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

21 files changed, 152 insertions, 73 deletions

diff --git a/libgo/go/runtime/atomic_pointer.go b/libgo/go/runtime/atomic_pointer.go
index 2d023d3..03d8d6a 100644
--- a/libgo/go/runtime/atomic_pointer.go
+++ b/libgo/go/runtime/atomic_pointer.go
@@ -52,10 +52,10 @@ func casp(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
 // We cannot just call the runtime routines, because the race detector expects
 // to be able to intercept the sync/atomic forms but not the runtime forms.
 
-//go:linkname sync_atomic_StoreUintptr sync_atomic.StoreUintptr
+//go:linkname sync_atomic_StoreUintptr sync..z2fatomic.StoreUintptr
 func sync_atomic_StoreUintptr(ptr *uintptr, new uintptr)
 
-//go:linkname sync_atomic_StorePointer sync_atomic.StorePointer
+//go:linkname sync_atomic_StorePointer sync..z2fatomic.StorePointer
 //go:nosplit
 func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
 	if writeBarrier.enabled {
@@ -64,10 +64,10 @@ func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
 	sync_atomic_StoreUintptr((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
 }
 
-//go:linkname sync_atomic_SwapUintptr sync_atomic.SwapUintptr
+//go:linkname sync_atomic_SwapUintptr sync..z2fatomic.SwapUintptr
 func sync_atomic_SwapUintptr(ptr *uintptr, new uintptr) uintptr
 
-//go:linkname sync_atomic_SwapPointer sync_atomic.SwapPointer
+//go:linkname sync_atomic_SwapPointer sync..z2fatomic.SwapPointer
 //go:nosplit
 func sync_atomic_SwapPointer(ptr *unsafe.Pointer, new unsafe.Pointer) unsafe.Pointer {
 	if writeBarrier.enabled {
@@ -77,10 +77,10 @@ func sync_atomic_SwapPointer(ptr *unsafe.Pointer, new unsafe.Pointer) unsafe.Poi
 	return old
 }
 
-//go:linkname sync_atomic_CompareAndSwapUintptr sync_atomic.CompareAndSwapUintptr
+//go:linkname sync_atomic_CompareAndSwapUintptr sync..z2fatomic.CompareAndSwapUintptr
 func sync_atomic_CompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool
 
-//go:linkname sync_atomic_CompareAndSwapPointer sync_atomic.CompareAndSwapPointer
+//go:linkname sync_atomic_CompareAndSwapPointer sync..z2fatomic.CompareAndSwapPointer
 //go:nosplit
 func sync_atomic_CompareAndSwapPointer(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
 	if writeBarrier.enabled {
diff --git a/libgo/go/runtime/cpuprof.go b/libgo/go/runtime/cpuprof.go
index b1a7c3b..e7cf1b4 100644
--- a/libgo/go/runtime/cpuprof.go
+++ b/libgo/go/runtime/cpuprof.go
@@ -186,7 +186,7 @@ func CPUProfile() []byte {
 	panic("CPUProfile no longer available")
 }
 
-//go:linkname runtime_pprof_runtime_cyclesPerSecond runtime_pprof.runtime_cyclesPerSecond
+//go:linkname runtime_pprof_runtime_cyclesPerSecond runtime..z2fpprof.runtime_cyclesPerSecond
 func runtime_pprof_runtime_cyclesPerSecond() int64 {
 	return tickspersecond()
 }
@@ -197,7 +197,7 @@ func runtime_pprof_runtime_cyclesPerSecond() int64 {
 // on has been returned, readProfile returns eof=true.
 // The caller must save the returned data and tags before calling readProfile again.
 //
-//go:linkname runtime_pprof_readProfile runtime_pprof.readProfile
+//go:linkname runtime_pprof_readProfile runtime..z2fpprof.readProfile
 func runtime_pprof_readProfile() ([]uint64, []unsafe.Pointer, bool) {
 	lock(&cpuprof.lock)
 	log := cpuprof.log
diff --git a/libgo/go/runtime/debug/stack_test.go b/libgo/go/runtime/debug/stack_test.go
index 67931d1..309eddd 100644
--- a/libgo/go/runtime/debug/stack_test.go
+++ b/libgo/go/runtime/debug/stack_test.go
@@ -51,10 +51,10 @@ func TestStack(t *testing.T) {
 		n++
 	}
 	n++
-	frame("stack.go", "runtime_debug.Stack")
+	frame("stack.go", "debug.Stack")
 	frame("stack_test.go", "ptrmethod")
 	frame("stack_test.go", "method")
-	frame("stack_test.go", "runtime_debug_test.TestStack")
+	frame("stack_test.go", "test.TestStack")
 	frame("testing.go", "")
 }
 
