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 package defines a high-level intermediate representation for |
8 | // Go programs using static single-assignment (SSA) form. |
9 | |
10 | import ( |
11 | "fmt" |
12 | "go/ast" |
13 | "go/constant" |
14 | "go/token" |
15 | "go/types" |
16 | "sync" |
17 | |
18 | "golang.org/x/tools/go/types/typeutil" |
19 | "golang.org/x/tools/internal/typeparams" |
20 | ) |
21 | |
22 | // A Program is a partial or complete Go program converted to SSA form. |
23 | type Program struct { |
24 | Fset *token.FileSet // position information for the files of this Program |
25 | imported map[string]*Package // all importable Packages, keyed by import path |
26 | packages map[*types.Package]*Package // all loaded Packages, keyed by object |
27 | mode BuilderMode // set of mode bits for SSA construction |
28 | MethodSets typeutil.MethodSetCache // cache of type-checker's method-sets |
29 | |
30 | canon *canonizer // type canonicalization map |
31 | ctxt *typeparams.Context // cache for type checking instantiations |
32 | |
33 | methodsMu sync.Mutex // guards the following maps: |
34 | methodSets typeutil.Map // maps type to its concrete methodSet |
35 | runtimeTypes typeutil.Map // types for which rtypes are needed |
36 | bounds map[boundsKey]*Function // bounds for curried x.Method closures |
37 | thunks map[selectionKey]*Function // thunks for T.Method expressions |
38 | instances map[*Function]*instanceSet // instances of generic functions |
39 | parameterized tpWalker // determines whether a type is parameterized. |
40 | } |
41 | |
42 | // A Package is a single analyzed Go package containing Members for |
43 | // all package-level functions, variables, constants and types it |
44 | // declares. These may be accessed directly via Members, or via the |
45 | // type-specific accessor methods Func, Type, Var and Const. |
46 | // |
47 | // Members also contains entries for "init" (the synthetic package |
48 | // initializer) and "init#%d", the nth declared init function, |
49 | // and unspecified other things too. |
50 | type Package struct { |
51 | Prog *Program // the owning program |
52 | Pkg *types.Package // the corresponding go/types.Package |
53 | Members map[string]Member // all package members keyed by name (incl. init and init#%d) |
54 | objects map[types.Object]Member // mapping of package objects to members (incl. methods). Contains *NamedConst, *Global, *Function. |
55 | init *Function // Func("init"); the package's init function |
56 | debug bool // include full debug info in this package |
57 | |
58 | // The following fields are set transiently, then cleared |
59 | // after building. |
60 | buildOnce sync.Once // ensures package building occurs once |
61 | ninit int32 // number of init functions |
62 | info *types.Info // package type information |
63 | files []*ast.File // package ASTs |
64 | created creator // members created as a result of building this package (includes declared functions, wrappers) |
65 | } |
66 | |
67 | // A Member is a member of a Go package, implemented by *NamedConst, |
68 | // *Global, *Function, or *Type; they are created by package-level |
69 | // const, var, func and type declarations respectively. |
70 | type Member interface { |
71 | Name() string // declared name of the package member |
72 | String() string // package-qualified name of the package member |
73 | RelString(*types.Package) string // like String, but relative refs are unqualified |
74 | Object() types.Object // typechecker's object for this member, if any |
75 | Pos() token.Pos // position of member's declaration, if known |
76 | Type() types.Type // type of the package member |
77 | Token() token.Token // token.{VAR,FUNC,CONST,TYPE} |
78 | Package() *Package // the containing package |
79 | } |
80 | |
81 | // A Type is a Member of a Package representing a package-level named type. |
82 | type Type struct { |
83 | object *types.TypeName |
84 | pkg *Package |
85 | } |
86 | |
87 | // A NamedConst is a Member of a Package representing a package-level |
88 | // named constant. |
89 | // |
90 | // Pos() returns the position of the declaring ast.ValueSpec.Names[*] |
91 | // identifier. |
92 | // |
93 | // NB: a NamedConst is not a Value; it contains a constant Value, which |
94 | // it augments with the name and position of its 'const' declaration. |
95 | type NamedConst struct { |
96 | object *types.Const |
97 | Value *Const |
98 | pkg *Package |
99 | } |
100 | |
101 | // A Value is an SSA value that can be referenced by an instruction. |
102 | type Value interface { |
103 | // Name returns the name of this value, and determines how |
104 | // this Value appears when used as an operand of an |
105 | // Instruction. |
106 | // |
107 | // This is the same as the source name for Parameters, |
108 | // Builtins, Functions, FreeVars, Globals. |
109 | // For constants, it is a representation of the constant's value |
110 | // and type. For all other Values this is the name of the |
