go/ssa: add Node interface: common parts of Value+Instruction, plus Operands/Referrers.
Also:
- extend Parent() to all Values and add to interface:
(Builtin/Const/Global => nil; Function => Enclosing)
- hide Function.Enclosing since it's now redundant wrt Parent()
- make (*Function).String robust for synthetics without pkg object
LGTM=gri
R=gri
CC=golang-codereviews, khr
https://golang.org/cl/87580044
diff --git a/go/pointer/gen.go b/go/pointer/gen.go
index f0ac1ae..69eda20 100644
--- a/go/pointer/gen.go
+++ b/go/pointer/gen.go
@@ -1104,7 +1104,6 @@
func (a *analysis) genRootCalls() *cgnode {
r := ssa.NewFunction("<root>", new(types.Signature), "root of callgraph")
r.Prog = a.prog // hack.
- r.Enclosing = r // hack, so Function.String() doesn't crash
r.String() // (asserts that it doesn't crash)
root := a.makeCGNode(r, 0, nil)
diff --git a/go/ssa/builder.go b/go/ssa/builder.go
index 9d7d9f3..be55bdb 100644
--- a/go/ssa/builder.go
+++ b/go/ssa/builder.go
@@ -472,7 +472,7 @@
name: fmt.Sprintf("%s$%d", fn.Name(), 1+len(fn.AnonFuncs)),
Signature: fn.Pkg.typeOf(e.Type).Underlying().(*types.Signature),
pos: e.Type.Func,
- Enclosing: fn,
+ parent: fn,
Pkg: fn.Pkg,
Prog: fn.Prog,
syntax: e,
diff --git a/go/ssa/const.go b/go/ssa/const.go
index 36ae99e..1a4a4d0 100644
--- a/go/ssa/const.go
+++ b/go/ssa/const.go
@@ -100,6 +100,8 @@
return nil
}
+func (c *Const) Parent() *Function { return nil }
+
func (c *Const) Pos() token.Pos {
return token.NoPos
}
diff --git a/go/ssa/doc.go b/go/ssa/doc.go
index c919823..9cb00e3 100644
--- a/go/ssa/doc.go
+++ b/go/ssa/doc.go
@@ -42,6 +42,7 @@
// - Member: a named member of a Go package.
// - Value: an expression that yields a value.
// - Instruction: a statement that consumes values and performs computation.
+// - Node: a Value or Instruction (emphasizing its membership in the SSA value graph)
//
// A computation that yields a result implements both the Value and
// Instruction interfaces. The following table shows for each
diff --git a/go/ssa/func.go b/go/ssa/func.go
index 5f8d216..1bd24ec 100644
--- a/go/ssa/func.go
+++ b/go/ssa/func.go
@@ -423,10 +423,10 @@
// Definition must be in an enclosing function;
// plumb it through intervening closures.
- if f.Enclosing == nil {
+ if f.parent == nil {
panic("no Value for type.Object " + obj.Name())
}
- outer := f.Enclosing.lookup(obj, true) // escaping
+ outer := f.parent.lookup(obj, true) // escaping
v := &Capture{
name: obj.Name(),
typ: outer.Type(),
@@ -466,7 +466,7 @@
//
func (f *Function) RelString(from *types.Package) string {
// Anonymous?
- if f.Enclosing != nil {
+ if f.parent != nil {
return f.name
}
@@ -544,8 +544,8 @@
fmt.Fprintf(buf, "# Location: %s\n", f.Prog.Fset.Position(pos))
}
- if f.Enclosing != nil {
- fmt.Fprintf(buf, "# Parent: %s\n", f.Enclosing.Name())
+ if f.parent != nil {
+ fmt.Fprintf(buf, "# Parent: %s\n", f.parent.Name())
}
if f.Recover != nil {
diff --git a/go/ssa/interp/interp.go b/go/ssa/interp/interp.go
index 53acb0d..60da061 100644
--- a/go/ssa/interp/interp.go
+++ b/go/ssa/interp/interp.go
@@ -489,7 +489,7 @@
caller: caller, // for panic/recover
fn: fn,
}
- if fn.Enclosing == nil {
+ if fn.Parent() == nil {
name := fn.String()
if ext := externals[name]; ext != nil {
if i.mode&EnableTracing != 0 {
diff --git a/go/ssa/sanity.go b/go/ssa/sanity.go
index dd80b5d..48e967a 100644
--- a/go/ssa/sanity.go
+++ b/go/ssa/sanity.go
@@ -357,11 +357,13 @@
case *Const, *Global, *Builtin:
continue // not local
case *Function:
- if val.Enclosing == nil {
+ if val.parent == nil {
continue // only anon functions are local
}
}
+ // TODO(adonovan): check val.Parent() != nil <=> val.Referrers() is defined.
