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Commit b76e6f88 authored by Bryan C. Mills's avatar Bryan C. Mills
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Revert "cmd/compile, cmd/link, runtime: make defers low-cost through inline... 

Revert "cmd/compile, cmd/link, runtime: make defers low-cost through inline code and extra funcdata"

This reverts CL 190098.

Reason for revert: broke several builders.

Change-Id: I69161352f9ded02537d8815f259c4d391edd9220
Reviewed-on: https://go-review.googlesource.com/c/go/+/201519
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: default avatarAustin Clements <austin@google.com>
Reviewed-by: default avatarDan Scales <danscales@google.com>
parent 2718789b
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Inline Side-by-side
Showing with 146 additions and 1188 deletions
src/cmd/compile/internal/gc/escape.go
View file @ b76e6f88
......@@ -371,7 +371,6 @@ func (e *Escape) stmt(n *Node) {
e.stmts(n.Right.Ninit)
e.call(e.addrs(n.List), n.Right, nil)
case ORETURN:
e.curfn.Func.numReturns++
results := e.curfn.Type.Results().FieldSlice()
for i, v := range n.List.Slice() {
e.assign(asNode(results[i].Nname), v, "return", n)
......@@ -379,16 +378,6 @@ func (e *Escape) stmt(n *Node) {
case OCALLFUNC, OCALLMETH, OCALLINTER, OCLOSE, OCOPY, ODELETE, OPANIC, OPRINT, OPRINTN, ORECOVER:
e.call(nil, n, nil)
case OGO, ODEFER:
if n.Op == ODEFER {
e.curfn.Func.SetHasDefer(true)
e.curfn.Func.numDefers++
if e.curfn.Func.numDefers > maxOpenDefers {
// Don't allow open defers if there are more than
// 8 defers in the function, since we use a single
// byte to record active defers.
e.curfn.Func.SetOpenCodedDeferDisallowed(true)
}
}
e.stmts(n.Left.Ninit)
e.call(nil, n.Left, n)
......@@ -883,13 +872,8 @@ func (e *Escape) augmentParamHole(k EscHole, where *Node) EscHole {
// non-transient location to avoid arguments from being
// transiently allocated.
if where.Op == ODEFER && e.loopDepth == 1 {
// force stack allocation of defer record, unless open-coded
// defers are used (see ssa.go)
where.Esc = EscNever
where.Esc = EscNever // force stack allocation of defer record (see ssa.go)
return e.later(k)
} else if where.Op == ODEFER {
// If any defer occurs in a loop, open-coded defers cannot be used
e.curfn.Func.SetOpenCodedDeferDisallowed(true)
}
return e.heapHole()
......
src/cmd/compile/internal/gc/main.go
View file @ b76e6f88
......@@ -52,7 +52,6 @@ var (
Debug_typecheckinl int
Debug_gendwarfinl int
Debug_softfloat int
Debug_defer int
)
// Debug arguments.
......@@ -82,7 +81,6 @@ var debugtab = []struct {
{"typecheckinl", "eager typechecking of inline function bodies", &Debug_typecheckinl},
{"dwarfinl", "print information about DWARF inlined function creation", &Debug_gendwarfinl},
{"softfloat", "force compiler to emit soft-float code", &Debug_softfloat},
{"defer", "print information about defer compilation", &Debug_defer},
}
const debugHelpHeader = `usage: -d arg[,arg]* and arg is <key>[=<value>]
......
src/cmd/compile/internal/gc/obj.go
View file @ b76e6f88
......@@ -294,9 +294,6 @@ func addGCLocals() {
}
ggloblsym(x, int32(len(x.P)), attr)
}
if x := s.Func.OpenCodedDeferInfo; x != nil {
ggloblsym(x, int32(len(x.P)), obj.RODATA|obj.DUPOK)
}
}
}
......
src/cmd/compile/internal/gc/reflect.go
View file @ b76e6f88
......@@ -338,7 +338,6 @@ func deferstruct(stksize int64) *types.Type {
makefield("siz", types.Types[TUINT32]),
makefield("started", types.Types[TBOOL]),
makefield("heap", types.Types[TBOOL]),
makefield("openDefer", types.Types[TBOOL]),
makefield("sp", types.Types[TUINTPTR]),
makefield("pc", types.Types[TUINTPTR]),
// Note: the types here don't really matter. Defer structures
......@@ -347,9 +346,6 @@ func deferstruct(stksize int64) *types.Type {
makefield("fn", types.Types[TUINTPTR]),
makefield("_panic", types.Types[TUINTPTR]),
makefield("link", types.Types[TUINTPTR]),
makefield("framepc", types.Types[TUINTPTR]),
makefield("varp", types.Types[TUINTPTR]),
makefield("fd", types.Types[TUINTPTR]),
makefield("args", argtype),
}
......
src/cmd/compile/internal/gc/sizeof_test.go
View file @ b76e6f88
......@@ -20,7 +20,7 @@ func TestSizeof(t *testing.T) {
_32bit uintptr // size on 32bit platforms
_64bit uintptr // size on 64bit platforms
}{
{Func{}, 124, 224},
{Func{}, 116, 208},
{Name{}, 32, 56},
{Param{}, 24, 48},
{Node{}, 76, 128},
......
src/cmd/compile/internal/gc/ssa.go
View file @ b76e6f88
......@@ -29,10 +29,6 @@ var ssaDumpStdout bool // whether to dump to stdout
var ssaDumpCFG string // generate CFGs for these phases
const ssaDumpFile = "ssa.html"
// The max number of defers in a function using open-coded defers. We enforce this
// limit because the deferBits bitmask is currently a single byte (to minimize code size)
const maxOpenDefers = 8
// ssaDumpInlined holds all inlined functions when ssaDump contains a function name.
var ssaDumpInlined []*Node
......@@ -169,107 +165,6 @@ func initssaconfig() {
SigPanic = sysfunc("sigpanic")
}
// getParam returns the Field of ith param of node n (which is a
// function/method/interface call), where the receiver of a method call is
// considered as the 0th parameter. This does not include the receiver of an
// interface call.
func getParam(n *Node, i int) *types.Field {
t := n.Left.Type
if n.Op == OCALLMETH {
if i == 0 {
return t.Recv()
}
return t.Params().Field(i - 1)
}
return t.Params().Field(i)
}
// dvarint writes a varint v to the funcdata in symbol x and returns the new offset
func dvarint(x *obj.LSym, off int, v int64) int {
if v < 0 || v > 1e9 {
panic(fmt.Sprintf("dvarint: bad offset for funcdata - %v", v))
}
if v < 1<<7 {
return duint8(x, off, uint8(v))
}
off = duint8(x, off, uint8((v&127)|128))
if v < 1<<14 {
return duint8(x, off, uint8(v>>7))
}
off = duint8(x, off, uint8(((v>>7)&127)|128))
if v < 1<<21 {
return duint8(x, off, uint8(v>>14))
}
off = duint8(x, off, uint8(((v>>14)&127)|128))
if v < 1<<28 {
return duint8(x, off, uint8(v>>21))
}
off = duint8(x, off, uint8(((v>>21)&127)|128))
return duint8(x, off, uint8(v>>28))
}
// emitOpenDeferInfo emits FUNCDATA information about the defers in a function
// that is using open-coded defers. This funcdata is used to determine the active
// defers in a function and execute those defers during panic processing.
//
// The funcdata is all encoded in varints (since values will almost always be less
// than 128, but stack offsets could potentially be up to 2Gbyte). All "locations"
// for stack variables are specified as the number of bytes below varp for their
// starting address. The format is:
//
// - Max total argument size among all the defers
// - Location of the deferBits variable
// - Number of defers in the function
// - Information about each defer call, in reverse order of appearance in the function:
// - Total argument size of the call
// - Location of the closure value to call
// - 1 or 0 to indicate if there is a receiver for the call
// - If yes, then the location of the receiver value
// - Number of arguments
// - Information about each argument
// - Location of the stored defer argument in this function's frame
// - Size of the argument
// - Offset of where argument should be placed in the args frame when making call
func emitOpenDeferInfo(s state) {
x := Ctxt.Lookup(s.curfn.Func.lsym.Name + ".opendefer")
s.curfn.Func.lsym.Func.OpenCodedDeferInfo = x
off := 0
// Compute maxargsize (max size of arguments for all defers)
// first, so we can output it first to the funcdata
var maxargsize int64
for i := len(s.opendefers) - 1; i >= 0; i-- {
r := s.opendefers[i]
argsize := r.n.Left.Type.ArgWidth()
if argsize > maxargsize {
maxargsize = argsize
}
}
off = dvarint(x, off, maxargsize)
off = dvarint(x, off, -s.deferBitsTemp.Xoffset)
off = dvarint(x, off, int64(len(s.opendefers)))
// Write in reverse-order, for ease of running in that order at runtime
for i := len(s.opendefers) - 1; i >= 0; i-- {
r := s.opendefers[i]
off = dvarint(x, off, r.n.Left.Type.ArgWidth())
off = dvarint(x, off, -r.closureNode.Xoffset)
if r.rcvrNode != nil {
off = dvarint(x, off, 1)
off = dvarint(x, off, -r.rcvrNode.Xoffset)
} else {
off = dvarint(x, off, 0)
}
off = dvarint(x, off, int64(len(r.argNodes)))
for j, arg := range r.argNodes {
f := getParam(r.n, j)
off = dvarint(x, off, -arg.Xoffset)
off = dvarint(x, off, f.Type.Size())
off = dvarint(x, off, f.Offset)
}
}
}
// buildssa builds an SSA function for fn.