diff --git a/libgo/go/runtime/heapdump.go b/libgo/go/runtime/heapdump.go
index e92ea39..5ebebf6 100644
--- a/libgo/go/runtime/heapdump.go
+++ b/libgo/go/runtime/heapdump.go
@@ -16,7 +16,7 @@ import (
 	"unsafe"
 )
 
-//go:linkname runtime_debug_WriteHeapDump runtime_debug.WriteHeapDump
+//go:linkname runtime_debug_WriteHeapDump runtime..z2fdebug.WriteHeapDump
 func runtime_debug_WriteHeapDump(fd uintptr) {
 	stopTheWorld("write heap dump")
 
diff --git a/libgo/go/runtime/internal/atomic/atomic.c b/libgo/go/runtime/internal/atomic/atomic.c
index 24820f2..b87fae9 100644
--- a/libgo/go/runtime/internal/atomic/atomic.c
+++ b/libgo/go/runtime/internal/atomic/atomic.c
@@ -7,7 +7,7 @@
 #include "runtime.h"
 
 uint32_t Load (uint32_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Load")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Load")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -17,7 +17,7 @@ Load (uint32_t *ptr)
 }
 
 void *Loadp (void *ptr)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Loadp")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Loadp")
   __attribute__ ((no_split_stack));
 
 void *
@@ -27,7 +27,7 @@ Loadp (void *ptr)
 }
 
 uint64_t Load64 (uint64_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Load64")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Load64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -39,7 +39,7 @@ Load64 (uint64_t *ptr)
 }
 
 uintptr_t Loaduintptr (uintptr_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Loaduintptr")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Loaduintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -49,7 +49,7 @@ Loaduintptr (uintptr_t *ptr)
 }
 
 uintgo Loaduint (uintgo *ptr)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Loaduint")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Loaduint")
   __attribute__ ((no_split_stack));
 
 uintgo
@@ -59,7 +59,7 @@ Loaduint (uintgo *ptr)
 }
 
 int64_t Loadint64 (int64_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Loadint64")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Loadint64")
   __attribute__ ((no_split_stack));
 
 int64_t
@@ -71,7 +71,7 @@ Loadint64 (int64_t *ptr)
 }
 
 uint32_t Xadd (uint32_t *ptr, int32_t delta)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Xadd")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xadd")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -81,7 +81,7 @@ Xadd (uint32_t *ptr, int32_t delta)
 }
 
 uint64_t Xadd64 (uint64_t *ptr, int64_t delta)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Xadd64")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xadd64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -93,7 +93,7 @@ Xadd64 (uint64_t *ptr, int64_t delta)
 }
 
 uintptr_t Xadduintptr (uintptr_t *ptr, uintptr_t delta)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Xadduintptr")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xadduintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -103,7 +103,7 @@ Xadduintptr (uintptr_t *ptr, uintptr_t delta)
 }
 
 int64_t Xaddint64 (int64_t *ptr, int64_t delta)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Xaddint64")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xaddint64")
   __attribute__ ((no_split_stack));
 
 int64_t
@@ -115,7 +115,7 @@ Xaddint64 (int64_t *ptr, int64_t delta)
 }
 
 uint32_t Xchg (uint32_t *ptr, uint32_t new)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Xchg")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xchg")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -125,7 +125,7 @@ Xchg (uint32_t *ptr, uint32_t new)
 }
 
 uint64_t Xchg64 (uint64_t *ptr, uint64_t new)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Xchg64")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xchg64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -137,7 +137,7 @@ Xchg64 (uint64_t *ptr, uint64_t new)
 }
 
 uintptr_t Xchguintptr (uintptr_t *ptr, uintptr_t new)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Xchguintptr")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xchguintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -147,7 +147,7 @@ Xchguintptr (uintptr_t *ptr, uintptr_t new)
 }
 
