| 1 | // Copyright 2013 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package ssa |
| 6 | |
| 7 | // This file implements the Function type. |
| 8 | |
| 9 | import ( |
| 10 | "bytes" |
| 11 | "fmt" |
| 12 | "go/ast" |
| 13 | "go/token" |
| 14 | "go/types" |
| 15 | "io" |
| 16 | "os" |
| 17 | "strings" |
| 18 | |
| 19 | "golang.org/x/tools/internal/typeparams" |
| 20 | ) |
| 21 | |
| 22 | // Like ObjectOf, but panics instead of returning nil. |
| 23 | // Only valid during f's create and build phases. |
| 24 | func (f *Function) objectOf(id *ast.Ident) types.Object { |
| 25 | if o := f.info.ObjectOf(id); o != nil { |
| 26 | return o |
| 27 | } |
| 28 | panic(fmt.Sprintf("no types.Object for ast.Ident %s @ %s", |
| 29 | id.Name, f.Prog.Fset.Position(id.Pos()))) |
| 30 | } |
| 31 | |
| 32 | // Like TypeOf, but panics instead of returning nil. |
| 33 | // Only valid during f's create and build phases. |
| 34 | func (f *Function) typeOf(e ast.Expr) types.Type { |
| 35 | if T := f.info.TypeOf(e); T != nil { |
| 36 | return f.typ(T) |
| 37 | } |
| 38 | panic(fmt.Sprintf("no type for %T @ %s", e, f.Prog.Fset.Position(e.Pos()))) |
| 39 | } |
| 40 | |
| 41 | // typ is the locally instantiated type of T. T==typ(T) if f is not an instantiation. |
| 42 | func (f *Function) typ(T types.Type) types.Type { |
| 43 | return f.subst.typ(T) |
| 44 | } |
| 45 | |
| 46 | // If id is an Instance, returns info.Instances[id].Type. |
| 47 | // Otherwise returns f.typeOf(id). |
| 48 | func (f *Function) instanceType(id *ast.Ident) types.Type { |
| 49 | if t, ok := typeparams.GetInstances(f.info)[id]; ok { |
| 50 | return t.Type |
| 51 | } |
| 52 | return f.typeOf(id) |
| 53 | } |
| 54 | |
| 55 | // selection returns a *selection corresponding to f.info.Selections[selector] |
| 56 | // with potential updates for type substitution. |
| 57 | func (f *Function) selection(selector *ast.SelectorExpr) *selection { |
| 58 | sel := f.info.Selections[selector] |
| 59 | if sel == nil { |
| 60 | return nil |
| 61 | } |
| 62 | |
| 63 | switch sel.Kind() { |
| 64 | case types.MethodExpr, types.MethodVal: |
| 65 | if recv := f.typ(sel.Recv()); recv != sel.Recv() { |
| 66 | // recv changed during type substitution. |
| 67 | pkg := f.declaredPackage().Pkg |
| 68 | obj, index, indirect := types.LookupFieldOrMethod(recv, true, pkg, sel.Obj().Name()) |
| 69 | |
| 70 | // sig replaces sel.Type(). See (types.Selection).Typ() for details. |
| 71 | sig := obj.Type().(*types.Signature) |
| 72 | sig = changeRecv(sig, newVar(sig.Recv().Name(), recv)) |
| 73 | if sel.Kind() == types.MethodExpr { |
| 74 | sig = recvAsFirstArg(sig) |
| 75 | } |
| 76 | return &selection{ |
| 77 | kind: sel.Kind(), |
| 78 | recv: recv, |
| 79 | typ: sig, |
| 80 | obj: obj, |
| 81 | index: index, |
| 82 | indirect: indirect, |
| 83 | } |
| 84 | } |
| 85 | } |
| 86 | return toSelection(sel) |
| 87 | } |
| 88 | |
| 89 | // Destinations associated with unlabelled for/switch/select stmts. |
| 90 | // We push/pop one of these as we enter/leave each construct and for |
| 91 | // each BranchStmt we scan for the innermost target of the right type. |
| 92 | type targets struct { |
| 93 | tail *targets // rest of stack |
| 94 | _break *BasicBlock |
| 95 | _continue *BasicBlock |
| 96 | _fallthrough *BasicBlock |