// worker indicates which of the backend workers is doing the processing.
func buildssa(fn *Node, worker int) *ssa.Func {
......@@ -332,48 +227,11 @@ func buildssa(fn *Node, worker int) *ssa.Func {
s.labeledNodes = map[*Node]*ssaLabel{}
s.fwdVars = map[*Node]*ssa.Value{}
s.startmem = s.entryNewValue0(ssa.OpInitMem, types.TypeMem)
s.hasOpenDefers = Debug['N'] == 0 && s.hasdefer && !s.curfn.Func.OpenCodedDeferDisallowed()
if s.hasOpenDefers && s.curfn.Func.Exit.Len() > 0 {
// Skip doing open defers if there is any extra exit code (likely
// copying heap-allocated return values or race detection), since
// we will not generate that code in the case of the extra
// deferreturn/ret segment.
s.hasOpenDefers = false
}
if s.hasOpenDefers &&
s.curfn.Func.numReturns*s.curfn.Func.numDefers > 15 {
// Since we are generating defer calls at every exit for
// open-coded defers, skip doing open-coded defers if there are
// too many returns (especially if there are multiple defers).
// Open-coded defers are most important for improving performance
// for smaller functions (which don't have many returns).
s.hasOpenDefers = false
}
s.sp = s.entryNewValue0(ssa.OpSP, types.Types[TUINTPTR]) // TODO: use generic pointer type (unsafe.Pointer?) instead
s.sb = s.entryNewValue0(ssa.OpSB, types.Types[TUINTPTR])
s.startBlock(s.f.Entry)
s.vars[&memVar] = s.startmem
if s.hasOpenDefers {
// Create the deferBits variable and stack slot. deferBits is a
// bitmask showing which of the open-coded defers in this function
// have been activated.
deferBitsTemp := tempAt(src.NoXPos, s.curfn, types.Types[TUINT8])
s.deferBitsTemp = deferBitsTemp
// For this value, AuxInt is initialized to zero by default
startDeferBits := s.entryNewValue0(ssa.OpConst8, types.Types[TUINT8])
s.vars[&deferBitsVar] = startDeferBits
s.deferBitsAddr = s.addr(deferBitsTemp, false)
s.store(types.Types[TUINT8], s.deferBitsAddr, startDeferBits)
// Make sure that the deferBits stack slot is kept alive (for use
// by panics) and stores to deferBits are not eliminated, even if
// all checking code on deferBits in the function exit can be
// eliminated, because the defer statements were all
// unconditional.
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, deferBitsTemp, s.mem(), false)
}
// Generate addresses of local declarations
s.decladdrs = map[*Node]*ssa.Value{}
......@@ -429,11 +287,6 @@ func buildssa(fn *Node, worker int) *ssa.Func {
// Main call to ssa package to compile function
ssa.Compile(s.f)
if s.hasOpenDefers {
emitOpenDeferInfo(s)
}
return s.f
}
......@@ -522,29 +375,6 @@ func (s *state) updateUnsetPredPos(b *ssa.Block) {
}
}
// Information about each open-coded defer.
type openDeferInfo struct {
// The ODEFER node representing the function call of the defer
n *Node
// If defer call is closure call, the address of the argtmp where the
// closure is stored.
closure *ssa.Value
// The node representing the argtmp where the closure is stored - used for
// function, method, or interface call, to store a closure that panic
// processing can use for this defer.
closureNode *Node
// If defer call is interface call, the address of the argtmp where the
// receiver is stored
rcvr *ssa.Value
// The node representing the argtmp where the receiver is stored
rcvrNode *Node
// The addresses of the argtmps where the evaluated arguments of the defer
// function call are stored.
argVals []*ssa.Value
// The nodes representing the argtmps where the args of the defer are stored
argNodes []*Node
}
type state struct {
// configuration (arch) information
config *ssa.Config
......@@ -586,9 +416,6 @@ type state struct {
startmem *ssa.Value
sp *ssa.Value
sb *ssa.Value
// value representing address of where deferBits autotmp is stored
deferBitsAddr *ssa.Value
deferBitsTemp *Node
// line number stack. The current line number is top of stack
line []src.XPos
......@@ -605,19 +432,6 @@ type state struct {
cgoUnsafeArgs bool
hasdefer bool // whether the function contains a defer statement
softFloat bool
hasOpenDefers bool // whether we are doing open-coded defers
// If doing open-coded defers, list of info about the defer calls in
// scanning order. Hence, at exit we should run these defers in reverse
// order of this list
opendefers []*openDeferInfo
// For open-coded defers, this is the beginning and end blocks of the last
// defer exit code that we have generated so far. We use these to share
// code between exits if the shareDeferExits option (disabled by default)
// is on.
lastDeferExit *ssa.Block // Entry block of last defer exit code we generated
lastDeferFinalBlock *ssa.Block // Final block of last defer exit code we generated
lastDeferCount int // Number of defers encountered at that point
}
type funcLine struct {
......@@ -661,7 +475,6 @@ var (
capVar = Node{Op: ONAME, Sym: &types.Sym{Name: "cap"}}
typVar = Node{Op: ONAME, Sym: &types.Sym{Name: "typ"}}
okVar = Node{Op: ONAME, Sym: &types.Sym{Name: "ok"}}
deferBitsVar = Node{Op: ONAME, Sym: &types.Sym{Name: "deferBits"}}
)
// startBlock sets the current block we're generating code in to b.
......@@ -1052,27 +865,11 @@ func (s *state) stmt(n *Node) {
}
}
case ODEFER:
if Debug_defer > 0 {
var defertype string
if s.hasOpenDefers {
defertype = "open-coded"
} else if n.Esc == EscNever {
defertype = "stack-allocated"
} else {
defertype = "heap-allocated"
}
Warnl(n.Pos, "defer: %s defer in function %s",
defertype, s.curfn.funcname())
}
if s.hasOpenDefers {
s.openDeferRecord(n.Left)
} else {
d := callDefer
if n.Esc == EscNever {
d = callDeferStack
}
s.call(n.Left, d)
}
case OGO:
s.call(n.Left, callGo)
......@@ -1489,29 +1286,13 @@ func (s *state) stmt(n *Node) {
}
}
// If true, share as many open-coded defer exits as possible (with the downside of
// worse line-number information)
const shareDeferExits = false
// exit processes any code that needs to be generated just before returning.
// It returns a BlockRet block that ends the control flow. Its control value
// will be set to the final memory state.
func (s *state) exit() *ssa.Block {
if s.hasdefer {
if s.hasOpenDefers {
if shareDeferExits && s.lastDeferExit != nil && len(s.opendefers) == s.lastDeferCount {
if s.curBlock.Kind != ssa.BlockPlain {
panic("Block for an exit should be BlockPlain")
}
s.curBlock.AddEdgeTo(s.lastDeferExit)
s.endBlock()
return s.lastDeferFinalBlock
}
s.openDeferExit()
} else {
s.rtcall(Deferreturn, true, nil)
}
}
// Run exit code. Typically, this code copies heap-allocated PPARAMOUT
// variables back to the stack.