 void And8 (uint8_t *ptr, uint8_t val)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.And8")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.And8")
   __attribute__ ((no_split_stack));
 
 void
@@ -157,7 +157,7 @@ And8 (uint8_t *ptr, uint8_t val)
 }
 
 void Or8 (uint8_t *ptr, uint8_t val)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Or8")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Or8")
   __attribute__ ((no_split_stack));
 
 void
@@ -167,7 +167,7 @@ Or8 (uint8_t *ptr, uint8_t val)
 }
 
 _Bool Cas (uint32_t *ptr, uint32_t old, uint32_t new)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Cas")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Cas")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -177,7 +177,7 @@ Cas (uint32_t *ptr, uint32_t old, uint32_t new)
 }
 
 _Bool Cas64 (uint64_t *ptr, uint64_t old, uint64_t new)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Cas64")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Cas64")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -189,7 +189,7 @@ Cas64 (uint64_t *ptr, uint64_t old, uint64_t new)
 }
 
 _Bool Casp1 (void **ptr, void *old, void *new)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Casp1")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Casp1")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -199,7 +199,7 @@ Casp1 (void **ptr, void *old, void *new)
 }
 
 _Bool Casuintptr (uintptr_t *ptr, uintptr_t old, uintptr_t new)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Casuintptr")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Casuintptr")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -209,7 +209,7 @@ Casuintptr (uintptr_t *ptr, uintptr_t old, uintptr_t new)
 }
 
 void Store (uint32_t *ptr, uint32_t val)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Store")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Store")
   __attribute__ ((no_split_stack));
 
 void
@@ -219,7 +219,7 @@ Store (uint32_t *ptr, uint32_t val)
 }
 
 void Store64 (uint64_t *ptr, uint64_t val)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Store64")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Store64")
   __attribute__ ((no_split_stack));
 
 void
@@ -231,7 +231,7 @@ Store64 (uint64_t *ptr, uint64_t val)
 }
 
 void Storeuintptr (uintptr_t *ptr, uintptr_t val)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.Storeuintptr")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Storeuintptr")
   __attribute__ ((no_split_stack));
 
 void
@@ -241,7 +241,7 @@ Storeuintptr (uintptr_t *ptr, uintptr_t val)
 }
 
 void StorepNoWB (void *ptr, void *val)
-  __asm__ (GOSYM_PREFIX "runtime_internal_atomic.StorepNoWB")
+  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.StorepNoWB")
   __attribute__ ((no_split_stack));
 
 void
diff --git a/libgo/go/runtime/mgc.go b/libgo/go/runtime/mgc.go
index 4ef982d..de84084 100644
--- a/libgo/go/runtime/mgc.go
+++ b/libgo/go/runtime/mgc.go
@@ -219,7 +219,7 @@ func gcenable() {
 	memstats.enablegc = true // now that runtime is initialized, GC is okay
 }
 
-//go:linkname setGCPercent runtime_debug.setGCPercent
+//go:linkname setGCPercent runtime..z2fdebug.setGCPercent
 func setGCPercent(in int32) (out int32) {
 	lock(&mheap_.lock)
 	out = gcpercent
diff --git a/libgo/go/runtime/mheap.go b/libgo/go/runtime/mheap.go
index 65622f4..eb98083 100644
--- a/libgo/go/runtime/mheap.go
+++ b/libgo/go/runtime/mheap.go
@@ -1165,7 +1165,7 @@ func (h *mheap) scavenge(k int32, now, limit uint64) {
 	}
 }
 
-//go:linkname runtime_debug_freeOSMemory runtime_debug.freeOSMemory
+//go:linkname runtime_debug_freeOSMemory runtime..z2fdebug.freeOSMemory
 func runtime_debug_freeOSMemory() {
 	GC()
 	systemstack(func() { mheap_.scavenge(-1, ^uint64(0), 0) })
diff --git a/libgo/go/runtime/mstats.go b/libgo/go/runtime/mstats.go
index f54ce9d..8aac850 100644
--- a/libgo/go/runtime/mstats.go
+++ b/libgo/go/runtime/mstats.go
@@ -477,7 +477,7 @@ func readmemstats_m(stats *MemStats) {
 	stats.StackSys += stats.StackInuse
 }
 