+
if refs := val.Referrers(); refs != nil {
for _, ref := range *refs {
if ref == instr {
@@ -442,8 +444,8 @@
s.block = nil
for i, anon := range fn.AnonFuncs {
- if anon.Enclosing != fn {
- s.errorf("AnonFuncs[%d]=%s but %s.Enclosing=%s", i, anon, anon, anon.Enclosing)
+ if anon.Parent() != fn {
+ s.errorf("AnonFuncs[%d]=%s but %s.Parent()=%s", i, anon, anon, anon.Parent())
}
}
s.fn = nil
diff --git a/go/ssa/ssa.go b/go/ssa/ssa.go
index 9151c97..b940255 100644
--- a/go/ssa/ssa.go
+++ b/go/ssa/ssa.go
@@ -123,6 +123,10 @@
// types of their operands.
Type() types.Type
+ // Parent returns the function to which this Value belongs.
+ // It returns nil for named Functions, Builtin, Const and Global.
+ Parent() *Function
+
// Referrers returns the list of instructions that have this
// value as one of their operands; it may contain duplicates
// if an instruction has a repeated operand.
@@ -130,9 +134,9 @@
// Referrers actually returns a pointer through which the
// caller may perform mutations to the object's state.
//
- // Referrers is currently only defined for the function-local
- // values Capture, Parameter, Functions (iff anonymous) and
- // all value-defining instructions.
+ // Referrers is currently only defined if Parent()!=nil,
+ // i.e. for the function-local values Capture, Parameter,
+ // Functions (iff anonymous) and all value-defining instructions.
// It returns nil for named Functions, Builtin, Const and Global.
//
// Instruction.Operands contains the inverse of this relation.
@@ -199,9 +203,10 @@
// user-provided slice, and returns the resulting slice,
// permitting avoidance of memory allocation.
//
- // The operands are appended in undefined order; the addresses
- // are always non-nil but may point to a nil Value. Clients
- // may store through the pointers, e.g. to effect a value
+ // The operands are appended in undefined order, but the order
+ // is consistent for a given Instruction; the addresses are
+ // always non-nil but may point to a nil Value. Clients may
+ // store through the pointers, e.g. to effect a value
// renaming.
//
// Value.Referrers is a subset of the inverse of this
@@ -229,6 +234,28 @@
Pos() token.Pos
}
+// A Node is a node in the SSA value graph. Every concrete type that
+// implements Node is also either a Value, an Instruction, or both.
+//
+// Node contains the methods common to Value and Instruction, plus the
+// Operands and Referrers methods generalized to return nil for
+// non-Instructions and non-Values, respectively.
+//
+// Node is provided to simplify SSA graph algorithms. Clients should
+// use the more specific and informative Value or Instruction
+// interfaces where appropriate.
+//
+type Node interface {
+ // Common methods:
+ String() string
+ Pos() token.Pos
+ Parent() *Function
+
+ // Partial methods:
+ Operands(rands []*Value) []*Value // nil for non-Instructions
+ Referrers() *[]Instruction // nil for non-Values
+}
+
// Function represents the parameters, results and code of a function
// or method.
//
@@ -250,11 +277,11 @@
// of the function's named return parameters followed by a return of
// the loaded values.
//
-// A nested function that refers to one or more lexically enclosing
-// local variables ("free variables") has Capture parameters. Such
-// functions cannot be called directly but require a value created by
-// MakeClosure which, via its Bindings, supplies values for these
-// parameters.
