Enable linking tools, shared libraries against libLLVM

Summary:
Three closely related changes, to have a mode in which we link all
executables and shared libraries against libLLVM. 

1. Add a new LLVM_LINK_LLVM_DYLIB cmake option, which, when ON, will link
   executables and shared libraries against libLLVM. For this to work, it
   is necessary to also set LLVM_BUILD_LLVM_DYLIB and LLVM_DYLIB_EXPORT_ALL.

   It is not strictly necessary to set LLVM_DISABLE_LLVM_DYLIB_ATEXIT, but
   we also default to OFF in this mode, or tools tend to misbehave (e.g.
   stdout may not flush on exit when output is buffered.)

   llvm-config and Tablegen do not use libLLVM, as they are dependencies of
   libLLVM.

2. Modify llvm-go to take a new flag, "linkmode=component-libs|dylib".
   Depending on which one is passed (default is component-libs), we link
   with the individual libraries or libLLVM respectively. We pass in dylib
   when LLVM_LINK_LLVM_DYLIB is ON.

3. Fix LLVM_DYLIB_EXPORT_ALL on Linux, and expand the symbols exported to
   actually export all. Don't strip leading underscore from symbols on Linux,
   and make sure we get all exported symbols and weak-with-default symbols
   ("W" in nm output). Without these changes, passes won't load because
   the "Annotate..." symbols defined in lib/Support/Valigrind.cpp are not
   found.

Testing:
 - Ran default build ("ninja") with LLVM, clang, compiler-rt, llgo, lldb.
 - Ran "check", "check-clang", "check-tsan", "check-libgo" targets. I've
   never had much success with LLDB tests, and llgoi is currently broken
   so check-llgo fails for an unrelated reason.
 - Ran "lldb" to ensure it loads.

Reviewers: chandlerc, beanz, pcc, rnk

Subscribers: rnk, chapuni, sylvestre.ledru, llvm-commits

Differential Revision: http://reviews.llvm.org/D12488

llvm-svn: 246527

1 files changed, 53 insertions, 38 deletions

diff --git a/llvm/tools/llvm-go/llvm-go.go b/llvm/tools/llvm-go/llvm-go.go
index c5c3fd244ca..ed79ca67b89 100644
--- a/llvm/tools/llvm-go/llvm-go.go
+++ b/llvm/tools/llvm-go/llvm-go.go
@@ -24,6 +24,11 @@ import (
 	"strings"
 )
 
+const (
+	linkmodeComponentLibs = "component-libs"
+	linkmodeDylib         = "dylib"
+)
+
 type pkg struct {
 	llvmpath, pkgpath string
 }
@@ -66,11 +71,12 @@ var components = []string{
 func llvmConfig(args ...string) string {
 	configpath := os.Getenv("LLVM_CONFIG")
 	if configpath == "" {
-		// strip llvm-go, add llvm-config
-		configpath = os.Args[0][:len(os.Args[0])-7] + "llvm-config"
+		bin, _ := filepath.Split(os.Args[0])
+		configpath = filepath.Join(bin, "llvm-config")
 	}
 
 	cmd := exec.Command(configpath, args...)
+	cmd.Stderr = os.Stderr
 	out, err := cmd.Output()
 	if err != nil {
 		panic(err.Error())
@@ -78,11 +84,21 @@ func llvmConfig(args ...string) string {
 
 	outstr := string(out)
 	outstr = strings.TrimSuffix(outstr, "\n")
-	return strings.Replace(outstr, "\n", " ", -1)
+	outstr = strings.Replace(outstr, "\n", " ", -1)
+	return outstr
 }
 
-func llvmFlags() compilerFlags {
-	ldflags := llvmConfig(append([]string{"--ldflags", "--libs", "--system-libs"}, components...)...)
+func llvmFlags(linkmode string) compilerFlags {
+	ldflags := llvmConfig("--ldflags")
+	switch linkmode {
+	case linkmodeComponentLibs:
+		ldflags += " " + llvmConfig(append([]string{"--libs"}, components...)...)
+	case linkmodeDylib:
+		ldflags += " -lLLVM"
+	default:
+		panic("invalid linkmode: " + linkmode)
+	}
+	ldflags += " " + llvmConfig("--system-libs")
 	if runtime.GOOS != "darwin" {
 		// OS X doesn't like -rpath with cgo. See:
 		// https://code.google.com/p/go/issues/detail?id=7293
@@ -117,8 +133,8 @@ func printComponents() {
 	fmt.Println(strings.Join(components, " "))
 }
 