-//go:linkname readGCStats runtime_debug.readGCStats
+//go:linkname readGCStats runtime..z2fdebug.readGCStats
 func readGCStats(pauses *[]uint64) {
 	systemstack(func() {
 		readGCStats_m(pauses)
diff --git a/libgo/go/runtime/net_plan9.go b/libgo/go/runtime/net_plan9.go
index 77ae8c6..907c319 100644
--- a/libgo/go/runtime/net_plan9.go
+++ b/libgo/go/runtime/net_plan9.go
@@ -8,12 +8,12 @@ import (
 	_ "unsafe"
 )
 
-//go:linkname runtime_ignoreHangup internal_poll.runtime_ignoreHangup
+//go:linkname runtime_ignoreHangup internal..z2fpoll.runtime_ignoreHangup
 func runtime_ignoreHangup() {
 	getg().m.ignoreHangup = true
 }
 
-//go:linkname runtime_unignoreHangup internal_poll.runtime_unignoreHangup
+//go:linkname runtime_unignoreHangup internal..z2fpoll.runtime_unignoreHangup
 func runtime_unignoreHangup(sig string) {
 	getg().m.ignoreHangup = false
 }
diff --git a/libgo/go/runtime/netpoll.go b/libgo/go/runtime/netpoll.go
index ab3d14d..6016b7d 100644
--- a/libgo/go/runtime/netpoll.go
+++ b/libgo/go/runtime/netpoll.go
@@ -85,7 +85,7 @@ var (
 	netpollWaiters uint32
 )
 
-//go:linkname poll_runtime_pollServerInit internal_poll.runtime_pollServerInit
+//go:linkname poll_runtime_pollServerInit internal..z2fpoll.runtime_pollServerInit
 func poll_runtime_pollServerInit() {
 	netpollinit()
 	atomic.Store(&netpollInited, 1)
@@ -95,7 +95,7 @@ func netpollinited() bool {
 	return atomic.Load(&netpollInited) != 0
 }
 
-//go:linkname poll_runtime_pollServerDescriptor internal_poll.runtime_pollServerDescriptor
+//go:linkname poll_runtime_pollServerDescriptor internal..z2fpoll.runtime_pollServerDescriptor
 
 // poll_runtime_pollServerDescriptor returns the descriptor being used,
 // or ^uintptr(0) if the system does not use a poll descriptor.
@@ -103,7 +103,7 @@ func poll_runtime_pollServerDescriptor() uintptr {
 	return netpolldescriptor()
 }
 
-//go:linkname poll_runtime_pollOpen internal_poll.runtime_pollOpen
+//go:linkname poll_runtime_pollOpen internal..z2fpoll.runtime_pollOpen
 func poll_runtime_pollOpen(fd uintptr) (*pollDesc, int) {
 	pd := pollcache.alloc()
 	lock(&pd.lock)
@@ -127,7 +127,7 @@ func poll_runtime_pollOpen(fd uintptr) (*pollDesc, int) {
 	return pd, int(errno)
 }
 
-//go:linkname poll_runtime_pollClose internal_poll.runtime_pollClose
+//go:linkname poll_runtime_pollClose internal..z2fpoll.runtime_pollClose
 func poll_runtime_pollClose(pd *pollDesc) {
 	if !pd.closing {
 		throw("runtime: close polldesc w/o unblock")
@@ -149,7 +149,7 @@ func (c *pollCache) free(pd *pollDesc) {
 	unlock(&c.lock)
 }
 
-//go:linkname poll_runtime_pollReset internal_poll.runtime_pollReset
+//go:linkname poll_runtime_pollReset internal..z2fpoll.runtime_pollReset
 func poll_runtime_pollReset(pd *pollDesc, mode int) int {
 	err := netpollcheckerr(pd, int32(mode))
 	if err != 0 {
@@ -163,7 +163,7 @@ func poll_runtime_pollReset(pd *pollDesc, mode int) int {
 	return 0
 }
 
-//go:linkname poll_runtime_pollWait internal_poll.runtime_pollWait
+//go:linkname poll_runtime_pollWait internal..z2fpoll.runtime_pollWait
 func poll_runtime_pollWait(pd *pollDesc, mode int) int {
 	err := netpollcheckerr(pd, int32(mode))
 	if err != 0 {
@@ -185,7 +185,7 @@ func poll_runtime_pollWait(pd *pollDesc, mode int) int {
 	return 0
 }
 
