compiler: improve name mangling for packpaths

    
    The current implementation of Gogo::pkgpath_for_symbol was written in
    a way that allowed two distinct package paths to map to the same
    symbol, which could cause collisions at link- time or compile-time.
    
    Switch to a better mangling scheme to insure that we get a unique
    packagepath symbol for each package. In the new scheme instead of having
    separate mangling schemes for identifiers and package paths, the
    main identifier mangler ("go_encode_id") now handles mangling of
    both packagepath characters and identifier characters.
    
    The new mangling scheme is more intrusive: "foo/bar.Baz" is mangled as
    "foo..z2fbar.Baz" instead of "foo_bar.Baz". To mitigate this, this
    patch also adds a demangling capability so that function names
    returned from runtime.CallersFrames are converted back to their
    original unmangled form.
    
    Changing the pkgpath_for_symbol scheme requires updating a number of
    //go:linkname directives and C "__asm__" directives to match the new
    scheme, as well as updating the 'gotest' driver (which makes
    assumptions about the correct mapping from pkgpath symbol to package
    name).
    
    Fixes golang/go#27534.
    
    Reviewed-on: https://go-review.googlesource.com/c/135455

From-SVN: r265510

1 files changed, 2 insertions, 2 deletions

diff --git a/libgo/go/runtime/rdebug.go b/libgo/go/runtime/rdebug.go
index 76535a9..358df11 100644
--- a/libgo/go/runtime/rdebug.go
+++ b/libgo/go/runtime/rdebug.go
@@ -11,14 +11,14 @@ import _ "unsafe" // for go:linkname
 // maxstacksize.
 var maxstacksize uintptr = 1 << 20 // enough until runtime.main sets it for real
 
-//go:linkname setMaxStack runtime_debug.setMaxStack
+//go:linkname setMaxStack runtime..z2fdebug.setMaxStack
 func setMaxStack(in int) (out int) {
 	out = int(maxstacksize)
 	maxstacksize = uintptr(in)
 	return out
 }
 
-//go:linkname setPanicOnFault runtime_debug.setPanicOnFault
+//go:linkname setPanicOnFault runtime..z2fdebug.setPanicOnFault
 func setPanicOnFault(new bool) (old bool) {
 	_g_ := getg()
 	old = _g_.paniconfault