......@@ -1533,9 +1314,6 @@ func (s *state) exit() *ssa.Block {
b := s.endBlock()
b.Kind = ssa.BlockRet
b.SetControl(m)
if s.hasdefer && s.hasOpenDefers {
s.lastDeferFinalBlock = b
}
return b
}
......@@ -3986,230 +3764,6 @@ func (s *state) intrinsicArgs(n *Node) []*ssa.Value {
return args
}
// openDeferRecord adds code to evaluate and store the args for an open-code defer
// call, and records info about the defer, so we can generate proper code on the
// exit paths. n is the sub-node of the defer node that is the actual function
// call. We will also record funcdata information on where the args are stored
// (as well as the deferBits variable), and this will enable us to run the proper
// defer calls during panics.
func (s *state) openDeferRecord(n *Node) {
index := len(s.opendefers)
// Do any needed expression evaluation for the args (including the
// receiver, if any). This may be evaluating something like 'autotmp_3 =
// once.mutex'. Such a statement will create a mapping in s.vars[] from
// the autotmp name to the evaluated SSA arg value, but won't do any
// stores to the stack.
s.stmtList(n.List)
args := []*ssa.Value{}
argNodes := []*Node{}
opendefer := &openDeferInfo{
n: n,
}
fn := n.Left
if n.Op == OCALLFUNC {
// We must always store the function value in a stack slot for the
// runtime panic code to use. But in the defer exit code, we will
// call the function directly if it is a static function.
closureVal := s.expr(fn)
closure := s.openDeferSave(fn, fn.Type, closureVal)
opendefer.closureNode = closure.Aux.(*Node)
if !(fn.Op == ONAME && fn.Class() == PFUNC) {
opendefer.closure = closure
}
} else if n.Op == OCALLMETH {
if fn.Op != ODOTMETH {
Fatalf("OCALLMETH: n.Left not an ODOTMETH: %v", fn)
}
closureVal := s.getMethodClosure(fn)
// We must always store the function value in a stack slot for the
// runtime panic code to use. But in the defer exit code, we will
// call the method directly.
closure := s.openDeferSave(fn, fn.Type, closureVal)
opendefer.closureNode = closure.Aux.(*Node)
} else {
if fn.Op != ODOTINTER {
Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op)
}
closure, rcvr := s.getClosureAndRcvr(fn)
opendefer.closure = s.openDeferSave(fn, closure.Type, closure)
// Important to get the receiver type correct, so it is recognized
// as a pointer for GC purposes.
opendefer.rcvr = s.openDeferSave(nil, fn.Type.Recv().Type, rcvr)
opendefer.closureNode = opendefer.closure.Aux.(*Node)
opendefer.rcvrNode = opendefer.rcvr.Aux.(*Node)
}
for _, argn := range n.Rlist.Slice() {
v := s.openDeferSave(argn, argn.Type, s.expr(argn))
args = append(args, v)
argNodes = append(argNodes, v.Aux.(*Node))
}
opendefer.argVals = args
opendefer.argNodes = argNodes
s.opendefers = append(s.opendefers, opendefer)
// Update deferBits only after evaluation and storage to stack of
// args/receiver/interface is successful.
bitvalue := s.constInt8(types.Types[TUINT8], 1<<uint(index))
newDeferBits := s.newValue2(ssa.OpOr8, types.Types[TUINT8], s.variable(&deferBitsVar, types.Types[TUINT8]), bitvalue)
s.vars[&deferBitsVar] = newDeferBits
s.store(types.Types[TUINT8], s.deferBitsAddr, newDeferBits)
}
// openDeferSave generates SSA nodes to store a value val (with type t) for an
// open-coded defer on the stack at an explicit autotmp location, so it can be
// reloaded and used for the appropriate call on exit. n is the associated node,
// which is only needed if the associated type is non-SSAable. It returns an SSA
// value representing a pointer to the stack location.
func (s *state) openDeferSave(n *Node, t *types.Type, val *ssa.Value) *ssa.Value {
argTemp := tempAt(val.Pos.WithNotStmt(), s.curfn, t)
var addrArgTemp *ssa.Value
// Use OpVarLive to make sure stack slots for the args, etc. are not
// removed by dead-store elimination
if s.curBlock.ID != s.f.Entry.ID {
// Force the argtmp storing this defer function/receiver/arg to be
// declared in the entry block, so that it will be live for the
// defer exit code (which will actually access it only if the
// associated defer call has been activated).
s.defvars[s.f.Entry.ID][&memVar] = s.entryNewValue1A(ssa.OpVarDef, types.TypeMem, argTemp, s.defvars[s.f.Entry.ID][&memVar])
s.defvars[s.f.Entry.ID][&memVar] = s.entryNewValue1A(ssa.OpVarLive, types.TypeMem, argTemp, s.defvars[s.f.Entry.ID][&memVar])
addrArgTemp = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(argTemp.Type), argTemp, s.sp, s.defvars[s.f.Entry.ID][&memVar])
} else {
// Special case if we're still in the entry block. We can't use
// the above code, since s.defvars[s.f.Entry.ID] isn't defined
// until we end the entry block with s.endBlock().
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, argTemp, s.mem(), false)
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, argTemp, s.mem(), false)
addrArgTemp = s.newValue2Apos(ssa.OpLocalAddr, types.NewPtr(argTemp.Type), argTemp, s.sp, s.mem(), false)
}
if types.Haspointers(t) {
// Since we may use this argTemp during exit depending on the
// deferBits, we must define it unconditionally on entry.
// Therefore, we must make sure it is zeroed out in the entry
// block if it contains pointers, else GC may wrongly follow an
// uninitialized pointer value.
argTemp.Name.SetNeedzero(true)
}
if !canSSAType(t) {
if n.Op != ONAME {
panic(fmt.Sprintf("Non-SSAable value should be a named location: %v", n))
}
a := s.addr(n, false)
s.move(t, addrArgTemp, a)
return addrArgTemp
}
// We are storing to the stack, hence we can avoid the full checks in
// storeType() (no write barrier) and do a simple store().
s.store(t, addrArgTemp, val)
return addrArgTemp
}
// openDeferExit generates SSA for processing all the open coded defers at exit.
// The code involves loading deferBits, and checking each of the bits to see if
// the corresponding defer statement was executed. For each bit that is turned
// on, the associated defer call is made.
func (s *state) openDeferExit() {
deferExit := s.f.NewBlock(ssa.BlockPlain)
s.endBlock().AddEdgeTo(deferExit)
s.startBlock(deferExit)
s.lastDeferExit = deferExit
s.lastDeferCount = len(s.opendefers)
zeroval := s.constInt8(types.Types[TUINT8], 0)
// Test for and run defers in reverse order
for i := len(s.opendefers) - 1; i >= 0; i-- {
r := s.opendefers[i]
bCond := s.f.NewBlock(ssa.BlockPlain)
bEnd := s.f.NewBlock(ssa.BlockPlain)
deferBits := s.variable(&deferBitsVar, types.Types[TUINT8])
// Generate code to check if the bit associated with the current
// defer is set.
bitval := s.constInt8(types.Types[TUINT8], 1<<uint(i))
andval := s.newValue2(ssa.OpAnd8, types.Types[TUINT8], deferBits, bitval)
eqVal := s.newValue2(ssa.OpEq8, types.Types[TBOOL], andval, zeroval)
b := s.endBlock()
b.Kind = ssa.BlockIf
b.SetControl(eqVal)
b.AddEdgeTo(bEnd)
b.AddEdgeTo(bCond)
bCond.AddEdgeTo(bEnd)
s.startBlock(bCond)
// Clear this bit in deferBits and force store back to stack, so
// we will not try to re-run this defer call if this defer call panics.
nbitval := s.newValue1(ssa.OpCom8, types.Types[TUINT8], bitval)
maskedval := s.newValue2(ssa.OpAnd8, types.Types[TUINT8], deferBits, nbitval)
s.store(types.Types[TUINT8], s.deferBitsAddr, maskedval)
// Use this value for following tests, so we keep previous
// bits cleared.
s.vars[&deferBitsVar] = maskedval
// Generate code to call the function call of the defer, using the
// closure/receiver/args that were stored in argtmps at the point
// of the defer statement.
argStart := Ctxt.FixedFrameSize()
fn := r.n.Left
stksize := fn.Type.ArgWidth()
if r.rcvr != nil {
// rcvr in case of OCALLINTER
v := s.load(r.rcvr.Type.Elem(), r.rcvr)
addr := s.constOffPtrSP(s.f.Config.Types.UintptrPtr, argStart)
s.store(types.Types[TUINTPTR], addr, v)
}
for j, argAddrVal := range r.argVals {
f := getParam(r.n, j)
pt := types.NewPtr(f.Type)
addr := s.constOffPtrSP(pt, argStart+f.Offset)
if !canSSAType(f.Type) {
s.move(f.Type, addr, argAddrVal)
} else {
argVal := s.load(f.Type, argAddrVal)
s.storeType(f.Type, addr, argVal, 0, false)
}
}
var call *ssa.Value
if r.closure != nil {
v := s.load(r.closure.Type.Elem(), r.closure)
s.maybeNilCheckClosure(v, callDefer)
codeptr := s.rawLoad(types.Types[TUINTPTR], v)
call = s.newValue3(ssa.OpClosureCall, types.TypeMem, codeptr, v, s.mem())
} else {
// Do a static call if the original call was a static function or method
call = s.newValue1A(ssa.OpStaticCall, types.TypeMem, fn.Sym.Linksym(), s.mem())
}
call.AuxInt = stksize
s.vars[&memVar] = call
// Make sure that the stack slots with pointers are kept live
// through the call (which is a pre-emption point). Also, we will
// use the first call of the last defer exit to compute liveness
// for the deferreturn, so we want all stack slots to be live.
if r.closureNode != nil {
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, r.closureNode, s.mem(), false)
}
if r.rcvrNode != nil {
if types.Haspointers(r.rcvrNode.Type) {
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, r.rcvrNode, s.mem(), false)
}
}
for _, argNode := range r.argNodes {
if types.Haspointers(argNode.Type) {
s.vars[&memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, argNode, s.mem(), false)
}
}
if i == len(s.opendefers)-1 {
// Record the call of the first defer. This will be used
// to set liveness info for the deferreturn (which is also
// used for any location that causes a runtime panic)
s.f.LastDeferExit = call
}
s.endBlock()
s.startBlock(bEnd)
}
}
// Calls the function n using the specified call type.