-//go:linkname poll_runtime_pollWaitCanceled internal_poll.runtime_pollWaitCanceled
+//go:linkname poll_runtime_pollWaitCanceled internal..z2fpoll.runtime_pollWaitCanceled
 func poll_runtime_pollWaitCanceled(pd *pollDesc, mode int) {
 	// This function is used only on windows after a failed attempt to cancel
 	// a pending async IO operation. Wait for ioready, ignore closing or timeouts.
@@ -193,7 +193,7 @@ func poll_runtime_pollWaitCanceled(pd *pollDesc, mode int) {
 	}
 }
 
-//go:linkname poll_runtime_pollSetDeadline internal_poll.runtime_pollSetDeadline
+//go:linkname poll_runtime_pollSetDeadline internal..z2fpoll.runtime_pollSetDeadline
 func poll_runtime_pollSetDeadline(pd *pollDesc, d int64, mode int) {
 	lock(&pd.lock)
 	if pd.closing {
@@ -263,7 +263,7 @@ func poll_runtime_pollSetDeadline(pd *pollDesc, d int64, mode int) {
 	}
 }
 
-//go:linkname poll_runtime_pollUnblock internal_poll.runtime_pollUnblock
+//go:linkname poll_runtime_pollUnblock internal..z2fpoll.runtime_pollUnblock
 func poll_runtime_pollUnblock(pd *pollDesc) {
 	lock(&pd.lock)
 	if pd.closing {
diff --git a/libgo/go/runtime/pprof/mprof_test.go b/libgo/go/runtime/pprof/mprof_test.go
index 5d77a1d..f428827 100644
--- a/libgo/go/runtime/pprof/mprof_test.go
+++ b/libgo/go/runtime/pprof/mprof_test.go
@@ -87,19 +87,19 @@ func TestMemoryProfiler(t *testing.T) {
 
 		fmt.Sprintf(`%v: %v \[%v: %v\] @ 0x[0-9,a-f x]+
 #	0x[0-9,a-f]+	pprof\.allocatePersistent1K\+0x[0-9,a-f]+	.*/mprof_test\.go:40
-#	0x[0-9,a-f]+	runtime_pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test\.go:74
+#	0x[0-9,a-f]+	runtime/pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test\.go:74
 `, 32*memoryProfilerRun, 1024*memoryProfilerRun, 32*memoryProfilerRun, 1024*memoryProfilerRun),
 
 		fmt.Sprintf(`0: 0 \[%v: %v\] @ 0x[0-9,a-f x]+
 #	0x[0-9,a-f]+	pprof\.allocateTransient1M\+0x[0-9,a-f]+	.*/mprof_test.go:21
-#	0x[0-9,a-f]+	runtime_pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:72
+#	0x[0-9,a-f]+	runtime/pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:72
 `, (1<<10)*memoryProfilerRun, (1<<20)*memoryProfilerRun),
 
 		// This should start with "0: 0" but gccgo's imprecise
 		// GC means that sometimes the value is not collected.
 		fmt.Sprintf(`(0|%v): (0|%v) \[%v: %v\] @ 0x[0-9,a-f x]+
 #	0x[0-9,a-f]+	pprof\.allocateTransient2M\+0x[0-9,a-f]+	.*/mprof_test.go:27
-#	0x[0-9,a-f]+	runtime_pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:73
+#	0x[0-9,a-f]+	runtime/pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:73
 `, memoryProfilerRun, (2<<20)*memoryProfilerRun, memoryProfilerRun, (2<<20)*memoryProfilerRun),
 
 		// This should start with "0: 0" but gccgo's imprecise
diff --git a/libgo/go/runtime/proc.go b/libgo/go/runtime/proc.go
index 77d379b..bb16924 100644
--- a/libgo/go/runtime/proc.go
+++ b/libgo/go/runtime/proc.go
@@ -4670,7 +4670,7 @@ func runqsteal(_p_, p2 *p, stealRunNextG bool) *g {
 	return gp
 }
 
-//go:linkname setMaxThreads runtime_debug.setMaxThreads
+//go:linkname setMaxThreads runtime..z2fdebug.setMaxThreads
 func setMaxThreads(in int) (out int) {
 	lock(&sched.lock)
 	out = int(sched.maxmcount)
@@ -4716,13 +4716,13 @@ func sync_runtime_procUnpin() {
 	procUnpin()
 }
 
