
llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
if err != nil {
return err
}
return ioutil.WriteFile(outpath, llvmBuf.Bytes(), 0666)
case ".bc":
data := llvm.WriteBitcodeToMemoryBuffer(mod).Bytes()
return ioutil.WriteFile(outpath, data, 0666)
case ".ll":
data := []byte(mod.String())
return ioutil.WriteFile(outpath, data, 0666)
default:
panic("unreachable")
}
}
// Act as a compiler driver, as we need to produce a complete executable.
// First add all jobs necessary to build this object file, then afterwards
// run all jobs in parallel as far as possible.
// Add job to write the output object file.
objfile := filepath.Join(dir, "main.o")
outputObjectFileJob := &compileJob{
description: "generate output file",
dependencies: []*compileJob{programJob},
result: objfile,
run: func(*compileJob) error {
llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
if err != nil {
return err
}
return ioutil.WriteFile(objfile, llvmBuf.Bytes(), 0666)
},
}
// Prepare link command.
linkerDependencies := []*compileJob{outputObjectFileJob}
executable := filepath.Join(dir, "main")
tmppath := executable // final file
ldflags := append(config.LDFlags(), "-o", executable)
// Add compiler-rt dependency if needed. Usually this is a simple load from
// a cache.
if config.Target.RTLib == "compiler-rt" {
job, err := CompilerRT.load(config.Triple(), config.CPU(), dir)
if err != nil {
return err
}
linkerDependencies = append(linkerDependencies, job)
}
// Add jobs to compile extra files. These files are in C or assembly and
// contain things like the interrupt vector table and low level operations
// such as stack switching.
root := goenv.Get("TINYGOROOT")
for _, path := range config.ExtraFiles() {
abspath := filepath.Join(root, path)
job := &compileJob{
description: "compile extra file " + path,
run: func(job *compileJob) error {
result, err := compileAndCacheCFile(abspath, dir, config.CFlags(), config.Options.PrintCommands)
job.result = result
return err
},
}
linkerDependencies = append(linkerDependencies, job)
}
// Add jobs to compile C files in all packages. This is part of CGo.
// TODO: do this as part of building the package to be able to link the
// bitcode files together.
for _, pkg := range lprogram.Sorted() {
pkg := pkg
for _, filename := range pkg.CFiles {
abspath := filepath.Join(pkg.Dir, filename)
job := &compileJob{
description: "compile CGo file " + abspath,
run: func(job *compileJob) error {
result, err := compileAndCacheCFile(abspath, dir, pkg.CFlags, config.Options.PrintCommands)
job.result = result
return err
},
}
linkerDependencies = append(linkerDependencies, job)
}
}
// Linker flags from CGo lines:
// #cgo LDFLAGS: foo
if len(lprogram.LDFlags) > 0 {
ldflags = append(ldflags, lprogram.LDFlags...)
}
// Add libc dependency if needed.
switch config.Target.Libc {
case "picolibc":
job, err := Picolibc.load(config.Triple(), config.CPU(), dir)
if err != nil {
return err
}
linkerDependencies = append(linkerDependencies, job)
case "wasi-libc":
path := filepath.Join(root, "lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a")
if _, err := os.Stat(path); os.IsNotExist(err) {
return errors.New("could not find wasi-libc, perhaps you need to run `make wasi-libc`?")
}
job := dummyCompileJob(path)
linkerDependencies = append(linkerDependencies, job)
case "":
// no library specified, so nothing to do
default:
return fmt.Errorf("unknown libc: %s", config.Target.Libc)
}
// Strip debug information with -no-debug.
if !config.Debug() {
for _, tag := range config.BuildTags() {
if tag == "baremetal" {
// Don't use -no-debug on baremetal targets. It makes no sense:
// the debug information isn't flashed to the device anyway.
return fmt.Errorf("stripping debug information is unnecessary for baremetal targets")
}
}
if config.Target.Linker == "wasm-ld" {
// Don't just strip debug information, also compress relocations
// while we're at it. Relocations can only be compressed when debug
// information is stripped.