// Returns the address of the return value (or nil if none).
func (s *state) call(n *Node, k callKind) *ssa.Value {
......@@ -4225,10 +3779,11 @@ func (s *state) call(n *Node, k callKind) *ssa.Value {
break
}
closure = s.expr(fn)
if k != callDefer && k != callDeferStack {
// Deferred nil function needs to panic when the function is invoked,
// not the point of defer statement.
s.maybeNilCheckClosure(closure, k)
if k != callDefer && k != callDeferStack && (thearch.LinkArch.Family == sys.Wasm || objabi.GOOS == "aix" && k != callGo) {
// Deferred nil function needs to panic when the function is invoked, not the point of defer statement.
// On AIX, the closure needs to be verified as fn can be nil, except if it's a call go. This needs to be handled by the runtime to have the "go of nil func value" error.
// TODO(neelance): On other architectures this should be eliminated by the optimization steps
s.nilCheck(closure)
}
case OCALLMETH:
if fn.Op != ODOTMETH {
......@@ -4238,20 +3793,35 @@ func (s *state) call(n *Node, k callKind) *ssa.Value {
sym = fn.Sym
break
}
closure = s.getMethodClosure(fn)
// Make a name n2 for the function.
// fn.Sym might be sync.(*Mutex).Unlock.
// Make a PFUNC node out of that, then evaluate it.
// We get back an SSA value representing &sync.(*Mutex).Unlock·f.
// We can then pass that to defer or go.
n2 := newnamel(fn.Pos, fn.Sym)
n2.Name.Curfn = s.curfn
n2.SetClass(PFUNC)
// n2.Sym already existed, so it's already marked as a function.
n2.Pos = fn.Pos
n2.Type = types.Types[TUINT8] // dummy type for a static closure. Could use runtime.funcval if we had it.
closure = s.expr(n2)
// Note: receiver is already present in n.Rlist, so we don't
// want to set it here.
case OCALLINTER:
if fn.Op != ODOTINTER {
s.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op)
}
var iclosure *ssa.Value
iclosure, rcvr = s.getClosureAndRcvr(fn)
i := s.expr(fn.Left)
itab := s.newValue1(ssa.OpITab, types.Types[TUINTPTR], i)
s.nilCheck(itab)
itabidx := fn.Xoffset + 2*int64(Widthptr) + 8 // offset of fun field in runtime.itab
itab = s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.UintptrPtr, itabidx, itab)
if k == callNormal {
codeptr = s.load(types.Types[TUINTPTR], iclosure)
codeptr = s.load(types.Types[TUINTPTR], itab)
} else {
closure = iclosure
closure = itab
}
rcvr = s.newValue1(ssa.OpIData, types.Types[TUINTPTR], i)
}
dowidth(fn.Type)
stksize := fn.Type.ArgWidth() // includes receiver, args, and results
......@@ -4277,22 +3847,18 @@ func (s *state) call(n *Node, k callKind) *ssa.Value {
s.constInt32(types.Types[TUINT32], int32(stksize)))
// 1: started, set in deferprocStack
// 2: heap, set in deferprocStack
// 3: openDefer
// 4: sp, set in deferprocStack
// 5: pc, set in deferprocStack
// 6: fn
// 3: sp, set in deferprocStack
// 4: pc, set in deferprocStack
// 5: fn
s.store(closure.Type,
s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(6), addr),
s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(5), addr),
closure)
// 7: panic, set in deferprocStack
// 8: link, set in deferprocStack
// 9: framepc
// 10: varp
// 11: fd
// 6: panic, set in deferprocStack
// 7: link, set in deferprocStack
// Then, store all the arguments of the defer call.
ft := fn.Type
off := t.FieldOff(12)
off := t.FieldOff(8)
args := n.Rlist.Slice()
// Set receiver (for interface calls). Always a pointer.
......@@ -4407,44 +3973,6 @@ func (s *state) call(n *Node, k callKind) *ssa.Value {
return s.constOffPtrSP(types.NewPtr(fp.Type), fp.Offset+Ctxt.FixedFrameSize())
}
// maybeNilCheckClosure checks if a nil check of a closure is needed in some
// architecture-dependent situations and, if so, emits the nil check.
func (s *state) maybeNilCheckClosure(closure *ssa.Value, k callKind) {
if thearch.LinkArch.Family == sys.Wasm || objabi.GOOS == "aix" && k != callGo {
// On AIX, the closure needs to be verified as fn can be nil, except if it's a call go. This needs to be handled by the runtime to have the "go of nil func value" error.
// TODO(neelance): On other architectures this should be eliminated by the optimization steps
s.nilCheck(closure)
}
}
// getMethodClosure returns a value representing the closure for a method call
func (s *state) getMethodClosure(fn *Node) *ssa.Value {
// Make a name n2 for the function.
// fn.Sym might be sync.(*Mutex).Unlock.
// Make a PFUNC node out of that, then evaluate it.
// We get back an SSA value representing &sync.(*Mutex).Unlock·f.
// We can then pass that to defer or go.
n2 := newnamel(fn.Pos, fn.Sym)
n2.Name.Curfn = s.curfn
n2.SetClass(PFUNC)
// n2.Sym already existed, so it's already marked as a function.
n2.Pos = fn.Pos
n2.Type = types.Types[TUINT8] // dummy type for a static closure. Could use runtime.funcval if we had it.
return s.expr(n2)
}
// getClosureAndRcvr returns values for the appropriate closure and receiver of an
// interface call
func (s *state) getClosureAndRcvr(fn *Node) (*ssa.Value, *ssa.Value) {
i := s.expr(fn.Left)
itab := s.newValue1(ssa.OpITab, types.Types[TUINTPTR], i)
s.nilCheck(itab)
itabidx := fn.Xoffset + 2*int64(Widthptr) + 8 // offset of fun field in runtime.itab
closure := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.UintptrPtr, itabidx, itab)
rcvr := s.newValue1(ssa.OpIData, types.Types[TUINTPTR], i)
return closure, rcvr
}
// etypesign returns the signed-ness of e, for integer/pointer etypes.
// -1 means signed, +1 means unsigned, 0 means non-integer/non-pointer.
func etypesign(e types.EType) int8 {
......@@ -5618,16 +5146,6 @@ func (s *state) addNamedValue(n *Node, v *ssa.Value) {
s.f.NamedValues[loc] = append(values, v)
}
// Generate a disconnected call to a runtime routine and a return.
func gencallret(pp *Progs, sym *obj.LSym) *obj.Prog {
p := pp.Prog(obj.ACALL)
p.To.Type = obj.TYPE_MEM
p.To.Name = obj.NAME_EXTERN
p.To.Sym = sym
p = pp.Prog(obj.ARET)
return p
}
// Branch is an unresolved branch.
type Branch struct {
P *obj.Prog // branch instruction
......@@ -5663,11 +5181,6 @@ type SSAGenState struct {
// wasm: The number of values on the WebAssembly stack. This is only used as a safeguard.
OnWasmStackSkipped int
// Liveness index for the first function call in the final defer exit code
// path that we generated. All defer functions and args should be live at
// this point. This will be used to set the liveness for the deferreturn.
lastDeferLiveness LivenessIndex
}
// Prog appends a new Prog.