| 97 | } |
| 98 | |
| 99 | // Destinations associated with a labelled block. |
| 100 | // We populate these as labels are encountered in forward gotos or |
| 101 | // labelled statements. |
| 102 | type lblock struct { |
| 103 | _goto *BasicBlock |
| 104 | _break *BasicBlock |
| 105 | _continue *BasicBlock |
| 106 | } |
| 107 | |
| 108 | // labelledBlock returns the branch target associated with the |
| 109 | // specified label, creating it if needed. |
| 110 | func (f *Function) labelledBlock(label *ast.Ident) *lblock { |
| 111 | obj := f.objectOf(label) |
| 112 | lb := f.lblocks[obj] |
| 113 | if lb == nil { |
| 114 | lb = &lblock{_goto: f.newBasicBlock(label.Name)} |
| 115 | if f.lblocks == nil { |
| 116 | f.lblocks = make(map[types.Object]*lblock) |
| 117 | } |
| 118 | f.lblocks[obj] = lb |
| 119 | } |
| 120 | return lb |
| 121 | } |
| 122 | |
| 123 | // addParam adds a (non-escaping) parameter to f.Params of the |
| 124 | // specified name, type and source position. |
| 125 | func (f *Function) addParam(name string, typ types.Type, pos token.Pos) *Parameter { |
| 126 | v := &Parameter{ |
| 127 | name: name, |
| 128 | typ: typ, |
| 129 | pos: pos, |
| 130 | parent: f, |
| 131 | } |
| 132 | f.Params = append(f.Params, v) |
| 133 | return v |
| 134 | } |
| 135 | |
| 136 | func (f *Function) addParamObj(obj types.Object) *Parameter { |
| 137 | name := obj.Name() |
| 138 | if name == "" { |
| 139 | name = fmt.Sprintf("arg%d", len(f.Params)) |
| 140 | } |
| 141 | param := f.addParam(name, f.typ(obj.Type()), obj.Pos()) |
| 142 | param.object = obj |
| 143 | return param |
| 144 | } |
| 145 | |
| 146 | // addSpilledParam declares a parameter that is pre-spilled to the |
| 147 | // stack; the function body will load/store the spilled location. |
| 148 | // Subsequent lifting will eliminate spills where possible. |
| 149 | func (f *Function) addSpilledParam(obj types.Object) { |
| 150 | param := f.addParamObj(obj) |
| 151 | spill := &Alloc{Comment: obj.Name()} |
| 152 | spill.setType(types.NewPointer(param.Type())) |
| 153 | spill.setPos(obj.Pos()) |
| 154 | f.objects[obj] = spill |
| 155 | f.Locals = append(f.Locals, spill) |
| 156 | f.emit(spill) |
| 157 | f.emit(&Store{Addr: spill, Val: param}) |
| 158 | } |
| 159 | |
| 160 | // startBody initializes the function prior to generating SSA code for its body. |
| 161 | // Precondition: f.Type() already set. |
| 162 | func (f *Function) startBody() { |
| 163 | f.currentBlock = f.newBasicBlock("entry") |
| 164 | f.objects = make(map[types.Object]Value) // needed for some synthetics, e.g. init |
| 165 | } |
| 166 | |
| 167 | // createSyntacticParams populates f.Params and generates code (spills |
| 168 | // and named result locals) for all the parameters declared in the |
| 169 | // syntax. In addition it populates the f.objects mapping. |
| 170 | // |
| 171 | // Preconditions: |
| 172 | // f.startBody() was called. f.info != nil. |
| 173 | // Postcondition: |
| 174 | // len(f.Params) == len(f.Signature.Params) + (f.Signature.Recv() ? 1 : 0) |
| 175 | func (f *Function) createSyntacticParams(recv *ast.FieldList, functype *ast.FuncType) { |
| 176 | // Receiver (at most one inner iteration). |
| 177 | if recv != nil { |
| 178 | for _, field := range recv.List { |
| 179 | for _, n := range field.Names { |
