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build: snapshot package linker state #2179

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55f6515
build: snapshot package linker state
zhouguangyuan0718 Jul 30, 2026
ebd6988
test: cover package summary boundaries
zhouguangyuan0718 Aug 1, 2026
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99 changes: 59 additions & 40 deletions internal/build/build.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1042,15 +1042,17 @@ func prePackageBuild(ctx *context, task *packageBuildTask, verbose bool) error {
if task.isDeclOnly() {
pkg.ExportFile = ""
task.skip = true
return nil
aPkg.Summary = summarizePackage(aPkg)
return ctx.collectFingerprint(aPkg)
}
if task.isLinkOnly() && !task.hasSource() {
pkg.ExportFile = ""
if task.kind == cl.PkgLinkExtern {
appendExternalLinkArgs(ctx, aPkg, task.kindParam)
}
task.skip = true
return nil
aPkg.Summary = summarizePackage(aPkg)
return ctx.collectFingerprint(aPkg)
}
if err := ctx.collectFingerprint(aPkg); err != nil {
return err
Expand Down Expand Up @@ -1091,6 +1093,7 @@ func finalizePackageBuild(ctx *context, task *packageBuildTask, verbose bool) (p
if task.kind == cl.PkgLinkExtern {
appendExternalLinkArgs(ctx, aPkg, task.kindParam)
}
aPkg.Summary = summarizePackage(aPkg)

@fennoai fennoai Bot Jul 25, 2026

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summarizePackage currently always returns non-nil on this path, so this is fine today. As defensive robustness: if saveToCache were ever reached with pkg.Summary == nil, metadata() returns nil and the entry is written with summary: absent — which tryLoadFromCache then treats as a permanent cache miss (meta.Summary == nil guard). That is a silently non-cacheable entry rather than an error. A short assertion/comment here that Summary must be set before saveToCache would make the invariant explicit.

if err := ctx.saveToCache(aPkg); err != nil && verbose {
fmt.Fprintf(os.Stderr, "warning: failed to save cache for %s: %v\n", aPkg.PkgPath, err)
}
Expand Down Expand Up @@ -1341,39 +1344,47 @@ func linkMainPkg(ctx *context, pkg *packages.Package, pkgs []*aPackage, outputPa
aPkg = ctx.pkgByID[p.ID]
}
if p.ExportFile != "" && aPkg != nil { // skip packages that only contain declarations
if aPkg.Summary == nil && isRuntimePkg(aPkg.PkgPath) {
return
}
linkedPkgs[p.ID] = true
linkedOrder = append(linkedOrder, aPkg)
}
})
linkedSummaries := make([]*PackageSummary, len(linkedOrder))
for i, aPkg := range linkedOrder {
if aPkg.Summary == nil {
return fmt.Errorf("package %s has no linker summary", aPkg.PkgPath)
}
linkedSummaries[i] = aPkg.Summary
}

// packages.Visit with a post callback yields dependencies before importers.
// Reverse that order so static archives are linked after the objects that use them.
for i := len(linkedOrder) - 1; i >= 0; i-- {
aPkg := linkedOrder[i]
p := aPkg.Package
summary := linkedSummaries[i]
// Defer linking runtime packages unless we actually need the runtime.
if isRuntimePkg(p.PkgPath) {
rtLinkArgs = append(rtLinkArgs, aPkg.LinkArgs...)
if aPkg.ArchiveFile != "" {
rtLinkInputs = append(rtLinkInputs, aPkg.ArchiveFile)
if isRuntimePkg(summary.PkgPath) {
rtLinkArgs = append(rtLinkArgs, summary.LinkArgs...)
if summary.ArchiveFile != "" {
rtLinkInputs = append(rtLinkInputs, summary.ArchiveFile)
}
continue
}
// Only let non-runtime packages influence whether runtime is needed.
need1, need2 := aPkg.isNeedRuntimeOrPyInit()
needRuntime = needRuntime || need1
needPyInit = needPyInit || need2
needAbiInit |= aPkg.LPkg.NeedAbiInit
for k, _ := range aPkg.LPkg.MethodByIndex {
methodByIndex[k] = none{}
needRuntime = needRuntime || summary.NeedRuntime
needPyInit = needPyInit || summary.NeedPyInit
needAbiInit |= summary.NeedAbiInit
for _, method := range summary.MethodByIndex {
methodByIndex[method] = none{}
}
for k, _ := range aPkg.LPkg.MethodByName {
methodByName[k] = none{}
for _, method := range summary.MethodByName {
methodByName[method] = none{}
}