......@@ -5795,17 +5308,6 @@ func genssa(f *ssa.Func, pp *Progs) {
s.livenessMap = liveness(e, f, pp)
emitStackObjects(e, pp)
openDeferInfo := e.curfn.Func.lsym.Func.OpenCodedDeferInfo
if openDeferInfo != nil {
// This function uses open-coded defers -- write out the funcdata
// info that we computed at the end of genssa.
p := pp.Prog(obj.AFUNCDATA)
Addrconst(&p.From, objabi.FUNCDATA_OpenCodedDeferInfo)
p.To.Type = obj.TYPE_MEM
p.To.Name = obj.NAME_EXTERN
p.To.Sym = openDeferInfo
}
// Remember where each block starts.
s.bstart = make([]*obj.Prog, f.NumBlocks())
s.pp = pp
......@@ -5870,12 +5372,6 @@ func genssa(f *ssa.Func, pp *Progs) {
// Attach this safe point to the next
// instruction.
s.pp.nextLive = s.livenessMap.Get(v)
// Remember the liveness index of the first defer call of
// the last defer exit
if v.Block.Func.LastDeferExit != nil && v == v.Block.Func.LastDeferExit {
s.lastDeferLiveness = s.pp.nextLive
}
switch v.Op {
case ssa.OpInitMem:
// memory arg needs no code
......@@ -5959,13 +5455,6 @@ func genssa(f *ssa.Func, pp *Progs) {
// nop (which will never execute) after the call.
thearch.Ginsnop(pp)
}
if openDeferInfo != nil {
// When doing open-coded defers, generate a disconnected call to
// deferreturn and a return. This will be used to during panic
// recovery to unwind the stack and return back to the runtime.
s.pp.nextLive = s.lastDeferLiveness
gencallret(pp, Deferreturn)
}
if inlMarks != nil {
// We have some inline marks. Try to find other instructions we're
......
src/cmd/compile/internal/gc/syntax.go
View file @ b76e6f88
......@@ -492,8 +492,6 @@ type Func struct {
Pragma syntax.Pragma // go:xxx function annotations
flags bitset16
numDefers int // number of defer calls in the function
numReturns int // number of explicit returns in the function
// nwbrCalls records the LSyms of functions called by this
// function for go:nowritebarrierrec analysis. Only filled in
......@@ -534,7 +532,6 @@ const (
funcInlinabilityChecked // inliner has already determined whether the function is inlinable
funcExportInline // include inline body in export data
funcInstrumentBody // add race/msan instrumentation during SSA construction
funcOpenCodedDeferDisallowed // can't do open-coded defers
)
func (f *Func) Dupok() bool { return f.flags&funcDupok != 0 }
......@@ -547,7 +544,6 @@ func (f *Func) NilCheckDisabled() bool { return f.flags&funcNilCheckDisa
func (f *Func) InlinabilityChecked() bool { return f.flags&funcInlinabilityChecked != 0 }
func (f *Func) ExportInline() bool { return f.flags&funcExportInline != 0 }
func (f *Func) InstrumentBody() bool { return f.flags&funcInstrumentBody != 0 }
func (f *Func) OpenCodedDeferDisallowed() bool { return f.flags&funcOpenCodedDeferDisallowed != 0 }
func (f *Func) SetDupok(b bool) { f.flags.set(funcDupok, b) }
func (f *Func) SetWrapper(b bool) { f.flags.set(funcWrapper, b) }
......@@ -559,7 +555,6 @@ func (f *Func) SetNilCheckDisabled(b bool) { f.flags.set(funcNilCheckDis
func (f *Func) SetInlinabilityChecked(b bool) { f.flags.set(funcInlinabilityChecked, b) }
func (f *Func) SetExportInline(b bool) { f.flags.set(funcExportInline, b) }
func (f *Func) SetInstrumentBody(b bool) { f.flags.set(funcInstrumentBody, b) }
func (f *Func) SetOpenCodedDeferDisallowed(b bool) { f.flags.set(funcOpenCodedDeferDisallowed, b) }
func (f *Func) setWBPos(pos src.XPos) {
if Debug_wb != 0 {
......
src/cmd/compile/internal/gc/walk.go
View file @ b76e6f88
......@@ -213,6 +213,7 @@ func walkstmt(n *Node) *Node {
yyerror("case statement out of place")
case ODEFER:
Curfn.Func.SetHasDefer(true)
fallthrough
case OGO:
switch n.Left.Op {
......
src/cmd/compile/internal/ssa/deadstore.go
View file @ b76e6f88
......@@ -170,11 +170,6 @@ func elimDeadAutosGeneric(f *Func) {
return
case OpVarLive:
// Don't delete the auto if it needs to be kept alive.
// We depend on this check to keep the autotmp stack slots
// for open-coded defers from being removed (since they
// may not be used by the inline code, but will be used by
// panic processing).
n, ok := v.Aux.(GCNode)
if !ok || n.StorageClass() != ClassAuto {
return
......
src/cmd/compile/internal/ssa/func.go
View file @ b76e6f88
......@@ -32,14 +32,6 @@ type Func struct {
Type *types.Type // type signature of the function.
Blocks []*Block // unordered set of all basic blocks (note: not indexable by ID)
Entry *Block // the entry basic block
// If we are using open-coded defers, this is the first call to a deferred
// function in the final defer exit sequence that we generated. This call
// should be after all defer statements, and will have all args, etc. of
// all defer calls as live. The liveness info of this call will be used
// for the deferreturn/ret segment generated for functions with open-coded
// defers.
LastDeferExit *Value
bid idAlloc // block ID allocator
vid idAlloc // value ID allocator
......
src/cmd/internal/obj/link.go
View file @ b76e6f88
......@@ -409,7 +409,6 @@ type FuncInfo struct {
GCLocals *LSym
GCRegs *LSym
StackObjects *LSym
OpenCodedDeferInfo *LSym
}
type InlMark struct {
......
src/cmd/internal/objabi/funcdata.go
View file @ b76e6f88
......@@ -20,7 +20,6 @@ const (
FUNCDATA_RegPointerMaps = 2
FUNCDATA_StackObjects = 3
FUNCDATA_InlTree = 4
FUNCDATA_OpenCodedDeferInfo = 5
// ArgsSizeUnknown is set in Func.argsize to mark all functions
// whose argument size is unknown (C vararg functions, and
......
src/cmd/internal/objabi/funcid.go
View file @ b76e6f88
......@@ -85,12 +85,6 @@ func GetFuncID(name, file string) FuncID {
return FuncID_panicwrap
case "runtime.handleAsyncEvent":
return FuncID_handleAsyncEvent
case "runtime.deferreturn":
// Don't show in the call stack (used when invoking defer functions)
return FuncID_wrapper
case "runtime.runOpenDeferFrame":
// Don't show in the call stack (used when invoking defer functions)
return FuncID_wrapper
}
if file == "<autogenerated>" {
return FuncID_wrapper
......
src/cmd/internal/objabi/stack.go
View file @ b76e6f88
......@@ -18,7 +18,7 @@ const (
)
// Initialize StackGuard and StackLimit according to target system.
var StackGuard = 896*stackGuardMultiplier() + StackSystem
var StackGuard = 880*stackGuardMultiplier() + StackSystem
var StackLimit = StackGuard - StackSystem - StackSmall
// stackGuardMultiplier returns a multiplier to apply to the default
......
src/cmd/link/internal/ld/pcln.go
View file @ b76e6f88
......@@ -11,7 +11,6 @@ import (
"cmd/internal/sys"
"cmd/link/internal/sym"
"encoding/binary"
"fmt"
"log"
"os"
"path/filepath"
......@@ -256,23 +255,13 @@ func (ctxt *Link) pclntab() {
}
if r.Type.IsDirectJump() && r.Sym != nil && r.Sym.Name == "runtime.deferreturn" {
if ctxt.Arch.Family == sys.Wasm {
deferreturn = lastWasmAddr - 1
deferreturn = lastWasmAddr
} else {
// Note: the relocation target is in the call instruction, but
// is not necessarily the whole instruction (for instance, on
// x86 the relocation applies to bytes [1:5] of the 5 byte call
// instruction).
deferreturn = uint32(r.Off)
switch ctxt.Arch.Family {
case sys.AMD64, sys.I386, sys.MIPS, sys.MIPS64, sys.RISCV64:
deferreturn--
case sys.PPC64, sys.ARM, sys.ARM64:
// no change
case sys.S390X:
deferreturn -= 2
default:
panic(fmt.Sprint("Unhandled architecture:", ctxt.Arch.Family))
}
}
break // only need one
}
......
src/cmd/link/internal/ld/symtab.go
View file @ b76e6f88
......@@ -498,8 +498,7 @@ func (ctxt *Link) symtab() {
case strings.HasPrefix(s.Name, "gcargs."),
strings.HasPrefix(s.Name, "gclocals."),
strings.HasPrefix(s.Name, "gclocals·"),
strings.HasPrefix(s.Name, "inltree."),
strings.HasSuffix(s.Name, ".opendefer"):
strings.HasPrefix(s.Name, "inltree."):
s.Type = sym.SGOFUNC
s.Attr |= sym.AttrNotInSymbolTable
s.Outer = symgofunc
......