-//go:linkname sync_atomic_runtime_procPin sync_atomic.runtime_procPin
+//go:linkname sync_atomic_runtime_procPin sync..z2fatomic.runtime_procPin
 //go:nosplit
 func sync_atomic_runtime_procPin() int {
 	return procPin()
 }
 
-//go:linkname sync_atomic_runtime_procUnpin sync_atomic.runtime_procUnpin
+//go:linkname sync_atomic_runtime_procUnpin sync..z2fatomic.runtime_procUnpin
 //go:nosplit
 func sync_atomic_runtime_procUnpin() {
 	procUnpin()
diff --git a/libgo/go/runtime/proflabel.go b/libgo/go/runtime/proflabel.go
index ff73fe4..fc655cc 100644
--- a/libgo/go/runtime/proflabel.go
+++ b/libgo/go/runtime/proflabel.go
@@ -8,7 +8,7 @@ import "unsafe"
 
 var labelSync uintptr
 
-//go:linkname runtime_setProfLabel runtime_pprof.runtime_setProfLabel
+//go:linkname runtime_setProfLabel runtime..z2fpprof.runtime_setProfLabel
 func runtime_setProfLabel(labels unsafe.Pointer) {
 	// Introduce race edge for read-back via profile.
 	// This would more properly use &getg().labels as the sync address,
@@ -34,7 +34,7 @@ func runtime_setProfLabel(labels unsafe.Pointer) {
 	getg().labels = labels
 }
 
-//go:linkname runtime_getProfLabel runtime_pprof.runtime_getProfLabel
+//go:linkname runtime_getProfLabel runtime..z2fpprof.runtime_getProfLabel
 func runtime_getProfLabel() unsafe.Pointer {
 	return getg().labels
 }
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
diff --git a/libgo/go/runtime/runtime1.go b/libgo/go/runtime/runtime1.go
index 8b1b0a0..050f180 100644
--- a/libgo/go/runtime/runtime1.go
+++ b/libgo/go/runtime/runtime1.go
@@ -413,7 +413,7 @@ func parsedebugvars() {
 	traceback_env = traceback_cache
 }
 
-//go:linkname setTraceback runtime_debug.SetTraceback
+//go:linkname setTraceback runtime..z2fdebug.SetTraceback
 func setTraceback(level string) {
 	var t uint32
 	switch level {
diff --git a/libgo/go/runtime/sema.go b/libgo/go/runtime/sema.go
index cb7d3cd..273e8aa 100644
--- a/libgo/go/runtime/sema.go
+++ b/libgo/go/runtime/sema.go
@@ -56,7 +56,7 @@ func sync_runtime_Semacquire(addr *uint32) {
 	semacquire1(addr, false, semaBlockProfile)
 }
 
-//go:linkname poll_runtime_Semacquire internal_poll.runtime_Semacquire
+//go:linkname poll_runtime_Semacquire internal..z2fpoll.runtime_Semacquire
 func poll_runtime_Semacquire(addr *uint32) {
 	semacquire1(addr, false, semaBlockProfile)
 }
@@ -71,7 +71,7 @@ func sync_runtime_SemacquireMutex(addr *uint32, lifo bool) {
 	semacquire1(addr, lifo, semaBlockProfile|semaMutexProfile)
 }
 
-//go:linkname poll_runtime_Semrelease internal_poll.runtime_Semrelease
+//go:linkname poll_runtime_Semrelease internal..z2fpoll.runtime_Semrelease
 func poll_runtime_Semrelease(addr *uint32) {
 	semrelease(addr)
 }
diff --git a/libgo/go/runtime/sigqueue.go b/libgo/go/runtime/sigqueue.go
index cf926a9..1a29b20 100644
--- a/libgo/go/runtime/sigqueue.go
+++ b/libgo/go/runtime/sigqueue.go
@@ -117,7 +117,7 @@ Send:
 