| 180 | f.addSpilledParam(f.info.Defs[n]) |
| 181 | } |
| 182 | // Anonymous receiver? No need to spill. |
| 183 | if field.Names == nil { |
| 184 | f.addParamObj(f.Signature.Recv()) |
| 185 | } |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | // Parameters. |
| 190 | if functype.Params != nil { |
| 191 | n := len(f.Params) // 1 if has recv, 0 otherwise |
| 192 | for _, field := range functype.Params.List { |
| 193 | for _, n := range field.Names { |
| 194 | f.addSpilledParam(f.info.Defs[n]) |
| 195 | } |
| 196 | // Anonymous parameter? No need to spill. |
| 197 | if field.Names == nil { |
| 198 | f.addParamObj(f.Signature.Params().At(len(f.Params) - n)) |
| 199 | } |
| 200 | } |
| 201 | } |
| 202 | |
| 203 | // Named results. |
| 204 | if functype.Results != nil { |
| 205 | for _, field := range functype.Results.List { |
| 206 | // Implicit "var" decl of locals for named results. |
| 207 | for _, n := range field.Names { |
| 208 | f.namedResults = append(f.namedResults, f.addLocalForIdent(n)) |
| 209 | } |
| 210 | } |
| 211 | } |
| 212 | } |
| 213 | |
| 214 | type setNumable interface { |
| 215 | setNum(int) |
| 216 | } |
| 217 | |
| 218 | // numberRegisters assigns numbers to all SSA registers |
| 219 | // (value-defining Instructions) in f, to aid debugging. |
| 220 | // (Non-Instruction Values are named at construction.) |
| 221 | func numberRegisters(f *Function) { |
| 222 | v := 0 |
| 223 | for _, b := range f.Blocks { |
| 224 | for _, instr := range b.Instrs { |
| 225 | switch instr.(type) { |
| 226 | case Value: |
| 227 | instr.(setNumable).setNum(v) |
| 228 | v++ |
| 229 | } |
| 230 | } |
| 231 | } |
| 232 | } |
| 233 | |
| 234 | // buildReferrers populates the def/use information in all non-nil |
| 235 | // Value.Referrers slice. |
| 236 | // Precondition: all such slices are initially empty. |
| 237 | func buildReferrers(f *Function) { |
| 238 | var rands []*Value |
| 239 | for _, b := range f.Blocks { |
| 240 | for _, instr := range b.Instrs { |
| 241 | rands = instr.Operands(rands[:0]) // recycle storage |
| 242 | for _, rand := range rands { |
| 243 | if r := *rand; r != nil { |
| 244 | if ref := r.Referrers(); ref != nil { |
| 245 | *ref = append(*ref, instr) |
| 246 | } |
| 247 | } |
| 248 | } |
| 249 | } |
| 250 | } |
| 251 | } |
| 252 | |
| 253 | // mayNeedRuntimeTypes returns all of the types in the body of fn that might need runtime types. |
| 254 | // |
| 255 | // EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu) |
| 256 | func mayNeedRuntimeTypes(fn *Function) []types.Type { |
| 257 | // Collect all types that may need rtypes, i.e. those that flow into an interface. |
| 258 | var ts []types.Type |
| 259 | for _, bb := range fn.Blocks { |
| 260 | for _, instr := range bb.Instrs { |
| 261 | if mi, ok := instr.(*MakeInterface); ok { |
| 262 | ts = append(ts, mi.X.Type()) |
| 263 | } |
| 264 | } |
| 265 | } |
| 266 | |
| 267 | // Types that contain a parameterized type are considered to not be runtime types. |
| 268 | if fn.typeparams.Len() == 0 { |
| 269 | return ts // No potentially parameterized types. |
| 270 | } |
| 271 | // Filter parameterized types, in place. |
| 272 | fn.Prog.methodsMu.Lock() |
| 273 | defer fn.Prog.methodsMu.Unlock() |
| 274 | filtered := ts[:0] |