111 | // virtual register defined by the instruction. |
112 | // |
113 | // The name of an SSA Value is not semantically significant, |
114 | // and may not even be unique within a function. |
115 | Name() string |
116 | |
117 | // If this value is an Instruction, String returns its |
118 | // disassembled form; otherwise it returns unspecified |
119 | // human-readable information about the Value, such as its |
120 | // kind, name and type. |
121 | String() string |
122 | |
123 | // Type returns the type of this value. Many instructions |
124 | // (e.g. IndexAddr) change their behaviour depending on the |
125 | // types of their operands. |
126 | Type() types.Type |
127 | |
128 | // Parent returns the function to which this Value belongs. |
129 | // It returns nil for named Functions, Builtin, Const and Global. |
130 | Parent() *Function |
131 | |
132 | // Referrers returns the list of instructions that have this |
133 | // value as one of their operands; it may contain duplicates |
134 | // if an instruction has a repeated operand. |
135 | // |
136 | // Referrers actually returns a pointer through which the |
137 | // caller may perform mutations to the object's state. |
138 | // |
139 | // Referrers is currently only defined if Parent()!=nil, |
140 | // i.e. for the function-local values FreeVar, Parameter, |
141 | // Functions (iff anonymous) and all value-defining instructions. |
142 | // It returns nil for named Functions, Builtin, Const and Global. |
143 | // |
144 | // Instruction.Operands contains the inverse of this relation. |
145 | Referrers() *[]Instruction |
146 | |
147 | // Pos returns the location of the AST token most closely |
148 | // associated with the operation that gave rise to this value, |
149 | // or token.NoPos if it was not explicit in the source. |
150 | // |
151 | // For each ast.Node type, a particular token is designated as |
152 | // the closest location for the expression, e.g. the Lparen |
153 | // for an *ast.CallExpr. This permits a compact but |
154 | // approximate mapping from Values to source positions for use |
155 | // in diagnostic messages, for example. |
156 | // |
157 | // (Do not use this position to determine which Value |
158 | // corresponds to an ast.Expr; use Function.ValueForExpr |
159 | // instead. NB: it requires that the function was built with |
160 | // debug information.) |
161 | Pos() token.Pos |
162 | } |
163 | |
164 | // An Instruction is an SSA instruction that computes a new Value or |
165 | // has some effect. |
166 | // |
167 | // An Instruction that defines a value (e.g. BinOp) also implements |
168 | // the Value interface; an Instruction that only has an effect (e.g. Store) |
169 | // does not. |
170 | type Instruction interface { |
171 | // String returns the disassembled form of this value. |
172 | // |
173 | // Examples of Instructions that are Values: |
174 | // "x + y" (BinOp) |
175 | // "len([])" (Call) |
176 | // Note that the name of the Value is not printed. |
177 | // |
178 | // Examples of Instructions that are not Values: |
179 | // "return x" (Return) |
180 | // "*y = x" (Store) |
181 | // |
182 | // (The separation Value.Name() from Value.String() is useful |
183 | // for some analyses which distinguish the operation from the |
184 | // value it defines, e.g., 'y = local int' is both an allocation |
185 | // of memory 'local int' and a definition of a pointer y.) |
186 | String() string |
187 | |
188 | // Parent returns the function to which this instruction |
189 | // belongs. |
190 | Parent() *Function |
191 | |
192 | // Block returns the basic block to which this instruction |
193 | // belongs. |
194 | Block() *BasicBlock |
195 | |
196 | // setBlock sets the basic block to which this instruction belongs. |
197 | setBlock(*BasicBlock) |
198 | |
199 | // Operands returns the operands of this instruction: the |
200 | // set of Values it references. |
201 | // |
202 | // Specifically, it appends their addresses to rands, a |
203 | // user-provided slice, and returns the resulting slice, |
204 | // permitting avoidance of memory allocation. |
205 | // |
206 | // The operands are appended in undefined order, but the order |
207 | // is consistent for a given Instruction; the addresses are |
208 | // always non-nil but may point to a nil Value. Clients may |
209 | // store through the pointers, e.g. to effect a value |
210 | // renaming. |
211 | // |
212 | // Value.Referrers is a subset of the inverse of this |
213 | // relation. (Referrers are not tracked for all types of |
214 | // Values.) |
215 | Operands(rands []*Value) []*Value |
216 | |
217 | // Pos returns the location of the AST token most closely |
218 | // associated with the operation that gave rise to this |
219 | // instruction, or token.NoPos if it was not explicit in the |
220 | // source. |
221 | // |
222 | // For each ast.Node type, a particular token is designated as |
223 | // the closest location for the expression, e.g. the Go token |
224 | // for an *ast.GoStmt. This permits a compact but approximate |