linkArgs = append(linkArgs, aPkg.LinkArgs...)
if aPkg.ArchiveFile != "" {
archiveInputs = append(archiveInputs, aPkg.ArchiveFile)
linkArgs = append(linkArgs, summary.LinkArgs...)
if summary.ArchiveFile != "" {
archiveInputs = append(archiveInputs, summary.ArchiveFile)
}
}

Expand All @@ -1390,17 +1401,17 @@ func linkMainPkg(ctx *context, pkg *packages.Package, pkgs []*aPackage, outputPa
var pcLineInfo []pcLineRecord
var funcInfoStubs []funcInfoStubRecord
if ctx.buildConf.PCLNMode != PCLNNone {
funcInfo = prepareFuncInfoTableRecords(collectFuncInfo(linkedOrder), nil)
pcLineInfo = collectPCLineInfo(linkedOrder)
funcInfoStubs = collectFuncInfoStubRecords(linkedOrder, funcInfo)
funcInfo = prepareFuncInfoTableRecords(collectFuncInfoSummaries(linkedSummaries), nil)
pcLineInfo = collectPCLineInfoSummaries(linkedSummaries)
funcInfoStubs = collectFuncInfoStubRecordsSummaries(linkedSummaries, funcInfo)
}
entryPkg := genMainModule(ctx, llssa.PkgRuntime, pkg, &genConfig{
rtInit: needRuntime,
pyInit: needPyInit,
abiInit: needAbiInit,
methodByIndex: methodByIndex,
methodByName: methodByName,
abiSymbols: linkedModuleGlobals(linkedOrder),
abiSymbols: linkedPackageGlobals(linkedSummaries),
funcInfo: funcInfo,
pcLineInfo: pcLineInfo,
funcInfoStubs: funcInfoStubs,
Expand Down Expand Up @@ -1440,7 +1451,7 @@ func linkMainPkg(ctx *context, pkg *packages.Package, pkgs []*aPackage, outputPa
}
}
}
linkArgs = append(linkArgs, cSharedExportArgs(ctx, linkedOrder)...)
linkArgs = append(linkArgs, cSharedExportArgsSummaries(ctx, linkedSummaries)...)

err = linkObjFiles(ctx, outputPath, linkInputs, linkArgs, verbose)
if err != nil {
Expand Down Expand Up @@ -1498,19 +1509,22 @@ func dceEntryRootCandidates(pkgs []Package, needRuntime bool) []string {
}

func linkedModuleGlobals(pkgs []Package) map[string]none {
if len(pkgs) == 0 {
return linkedPackageGlobals(summariesForPackages(pkgs))
}

func linkedPackageGlobals(summaries []*PackageSummary) map[string]none {
if len(summaries) == 0 {
return nil
}
seen := make(map[string]none)
for _, pkg := range pkgs {
if pkg == nil || pkg.LPkg == nil {
for _, summary := range summaries {
if summary == nil {
continue
}
for g := pkg.LPkg.Module().FirstGlobal(); !g.IsNil(); g = gllvm.NextGlobal(g) {
if g.IsDeclaration() {
continue
for _, name := range summary.GlobalSymbols {
if name != "" {
seen[name] = none{}
}
seen[g.Name()] = none{}
}
}
return seen
Expand Down Expand Up @@ -1589,22 +1603,26 @@ func linkObjFiles(ctx *context, app string, objFiles, linkArgs []string, verbose
// shared-library link roots. They live in package archives and otherwise remain
// unreferenced, so the linker can omit both their object files and symbols.
func cSharedExportArgs(ctx *context, pkgs []*aPackage) []string {
return cSharedExportArgsSummaries(ctx, summariesForPackages(pkgs))
}