+// A nested function (Parent()!=nil) that refers to one or more
+// lexically enclosing local variables ("free variables") has Capture
+// parameters. Such functions cannot be called directly but require a
+// value created by MakeClosure which, via its Bindings, supplies
+// values for these parameters.
//
// If the function is a method (Signature.Recv() != nil) then the first
// element of Params is the receiver parameter.
@@ -275,7 +302,7 @@
Synthetic string // provenance of synthetic function; "" for true source functions
syntax ast.Node // *ast.Func{Decl,Lit}; replaced with simple ast.Node after build, unless debug mode
- Enclosing *Function // enclosing function if anon; nil if global
+ parent *Function // enclosing function if anon; nil if global
Pkg *Package // enclosing package; nil for shared funcs (wrappers and error.Error)
Prog *Program // enclosing program
Params []*Parameter // function parameters; for methods, includes receiver
@@ -284,7 +311,7 @@
Blocks []*BasicBlock // basic blocks of the function; nil => external
Recover *BasicBlock // optional; control transfers here after recovered panic
AnonFuncs []*Function // anonymous functions directly beneath this one
- referrers []Instruction // referring instructions (iff Enclosing != nil)
+ referrers []Instruction // referring instructions (iff Parent() != nil)
// The following fields are set transiently during building,
// then cleared.
@@ -1359,6 +1386,7 @@
func (*Builtin) Referrers() *[]Instruction { return nil }
func (v *Builtin) Pos() token.Pos { return token.NoPos }
func (v *Builtin) Object() types.Object { return v.object }
+func (v *Builtin) Parent() *Function { return nil }
func (v *Capture) Type() types.Type { return v.typ }
func (v *Capture) Name() string { return v.name }
@@ -1368,6 +1396,7 @@
func (v *Global) Type() types.Type { return v.typ }
func (v *Global) Name() string { return v.name }
+func (v *Global) Parent() *Function { return nil }
func (v *Global) Pos() token.Pos { return v.pos }
func (v *Global) Referrers() *[]Instruction { return nil }
func (v *Global) Token() token.Token { return token.VAR }
@@ -1383,8 +1412,9 @@
func (v *Function) Object() types.Object { return v.object }
func (v *Function) String() string { return v.RelString(nil) }
func (v *Function) Package() *Package { return v.Pkg }
+func (v *Function) Parent() *Function { return v.parent }
func (v *Function) Referrers() *[]Instruction {
- if v.Enclosing != nil {
+ if v.parent != nil {
return &v.referrers
}
return nil
@@ -1412,6 +1442,7 @@
func (v *anInstruction) Parent() *Function { return v.block.parent }
func (v *anInstruction) Block() *BasicBlock { return v.block }
func (v *anInstruction) setBlock(block *BasicBlock) { v.block = block }
+func (v *anInstruction) Referrers() *[]Instruction { return nil }
func (t *Type) Name() string { return t.object.Name() }
func (t *Type) Pos() token.Pos { return t.object.Pos() }
@@ -1638,3 +1669,11 @@
func (v *UnOp) Operands(rands []*Value) []*Value {
return append(rands, &v.X)
}
+
+// Non-Instruction Values:
+func (v *Builtin) Operands(rands []*Value) []*Value { return rands }
+func (v *Capture) Operands(rands []*Value) []*Value { return rands }
+func (v *Const) Operands(rands []*Value) []*Value { return rands }
+func (v *Function) Operands(rands []*Value) []*Value { return rands }
+func (v *Global) Operands(rands []*Value) []*Value { return rands }
+func (v *Parameter) Operands(rands []*Value) []*Value { return rands }
diff --git a/go/ssa/testmain.go b/go/ssa/testmain.go
index 51c8d4e..a5d8a82 100644
--- a/go/ssa/testmain.go
+++ b/go/ssa/testmain.go
@@ -104,7 +104,7 @@
name: "matcher",
Signature: testingMainParams.At(0).Type().(*types.Signature),
Synthetic: "test matcher predicate",
- Enclosing: main,
+ parent: main,
Pkg: testmain,
Prog: prog,
}
