cmd/go: cgo for Linux/ARM

        Part 4 of CL 5601044 (cgo: Linux/ARM support)

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/5989058

diff --git a/src/cmd/go/build.go b/src/cmd/go/build.go
index 4bb83f1618849aff4b38271bdc9eeb5b06cc183e..2b9995d1c6c2d4af08490dfd45d68427e9f9f2f4 100644 (file)
--- a/src/cmd/go/build.go
+++ b/src/cmd/go/build.go
@@ -1394,6 +1394,8 @@ func (b *builder) gccCmd(objdir string) []string {
                a = append(a, "-m32")
        case "6":
                a = append(a, "-m64")
+       case "5":
+               a = append(a, "-marm") // not thumb
        }
        // gcc-4.5 and beyond require explicit "-pthread" flag
        // for multithreading with pthread library.
@@ -1513,9 +1515,15 @@ func (b *builder) cgo(p *Package, cgoExe, obj string, gccfiles []string) (outGo,
                outObj = append(outObj, ofile)
        }
        dynobj := obj + "_cgo_.o"
+       if goarch == "arm" && goos == "linux" { // we need to use -pie for Linux/ARM to get accurate imported sym
+               cgoLDFLAGS = append(cgoLDFLAGS, "-pie")
+       }
        if err := b.gccld(p, dynobj, cgoLDFLAGS, linkobj); err != nil {
                return nil, nil, err
        }
+       if goarch == "arm" && goos == "linux" { // but we don't need -pie for normal cgo programs
+               cgoLDFLAGS = cgoLDFLAGS[0 : len(cgoLDFLAGS)-1]
+       }
 
        if _, ok := buildToolchain.(gccgcToolchain); ok {
                // we don't use dynimport when using gccgo.