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runtime: unify fetching of locals and arguments maps

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Currently we have two nearly identical copies of the code that fetches
the locals and arguments liveness maps for a frame, plus a third
that's a poor knock-off. Unify these all into a single function.

Change-Id: Ibce7926a0b0e3d23182112da4e25df899579a585
Reviewed-on: https://go-review.googlesource.com/109698
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Austin Clements 2018-04-26 21:20:41 -04:00
parent 66a67ee6b4
commit 3080b7d0af
3 changed files with 101 additions and 149 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
src/runtime/mbitmap.go
View File

@ -1999,30 +1999,16 @@ func getgcmask(ep interface{}) (mask []byte) {
_g_ := getg()
gentraceback(_g_.m.curg.sched.pc, _g_.m.curg.sched.sp, 0, _g_.m.curg, 0, nil, 1000, getgcmaskcb, noescape(unsafe.Pointer(&frame)), 0)
if frame.fn.valid() {
f := frame.fn
targetpc := frame.continpc
if targetpc == 0 {
locals, _ := getStackMap(&frame, nil, false)
if locals.n == 0 {
return
}
pcdata := int32(-1) // Use the entry map at function entry
if targetpc != f.entry {
targetpc--
pcdata = pcdatavalue(f, _PCDATA_StackMapIndex, targetpc, nil)
}
if pcdata == -1 {
return
}
stkmap := (*stackmap)(funcdata(f, _FUNCDATA_LocalsPointerMaps))
if stkmap == nil || stkmap.n <= 0 {
return
}
bv := stackmapdata(stkmap, pcdata)
size := uintptr(bv.n) * sys.PtrSize
size := uintptr(locals.n) * sys.PtrSize
n := (*ptrtype)(unsafe.Pointer(t)).elem.size
mask = make([]byte, n/sys.PtrSize)
for i := uintptr(0); i < n; i += sys.PtrSize {
off := (uintptr(p) + i - frame.varp + size) / sys.PtrSize
mask[i/sys.PtrSize] = bv.ptrbit(off)
mask[i/sys.PtrSize] = locals.ptrbit(off)
}
}
return

79
src/runtime/mgcmark.go
View File

@ -791,82 +791,21 @@ func scanstack(gp *g, gcw *gcWork) {
// Scan a stack frame: local variables and function arguments/results.
//go:nowritebarrier
func scanframeworker(frame *stkframe, cache *pcvalueCache, gcw *gcWork) {
if _DebugGC > 1 && frame.continpc != 0 {
print("scanframe ", funcname(frame.fn), "\n")
}
f := frame.fn
targetpc := frame.continpc
if targetpc == 0 {
// Frame is dead.
return
}
if _DebugGC > 1 {
print("scanframe ", funcname(f), "\n")
}
pcdata := int32(-1)
if targetpc != f.entry {
// Back up to the CALL. If we're at the function entry
// point, we want to use the entry map (-1), even if
// the first instruction of the function changes the
// stack map.
targetpc--
pcdata = pcdatavalue(f, _PCDATA_StackMapIndex, targetpc, cache)
}
if pcdata == -1 {
// We do not have a valid pcdata value but there might be a
// stackmap for this function. It is likely that we are looking
// at the function prologue, assume so and hope for the best.
pcdata = 0
}
locals, args := getStackMap(frame, cache, false)
// Scan local variables if stack frame has been allocated.
size := frame.varp - frame.sp
var minsize uintptr
switch sys.ArchFamily {
case sys.ARM64:
minsize = sys.SpAlign
default:
minsize = sys.MinFrameSize
}
if size > minsize {
stkmap := (*stackmap)(funcdata(f, _FUNCDATA_LocalsPointerMaps))
if stkmap == nil || stkmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped locals ", hex(frame.varp-size), "+", hex(size), "\n")
throw("missing stackmap")
}
// Locals bitmap information, scan just the pointers in locals.
if pcdata < 0 || pcdata >= stkmap.n {
// don't know where we are
print("runtime: pcdata is ", pcdata, " and ", stkmap.n, " locals stack map entries for ", funcname(f), " (targetpc=", targetpc, ")\n")
throw("scanframe: bad symbol table")
}
if stkmap.nbit > 0 {
bv := stackmapdata(stkmap, pcdata)
size = uintptr(bv.n) * sys.PtrSize
scanblock(frame.varp-size, size, bv.bytedata, gcw)
}
if locals.n > 0 {
size := uintptr(locals.n) * sys.PtrSize
scanblock(frame.varp-size, size, locals.bytedata, gcw)
}
// Scan arguments.
if frame.arglen > 0 {
var bv bitvector
if frame.argmap != nil {
bv = *frame.argmap
} else {
stkmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
if stkmap == nil || stkmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped args ", hex(frame.argp), "+", hex(frame.arglen), "\n")
throw("missing stackmap")
}
if pcdata < 0 || pcdata >= stkmap.n {
// don't know where we are
print("runtime: pcdata is ", pcdata, " and ", stkmap.n, " args stack map entries for ", funcname(f), " (targetpc=", targetpc, ")\n")
throw("scanframe: bad symbol table")
}
bv = stackmapdata(stkmap, pcdata)
}
if bv.n > 0 {
scanblock(frame.argp, uintptr(bv.n)*sys.PtrSize, bv.bytedata, gcw)
}
if args.n > 0 {
scanblock(frame.argp, uintptr(args.n)*sys.PtrSize, args.bytedata, gcw)
}
}

