cmd/go: clean up compile vs link vs shared library actions

Everything got a bit tangled together in b.action1.
Try to tease things apart again.

In general this is a refactoring of the existing code, with limited
changes to the effect of the code.

The main additional change is to complete a.Deps for link actions.
That list now directly contains all the inputs the linker will attempt
to read, eliminating the need for a transitive traversal of the entire
action graph to find those. The comepleteness of a.Deps will be
important when we eventually use it to decide whether an cached
action output can be reused.

all.bash passes, but it's possible I've broken some subtety of
buildmode=shared again. Certainly that code took the longest
to get working.

Change-Id: I34e849eda446dca45a9cfce02b07bec6edb6d0d4
Reviewed-on: https://go-review.googlesource.com/69831
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

misc/cgo/testcarchive/carchive_test.go

@@ -134,8 +134,10 @@ func cmdToRun(name string) []string {
 }
 
 func testInstall(t *testing.T, exe, libgoa, libgoh string, buildcmd ...string) {
+	t.Helper()
 	cmd := exec.Command(buildcmd[0], buildcmd[1:]...)
 	cmd.Env = gopathEnv
+	t.Log(buildcmd)
 	if out, err := cmd.CombinedOutput(); err != nil {
 		t.Logf("%s", out)
 		t.Fatal(err)

misc/cgo/testshared/shared_test.go

@@ -465,13 +465,13 @@ func TestGopathShlib(t *testing.T) {
 // that is not mapped into memory.
 func testPkgListNote(t *testing.T, f *elf.File, note *note) {
 	if note.section.Flags != 0 {
-		t.Errorf("package list section has flags %v", note.section.Flags)
+		t.Errorf("package list section has flags %v, want 0", note.section.Flags)
 	}
 	if isOffsetLoaded(f, note.section.Offset) {
 		t.Errorf("package list section contained in PT_LOAD segment")
 	}
 	if note.desc != "depBase\n" {
-		t.Errorf("incorrect package list %q", note.desc)
+		t.Errorf("incorrect package list %q, want %q", note.desc, "depBase\n")
 	}
 }
 
@@ -480,7 +480,7 @@ func testPkgListNote(t *testing.T, f *elf.File, note *note) {
 // bytes into it.
 func testABIHashNote(t *testing.T, f *elf.File, note *note) {
 	if note.section.Flags != elf.SHF_ALLOC {
-		t.Errorf("abi hash section has flags %v", note.section.Flags)
+		t.Errorf("abi hash section has flags %v, want SHF_ALLOC", note.section.Flags)
 	}
 	if !isOffsetLoaded(f, note.section.Offset) {
 		t.Errorf("abihash section not contained in PT_LOAD segment")
@@ -501,13 +501,13 @@ func testABIHashNote(t *testing.T, f *elf.File, note *note) {
 		return
 	}
 	if elf.ST_BIND(hashbytes.Info) != elf.STB_LOCAL {
-		t.Errorf("%s has incorrect binding %v", hashbytes.Name, elf.ST_BIND(hashbytes.Info))
+		t.Errorf("%s has incorrect binding %v, want STB_LOCAL", hashbytes.Name, elf.ST_BIND(hashbytes.Info))
 	}
 	if f.Sections[hashbytes.Section] != note.section {
-		t.Errorf("%s has incorrect section %v", hashbytes.Name, f.Sections[hashbytes.Section].Name)
+		t.Errorf("%s has incorrect section %v, want %s", hashbytes.Name, f.Sections[hashbytes.Section].Name, note.section)
 	}
 	if hashbytes.Value-note.section.Addr != 16 {
-		t.Errorf("%s has incorrect offset into section %d", hashbytes.Name, hashbytes.Value-note.section.Addr)
+		t.Errorf("%s has incorrect offset into section %d, want 16", hashbytes.Name, hashbytes.Value-note.section.Addr)
 	}
 }
 
