}
}
- // Just before compilation, compile itabs found on
- // the right side of OCONVIFACE so that methods
- // can be de-virtualized during compilation.
Curfn = nil
- peekitabs()
// Phase 8: Compile top level functions.
// Don't use range--walk can add functions to xtop.
type itabEntry struct {
t, itype *Type
sym *Sym
-
- // symbol of the itab itself;
- // filled in lazily after typecheck
- lsym *obj.LSym
-
- // symbols of each method in
- // the itab, sorted by byte offset;
- // filled in at the same time as lsym
- entries []*obj.LSym
}
type ptabEntry struct {
// Generate the method body, so that compiled
// code can refer to it.
isym := methodsym(method, t, 0)
+
if !isym.Siggen() {
isym.SetSiggen(true)
genwrapper(t, f, isym, 0)
return s
}
-// for each itabEntry, gather the methods on
-// the concrete type that implement the interface
-func peekitabs() {
- for i := range itabs {
- tab := &itabs[i]
- methods := genfun(tab.t, tab.itype)
- if len(methods) == 0 {
- continue
- }
- tab.lsym = Linksym(tab.sym)
- tab.entries = methods
- }
-}
-
-// for the given concrete type and interface
-// type, return the (sorted) set of methods
-// on the concrete type that implement the interface
-func genfun(t, it *Type) []*obj.LSym {
- if t == nil || it == nil {
- return nil
- }
- sigs := imethods(it)
- methods := methods(t)
- out := make([]*obj.LSym, 0, len(sigs))
- if len(sigs) == 0 {
- return nil
- }
-
- // both sigs and methods are sorted by name,
- // so we can find the intersect in a single pass
- for _, m := range methods {
- if m.name == sigs[0].name {
- out = append(out, Linksym(m.isym))
- sigs = sigs[1:]
- if len(sigs) == 0 {
- break
- }
- }
- }
-
- return out
-}
-
-// itabsym uses the information gathered in
-// peekitabs to de-virtualize interface methods.
-// Since this is called by the SSA backend, it shouldn't
-// generate additional Nodes, Syms, etc.
-func itabsym(it *obj.LSym, offset int64) *obj.LSym {
- var syms []*obj.LSym
- if it == nil {
- return nil
- }
-
- for i := range itabs {
- e := &itabs[i]
- if e.lsym == it {
- syms = e.entries
- break
- }
- }
- if syms == nil {
- return nil
- }
-
- // keep this arithmetic in sync with *itab layout
- methodnum := int((offset - 3*int64(Widthptr) - 8) / int64(Widthptr))
- if methodnum >= len(syms) {
- return nil
- }
- return syms[methodnum]
-}
-
func dumptypestructs() {
// copy types from externdcl list to signatlist
for _, n := range externdcl {
return ssa.LocalSlot{N: n, Type: et, Off: name.Off}
}
-func (e *ssaExport) DerefItab(it *obj.LSym, offset int64) *obj.LSym {
- return itabsym(it, offset)
-}
-
// namedAuto returns a new AUTO variable with the given name and type.
// These are exposed to the debugger.
func (e *ssaExport) namedAuto(name string, typ ssa.Type) ssa.GCNode {
// rcvr - U
// method - M func (t T)(), a TFIELD type struct
// newnam - the eventual mangled name of this function
+
func genwrapper(rcvr *Type, method *Field, newnam *Sym, iface int) {
if false && Debug['r'] != 0 {
fmt.Printf("genwrapper rcvrtype=%v method=%v newnam=%v\n", rcvr, method, newnam)
fn.Func.Nname = newname(newnam)
fn.Func.Nname.Name.Defn = fn
fn.Func.Nname.Name.Param.Ntype = t
- fn.Func.Nname.Sym.SetExported(true) // prevent export; see closure.go
declare(fn.Func.Nname, PFUNC)
funchdr(fn)
}
}
- // We're going to emit an OCONVIFACE.
- // Call itabname so that (t, iface)
- // gets added to itabs early, which allows
- // us to de-virtualize calls through this
- // type/interface pair later. See peekitabs in reflect.go
- if isdirectiface(t0) && !iface.IsEmptyInterface() {
- itabname(t0, iface)
- }
return true
}
SplitArray(LocalSlot) LocalSlot // array must be length 1
SplitInt64(LocalSlot) (LocalSlot, LocalSlot) // returns (hi, lo)
- // DerefItab dereferences an itab function
- // entry, given the symbol of the itab and
- // the byte offset of the function pointer.