-func printConfig() {
-	flags := llvmFlags()
+func printConfig(linkmode string) {
+	flags := llvmFlags(linkmode)
 
 	fmt.Printf(`// +build !byollvm
 
@@ -137,7 +153,7 @@ type (run_build_sh int)
 `, flags.cpp, flags.cxx, flags.ld)
 }
 
-func runGoWithLLVMEnv(args []string, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags string) {
+func runGoWithLLVMEnv(args []string, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags, linkmode string) {
 	args = addTag(args, "byollvm")
 
 	srcdir := llvmConfig("--src-root")
@@ -166,7 +182,7 @@ func runGoWithLLVMEnv(args []string, cc, cxx, gocmd, llgo, cppflags, cxxflags, l
 	newgopathlist = append(newgopathlist, filepath.SplitList(os.Getenv("GOPATH"))...)
 	newgopath := strings.Join(newgopathlist, string(filepath.ListSeparator))
 
-	flags := llvmFlags()
+	flags := llvmFlags(linkmode)
 
 	newenv := []string{
 		"CC=" + cc,
@@ -178,7 +194,7 @@ func runGoWithLLVMEnv(args []string, cc, cxx, gocmd, llgo, cppflags, cxxflags, l
 		"PATH=" + newpath,
 	}
 	if llgo != "" {
-		newenv = append(newenv, "GCCGO=" + llgo)
+		newenv = append(newenv, "GCCGO="+llgo)
 	}
 
 	for _, v := range os.Environ() {
@@ -234,45 +250,44 @@ func main() {
 	ldflags := os.Getenv("CGO_LDFLAGS")
 	gocmd := "go"
 	llgo := ""
+	linkmode := linkmodeComponentLibs
+
+	flags := []struct {
+		name string
+		dest *string
+	}{
+		{"cc", &cc},
+		{"cxx", &cxx},
+		{"go", &gocmd},
+		{"llgo", &llgo},
+		{"cppflags", &cppflags},
+		{"ldflags", &ldflags},
+		{"linkmode", &linkmode},
+	}
 
 	args := os.Args[1:]
-	DONE: for {
-		switch {
-		case len(args) == 0:
+LOOP:
+	for {
+		if len(args) == 0 {
 			usage()
-		case strings.HasPrefix(args[0], "cc="):
-			cc = args[0][3:]
-			args = args[1:]
-		case strings.HasPrefix(args[0], "cxx="):
-			cxx = args[0][4:]
-			args = args[1:]
-		case strings.HasPrefix(args[0], "go="):
-			gocmd = args[0][3:]
-			args = args[1:]
-		case strings.HasPrefix(args[0], "llgo="):
-			llgo = args[0][5:]
-			args = args[1:]
-		case strings.HasPrefix(args[0], "cppflags="):
-			cppflags = args[0][9:]
-			args = args[1:]
-		case strings.HasPrefix(args[0], "cxxflags="):
-			cxxflags = args[0][9:]
-			args = args[1:]
-		case strings.HasPrefix(args[0], "ldflags="):
-			ldflags = args[0][8:]
-			args = args[1:]
-		default:
-			break DONE
 		}
+		for _, flag := range flags {
+			if strings.HasPrefix(args[0], flag.name+"=") {
+				*flag.dest = args[0][len(flag.name)+1:]
+				args = args[1:]
+				continue LOOP
+			}
+		}
+		break
 	}
 
 	switch args[0] {
 	case "build", "get", "install", "run", "test":
-		runGoWithLLVMEnv(args, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags)
+		runGoWithLLVMEnv(args, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags, linkmode)
 	case "print-components":
 		printComponents()
 	case "print-config":
-		printConfig()
+		printConfig(linkmode)
 	default:
 		usage()
 	}