ldflags = append(ldflags, "--strip-debug", "--compress-relocations")
} 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.
ldflags = append(ldflags, "-Wl,--strip-debug")
case "darwin":
// MacOS (darwin) doesn't have a linker flag to strip debug
// information. Apple expects you to use the strip command
// instead.
return errors.New("cannot remove debug information: MacOS doesn't suppor this linker flag")
default:
// Other OSes may have different flags.
return errors.New("cannot remove debug information: unknown OS: " + config.GOOS())
}
}
}
// Create a linker job, which links all object files together and does some
// extra stuff that can only be done after linking.
linkJob := &compileJob{
description: "link",
dependencies: linkerDependencies,
run: func(job *compileJob) error {
for _, dependency := range job.dependencies {
if dependency.result == "" {
return errors.New("dependency without result: " + dependency.description)
}
ldflags = append(ldflags, dependency.result)
}
if config.Options.PrintCommands != nil {
config.Options.PrintCommands(config.Target.Linker, ldflags...)
}
err = link(config.Target.Linker, ldflags...)
if err != nil {
return &commandError{"failed to link", executable, err}
}
var calculatedStacks []string
var stackSizes map[string]functionStackSize
if config.Options.PrintStacks || config.AutomaticStackSize() {
// Try to determine stack sizes at compile time.
// Don't do this by default as it usually doesn't work on
// unsupported architectures.
calculatedStacks, stackSizes, err = determineStackSizes(mod, executable)
if err != nil {
return err
}
}
// Apply ELF patches
if config.AutomaticStackSize() {
// Modify the .tinygo_stacksizes section that contains a stack size
// for each goroutine.
err = modifyStackSizes(executable, stackSizeLoads, stackSizes)
if err != nil {
return fmt.Errorf("could not modify stack sizes: %w", err)
}
}
if config.RP2040BootPatch() {
// Patch the second stage bootloader CRC into the .boot2 section
err = patchRP2040BootCRC(executable)
if err != nil {
return fmt.Errorf("could not patch RP2040 second stage boot loader: %w", err)
}
}
if config.Options.PrintSizes == "short" || config.Options.PrintSizes == "full" {
sizes, err := loadProgramSize(executable)
if err != nil {
return err
}
if config.Options.PrintSizes == "short" {
fmt.Printf(" code data bss | flash ram\n")
fmt.Printf("%7d %7d %7d | %7d %7d\n", sizes.Code, sizes.Data, sizes.BSS, sizes.Code+sizes.Data, sizes.Data+sizes.BSS)
} else {
fmt.Printf(" code rodata data bss | flash ram | package\n")
for _, name := range sizes.sortedPackageNames() {
pkgSize := sizes.Packages[name]
fmt.Printf("%7d %7d %7d %7d | %7d %7d | %s\n", pkgSize.Code, pkgSize.ROData, pkgSize.Data, pkgSize.BSS, pkgSize.Flash(), pkgSize.RAM(), name)
}
fmt.Printf("%7d %7d %7d %7d | %7d %7d | (sum)\n", sizes.Sum.Code, sizes.Sum.ROData, sizes.Sum.Data, sizes.Sum.BSS, sizes.Sum.Flash(), sizes.Sum.RAM())
fmt.Printf("%7d - %7d %7d | %7d %7d | (all)\n", sizes.Code, sizes.Data, sizes.BSS, sizes.Code+sizes.Data, sizes.Data+sizes.BSS)
}
}
// Print goroutine stack sizes, as far as possible.
if config.Options.PrintStacks {
printStacks(calculatedStacks, stackSizes)
}
return nil
},
}
// Run all jobs to compile and link the program.