- // It may return nil.
- DerefItab(sym *obj.LSym, offset int64) *obj.LSym
-
// Line returns a string describing the given position.
Line(src.XPos) string
func (d DummyFrontend) Debug_checknil() bool { return false }
func (d DummyFrontend) Debug_wb() bool { return false }
-func (d DummyFrontend) TypeBool() Type { return TypeBool }
-func (d DummyFrontend) TypeInt8() Type { return TypeInt8 }
-func (d DummyFrontend) TypeInt16() Type { return TypeInt16 }
-func (d DummyFrontend) TypeInt32() Type { return TypeInt32 }
-func (d DummyFrontend) TypeInt64() Type { return TypeInt64 }
-func (d DummyFrontend) TypeUInt8() Type { return TypeUInt8 }
-func (d DummyFrontend) TypeUInt16() Type { return TypeUInt16 }
-func (d DummyFrontend) TypeUInt32() Type { return TypeUInt32 }
-func (d DummyFrontend) TypeUInt64() Type { return TypeUInt64 }
-func (d DummyFrontend) TypeFloat32() Type { return TypeFloat32 }
-func (d DummyFrontend) TypeFloat64() Type { return TypeFloat64 }
-func (d DummyFrontend) TypeInt() Type { return TypeInt64 }
-func (d DummyFrontend) TypeUintptr() Type { return TypeUInt64 }
-func (d DummyFrontend) TypeString() Type { panic("unimplemented") }
-func (d DummyFrontend) TypeBytePtr() Type { return TypeBytePtr }
-func (d DummyFrontend) DerefItab(sym *obj.LSym, off int64) *obj.LSym { return nil }
+func (d DummyFrontend) TypeBool() Type { return TypeBool }
+func (d DummyFrontend) TypeInt8() Type { return TypeInt8 }
+func (d DummyFrontend) TypeInt16() Type { return TypeInt16 }
+func (d DummyFrontend) TypeInt32() Type { return TypeInt32 }
+func (d DummyFrontend) TypeInt64() Type { return TypeInt64 }
+func (d DummyFrontend) TypeUInt8() Type { return TypeUInt8 }
+func (d DummyFrontend) TypeUInt16() Type { return TypeUInt16 }
+func (d DummyFrontend) TypeUInt32() Type { return TypeUInt32 }
+func (d DummyFrontend) TypeUInt64() Type { return TypeUInt64 }
+func (d DummyFrontend) TypeFloat32() Type { return TypeFloat32 }
+func (d DummyFrontend) TypeFloat64() Type { return TypeFloat64 }
+func (d DummyFrontend) TypeInt() Type { return TypeInt64 }
+func (d DummyFrontend) TypeUintptr() Type { return TypeUInt64 }
+func (d DummyFrontend) TypeString() Type { panic("unimplemented") }
+func (d DummyFrontend) TypeBytePtr() Type { return TypeBytePtr }
func (d DummyFrontend) CanSSA(t Type) bool {
// There are no un-SSAable types in dummy land.
&& c == config.ctxt.FixedFrameSize() + config.RegSize // offset of return value
&& warnRule(config.Debug_checknil() && v.Pos.Line() > 1, v, "removed nil check")
-> (Invalid)
-
-// De-virtualize interface calls into static calls.
-// Note that (ITab (IMake)) doesn't get
-// rewritten until after the first opt pass,
-// so this rule should trigger reliably.
-(InterCall [argsize] (Load (OffPtr [off] (ITab (IMake (Addr {itab} (SB)) _))) _) mem) && devirt(v, itab, off) != nil ->
- (StaticCall [argsize] {devirt(v, itab, off)} mem)
package ssa
import (
- "cmd/internal/obj"
"crypto/sha1"
"fmt"
"math"
return uint64(a)+uint64(b) < uint64(a)
}
-// de-virtualize an InterCall
-// 'sym' is the symbol for the itab
-func devirt(v *Value, sym interface{}, offset int64) *obj.LSym {
- f := v.Block.Func
- ext, ok := sym.(*ExternSymbol)
- if !ok {
- return nil
- }
- lsym := f.Config.Frontend().DerefItab(ext.Sym, offset)
- if f.pass.debug > 0 {
- if lsym != nil {
- f.Config.Warnl(v.Pos, "de-virtualizing call")
- } else {
- f.Config.Warnl(v.Pos, "couldn't de-virtualize call")
- }
- }
- return lsym
-}
-
// isSamePtr reports whether p1 and p2 point to the same address.