 // Called to receive the next queued signal.
 // Must only be called from a single goroutine at a time.
-//go:linkname signal_recv os_signal.signal_recv
+//go:linkname signal_recv os..z2fsignal.signal_recv
 func signal_recv() uint32 {
 	for {
 		// Serve any signals from local copy.
@@ -161,7 +161,7 @@ func signal_recv() uint32 {
 // the signal(s) in question, and here we are just waiting to make sure
 // that all the signals have been delivered to the user channels
 // by the os/signal package.
-//go:linkname signalWaitUntilIdle os_signal.signalWaitUntilIdle
+//go:linkname signalWaitUntilIdle os..z2fsignal.signalWaitUntilIdle
 func signalWaitUntilIdle() {
 	// Although the signals we care about have been removed from
 	// sig.wanted, it is possible that another thread has received
@@ -181,7 +181,7 @@ func signalWaitUntilIdle() {
 }
 
 // Must only be called from a single goroutine at a time.
-//go:linkname signal_enable os_signal.signal_enable
+//go:linkname signal_enable os..z2fsignal.signal_enable
 func signal_enable(s uint32) {
 	if !sig.inuse {
 		// The first call to signal_enable is for us
@@ -208,7 +208,7 @@ func signal_enable(s uint32) {
 }
 
 // Must only be called from a single goroutine at a time.
-//go:linkname signal_disable os_signal.signal_disable
+//go:linkname signal_disable os..z2fsignal.signal_disable
 func signal_disable(s uint32) {
 	if s >= uint32(len(sig.wanted)*32) {
 		return
@@ -221,7 +221,7 @@ func signal_disable(s uint32) {
 }
 
 // Must only be called from a single goroutine at a time.
-//go:linkname signal_ignore os_signal.signal_ignore
+//go:linkname signal_ignore os..z2fsignal.signal_ignore
 func signal_ignore(s uint32) {
 	if s >= uint32(len(sig.wanted)*32) {
 		return
@@ -248,7 +248,7 @@ func sigInitIgnored(s uint32) {
 }
 
 // Checked by signal handlers.
-//go:linkname signal_ignored os_signal.signal_ignored
+//go:linkname signal_ignored os..z2fsignal.signal_ignored
 func signal_ignored(s uint32) bool {
 	i := atomic.Load(&sig.ignored[s/32])
 	return i&(1<<(s&31)) != 0
diff --git a/libgo/go/runtime/symtab.go b/libgo/go/runtime/symtab.go
index 861921c..d137122 100644
--- a/libgo/go/runtime/symtab.go
+++ b/libgo/go/runtime/symtab.go
@@ -83,6 +83,11 @@ func (ci *Frames) Next() (frame Frame, more bool) {
 	if function == "" && file == "" {
 		return Frame{}, more
 	}
+
+	// Demangle function name if needed.
+	function = demangleSymbol(function)
+
+	// Create entry.
 	entry := funcentry(pc - 1)
 	f := &Func{name: function, entry: entry}
 
@@ -182,6 +187,75 @@ func (f *Func) FileLine(pc uintptr) (file string, line int) {
 	return file, line
 }
 
+func hexval(b byte) uint {
+	if b >= '0' && b <= '9' {
+		return uint(b - '0')
+	}
+	if b >= 'a' && b <= 'f' {
+		return uint(b-'a') + 10
+	}
+	return 0
+}
+
+func hexDigitsToRune(digits []byte, ndig int) rune {
+	result := uint(0)
+	for i := 0; i < ndig; i++ {
+		result <<= uint(4)
+		result |= hexval(digits[i])
+	}
+	return rune(result)
+}
+
+// Perform an in-place decoding on the input byte slice. This looks
+// for "..z<hex 2 >", "..u<hex x 4>" and "..U<hex x 8>" and overwrites
+// with the encoded bytes corresponding to the unicode in question.
+// Return value is the number of bytes taken by the result.
+
+func decodeIdentifier(bsl []byte) int {
+	j := 0
+	for i := 0; i < len(bsl); i++ {
+		b := bsl[i]
+
+		if i+1 < len(bsl) && bsl[i] == '.' && bsl[i+1] == '.' {
+			if i+4 < len(bsl) && bsl[i+2] == 'z' {
+				digits := bsl[i+3:]
+				r := hexDigitsToRune(digits, 2)
+				nc := encoderune(bsl[j:], r)
+				j += nc
+				i += 4
+				continue
+			} else if i+6 < len(bsl) && bsl[i+2] == 'u' {
+				digits := bsl[i+3:]
+				r := hexDigitsToRune(digits, 4)
+				nc := encoderune(bsl[j:], r)
+				j += nc
+				i += 6
+				continue
+			} else if i+10 < len(bsl) && bsl[i+2] == 'U' {
+				digits := bsl[i+3:]
+				r := hexDigitsToRune(digits, 8)
+				nc := encoderune(bsl[j:], r)
+				j += nc
+				i += 10
+				continue
+			}
+		}
+		bsl[j] = b
+		j += 1
+	}
+	return j
+}
+
+// Demangle a function symbol. Applies the reverse of go_encode_id()
+// as used in the compiler.
+
+func demangleSymbol(s string) string {
+	bsl := []byte(s)
+	nchars := decodeIdentifier(bsl)
+	bsl = bsl[:nchars]
+	return string(bsl)
+}
+
 // implemented in go-caller.c
 func funcfileline(uintptr, int32) (string, string, int)
 func funcentry(uintptr) uintptr
diff --git a/libgo/go/runtime/time.go b/libgo/go/runtime/time.go
index a95d95b..ea61baa 100644
--- a/libgo/go/runtime/time.go
+++ b/libgo/go/runtime/time.go
@@ -441,7 +441,7 @@ func badTimer() {
 