src/runtime/callers_test.go
View file @ b76e6f88
......@@ -5,7 +5,6 @@
package runtime_test
import (
"internal/race"
"reflect"
"runtime"
"strings"
......@@ -13,19 +12,19 @@ import (
)
func f1(pan bool) []uintptr {
return f2(pan) // line 16
return f2(pan) // line 15
}
func f2(pan bool) []uintptr {
return f3(pan) // line 20
return f3(pan) // line 19
}
func f3(pan bool) []uintptr {
if pan {
panic("f3") // line 25
panic("f3") // line 24
}
ret := make([]uintptr, 20)
return ret[:runtime.Callers(0, ret)] // line 28
return ret[:runtime.Callers(0, ret)] // line 27
}
func testCallers(t *testing.T, pcs []uintptr, pan bool) {
......@@ -49,16 +48,16 @@ func testCallers(t *testing.T, pcs []uintptr, pan bool) {
var f3Line int
if pan {
f3Line = 25
f3Line = 24
} else {
f3Line = 28
f3Line = 27
}
want := []struct {
name string
line int
}{
{"f1", 16},
{"f2", 20},
{"f1", 15},
{"f2", 19},
{"f3", f3Line},
}
for _, w := range want {
......@@ -189,36 +188,3 @@ func TestCallersDivZeroPanic(t *testing.T) {
t.Fatal("did not see divide-by-sizer panic")
}
}
// This test will have a slightly different callstack if non-open-coded defers are
// called (e.g. if race checks enabled), because of a difference in the way the
// defer function is invoked.
func TestCallersDeferNilFuncPanic(t *testing.T) {
if race.Enabled {
t.Skip("skipping TestCallersDeferNilFuncPanic under race detector")
}
// Make sure we don't have any extra frames on the stack (due to
// open-coded defer processing)
state := 1
want := []string{"runtime.Callers", "runtime_test.TestCallersDeferNilFuncPanic.func1",
"runtime.gopanic", "runtime.panicmem", "runtime.sigpanic",
"runtime_test.TestCallersDeferNilFuncPanic"}
defer func() {
if r := recover(); r == nil {
t.Fatal("did not panic")
}
pcs := make([]uintptr, 20)
pcs = pcs[:runtime.Callers(0, pcs)]
testCallersEqual(t, pcs, want)
if state == 1 {
t.Fatal("nil defer func panicked at defer time rather than function exit time")
}
}()
var f func()
defer f()
// Use the value of 'state' to make sure nil defer func f causes panic at
// function exit, rather than at the defer statement.
state = 2
}
src/runtime/defer_test.go
View file @ b76e6f88
......@@ -15,11 +15,11 @@ import (
// unconditional panic (hence no return from the function)
func TestUnconditionalPanic(t *testing.T) {
defer func() {
if recover() != "testUnconditional" {
if recover() == nil {
t.Fatal("expected unconditional panic")
}
}()
panic("testUnconditional")
panic("panic should be recovered")
}
var glob int = 3
......@@ -30,7 +30,7 @@ func TestOpenAndNonOpenDefers(t *testing.T) {
for {
// Non-open defer because in a loop
defer func(n int) {
if recover() != "testNonOpenDefer" {
if recover() == nil {
t.Fatal("expected testNonOpen panic")
}
}(3)
......@@ -45,7 +45,7 @@ func TestOpenAndNonOpenDefers(t *testing.T) {
//go:noinline
func testOpen(t *testing.T, arg int) {
defer func(n int) {
if recover() != "testOpenDefer" {
if recover() == nil {
t.Fatal("expected testOpen panic")
}
}(4)
......@@ -61,7 +61,7 @@ func TestNonOpenAndOpenDefers(t *testing.T) {
for {
// Non-open defer because in a loop
defer func(n int) {
if recover() != "testNonOpenDefer" {
if recover() == nil {
t.Fatal("expected testNonOpen panic")
}
}(3)
......@@ -80,7 +80,7 @@ func TestConditionalDefers(t *testing.T) {
list = make([]int, 0, 10)
defer func() {
if recover() != "testConditional" {
if recover() == nil {
t.Fatal("expected panic")
}
want := []int{4, 2, 1}
......@@ -106,7 +106,7 @@ func testConditionalDefers(n int) {
defer doappend(4)
}
}
panic("testConditional")
panic("test")
}
// Test that there is no compile-time or run-time error if an open-coded defer
......@@ -174,52 +174,3 @@ func TestRecoverMatching(t *testing.T) {
}()
panic("panic1")
}
type nonSSAable [128]byte
type bigStruct struct {
x, y, z, w, p, q int64
}
func mknonSSAable() nonSSAable {
globint1++
return nonSSAable{0, 0, 0, 0, 5}
}
var globint1, globint2 int
//go:noinline
func sideeffect(n int64) int64 {
globint2++
return n
}
// Test that nonSSAable arguments to defer are handled correctly and only evaluated once.
func TestNonSSAableArgs(t *testing.T) {
globint1 = 0
globint2 = 0
var save1 byte
var save2 int64
defer func() {
if globint1 != 1 {
t.Fatal(fmt.Sprintf("globint1: wanted: 1, got %v", globint1))
}
if save1 != 5 {
t.Fatal(fmt.Sprintf("save1: wanted: 5, got %v", save1))
}
if globint2 != 1 {
t.Fatal(fmt.Sprintf("globint2: wanted: 1, got %v", globint2))
}
if save2 != 2 {
t.Fatal(fmt.Sprintf("save2: wanted: 2, got %v", save2))
}
}()
defer func(n nonSSAable) {
save1 = n[4]
}(mknonSSAable())
defer func(b bigStruct) {
save2 = b.y
}(bigStruct{1, 2, 3, 4, 5, sideeffect(6)})
}
src/runtime/funcdata.h
View file @ b76e6f88
......@@ -17,7 +17,6 @@
#define FUNCDATA_RegPointerMaps 2
#define FUNCDATA_StackObjects 3
#define FUNCDATA_InlTree 4
#define FUNCDATA_OpenCodedDeferInfo 5 /* info for func with open-coded defers */
// Pseudo-assembly statements.
......
src/runtime/panic.go
View file @ b76e6f88
......@@ -10,19 +10,6 @@ import (
"unsafe"
)
// We have two different ways of doing defers. The older way involves creating a
// defer record at the time that a defer statement is executing and adding it to a
// defer chain. This chain is inspected by the deferreturn call at all function
// exits in order to run the appropriate defer calls. A cheaper way (which we call
// open-coded defers) is used for functions in which no defer statements occur in
// loops. In that case, we simply store the defer function/arg information into
// specific stack slots at the point of each defer statement, as well as setting a
// bit in a bitmask. At each function exit, we add inline code to directly make
// the appropriate defer calls based on the bitmask and fn/arg information stored
// on the stack. During panic/Goexit processing, the appropriate defer calls are
// made using extra funcdata info that indicates the exact stack slots that
// contain the bitmask and defer fn/args.
// Check to make sure we can really generate a panic. If the panic
// was generated from the runtime, or from inside malloc, then convert
// to a throw of msg.
......@@ -276,24 +263,19 @@ func deferprocStack(d *_defer) {
// are initialized here.
d.started = false
d.heap = false
d.openDefer = false
d.sp = getcallersp()
d.pc = getcallerpc()
d.framepc = 0
d.varp = 0
// The lines below implement:
// d.panic = nil
// d.fp = nil
// d.link = gp._defer
// gp._defer = d
// But without write barriers. The first three are writes to
// But without write barriers. The first two are writes to
// the stack so they don't need a write barrier, and furthermore
// are to uninitialized memory, so they must not use a write barrier.
// The fourth write does not require a write barrier because we
// The third write does not require a write barrier because we
// explicitly mark all the defer structures, so we don't need to
// keep track of pointers to them with a write barrier.
*(*uintptr)(unsafe.Pointer(&d._panic)) = 0
*(*uintptr)(unsafe.Pointer(&d.fd)) = 0
*(*uintptr)(unsafe.Pointer(&d.link)) = uintptr(unsafe.Pointer(gp._defer))
*(*uintptr)(unsafe.Pointer(&gp._defer)) = uintptr(unsafe.Pointer(d))
......@@ -481,12 +463,8 @@ func freedefer(d *_defer) {
// started causing a nosplit stack overflow via typedmemmove.
d.siz = 0
d.started = false
d.openDefer = false
d.sp = 0
d.pc = 0
d.framepc = 0
d.varp = 0
d.fd = nil
// d._panic and d.fn must be nil already.
// If not, we would have called freedeferpanic or freedeferfn above,
// both of which throw.
......@@ -515,11 +493,9 @@ func freedeferfn() {
// to have been called by the caller of deferreturn at the point
// just before deferreturn was called. The effect is that deferreturn
// is called again and again until there are no more deferred functions.
//
// Declared as nosplit, because the function should not be preempted once we start
// modifying the caller's frame in order to reuse the frame to call the deferred
// function.
//
// Cannot split the stack because we reuse the caller's frame to
// call the deferred function.
// The single argument isn't actually used - it just has its address
// taken so it can be matched against pending defers.
//go:nosplit
......@@ -533,15 +509,6 @@ func deferreturn(arg0 uintptr) {
if d.sp != sp {
return
}
if d.openDefer {
done := runOpenDeferFrame(gp, d)
if !done {
throw("unfinished open-coded defers in deferreturn")
}
gp._defer = d.link
freedefer(d)
return
}
// Moving arguments around.