149
src/runtime/stack.go
View File

@ -606,8 +606,7 @@ func adjustpointers(scanp unsafe.Pointer, bv *bitvector, adjinfo *adjustinfo, f
// Note: the argument/return area is adjusted by the callee.
func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
adjinfo := (*adjustinfo)(arg)
targetpc := frame.continpc
if targetpc == 0 {
if frame.continpc == 0 {
// Frame is dead.
return true
}
@ -621,47 +620,13 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
// have full GC info for it (because it is written in asm).
return true
}
pcdata := int32(-1) // Use the entry map at function entry
if targetpc != f.entry {
targetpc--
pcdata = pcdatavalue(f, _PCDATA_StackMapIndex, targetpc, &adjinfo.cache)
}
if pcdata == -1 {
pcdata = 0 // in prologue
}
locals, args := getStackMap(frame, &adjinfo.cache, true)
// Adjust local variables if stack frame has been allocated.
size := frame.varp - frame.sp
var minsize uintptr
switch sys.ArchFamily {
case sys.ARM64:
minsize = sys.SpAlign
default:
minsize = sys.MinFrameSize
}
if size > minsize {
stackmap := (*stackmap)(funcdata(f, _FUNCDATA_LocalsPointerMaps))
if stackmap == nil || stackmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped locals ", hex(frame.varp-size), "+", hex(size), "\n")
throw("missing stackmap")
}
// If nbit == 0, there's no work to do.
if stackmap.nbit > 0 {
// Locals bitmap information, scan just the pointers in locals.
if pcdata < 0 || pcdata >= stackmap.n {
// don't know where we are
print("runtime: pcdata is ", pcdata, " and ", stackmap.n, " locals stack map entries for ", funcname(f), " (targetpc=", targetpc, ")\n")
throw("bad symbol table")
}
bv := stackmapdata(stackmap, pcdata)
size = uintptr(bv.n) * sys.PtrSize
if stackDebug >= 3 {
print(" locals ", pcdata, "/", stackmap.n, " ", size/sys.PtrSize, " words ", bv.bytedata, "\n")
}
adjustpointers(unsafe.Pointer(frame.varp-size), &bv, adjinfo, f)
} else if stackDebug >= 3 {
print(" no locals to adjust\n")
}
if locals.n > 0 {
size := uintptr(locals.n) * sys.PtrSize
adjustpointers(unsafe.Pointer(frame.varp-size), &locals, adjinfo, f)
}
// Adjust saved base pointer if there is one.
@ -688,29 +653,11 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
}
// Adjust arguments.
if frame.arglen > 0 {
var bv bitvector
if frame.argmap != nil {
bv = *frame.argmap
} else {
stackmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
if stackmap == nil || stackmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped args ", frame.argp, "+", frame.arglen, "\n")
throw("missing stackmap")
}
if pcdata < 0 || pcdata >= stackmap.n {
// don't know where we are
print("runtime: pcdata is ", pcdata, " and ", stackmap.n, " args stack map entries for ", funcname(f), " (targetpc=", targetpc, ")\n")
throw("bad symbol table")
}
bv = stackmapdata(stackmap, pcdata)