// Do this now (instead of after elf-to-hex and similar conversions) as it
// is simpler and cannot be parallelized.
err = runJobs(linkJob)
if err != nil {
return err
}
// Get an Intel .hex file or .bin file from the .elf file.
outputBinaryFormat := config.BinaryFormat(outext)
switch outputBinaryFormat {
case "elf":
// do nothing, file is already in ELF format
case "hex", "bin":
// Extract raw binary, either encoding it as a hex file or as a raw
// firmware file.
tmppath = filepath.Join(dir, "main"+outext)
err := objcopy(executable, tmppath, outputBinaryFormat)
if err != nil {
return err
}
case "uf2":
// Get UF2 from the .elf file.
tmppath = filepath.Join(dir, "main"+outext)
err := convertELFFileToUF2File(executable, tmppath, config.Target.UF2FamilyID)
if err != nil {
return err
}
case "esp32", "esp32c3", "esp8266":
// Special format for the ESP family of chips (parsed by the ROM
// bootloader).
tmppath = filepath.Join(dir, "main"+outext)
err := makeESPFirmareImage(executable, tmppath, outputBinaryFormat)
if err != nil {
return err
}
case "nrf-dfu":
// special format for nrfutil for Nordic chips
tmphexpath := filepath.Join(dir, "main.hex")
err := objcopy(executable, tmphexpath, "hex")
if err != nil {
return err
}
tmppath = filepath.Join(dir, "main"+outext)
err = makeDFUFirmwareImage(config.Options, tmphexpath, tmppath)
if err != nil {
return err
}
default:
return fmt.Errorf("unknown output binary format: %s", outputBinaryFormat)
}
return action(BuildResult{
Binary: tmppath,
MainDir: lprogram.MainPkg().Dir,
ImportPath: lprogram.MainPkg().ImportPath,
})
}
// optimizeProgram runs a series of optimizations and transformations that are
// needed to convert a program to its final form. Some transformations are not
// optional and must be run as the compiler expects them to run.
func optimizeProgram(mod llvm.Module, config *compileopts.Config) error {
err := interp.Run(mod, config.DumpSSA())
if err != nil {
return err
}
if config.VerifyIR() {
// Only verify if we really need it.
// The IR has already been verified before writing the bitcode to disk
// and the interp function above doesn't need to do a lot as most of the
// package initializers have already run. Additionally, verifying this
// linked IR is _expensive_ because dead code hasn't been removed yet,
// easily costing a few hundred milliseconds. Therefore, only do it when
// specifically requested.
if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
return errors.New("verification error after interpreting runtime.initAll")
}
}
if config.GOOS() != "darwin" {
transform.ApplyFunctionSections(mod) // -ffunction-sections
}
// Insert values from -ldflags="-X ..." into the IR.
err = setGlobalValues(mod, config.Options.GlobalValues)
if err != nil {
return err
}
// Browsers cannot handle external functions that have type i64 because it
// cannot be represented exactly in JavaScript (JS only has doubles). To
// keep functions interoperable, pass int64 types as pointers to
// stack-allocated values.
// Use -wasm-abi=generic to disable this behaviour.
if config.WasmAbi() == "js" {
err := transform.ExternalInt64AsPtr(mod)
if err != nil {
return err
}
}
// Optimization levels here are roughly the same as Clang, but probably not
// exactly.
optLevel, sizeLevel, inlinerThreshold := config.OptLevels()
errs := transform.Optimize(mod, config, optLevel, sizeLevel, inlinerThreshold)
if len(errs) > 0 {
return newMultiError(errs)
}
if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
return errors.New("verification failure after LLVM optimization passes")
}
// LLVM 11 by default tries to emit tail calls (even with the target feature
// disabled) unless it is explicitly disabled with a function attribute.
// This is a problem, as it tries to emit them and prints an error when it
// can't with this feature disabled.