func isSamePtr(p1, p2 *Value) bool {
if p1 == p2 {
return rewriteValuegeneric_OpGreater8U(v, config)
case OpIMake:
return rewriteValuegeneric_OpIMake(v, config)
- case OpInterCall:
- return rewriteValuegeneric_OpInterCall(v, config)
case OpIsInBounds:
return rewriteValuegeneric_OpIsInBounds(v, config)
case OpIsNonNil:
}
return false
}
-func rewriteValuegeneric_OpInterCall(v *Value, config *Config) bool {
- b := v.Block
- _ = b
- // match: (InterCall [argsize] (Load (OffPtr [off] (ITab (IMake (Addr {itab} (SB)) _))) _) mem)
- // cond: devirt(v, itab, off) != nil
- // result: (StaticCall [argsize] {devirt(v, itab, off)} mem)
- for {
- argsize := v.AuxInt
- v_0 := v.Args[0]
- if v_0.Op != OpLoad {
- break
- }
- v_0_0 := v_0.Args[0]
- if v_0_0.Op != OpOffPtr {
- break
- }
- off := v_0_0.AuxInt
- v_0_0_0 := v_0_0.Args[0]
- if v_0_0_0.Op != OpITab {
- break
- }
- v_0_0_0_0 := v_0_0_0.Args[0]
- if v_0_0_0_0.Op != OpIMake {
- break
- }
- v_0_0_0_0_0 := v_0_0_0_0.Args[0]
- if v_0_0_0_0_0.Op != OpAddr {
- break
- }
- itab := v_0_0_0_0_0.Aux
- v_0_0_0_0_0_0 := v_0_0_0_0_0.Args[0]
- if v_0_0_0_0_0_0.Op != OpSB {
- break
- }
- mem := v.Args[1]
- if !(devirt(v, itab, off) != nil) {
- break
- }
- v.reset(OpStaticCall)
- v.AuxInt = argsize
- v.Aux = devirt(v, itab, off)
- v.AddArg(mem)
- return true
- }
- return false
-}
func rewriteValuegeneric_OpIsInBounds(v *Value, config *Config) bool {
b := v.Block
_ = b
+++ /dev/null
-// errorcheck -0 -d=ssa/opt/debug=3
-
-package main
-
-import (
- "crypto/sha1"
- "errors"
- "fmt"
- "sync"
-)
-
-func f0() {
- v := errors.New("error string")
- _ = v.Error() // ERROR "de-virtualizing call$"
-}
-
-func f1() {
- h := sha1.New()
- buf := make([]byte, 4)
- h.Write(buf) // ERROR "de-virtualizing call$"
- _ = h.Sum(nil) // ERROR "de-virtualizing call$"
-}
-
-func f2() {
- // trickier case: make sure we see this is *sync.rlocker
- // instead of *sync.RWMutex,
- // even though they are the same pointers
- var m sync.RWMutex
- r := m.RLocker()
-
- // deadlock if the type of 'r' is improperly interpreted
- // as *sync.RWMutex
- r.Lock() // ERROR "de-virtualizing call$"
- m.RLock()
- r.Unlock() // ERROR "de-virtualizing call$"
- m.RUnlock()
-}
-
-type multiword struct{ a, b, c int }
-
-func (m multiword) Error() string { return fmt.Sprintf("%d, %d, %d", m.a, m.b, m.c) }
-
-func f3() {
- // can't de-virtualize this one yet;
- // it passes through a call to iconvT2I
- var err error
- err = multiword{1, 2, 3}
- if err.Error() != "1, 2, 3" {
- panic("bad call")
- }
-
- // ... but we can do this one
- err = &multiword{1, 2, 3}
- if err.Error() != "1, 2, 3" { // ERROR "de-virtualizing call$"
- panic("bad call")
- }
-}
-
-func main() {
- f0()
- f1()
- f2()
- f3()
-}