cmd/go: refactor creation of top-level actions for -buildmode=shared

Change-Id: I429402dd91243cd9415b054ee17bfebccc68ed57
Reviewed-on: https://go-review.googlesource.com/9197
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

diff --git a/src/cmd/go/build.go b/src/cmd/go/build.go
index e470cacda81bc5dd5344cc3656df0165f89b6d8b..a21d4cbbd2a5f81505bf953075277694ee223802 100644 (file)
--- a/src/cmd/go/build.go
+++ b/src/cmd/go/build.go
@@ -402,7 +402,6 @@ func runBuild(cmd *Command, args []string) {
        }
 
        depMode := modeBuild
-       mode := modeBuild
        if buildI {
                depMode = modeInstall
        }
@@ -423,23 +422,12 @@ func runBuild(cmd *Command, args []string) {
 
        var a *action
        if buildBuildmode == "shared" {
-               a = b.libaction(libname(args))
-               mode = depMode
-
-               // Currently build mode shared forces external linking
-               // mode, and external linking mode forces an import of
-               // runtime/cgo.
-               var stk importStack
-               p := loadPackage("runtime/cgo", &stk)
-               if p.Error != nil {
-                       fatalf("load runtime/cgo: %v", p.Error)
-               }
-               a.deps = append(a.deps, b.action(mode, depMode, p))
+               a = b.libaction(libname(args), pkgsFilter(packages(args)), modeBuild, depMode)
        } else {
                a = &action{}
-       }
-       for _, p := range pkgsFilter(packages(args)) {
-               a.deps = append(a.deps, b.action(mode, depMode, p))
+               for _, p := range pkgsFilter(packages(args)) {
+                       a.deps = append(a.deps, b.action(modeBuild, depMode, p))
+               }
        }
        b.do(a)
 }
@@ -504,32 +492,7 @@ func runInstall(cmd *Command, args []string) {
        b.init()
        a := &action{}
        if buildBuildmode == "shared" {
-               var libdir string
-               for _, p := range pkgs {
-                       plibdir := p.build.PkgTargetRoot
-                       if libdir == "" {
-                               libdir = plibdir
-                       } else if libdir != plibdir {
-                               fatalf("multiple roots %s & %s", libdir, plibdir)
-                       }
-               }
-
-               a.f = (*builder).install
-               libfilename := libname(args)
-               linkSharedAction := b.libaction(libfilename)
-               a.target = filepath.Join(libdir, libfilename)
-               a.deps = append(a.deps, linkSharedAction)
-               for _, p := range pkgs {
-                       if p.target == "" {
-                               continue
-                       }
-                       shlibnameaction := &action{}
-                       shlibnameaction.f = (*builder).installShlibname
-                       shlibnameaction.target = p.target[:len(p.target)-2] + ".shlibname"
-                       a.deps = append(a.deps, shlibnameaction)
-                       shlibnameaction.deps = append(shlibnameaction.deps, linkSharedAction)
-                       linkSharedAction.deps = append(linkSharedAction.deps, b.action(modeInstall, modeInstall, p))
-               }
+               a = b.libaction(libname(args), pkgs, modeInstall, modeInstall)
        } else {
                var tools []*action
                for _, p := range pkgs {
@@ -849,10 +812,53 @@ func (b *builder) action(mode buildMode, depMode buildMode, p *Package) *action
        return a
 }
 
-func (b *builder) libaction(libname string) *action {
+func (b *builder) libaction(libname string, pkgs []*Package, mode, depMode buildMode) *action {
        a := &action{}
-       a.f = (*builder).linkShared
-       a.target = filepath.Join(b.work, libname)
+       if mode == modeBuild {
+               a.f = (*builder).linkShared
+               a.target = filepath.Join(b.work, libname)
+               for _, p := range pkgs {
+                       if p.target == "" {
+                               continue
+                       }
+                       a.deps = append(a.deps, b.action(depMode, depMode, p))
+               }
+               // Currently build mode shared forces external linking
+               // mode, and external linking mode forces an import of
+               // runtime/cgo.
+               var stk importStack
+               p := loadPackage("runtime/cgo", &stk)
+               if p.Error != nil {
+                       fatalf("load runtime/cgo: %v", p.Error)
+               }
+               a.deps = append(a.deps, b.action(depMode, depMode, p))
+       } else if mode == modeInstall {
+               a.f = (*builder).install
+               var libdir string
+               for _, p := range pkgs {
+                       plibdir := p.build.PkgTargetRoot
+                       if libdir == "" {
+                               libdir = plibdir
+                       } else if libdir != plibdir {
+                               fatalf("multiple roots %s & %s", libdir, plibdir)
+                       }
+               }
+               a.target = filepath.Join(libdir, libname)
+               linkSharedAction := b.libaction(libname, pkgs, modeBuild, depMode)
+               a.deps = append(a.deps, linkSharedAction)
+               for _, p := range pkgs {
+                       if p.target == "" {
+                               continue
+                       }
+                       shlibnameaction := &action{}
+                       shlibnameaction.f = (*builder).installShlibname
+                       shlibnameaction.target = p.target[:len(p.target)-2] + ".shlibname"
+                       a.deps = append(a.deps, shlibnameaction)
+                       shlibnameaction.deps = append(shlibnameaction.deps, linkSharedAction)
+               }
+       } else {
+               fatalf("unregonized mode %v", mode)
+       }
        return a
 }
 
@@ -1297,9 +1303,19 @@ func (b *builder) linkShared(a *action) (err error) {
        ldflags = append(ldflags, "-buildmode="+ldBuildmode)
        ldflags = append(ldflags, buildLdflags...)
        for _, d := range a.deps {
-               if d.target != "" { // omit unsafe etc
-                       ldflags = append(ldflags, d.p.ImportPath+"="+d.target)
+               if d.target == "" { // omit unsafe etc
+                       continue
+               }
+               if d.p.ImportPath == "runtime/cgo" {
+                       // Fudge: we always ensure runtime/cgo is built, but sometimes it is
+                       // already available as a shared library.  The linker will always look
+                       // for runtime/cgo and knows how to tell if it's in a shared library so
+                       // rather than duplicate the logic here, just don't pass it.
+                       // TODO(mwhudson): fix this properly as part of implementing the
+                       // rebuilding of stale shared libraries
+                       continue
                }
+               ldflags = append(ldflags, d.p.ImportPath+"="+d.target)
        }
        return b.run(".", a.target, nil, buildToolExec, tool(archChar()+"l"), "-o", a.target, importArgs, ldflags)
 }