// Because as of september 2020 tail calls are not yet widely supported,
// they need to be disabled until they are widely supported (at which point
// the +tail-call target feautre can be set).
if strings.HasPrefix(config.Triple(), "wasm") {
transform.DisableTailCalls(mod)
}
return nil
}
// setGlobalValues sets the global values from the -ldflags="-X ..." compiler
// option in the given module. An error may be returned if the global is not of
// the expected type.
func setGlobalValues(mod llvm.Module, globals map[string]map[string]string) error {
var pkgPaths []string
for pkgPath := range globals {
pkgPaths = append(pkgPaths, pkgPath)
}
sort.Strings(pkgPaths)
for _, pkgPath := range pkgPaths {
pkg := globals[pkgPath]
var names []string
for name := range pkg {
names = append(names, name)
}
sort.Strings(names)
for _, name := range names {
value := pkg[name]
globalName := pkgPath + "." + name
global := mod.NamedGlobal(globalName)
if global.IsNil() || !global.Initializer().IsNil() {
// The global either does not exist (optimized away?) or has
// some value, in which case it has already been initialized at
// package init time.
continue
}
// A strin is a {ptr, len} pair. We need these types to build the
// initializer.
initializerType := global.Type().ElementType()
if initializerType.TypeKind() != llvm.StructTypeKind || initializerType.StructName() == "" {
return fmt.Errorf("%s: not a string", globalName)
}
elementTypes := initializerType.StructElementTypes()
if len(elementTypes) != 2 {
return fmt.Errorf("%s: not a string", globalName)
}
// Create a buffer for the string contents.
bufInitializer := mod.Context().ConstString(value, false)
buf := llvm.AddGlobal(mod, bufInitializer.Type(), ".string")
buf.SetInitializer(bufInitializer)
buf.SetAlignment(1)
buf.SetUnnamedAddr(true)
buf.SetLinkage(llvm.PrivateLinkage)
// Create the string value, which is a {ptr, len} pair.
zero := llvm.ConstInt(mod.Context().Int32Type(), 0, false)
ptr := llvm.ConstGEP(buf, []llvm.Value{zero, zero})
if ptr.Type() != elementTypes[0] {
return fmt.Errorf("%s: not a string", globalName)
}
length := llvm.ConstInt(elementTypes[1], uint64(len(value)), false)
initializer := llvm.ConstNamedStruct(initializerType, []llvm.Value{
ptr,
length,
})
// Set the initializer. No initializer should be set at this point.
global.SetInitializer(initializer)
}
}
return nil
}
// functionStackSizes keeps stack size information about a single function
// (usually a goroutine).
type functionStackSize struct {
humanName string
stackSize uint64
stackSizeType stacksize.SizeType
missingStackSize *stacksize.CallNode
}
// determineStackSizes tries to determine the stack sizes of all started
// goroutines and of the reset vector. The LLVM module is necessary to find
// functions that call a function pointer.
func determineStackSizes(mod llvm.Module, executable string) ([]string, map[string]functionStackSize, error) {
var callsIndirectFunction []string
gowrappers := []string{}
gowrapperNames := make(map[string]string)
for fn := mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
// Determine which functions call a function pointer.
for bb := fn.FirstBasicBlock(); !bb.IsNil(); bb = llvm.NextBasicBlock(bb) {
for inst := bb.FirstInstruction(); !inst.IsNil(); inst = llvm.NextInstruction(inst) {
if inst.IsACallInst().IsNil() {
continue
}
if callee := inst.CalledValue(); callee.IsAFunction().IsNil() && callee.IsAInlineAsm().IsNil() {
callsIndirectFunction = append(callsIndirectFunction, fn.Name())
}
}
}
// Get a list of "go wrappers", small wrapper functions that decode
// parameters when starting a new goroutine.
attr := fn.GetStringAttributeAtIndex(-1, "tinygo-gowrapper")
if !attr.IsNil() {
gowrappers = append(gowrappers, fn.Name())
gowrapperNames[fn.Name()] = attr.GetStringValue()
}
}
sort.Strings(gowrappers)
// Load the ELF binary.