//
......@@ -577,8 +544,6 @@ func Goexit() {
// This code is similar to gopanic, see that implementation
// for detailed comments.
gp := getg()
addOneOpenDeferFrame(gp, getcallerpc(), unsafe.Pointer(getcallersp()))
for {
d := gp._defer
if d == nil {
......@@ -589,26 +554,13 @@ func Goexit() {
d._panic.aborted = true
d._panic = nil
}
if !d.openDefer {
d.fn = nil
gp._defer = d.link
freedefer(d)
continue
}
}
d.started = true
if d.openDefer {
done := runOpenDeferFrame(gp, d)
if !done {
// We should always run all defers in the frame,
// since there is no panic associated with this
// defer that can be recovered.
throw("unfinished open-coded defers in Goexit")
}
addOneOpenDeferFrame(gp, 0, nil)
} else {
reflectcall(nil, unsafe.Pointer(d.fn), deferArgs(d), uint32(d.siz), uint32(d.siz))
}
if gp._defer != d {
throw("bad defer entry in Goexit")
}
......@@ -655,182 +607,6 @@ func printpanics(p *_panic) {
print("\n")
}
// addOneOpenDeferFrame scans the stack for the first frame (if any) with
// open-coded defers and if it finds one, adds a single record to the defer chain
// for that frame. If sp is non-nil, it starts the stack scan from the frame
// specified by sp. If sp is nil, it uses the sp from the current defer record
// (which has just been finished). Hence, it continues the stack scan from the
// frame of the defer that just finished. It skips any frame that already has an
// open-coded _defer record, which would have been been created from a previous
// (unrecovered) panic.
//
// Note: All entries of the defer chain (including this new open-coded entry) have
// their pointers (including sp) adjusted properly if the stack moves while
// running deferred functions. Also, it is safe to pass in the sp arg (which is
// the direct result of calling getcallersp()), because all pointer variables
// (including arguments) are adjusted as needed during stack copies.
func addOneOpenDeferFrame(gp *g, pc uintptr, sp unsafe.Pointer) {
var prevDefer *_defer
if sp == nil {
prevDefer = gp._defer
pc = prevDefer.framepc
sp = unsafe.Pointer(prevDefer.sp)
}
systemstack(func() {
gentraceback(pc, uintptr(sp), 0, gp, 0, nil, 0x7fffffff,
func(frame *stkframe, unused unsafe.Pointer) bool {
if prevDefer != nil && prevDefer.sp == frame.sp {
// Skip the frame for the previous defer that
// we just finished (and was used to set
// where we restarted the stack scan)
return true
}
f := frame.fn
fd := funcdata(f, _FUNCDATA_OpenCodedDeferInfo)
if fd == nil {
return true
}
// Insert the open defer record in the
// chain, in order sorted by sp.
d := gp._defer
var prev *_defer
for d != nil {
dsp := d.sp
if frame.sp < dsp {
break
}
if frame.sp == dsp {
if !d.openDefer {
throw("duplicated defer entry")
}
return true
}
prev = d
d = d.link
}
if frame.fn.deferreturn == 0 {
throw("missing deferreturn")
}
maxargsize, _ := readvarintUnsafe(fd)
d1 := newdefer(int32(maxargsize))
d1.openDefer = true
d1._panic = nil
// These are the pc/sp to set after we've
// run a defer in this frame that did a
// recover. We return to a special
// deferreturn that runs any remaining
// defers and then returns from the
// function.
d1.pc = frame.fn.entry + uintptr(frame.fn.deferreturn)
d1.varp = frame.varp
d1.fd = fd
// Save the SP/PC associated with current frame,
// so we can continue stack trace later if needed.
d1.framepc = frame.pc
d1.sp = frame.sp
d1.link = d
if prev == nil {
gp._defer = d1
} else {
prev.link = d1
}
// Stop stack scanning after adding one open defer record
return false
},
nil, 0)
})
}
// readvarintUnsafe reads the uint32 in varint format starting at fd, and returns the
// uint32 and a pointer to the byte following the varint.
//
// There is a similar function runtime.readvarint, which takes a slice of bytes,
// rather than an unsafe pointer. These functions are duplicated, because one of
// the two use cases for the functions would get slower if the functions were
// combined.
func readvarintUnsafe(fd unsafe.Pointer) (uint32, unsafe.Pointer) {
var r uint32
var shift int
for {
b := *(*uint8)((unsafe.Pointer(fd)))
fd = add(fd, unsafe.Sizeof(b))
if b < 128 {
return r + uint32(b)<<shift, fd
}
r += ((uint32(b) &^ 128) << shift)
shift += 7
if shift > 28 {
panic("Bad varint")
}
}
}
// runOpenDeferFrame runs the active open-coded defers in the frame specified by
// d. It normally processes all active defers in the frame, but stops immediately
// if a defer does a successful recover. It returns true if there are no
// remaining defers to run in the frame.
func runOpenDeferFrame(gp *g, d *_defer) bool {
done := true
fd := d.fd
// Skip the maxargsize
_, fd = readvarintUnsafe(fd)
deferBitsOffset, fd := readvarintUnsafe(fd)
nDefers, fd := readvarintUnsafe(fd)
deferBits := *(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset)))
for i := int(nDefers) - 1; i >= 0; i-- {
// read the funcdata info for this defer
var argWidth, closureOffset, hasRcvrOffset, rcvrOffset, nArgs uint32
argWidth, fd = readvarintUnsafe(fd)
closureOffset, fd = readvarintUnsafe(fd)
hasRcvrOffset, fd = readvarintUnsafe(fd)
if hasRcvrOffset > 0 {
rcvrOffset, fd = readvarintUnsafe(fd)
}
nArgs, fd = readvarintUnsafe(fd)
if deferBits&(1<<i) == 0 {
for j := uint32(0); j < nArgs; j++ {
_, fd = readvarintUnsafe(fd)
_, fd = readvarintUnsafe(fd)
_, fd = readvarintUnsafe(fd)
}
continue
}
closure := *(**funcval)(unsafe.Pointer(d.varp - uintptr(closureOffset)))
d.fn = closure
deferArgs := deferArgs(d)
if hasRcvrOffset > 0 {
*(*unsafe.Pointer)(deferArgs) = *(*unsafe.Pointer)((unsafe.Pointer)((d.varp - uintptr(rcvrOffset))))
}
for j := uint32(0); j < nArgs; j++ {
var argOffset, argLen, argCallOffset uint32
argOffset, fd = readvarintUnsafe(fd)
argLen, fd = readvarintUnsafe(fd)
argCallOffset, fd = readvarintUnsafe(fd)
memmove(unsafe.Pointer(uintptr(deferArgs)+uintptr(argCallOffset)),
unsafe.Pointer(d.varp-uintptr(argOffset)),
uintptr(argLen))
}
deferBits = deferBits &^ (1 << i)
*(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset))) = deferBits
if d._panic != nil {
d._panic.argp = unsafe.Pointer(getargp(0))
}
reflectcall(nil, unsafe.Pointer(closure), deferArgs, argWidth, argWidth)
d.fn = nil
// These args are just a copy, so can be cleared immediately
memclrNoHeapPointers(deferArgs, uintptr(argWidth))
if d._panic != nil && d._panic.recovered {
done = deferBits == 0
break
}
}
return done
}
// The implementation of the predeclared function panic.
func gopanic(e interface{}) {
gp := getg()
......@@ -870,10 +646,6 @@ func gopanic(e interface{}) {
atomic.Xadd(&runningPanicDefers, 1)
// By calculating getcallerpc/getcallersp here, we avoid scanning the
// gopanic frame (stack scanning is slow...)
addOneOpenDeferFrame(gp, getcallerpc(), unsafe.Pointer(getcallersp()))
for {
d := gp._defer
if d == nil {
......@@ -887,17 +659,11 @@ func gopanic(e interface{}) {
d._panic.aborted = true
}
d._panic = nil
if !d.openDefer {
// For open-coded defers, we need to process the
// defer again, in case there are any other defers
// to call in the frame (not including the defer
// call that caused the panic).
d.fn = nil
gp._defer = d.link
freedefer(d)
continue
}
}
// Mark defer as started, but keep on list, so that traceback
// can find and update the defer's argument frame if stack growth
......@@ -909,16 +675,8 @@ func gopanic(e interface{}) {
// will find d in the list and will mark d._panic (this panic) aborted.
d._panic = (*_panic)(noescape(unsafe.Pointer(&p)))
done := true
if d.openDefer {
done = runOpenDeferFrame(gp, d)
if done && !d._panic.recovered {
addOneOpenDeferFrame(gp, 0, nil)
}
} else {
p.argp = unsafe.Pointer(getargp(0))
reflectcall(nil, unsafe.Pointer(d.fn), deferArgs(d), uint32(d.siz), uint32(d.siz))
}
p.argp = nil
// reflectcall did not panic. Remove d.