| 275 | for _, t := range ts { |
| 276 | if !fn.Prog.parameterized.isParameterized(t) { |
| 277 | filtered = append(filtered, t) |
| 278 | } |
| 279 | } |
| 280 | return filtered |
| 281 | } |
| 282 | |
| 283 | // finishBody() finalizes the contents of the function after SSA code generation of its body. |
| 284 | // |
| 285 | // The function is not done being built until done() is called. |
| 286 | func (f *Function) finishBody() { |
| 287 | f.objects = nil |
| 288 | f.currentBlock = nil |
| 289 | f.lblocks = nil |
| 290 | |
| 291 | // Don't pin the AST in memory (except in debug mode). |
| 292 | if n := f.syntax; n != nil && !f.debugInfo() { |
| 293 | f.syntax = extentNode{n.Pos(), n.End()} |
| 294 | } |
| 295 | |
| 296 | // Remove from f.Locals any Allocs that escape to the heap. |
| 297 | j := 0 |
| 298 | for _, l := range f.Locals { |
| 299 | if !l.Heap { |
| 300 | f.Locals[j] = l |
| 301 | j++ |
| 302 | } |
| 303 | } |
| 304 | // Nil out f.Locals[j:] to aid GC. |
| 305 | for i := j; i < len(f.Locals); i++ { |
| 306 | f.Locals[i] = nil |
| 307 | } |
| 308 | f.Locals = f.Locals[:j] |
| 309 | |
| 310 | optimizeBlocks(f) |
| 311 | |
| 312 | buildReferrers(f) |
| 313 | |
| 314 | buildDomTree(f) |
| 315 | |
| 316 | if f.Prog.mode&NaiveForm == 0 { |
| 317 | // For debugging pre-state of lifting pass: |
| 318 | // numberRegisters(f) |
| 319 | // f.WriteTo(os.Stderr) |
| 320 | lift(f) |
| 321 | } |
| 322 | |
| 323 | // clear remaining stateful variables |
| 324 | f.namedResults = nil // (used by lifting) |
| 325 | f.info = nil |
| 326 | f.subst = nil |
| 327 | |
| 328 | numberRegisters(f) // uses f.namedRegisters |
| 329 | } |
| 330 | |
| 331 | // After this, function is done with BUILD phase. |
| 332 | func (f *Function) done() { |
| 333 | assert(f.parent == nil, "done called on an anonymous function") |
| 334 | |
| 335 | var visit func(*Function) |
| 336 | visit = func(f *Function) { |
| 337 | for _, anon := range f.AnonFuncs { |
| 338 | visit(anon) // anon is done building before f. |
| 339 | } |
| 340 | |
| 341 | f.built = true // function is done with BUILD phase |
| 342 | |
| 343 | if f.Prog.mode&PrintFunctions != 0 { |
| 344 | printMu.Lock() |
| 345 | f.WriteTo(os.Stdout) |
| 346 | printMu.Unlock() |
| 347 | } |
| 348 | |
| 349 | if f.Prog.mode&SanityCheckFunctions != 0 { |
| 350 | mustSanityCheck(f, nil) |
| 351 | } |
| 352 | } |
| 353 | visit(f) |
| 354 | } |
| 355 | |
| 356 | // removeNilBlocks eliminates nils from f.Blocks and updates each |
| 357 | // BasicBlock.Index. Use this after any pass that may delete blocks. |
| 358 | func (f *Function) removeNilBlocks() { |
| 359 | j := 0 |
| 360 | for _, b := range f.Blocks { |
| 361 | if b != nil { |
| 362 | b.Index = j |
| 363 | f.Blocks[j] = b |
| 364 | j++ |
| 365 | } |
| 366 | } |
| 367 | // Nil out f.Blocks[j:] to aid GC. |
| 368 | for i := j; i < len(f.Blocks); i++ { |
| 369 | f.Blocks[i] = nil |
| 370 | } |
| 371 | f.Blocks = f.Blocks[:j] |
| 372 | } |
| 373 | |
| 374 | // SetDebugMode sets the debug mode for package pkg. If true, all its |
| 375 | // functions will include full debug info. This greatly increases the |
| 376 | // size of the instruction stream, and causes Functions to depend upon |
| 377 | // the ASTs, potentially keeping them live in memory for longer. |