f, err := elf.Open(executable)
if err != nil {
return nil, nil, fmt.Errorf("could not load executable for stack size analysis: %w", err)
}
defer f.Close()
// Determine the frame size of each function (if available) and the callgraph.
functions, err := stacksize.CallGraph(f, callsIndirectFunction)
if err != nil {
return nil, nil, fmt.Errorf("could not parse executable for stack size analysis: %w", err)
}
// Goroutines need to be started and finished and take up some stack space
// that way. This can be measured by measuing the stack size of
// tinygo_startTask.
if numFuncs := len(functions["tinygo_startTask"]); numFuncs != 1 {
return nil, nil, fmt.Errorf("expected exactly one definition of tinygo_startTask, got %d", numFuncs)
}
baseStackSize, baseStackSizeType, baseStackSizeFailedAt := functions["tinygo_startTask"][0].StackSize()
sizes := make(map[string]functionStackSize)
// Add the reset handler function, for convenience. The reset handler runs
// startup code and the scheduler. The listed stack size is not the full
// stack size: interrupts are not counted.
var resetFunction string
switch f.Machine {
case elf.EM_ARM:
// Note: all interrupts happen on this stack so the real size is bigger.
resetFunction = "Reset_Handler"
}
if resetFunction != "" {
funcs := functions[resetFunction]
if len(funcs) != 1 {
return nil, nil, fmt.Errorf("expected exactly one definition of %s in the callgraph, found %d", resetFunction, len(funcs))
}
stackSize, stackSizeType, missingStackSize := funcs[0].StackSize()
sizes[resetFunction] = functionStackSize{
stackSize: stackSize,
stackSizeType: stackSizeType,
missingStackSize: missingStackSize,
humanName: resetFunction,
}
}
// Add all goroutine wrapper functions.
for _, name := range gowrappers {
funcs := functions[name]
if len(funcs) != 1 {
return nil, nil, fmt.Errorf("expected exactly one definition of %s in the callgraph, found %d", name, len(funcs))
}
humanName := gowrapperNames[name]
if humanName == "" {
humanName = name // fallback
}
stackSize, stackSizeType, missingStackSize := funcs[0].StackSize()
if baseStackSizeType != stacksize.Bounded {
// It was not possible to determine the stack size at compile time
// because tinygo_startTask does not have a fixed stack size. This
// can happen when using -opt=1.
stackSizeType = baseStackSizeType
missingStackSize = baseStackSizeFailedAt
} else if stackSize < baseStackSize {
// This goroutine has a very small stack, but still needs to fit all
// registers to start and suspend the goroutine. Otherwise a stack
// overflow will occur even before the goroutine is started.
stackSize = baseStackSize
}
sizes[name] = functionStackSize{
stackSize: stackSize,
stackSizeType: stackSizeType,
missingStackSize: missingStackSize,
humanName: humanName,
}
}
if resetFunction != "" {
return append([]string{resetFunction}, gowrappers...), sizes, nil
}
return gowrappers, sizes, nil
}
// modifyStackSizes modifies the .tinygo_stacksizes section with the updated
// stack size information. Before this modification, all stack sizes in the
// section assume the default stack size (which is relatively big).
func modifyStackSizes(executable string, stackSizeLoads []string, stackSizes map[string]functionStackSize) error {
data, fileHeader, err := getElfSectionData(executable, ".tinygo_stacksizes")
if err != nil {
return err
}
if len(stackSizeLoads)*4 != len(data) {
// Note: while AVR should use 2 byte stack sizes, even 64-bit platforms
// should probably stick to 4 byte stack sizes as a larger than 4GB
// stack doesn't make much sense.
return errors.New("expected 4 byte stack sizes")
}
// Modify goroutine stack sizes with a compile-time known worst case stack
// size.
for i, name := range stackSizeLoads {
fn, ok := stackSizes[name]
if !ok {
return fmt.Errorf("could not find symbol %s in ELF file", name)
}
if fn.stackSizeType == stacksize.Bounded {
stackSize := uint32(fn.stackSize)
// Add stack size used by interrupts.