}
if args.n > 0 {
if stackDebug >= 3 {
print(" args\n")
}
if bv.n > 0 {
adjustpointers(unsafe.Pointer(frame.argp), &bv, adjinfo, funcInfo{})
}
adjustpointers(unsafe.Pointer(frame.argp), &args, adjinfo, funcInfo{})
}
return true
}
@ -1186,6 +1133,86 @@ func freeStackSpans() {
unlock(&stackLarge.lock)
}
// getStackMap returns the locals and arguments live pointer maps for
// frame.
func getStackMap(frame *stkframe, cache *pcvalueCache, debug bool) (locals, args bitvector) {
targetpc := frame.continpc
if targetpc == 0 {
// Frame is dead. Return empty bitvectors.
return
}
f := frame.fn
pcdata := int32(-1)
if targetpc != f.entry {
// Back up to the CALL. If we're at the function entry
// point, we want to use the entry map (-1), even if
// the first instruction of the function changes the
// stack map.
targetpc--
pcdata = pcdatavalue(f, _PCDATA_StackMapIndex, targetpc, cache)
}
if pcdata == -1 {
// We do not have a valid pcdata value but there might be a
// stackmap for this function. It is likely that we are looking
// at the function prologue, assume so and hope for the best.
pcdata = 0
}
// Local variables.
size := frame.varp - frame.sp
var minsize uintptr
switch sys.ArchFamily {
case sys.ARM64:
minsize = sys.SpAlign
default:
minsize = sys.MinFrameSize
}
if size > minsize {
stackmap := (*stackmap)(funcdata(f, _FUNCDATA_LocalsPointerMaps))
if stackmap == nil || stackmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped locals ", hex(frame.varp-size), "+", hex(size), "\n")
throw("missing stackmap")
}
// If nbit == 0, there's no work to do.
if stackmap.nbit > 0 {
if pcdata < 0 || pcdata >= stackmap.n {
// don't know where we are
print("runtime: pcdata is ", pcdata, " and ", stackmap.n, " locals stack map entries for ", funcname(f), " (targetpc=", hex(targetpc), ")\n")
throw("bad symbol table")
}
locals = stackmapdata(stackmap, pcdata)
if stackDebug >= 3 && debug {
print(" locals ", pcdata, "/", stackmap.n, " ", locals.n, " words ", locals.bytedata, "\n")
}
} else if stackDebug >= 3 && debug {
print(" no locals to adjust\n")
}
}
// Arguments.
if frame.arglen > 0 {
if frame.argmap != nil {
args = *frame.argmap
} else {
stackmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
if stackmap == nil || stackmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped args ", hex(frame.argp), "+", hex(frame.arglen), "\n")
throw("missing stackmap")
}
if pcdata < 0 || pcdata >= stackmap.n {
// don't know where we are
print("runtime: pcdata is ", pcdata, " and ", stackmap.n, " args stack map entries for ", funcname(f), " (targetpc=", hex(targetpc), ")\n")
throw("bad symbol table")
}
if stackmap.nbit > 0 {
args = stackmapdata(stackmap, pcdata)
}
}
}
return
}
//go:nosplit
func morestackc() {
throw("attempt to execute system stack code on user stack")