| 378 | func (pkg *Package) SetDebugMode(debug bool) { |
| 379 | // TODO(adonovan): do we want ast.File granularity? |
| 380 | pkg.debug = debug |
| 381 | } |
| 382 | |
| 383 | // debugInfo reports whether debug info is wanted for this function. |
| 384 | func (f *Function) debugInfo() bool { |
| 385 | return f.Pkg != nil && f.Pkg.debug |
| 386 | } |
| 387 | |
| 388 | // addNamedLocal creates a local variable, adds it to function f and |
| 389 | // returns it. Its name and type are taken from obj. Subsequent |
| 390 | // calls to f.lookup(obj) will return the same local. |
| 391 | func (f *Function) addNamedLocal(obj types.Object) *Alloc { |
| 392 | l := f.addLocal(obj.Type(), obj.Pos()) |
| 393 | l.Comment = obj.Name() |
| 394 | f.objects[obj] = l |
| 395 | return l |
| 396 | } |
| 397 | |
| 398 | func (f *Function) addLocalForIdent(id *ast.Ident) *Alloc { |
| 399 | return f.addNamedLocal(f.info.Defs[id]) |
| 400 | } |
| 401 | |
| 402 | // addLocal creates an anonymous local variable of type typ, adds it |
| 403 | // to function f and returns it. pos is the optional source location. |
| 404 | func (f *Function) addLocal(typ types.Type, pos token.Pos) *Alloc { |
| 405 | typ = f.typ(typ) |
| 406 | v := &Alloc{} |
| 407 | v.setType(types.NewPointer(typ)) |
| 408 | v.setPos(pos) |
| 409 | f.Locals = append(f.Locals, v) |
| 410 | f.emit(v) |
| 411 | return v |
| 412 | } |
| 413 | |
| 414 | // lookup returns the address of the named variable identified by obj |
| 415 | // that is local to function f or one of its enclosing functions. |
| 416 | // If escaping, the reference comes from a potentially escaping pointer |
| 417 | // expression and the referent must be heap-allocated. |
| 418 | func (f *Function) lookup(obj types.Object, escaping bool) Value { |
| 419 | if v, ok := f.objects[obj]; ok { |
| 420 | if alloc, ok := v.(*Alloc); ok && escaping { |
| 421 | alloc.Heap = true |
| 422 | } |
| 423 | return v // function-local var (address) |
| 424 | } |
| 425 | |
| 426 | // Definition must be in an enclosing function; |
| 427 | // plumb it through intervening closures. |
| 428 | if f.parent == nil { |
| 429 | panic("no ssa.Value for " + obj.String()) |
| 430 | } |
| 431 | outer := f.parent.lookup(obj, true) // escaping |
| 432 | v := &FreeVar{ |
| 433 | name: obj.Name(), |
| 434 | typ: outer.Type(), |
| 435 | pos: outer.Pos(), |
| 436 | outer: outer, |
| 437 | parent: f, |
| 438 | } |
| 439 | f.objects[obj] = v |
| 440 | f.FreeVars = append(f.FreeVars, v) |
| 441 | return v |
| 442 | } |
| 443 | |
| 444 | // emit emits the specified instruction to function f. |
| 445 | func (f *Function) emit(instr Instruction) Value { |
| 446 | return f.currentBlock.emit(instr) |
| 447 | } |
| 448 | |
| 449 | // RelString returns the full name of this function, qualified by |
| 450 | // package name, receiver type, etc. |
| 451 | // |
| 452 | // The specific formatting rules are not guaranteed and may change. |
| 453 | // |
| 454 | // Examples: |
| 455 | // |
| 456 | // "math.IsNaN" // a package-level function |
| 457 | // "(*bytes.Buffer).Bytes" // a declared method or a wrapper |
| 458 | // "(*bytes.Buffer).Bytes$thunk" // thunk (func wrapping method; receiver is param 0) |
| 459 | // "(*bytes.Buffer).Bytes$bound" // bound (func wrapping method; receiver supplied by closure) |