func cSharedExportArgsSummaries(ctx *context, summaries []*PackageSummary) []string {
if ctx == nil || ctx.buildConf == nil || ctx.buildConf.BuildMode != BuildModeCShared {
return nil
}
exports := make(map[string]none)
for _, pkg := range pkgs {
if pkg == nil || pkg.LPkg == nil {
for _, summary := range summaries {
if summary == nil {
continue
}
for _, name := range pkg.LPkg.ExportFuncs() {
for _, name := range summary.CSharedExports {
if name != "" {
exports[name] = none{}
}
}
if ctx.mode == ModeTest && pkg.Package != nil && pkg.Name == "main" && strings.HasSuffix(pkg.PkgPath, ".test") {
exports[pkg.PkgPath+".init"] = none{}
exports[pkg.PkgPath+".main"] = none{}
if ctx.mode == ModeTest && summary.Name == "main" && strings.HasSuffix(summary.PkgPath, ".test") {
exports[summary.PkgPath+".init"] = none{}
exports[summary.PkgPath+".main"] = none{}
}
}
names := make([]string, 0, len(exports))
Expand Down Expand Up @@ -2238,9 +2256,10 @@ func registerAltSSAPkgs(prog *ssa.Program, patches cl.Patches, alts []*packages.

type aPackage struct {
*packages.Package
SSA *ssa.Package
AltPkg *packages.Cached
LPkg llssa.Package
SSA *ssa.Package
AltPkg *packages.Cached
LPkg llssa.Package
Summary *PackageSummary

NeedRt bool
NeedPyInit bool
Expand Down
19 changes: 14 additions & 5 deletions internal/build/collect.go
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Original file line number Diff line number Diff line change
Expand Up @@ -334,6 +334,9 @@ func (c *context) tryLoadFromCache(pkg *aPackage) bool {
if c.packageCacheDisabled(pkg.ID) {
return false
}
if c.buildConf != nil && (c.buildConf.BuildMode == BuildModeCArchive || c.buildConf.BuildMode == BuildModeCShared) {
return false
}

// Main packages are intentionally not written to the build cache because
// each executable's entry module is linked against the current main archive.
Expand Down Expand Up @@ -377,6 +380,9 @@ func (c *context) tryLoadFromCache(pkg *aPackage) bool {
if err != nil {
return false
}
if meta.Summary == nil {
return false
}

// Use the .a archive directly for linking (no extraction needed)
pkg.ArchiveFile = paths.Archive
Expand All @@ -385,6 +391,7 @@ func (c *context) tryLoadFromCache(pkg *aPackage) bool {
pkg.NeedPyInit = meta.NeedPyInit
pkg.Meta = pkgMeta
pkg.CacheHit = true
pkg.Summary = summaryFromMetadata(pkg, meta)

return true
}
Expand All @@ -399,6 +406,7 @@ func parseManifestMetadata(content string) (*cacheArchiveMetadata, error) {
meta.LinkArgs = append([]string(nil), data.Metadata.LinkArgs...)
meta.NeedRt = data.Metadata.NeedRt
meta.NeedPyInit = data.Metadata.NeedPyInit
meta.Summary = data.Metadata.Summary
}
return meta, nil
}
Expand Down Expand Up @@ -452,6 +460,7 @@ type cacheArchiveMetadata struct {
LinkArgs []string
NeedRt bool
NeedPyInit bool
Summary *packageSummaryMetadata
}

// saveToCache saves a built package to cache.
Expand Down Expand Up @@ -511,16 +520,16 @@ func (c *context) saveToCache(pkg *aPackage) error {
return fmt.Errorf("decode manifest: %w", err)
}

if pkg.Summary == nil {
pkg.Summary = summarizePackage(pkg)
}
meta := &manifestMetadata{
LinkArgs: append([]string(nil), pkg.LinkArgs...),
NeedRt: pkg.NeedRt,
NeedPyInit: pkg.NeedPyInit,
Summary: pkg.Summary.metadata(),
}
if len(meta.LinkArgs) == 0 && !meta.NeedRt && !meta.NeedPyInit {
data.Metadata = nil
} else {
data.Metadata = meta
}
data.Metadata = meta

manifestWithMeta, err := buildManifestYAML(data)
if err != nil {
Expand Down
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