......@@ -926,52 +684,18 @@ func gopanic(e interface{}) {
throw("bad defer entry in panic")
}
d._panic = nil
d.fn = nil
gp._defer = d.link
// trigger shrinkage to test stack copy. See stack_test.go:TestStackPanic
//GC()
pc := d.pc
sp := unsafe.Pointer(d.sp) // must be pointer so it gets adjusted during stack copy
if done {
d.fn = nil
gp._defer = d.link
freedefer(d)
}
if p.recovered {
atomic.Xadd(&runningPanicDefers, -1)
if done {
// Remove any remaining non-started, open-coded defer
// entry after a recover (there's at most one, if we just
// ran a non-open-coded defer), since the entry will
// become out-dated and the defer will be executed
// normally.
d := gp._defer
var prev *_defer
for d != nil {
if d.openDefer {
if d.started {
// This defer is started but we
// are in the middle of a
// defer-panic-recover inside of
// it, so don't remove it or any
// further defer entries
break
}
if prev == nil {
gp._defer = d.link
} else {
prev.link = d.link
}
freedefer(d)
break
} else {
prev = d
d = d.link
}
}
}
gp._panic = p.link
// Aborted panics are marked but remain on the g.panic list.
// Remove them from the list.
......
src/runtime/runtime2.go
View file @ b76e6f88
......@@ -701,7 +701,7 @@ type _func struct {
nameoff int32 // function name
args int32 // in/out args size
deferreturn uint32 // offset of start of a deferreturn call instruction from entry, if any.
deferreturn uint32 // offset of a deferreturn block from entry, if any.
pcsp int32
pcfile int32
......@@ -774,7 +774,7 @@ func extendRandom(r []byte, n int) {
}
// A _defer holds an entry on the list of deferred calls.
// If you add a field here, add code to clear it in freedefer and deferProcStack
// If you add a field here, add code to clear it in freedefer.
// This struct must match the code in cmd/compile/internal/gc/reflect.go:deferstruct
// and cmd/compile/internal/gc/ssa.go:(*state).call.
// Some defers will be allocated on the stack and some on the heap.
......@@ -785,27 +785,11 @@ type _defer struct {
siz int32 // includes both arguments and results
started bool
heap bool
// openDefer indicates that this _defer is for a frame with open-coded
// defers. We have only one defer record for the entire frame (which may
// currently have 0, 1, or more defers active).
openDefer bool
sp uintptr // sp at time of defer
pc uintptr // pc at time of defer
pc uintptr
fn *funcval
_panic *_panic // panic that is running defer
link *_defer
// If openDefer is true, the fields below record values about the stack
// frame and associated function that has the open-coded defer(s). sp
// above will be the sp for the frame, and pc will be address of the
// deferreturn call in the function.
fd unsafe.Pointer // funcdata for the function associated with the frame
varp uintptr // value of varp for the stack frame
// framepc is the current pc associated with the stack frame. Together,
// with sp above (which is the sp associated with the stack frame),
// framepc/sp can be used as pc/sp pair to continue a stack trace via
// gentraceback().
framepc uintptr
}
// A _panic holds information about an active panic.
......
src/runtime/runtime_test.go
View file @ b76e6f88
......@@ -89,7 +89,7 @@ func BenchmarkDefer(b *testing.B) {
}
func defer1() {
func(x, y, z int) {
defer func(x, y, z int) {
if recover() != nil || x != 1 || y != 2 || z != 3 {
panic("bad recover")
}
......
src/runtime/stack.go
View file @ b76e6f88
......@@ -91,7 +91,7 @@ const (
// The stack guard is a pointer this many bytes above the
// bottom of the stack.
_StackGuard = 896*sys.StackGuardMultiplier + _StackSystem
_StackGuard = 880*sys.StackGuardMultiplier + _StackSystem
// After a stack split check the SP is allowed to be this
// many bytes below the stack guard. This saves an instruction
......@@ -736,8 +736,6 @@ func adjustdefers(gp *g, adjinfo *adjustinfo) {
adjustpointer(adjinfo, unsafe.Pointer(&d.sp))
adjustpointer(adjinfo, unsafe.Pointer(&d._panic))
adjustpointer(adjinfo, unsafe.Pointer(&d.link))
adjustpointer(adjinfo, unsafe.Pointer(&d.varp))
adjustpointer(adjinfo, unsafe.Pointer(&d.fd))
}
// Adjust defer argument blocks the same way we adjust active stack frames.
......
src/runtime/symtab.go
View file @ b76e6f88
......@@ -221,7 +221,6 @@ const (
_FUNCDATA_RegPointerMaps = 2
_FUNCDATA_StackObjects = 3
_FUNCDATA_InlTree = 4
_FUNCDATA_OpenCodedDeferInfo = 5
_ArgsSizeUnknown = -0x80000000
)
......
test/defererrcheck.go deleted 100644 → 0
View file @ 2718789b
// errorcheck -0 -l -d=defer
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// check that open-coded defers are used in expected situations
package main
import "fmt"
var glob = 3
func f1() {
for i := 0; i < 10; i++ {
fmt.Println("loop")
}
defer func() { // ERROR "open-coded defer in function f1"
fmt.Println("defer")
}()
}
func f2() {
for {
defer func() { // ERROR "heap-allocated defer in function f2"
fmt.Println("defer1")
}()
if glob > 2 {
break
}
}
defer func() { // ERROR "stack-allocated defer in function f2"
fmt.Println("defer2")
}()
}
func f3() {
defer func() { // ERROR "stack-allocated defer in function f3"
fmt.Println("defer2")
}()
for {
defer func() { // ERROR "heap-allocated defer in function f3"
fmt.Println("defer1")
}()
if glob > 2 {
break
}
}
}
func f4() {
defer func() { // ERROR "open-coded defer in function f4"
fmt.Println("defer")
}()
label:
fmt.Println("goto loop")
if glob > 2 {
goto label
}
}
func f5() {
label:
fmt.Println("goto loop")
defer func() { // ERROR "heap-allocated defer in function f5"
fmt.Println("defer")
}()
if glob > 2 {
goto label
}
}
func f6() {
label:
fmt.Println("goto loop")
if glob > 2 {
goto label
}
// The current analysis doesn't end a backward goto loop, so this defer is
// considered to be inside a loop
defer func() { // ERROR "heap-allocated defer in function f6"
fmt.Println("defer")
}()
}
test/live.go
View file @ b76e6f88
......@@ -367,19 +367,16 @@ func f24() {
m2[[2]string{"x", "y"}] = nil
}
// Non-open-coded defers should not cause autotmps. (Open-coded defers do create extra autotmps).
// defer should not cause spurious ambiguously live variables
func f25(b bool) {
for i := 0; i < 2; i++ {
// Put in loop to make sure defer is not open-coded
defer g25()
}
if b {
return
}
var x string
x = g14()
printstring(x)
return
}
func g25()
......@@ -420,8 +417,7 @@ func f27defer(b bool) {
defer call27(func() { x++ }) // ERROR "stack object .autotmp_[0-9]+ struct \{"
}
defer call27(func() { x++ }) // ERROR "stack object .autotmp_[0-9]+ struct \{"
printnl() // ERROR "live at call to printnl: .autotmp_[0-9]+ .autotmp_[0-9]+"
return // ERROR "live at call to call27: .autotmp_[0-9]+"
printnl()
}
// and newproc (go) escapes to the heap
......@@ -691,12 +687,12 @@ type R struct{ *T } // ERRORAUTO "live at entry to \(\*R\)\.Foo: \.this ptr" "li
// In particular, at printint r must be live.
func f41(p, q *int) (r *int) { // ERROR "live at entry to f41: p q$"
r = p
defer func() {
defer func() { // ERROR "live at call to deferprocStack: q r$" "live at call to deferreturn: r$"
recover()
}()
printint(0) // ERROR "live at call to printint: q r .autotmp_[0-9]+$"
printint(0) // ERROR "live at call to printint: q r$"
r = q
return // ERROR "live at call to f41.func1: r .autotmp_[0-9]+$"
return // ERROR "live at call to deferreturn: r$"
}
func f42() {
......
test/nosplit.go
View file @ b76e6f88
......@@ -309,17 +309,17 @@ TestCases:
name := m[1]
size, _ := strconv.Atoi(m[2])
// The limit was originally 128 but is now 768 (896-128).
// The limit was originally 128 but is now 752 (880-128).
// Instead of rewriting the test cases above, adjust
// the first stack frame to use up the extra bytes.
if i == 0 {
size += (896 - 128) - 128
size += (880 - 128) - 128
// Noopt builds have a larger stackguard.
// See ../src/cmd/dist/buildruntime.go:stackGuardMultiplier
// This increase is included in objabi.StackGuard
for _, s := range strings.Split(os.Getenv("GO_GCFLAGS"), " ") {
if s == "-N" {
size += 896
size += 880
}
}
}
......
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