| 460 | // "main.main$1" // an anonymous function in main |
| 461 | // "main.init#1" // a declared init function |
| 462 | // "main.init" // the synthesized package initializer |
| 463 | // |
| 464 | // When these functions are referred to from within the same package |
| 465 | // (i.e. from == f.Pkg.Object), they are rendered without the package path. |
| 466 | // For example: "IsNaN", "(*Buffer).Bytes", etc. |
| 467 | // |
| 468 | // All non-synthetic functions have distinct package-qualified names. |
| 469 | // (But two methods may have the same name "(T).f" if one is a synthetic |
| 470 | // wrapper promoting a non-exported method "f" from another package; in |
| 471 | // that case, the strings are equal but the identifiers "f" are distinct.) |
| 472 | func (f *Function) RelString(from *types.Package) string { |
| 473 | // Anonymous? |
| 474 | if f.parent != nil { |
| 475 | // An anonymous function's Name() looks like "parentName$1", |
| 476 | // but its String() should include the type/package/etc. |
| 477 | parent := f.parent.RelString(from) |
| 478 | for i, anon := range f.parent.AnonFuncs { |
| 479 | if anon == f { |
| 480 | return fmt.Sprintf("%s$%d", parent, 1+i) |
| 481 | } |
| 482 | } |
| 483 | |
| 484 | return f.name // should never happen |
| 485 | } |
| 486 | |
| 487 | // Method (declared or wrapper)? |
| 488 | if recv := f.Signature.Recv(); recv != nil { |
| 489 | return f.relMethod(from, recv.Type()) |
| 490 | } |
| 491 | |
| 492 | // Thunk? |
| 493 | if f.method != nil { |
| 494 | return f.relMethod(from, f.method.recv) |
| 495 | } |
| 496 | |
| 497 | // Bound? |
| 498 | if len(f.FreeVars) == 1 && strings.HasSuffix(f.name, "$bound") { |
| 499 | return f.relMethod(from, f.FreeVars[0].Type()) |
| 500 | } |
| 501 | |
| 502 | // Package-level function? |
| 503 | // Prefix with package name for cross-package references only. |
| 504 | if p := f.relPkg(); p != nil && p != from { |
| 505 | return fmt.Sprintf("%s.%s", p.Path(), f.name) |
| 506 | } |
| 507 | |
| 508 | // Unknown. |
| 509 | return f.name |
| 510 | } |
| 511 | |
| 512 | func (f *Function) relMethod(from *types.Package, recv types.Type) string { |
| 513 | return fmt.Sprintf("(%s).%s", relType(recv, from), f.name) |
| 514 | } |
| 515 | |
| 516 | // writeSignature writes to buf the signature sig in declaration syntax. |
| 517 | func writeSignature(buf *bytes.Buffer, from *types.Package, name string, sig *types.Signature, params []*Parameter) { |
| 518 | buf.WriteString("func ") |
| 519 | if recv := sig.Recv(); recv != nil { |
| 520 | buf.WriteString("(") |
| 521 | if n := params[0].Name(); n != "" { |
| 522 | buf.WriteString(n) |
| 523 | buf.WriteString(" ") |
| 524 | } |
| 525 | types.WriteType(buf, params[0].Type(), types.RelativeTo(from)) |
| 526 | buf.WriteString(") ") |
| 527 | } |
| 528 | buf.WriteString(name) |
| 529 | types.WriteSignature(buf, sig, types.RelativeTo(from)) |
| 530 | } |
| 531 | |
| 532 | // declaredPackage returns the package fn is declared in or nil if the |
| 533 | // function is not declared in a package. |
| 534 | func (fn *Function) declaredPackage() *Package { |
| 535 | switch { |
| 536 | case fn.Pkg != nil: |
| 537 | return fn.Pkg // non-generic function |
| 538 | case fn.topLevelOrigin != nil: |