 // Entry points for net, time to call nanotime.
 
-//go:linkname poll_runtimeNano internal_poll.runtimeNano
+//go:linkname poll_runtimeNano internal..z2fpoll.runtimeNano
 func poll_runtimeNano() int64 {
 	return nanotime()
 }
diff --git a/libgo/go/runtime/trace.go b/libgo/go/runtime/trace.go
index 7aed9a9..530d5e4 100644
--- a/libgo/go/runtime/trace.go
+++ b/libgo/go/runtime/trace.go
@@ -1143,7 +1143,7 @@ func traceNextGC() {
 // To access runtime functions from runtime/trace.
 // See runtime/trace/annotation.go
 
-//go:linkname trace_userTaskCreate runtime_trace.userTaskCreate
+//go:linkname trace_userTaskCreate runtime..z2ftrace.userTaskCreate
 func trace_userTaskCreate(id, parentID uint64, taskType string) {
 	if !trace.enabled {
 		return
@@ -1161,12 +1161,12 @@ func trace_userTaskCreate(id, parentID uint64, taskType string) {
 	traceReleaseBuffer(pid)
 }
 
-//go:linkname trace_userTaskEnd runtime_trace.userTaskEnd
+//go:linkname trace_userTaskEnd runtime..z2ftrace.userTaskEnd
 func trace_userTaskEnd(id uint64) {
 	traceEvent(traceEvUserTaskEnd, 2, id)
 }
 
-//go:linkname trace_userRegion runtime_trace.userRegion
+//go:linkname trace_userRegion runtime..z2ftrace.userRegion
 func trace_userRegion(id, mode uint64, name string) {
 	if !trace.enabled {
 		return
@@ -1183,7 +1183,7 @@ func trace_userRegion(id, mode uint64, name string) {
 	traceReleaseBuffer(pid)
 }
 
-//go:linkname trace_userLog runtime_trace.userLog
+//go:linkname trace_userLog runtime..z2ftrace.userLog
 func trace_userLog(id uint64, category, message string) {
 	if !trace.enabled {
 		return
diff --git a/libgo/go/runtime/traceback_gccgo.go b/libgo/go/runtime/traceback_gccgo.go
index e97071e..7347cea 100644
--- a/libgo/go/runtime/traceback_gccgo.go
+++ b/libgo/go/runtime/traceback_gccgo.go
@@ -110,9 +110,14 @@ func showframe(name string, gp *g) bool {
 }
 
 // isExportedRuntime reports whether name is an exported runtime function.
-// It is only for runtime functions, so ASCII A-Z is fine.
+// It is only for runtime functions, so ASCII A-Z is fine. Here also check
+// for mangled functions from runtime/<...>, which will be prefixed with
+// "runtime..z2f".
 func isExportedRuntime(name string) bool {
 	const n = len("runtime.")
+	if hasprefix(name, "runtime..z2f") {
+		return true
+	}
 	return len(name) > n && name[:n] == "runtime." && 'A' <= name[n] && name[n] <= 'Z'
 }