@@ -515,14 +515,14 @@ func testABIHashNote(t *testing.T, f *elf.File, note *note) {
 // was linked against in an unmapped section.
 func testDepsNote(t *testing.T, f *elf.File, note *note) {
 	if note.section.Flags != 0 {
-		t.Errorf("package list section has flags %v", note.section.Flags)
+		t.Errorf("package list section has flags %v, want 0", note.section.Flags)
 	}
 	if isOffsetLoaded(f, note.section.Offset) {
 		t.Errorf("package list section contained in PT_LOAD segment")
 	}
 	// libdepBase.so just links against the lib containing the runtime.
 	if note.desc != soname {
-		t.Errorf("incorrect dependency list %q", note.desc)
+		t.Errorf("incorrect dependency list %q, want %q", note.desc, soname)
 	}
 }
 
@@ -560,7 +560,7 @@ func TestNotes(t *testing.T) {
 			abiHashNoteFound = true
 		case 3: // ELF_NOTE_GODEPS_TAG
 			if depsNoteFound {
-				t.Error("multiple abi hash notes")
+				t.Error("multiple depedency list notes")
 			}
 			testDepsNote(t, f, note)
 			depsNoteFound = true

src/cmd/go/internal/load/pkg.go

@@ -911,16 +911,16 @@ func (p *Package) load(stk *ImportStack, bp *build.Package, err error) {
 		if cfg.BuildLinkshared {
 			shlibnamefile := p.Internal.Target[:len(p.Internal.Target)-2] + ".shlibname"
 			shlib, err := ioutil.ReadFile(shlibnamefile)
+			if err != nil && !os.IsNotExist(err) {
+				base.Fatalf("reading shlibname: %v", err)
+			}
 			if err == nil {
 				libname := strings.TrimSpace(string(shlib))
 				if cfg.BuildContext.Compiler == "gccgo" {
 					p.Shlib = filepath.Join(p.Internal.Build.PkgTargetRoot, "shlibs", libname)
 				} else {
 					p.Shlib = filepath.Join(p.Internal.Build.PkgTargetRoot, libname)
-
 				}
-			} else if !os.IsNotExist(err) {
-				base.Fatalf("unexpected error reading %s: %v", shlibnamefile, err)
 			}
 		}
 	}

src/cmd/go/internal/run/run.go

@@ -110,7 +110,7 @@ func runRun(cmd *base.Command, args []string) {
 		base.Fatalf("go run: no suitable source files%s", hint)
 	}
 	p.Internal.ExeName = src[:len(src)-len(".go")] // name temporary executable for first go file
-	a1 := b.Action(work.ModeBuild, work.ModeBuild, p)
+	a1 := b.LinkAction(work.ModeBuild, work.ModeBuild, p)
 	a := &work.Action{Mode: "go run", Func: buildRunProgram, Args: cmdArgs, Deps: []*work.Action{a1}}
 	b.Do(a)
 }

src/cmd/go/internal/test/test.go

@@ -524,7 +524,7 @@ func runTest(cmd *base.Command, args []string) {
 
 		a := &work.Action{Mode: "go test -i"}
 		for _, p := range load.PackagesForBuild(all) {
-			a.Deps = append(a.Deps, b.Action(work.ModeInstall, work.ModeInstall, p))
+			a.Deps = append(a.Deps, b.CompileAction(work.ModeInstall, work.ModeInstall, p))
 		}
 		b.Do(a)
 		if !testC || a.Failed {
@@ -651,7 +651,7 @@ var windowsBadWords = []string{
 
 func builderTest(b *work.Builder, p *load.Package) (buildAction, runAction, printAction *work.Action, err error) {
 	if len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 {
-		build := b.Action(work.ModeBuild, work.ModeBuild, p)
+		build := b.CompileAction(work.ModeBuild, work.ModeBuild, p)
 		run := &work.Action{Mode: "test run", Package: p, Deps: []*work.Action{build}}
 		print := &work.Action{Mode: "test print", Func: builderNoTest, Package: p, Deps: []*work.Action{run}}
 		return build, run, print, nil
@@ -896,7 +896,7 @@ func builderTest(b *work.Builder, p *load.Package) (buildAction, runAction, prin
 
 	load.ComputeStale(pmain)
 
-	a := b.Action(work.ModeBuild, work.ModeBuild, pmain)
+	a := b.LinkAction(work.ModeBuild, work.ModeBuild, pmain)
 	a.Target = testDir + testBinary + cfg.ExeSuffix
 	if cfg.Goos == "windows" {
 		// There are many reserved words on Windows that,