| 539 | return fn.topLevelOrigin.Pkg // instance of a named generic function |
| 540 | case fn.parent != nil: |
| 541 | return fn.parent.declaredPackage() // instance of an anonymous [generic] function |
| 542 | default: |
| 543 | return nil // function is not declared in a package, e.g. a wrapper. |
| 544 | } |
| 545 | } |
| 546 | |
| 547 | // relPkg returns types.Package fn is printed in relationship to. |
| 548 | func (fn *Function) relPkg() *types.Package { |
| 549 | if p := fn.declaredPackage(); p != nil { |
| 550 | return p.Pkg |
| 551 | } |
| 552 | return nil |
| 553 | } |
| 554 | |
| 555 | var _ io.WriterTo = (*Function)(nil) // *Function implements io.Writer |
| 556 | |
| 557 | func (f *Function) WriteTo(w io.Writer) (int64, error) { |
| 558 | var buf bytes.Buffer |
| 559 | WriteFunction(&buf, f) |
| 560 | n, err := w.Write(buf.Bytes()) |
| 561 | return int64(n), err |
| 562 | } |
| 563 | |
| 564 | // WriteFunction writes to buf a human-readable "disassembly" of f. |
| 565 | func WriteFunction(buf *bytes.Buffer, f *Function) { |
| 566 | fmt.Fprintf(buf, "# Name: %s\n", f.String()) |
| 567 | if f.Pkg != nil { |
| 568 | fmt.Fprintf(buf, "# Package: %s\n", f.Pkg.Pkg.Path()) |
| 569 | } |
| 570 | if syn := f.Synthetic; syn != "" { |
| 571 | fmt.Fprintln(buf, "# Synthetic:", syn) |
| 572 | } |
| 573 | if pos := f.Pos(); pos.IsValid() { |
| 574 | fmt.Fprintf(buf, "# Location: %s\n", f.Prog.Fset.Position(pos)) |
| 575 | } |
| 576 | |
| 577 | if f.parent != nil { |
| 578 | fmt.Fprintf(buf, "# Parent: %s\n", f.parent.Name()) |
| 579 | } |
| 580 | |
| 581 | if f.Recover != nil { |
| 582 | fmt.Fprintf(buf, "# Recover: %s\n", f.Recover) |
| 583 | } |
| 584 | |
| 585 | from := f.relPkg() |
| 586 | |
| 587 | if f.FreeVars != nil { |
| 588 | buf.WriteString("# Free variables:\n") |
| 589 | for i, fv := range f.FreeVars { |
| 590 | fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, fv.Name(), relType(fv.Type(), from)) |
| 591 | } |
| 592 | } |
| 593 | |
| 594 | if len(f.Locals) > 0 { |
| 595 | buf.WriteString("# Locals:\n") |
| 596 | for i, l := range f.Locals { |
| 597 | fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, l.Name(), relType(deref(l.Type()), from)) |
| 598 | } |
| 599 | } |
| 600 | writeSignature(buf, from, f.Name(), f.Signature, f.Params) |
| 601 | buf.WriteString(":\n") |
| 602 | |
| 603 | if f.Blocks == nil { |
| 604 | buf.WriteString("\t(external)\n") |
| 605 | } |
| 606 | |
| 607 | // NB. column calculations are confused by non-ASCII |
| 608 | // characters and assume 8-space tabs. |
| 609 | const punchcard = 80 // for old time's sake. |
| 610 | const tabwidth = 8 |
| 611 | for _, b := range f.Blocks { |
| 612 | if b == nil { |
| 613 | // Corrupt CFG. |
| 614 | fmt.Fprintf(buf, ".nil:\n") |
| 615 | continue |
| 616 | } |
| 617 | n, _ := fmt.Fprintf(buf, "%d:", b.Index) |
| 618 | bmsg := fmt.Sprintf("%s P:%d S:%d", b.Comment, len(b.Preds), len(b.Succs)) |
| 619 | fmt.Fprintf(buf, "%*s%s\n", punchcard-1-n-len(bmsg), "", bmsg) |
| 620 | |
| 621 | if false { // CFG debugging |
| 622 | fmt.Fprintf(buf, "\t# CFG: %s --> %s --> %s\n", b.Preds, b, b.Succs) |
| 623 | } |
| 624 | for _, instr := range b.Instrs { |
| 625 | buf.WriteString("\t") |
| 626 | switch v := instr.(type) { |
| 627 | case Value: |
| 628 | l := punchcard - tabwidth |