switch fileHeader.Machine {
case elf.EM_ARM:
if stackSize%8 != 0 {
// If the stack isn't a multiple of 8, it means the leaf
// function with the biggest stack depth doesn't have an aligned
// stack. If the STKALIGN flag is set (which it is by default)
// the interrupt controller will forcibly align the stack before
// storing in-use registers. This will thus overwrite one word
// past the end of the stack (off-by-one).
stackSize += 4
}
// On Cortex-M (assumed here), this stack size is 8 words or 32
// bytes. This is only to store the registers that the interrupt
// may modify, the interrupt will switch to the interrupt stack
// (MSP).
// Some background:
// https://interrupt.memfault.com/blog/cortex-m-rtos-context-switching
stackSize += 32
// Adding 4 for the stack canary, and another 4 to keep the
// stack aligned. Even though the size may be automatically
// determined, stack overflow checking is still important as the
// stack size cannot be determined for all goroutines.
stackSize += 8
default:
return fmt.Errorf("unknown architecture: %s", fileHeader.Machine.String())
}
// Finally write the stack size to the binary.
binary.LittleEndian.PutUint32(data[i*4:], stackSize)
}
}
return replaceElfSection(executable, ".tinygo_stacksizes", data)
}
// printStacks prints the maximum stack depth for functions that are started as
// goroutines. Stack sizes cannot always be determined statically, in particular
// recursive functions and functions that call interface methods or function
// pointers may have an unknown stack depth (depending on what the optimizer
// manages to optimize away).
//
// It might print something like the following:
//
// function stack usage (in bytes)
// Reset_Handler 316
// examples/blinky2.led1 92
// runtime.run$1 300
func printStacks(calculatedStacks []string, stackSizes map[string]functionStackSize) {
// Print the sizes of all stacks.
fmt.Printf("%-32s %s\n", "function", "stack usage (in bytes)")
for _, name := range calculatedStacks {
fn := stackSizes[name]
switch fn.stackSizeType {
case stacksize.Bounded:
fmt.Printf("%-32s %d\n", fn.humanName, fn.stackSize)
case stacksize.Unknown:
fmt.Printf("%-32s unknown, %s does not have stack frame information\n", fn.humanName, fn.missingStackSize)
case stacksize.Recursive:
fmt.Printf("%-32s recursive, %s may call itself\n", fn.humanName, fn.missingStackSize)
case stacksize.IndirectCall:
fmt.Printf("%-32s unknown, %s calls a function pointer\n", fn.humanName, fn.missingStackSize)
}
}
}
// RP2040 second stage bootloader CRC32 calculation
//
// Spec: https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf
// Section: 2.8.1.3.1. Checksum
func patchRP2040BootCRC(executable string) error {
bytes, _, err := getElfSectionData(executable, ".boot2")
if err != nil {
return err
}
if len(bytes) != 256 {
return fmt.Errorf("rp2040 .boot2 section must be exactly 256 bytes")
}
// From the 'official' RP2040 checksum script:
//
// Our bootrom CRC32 is slightly bass-ackward but it's
// best to work around for now (FIXME)
// 100% worth it to save two Thumb instructions
revBytes := make([]byte, len(bytes))
for i := range bytes {
revBytes[i] = bits.Reverse8(bytes[i])
}
// crc32.Update does an initial negate and negates the
// result, so to meet RP2040 spec, pass 0x0 as initial
// hash and negate returned value.
//
// Note: checksum is over 252 bytes (256 - 4)
hash := bits.Reverse32(crc32.Update(0x0, crc32.IEEETable, revBytes[:252]) ^ 0xFFFFFFFF)
// Write the CRC to the end of the bootloader.
binary.LittleEndian.PutUint32(bytes[252:], hash)
// Update the .boot2 section to included the CRC
return replaceElfSection(executable, ".boot2", bytes)
}
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