| 629 | // Left-align the instruction. |
| 630 | if name := v.Name(); name != "" { |
| 631 | n, _ := fmt.Fprintf(buf, "%s = ", name) |
| 632 | l -= n |
| 633 | } |
| 634 | n, _ := buf.WriteString(instr.String()) |
| 635 | l -= n |
| 636 | // Right-align the type if there's space. |
| 637 | if t := v.Type(); t != nil { |
| 638 | buf.WriteByte(' ') |
| 639 | ts := relType(t, from) |
| 640 | l -= len(ts) + len(" ") // (spaces before and after type) |
| 641 | if l > 0 { |
| 642 | fmt.Fprintf(buf, "%*s", l, "") |
| 643 | } |
| 644 | buf.WriteString(ts) |
| 645 | } |
| 646 | case nil: |
| 647 | // Be robust against bad transforms. |
| 648 | buf.WriteString("<deleted>") |
| 649 | default: |
| 650 | buf.WriteString(instr.String()) |
| 651 | } |
| 652 | buf.WriteString("\n") |
| 653 | } |
| 654 | } |
| 655 | fmt.Fprintf(buf, "\n") |
| 656 | } |
| 657 | |
| 658 | // newBasicBlock adds to f a new basic block and returns it. It does |
| 659 | // not automatically become the current block for subsequent calls to emit. |
| 660 | // comment is an optional string for more readable debugging output. |
| 661 | func (f *Function) newBasicBlock(comment string) *BasicBlock { |
| 662 | b := &BasicBlock{ |
| 663 | Index: len(f.Blocks), |
| 664 | Comment: comment, |
| 665 | parent: f, |
| 666 | } |
| 667 | b.Succs = b.succs2[:0] |
| 668 | f.Blocks = append(f.Blocks, b) |
| 669 | return b |
| 670 | } |
| 671 | |
| 672 | // NewFunction returns a new synthetic Function instance belonging to |
| 673 | // prog, with its name and signature fields set as specified. |
| 674 | // |
| 675 | // The caller is responsible for initializing the remaining fields of |
| 676 | // the function object, e.g. Pkg, Params, Blocks. |
| 677 | // |
| 678 | // It is practically impossible for clients to construct well-formed |
| 679 | // SSA functions/packages/programs directly, so we assume this is the |
| 680 | // job of the Builder alone. NewFunction exists to provide clients a |
| 681 | // little flexibility. For example, analysis tools may wish to |
| 682 | // construct fake Functions for the root of the callgraph, a fake |
| 683 | // "reflect" package, etc. |
| 684 | // |
| 685 | // TODO(adonovan): think harder about the API here. |
| 686 | func (prog *Program) NewFunction(name string, sig *types.Signature, provenance string) *Function { |
| 687 | return &Function{Prog: prog, name: name, Signature: sig, Synthetic: provenance} |
| 688 | } |
| 689 | |
| 690 | type extentNode [2]token.Pos |
| 691 | |
| 692 | func (n extentNode) Pos() token.Pos { return n[0] } |
| 693 | func (n extentNode) End() token.Pos { return n[1] } |
| 694 | |
| 695 | // Syntax returns an ast.Node whose Pos/End methods provide the |
| 696 | // lexical extent of the function if it was defined by Go source code |
| 697 | // (f.Synthetic==""), or nil otherwise. |
| 698 | // |
| 699 | // If f was built with debug information (see Package.SetDebugRef), |
| 700 | // the result is the *ast.FuncDecl or *ast.FuncLit that declared the |
| 701 | // function. Otherwise, it is an opaque Node providing only position |
| 702 | // information; this avoids pinning the AST in memory. |
| 703 | func (f *Function) Syntax() ast.Node { return f.syntax } |
| 704 |
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