225 | // mapping from Instructions to source positions for use in |
226 | // diagnostic messages, for example. |
227 | // |
228 | // (Do not use this position to determine which Instruction |
229 | // corresponds to an ast.Expr; see the notes for Value.Pos. |
230 | // This position may be used to determine which non-Value |
231 | // Instruction corresponds to some ast.Stmts, but not all: If |
232 | // and Jump instructions have no Pos(), for example.) |
233 | Pos() token.Pos |
234 | } |
235 | |
236 | // A Node is a node in the SSA value graph. Every concrete type that |
237 | // implements Node is also either a Value, an Instruction, or both. |
238 | // |
239 | // Node contains the methods common to Value and Instruction, plus the |
240 | // Operands and Referrers methods generalized to return nil for |
241 | // non-Instructions and non-Values, respectively. |
242 | // |
243 | // Node is provided to simplify SSA graph algorithms. Clients should |
244 | // use the more specific and informative Value or Instruction |
245 | // interfaces where appropriate. |
246 | type Node interface { |
247 | // Common methods: |
248 | String() string |
249 | Pos() token.Pos |
250 | Parent() *Function |
251 | |
252 | // Partial methods: |
253 | Operands(rands []*Value) []*Value // nil for non-Instructions |
254 | Referrers() *[]Instruction // nil for non-Values |
255 | } |
256 | |
257 | // Function represents the parameters, results, and code of a function |
258 | // or method. |
259 | // |
260 | // If Blocks is nil, this indicates an external function for which no |
261 | // Go source code is available. In this case, FreeVars and Locals |
262 | // are nil too. Clients performing whole-program analysis must |
263 | // handle external functions specially. |
264 | // |
265 | // Blocks contains the function's control-flow graph (CFG). |
266 | // Blocks[0] is the function entry point; block order is not otherwise |
267 | // semantically significant, though it may affect the readability of |
268 | // the disassembly. |
269 | // To iterate over the blocks in dominance order, use DomPreorder(). |
270 | // |
271 | // Recover is an optional second entry point to which control resumes |
272 | // after a recovered panic. The Recover block may contain only a return |
273 | // statement, preceded by a load of the function's named return |
274 | // parameters, if any. |
275 | // |
276 | // A nested function (Parent()!=nil) that refers to one or more |
277 | // lexically enclosing local variables ("free variables") has FreeVars. |
278 | // Such functions cannot be called directly but require a |
279 | // value created by MakeClosure which, via its Bindings, supplies |
280 | // values for these parameters. |
281 | // |
282 | // If the function is a method (Signature.Recv() != nil) then the first |
283 | // element of Params is the receiver parameter. |
284 | // |
285 | // A Go package may declare many functions called "init". |
286 | // For each one, Object().Name() returns "init" but Name() returns |
287 | // "init#1", etc, in declaration order. |
288 | // |
289 | // Pos() returns the declaring ast.FuncLit.Type.Func or the position |
290 | // of the ast.FuncDecl.Name, if the function was explicit in the |
291 | // source. Synthetic wrappers, for which Synthetic != "", may share |
292 | // the same position as the function they wrap. |
293 | // Syntax.Pos() always returns the position of the declaring "func" token. |
294 | // |
295 | // Type() returns the function's Signature. |
296 | // |
297 | // A generic function is a function or method that has uninstantiated type |
298 | // parameters (TypeParams() != nil). Consider a hypothetical generic |
299 | // method, (*Map[K,V]).Get. It may be instantiated with all ground |
300 | // (non-parameterized) types as (*Map[string,int]).Get or with |
301 | // parameterized types as (*Map[string,U]).Get, where U is a type parameter. |
302 | // In both instantiations, Origin() refers to the instantiated generic |
303 | // method, (*Map[K,V]).Get, TypeParams() refers to the parameters [K,V] of |
304 | // the generic method. TypeArgs() refers to [string,U] or [string,int], |
305 | // respectively, and is nil in the generic method. |
306 | type Function struct { |
307 | name string |
308 | object types.Object // a declared *types.Func or one of its wrappers |
309 | method *selection // info about provenance of synthetic methods; thunk => non-nil |
310 | Signature *types.Signature |
311 | pos token.Pos |
312 | |
313 | Synthetic string // provenance of synthetic function; "" for true source functions |
314 | syntax ast.Node // *ast.Func{Decl,Lit}; replaced with simple ast.Node after build, unless debug mode |
315 | parent *Function // enclosing function if anon; nil if global |
316 | Pkg *Package // enclosing package; nil for shared funcs (wrappers and error.Error) |
317 | Prog *Program // enclosing program |
318 | Params []*Parameter // function parameters; for methods, includes receiver |
319 | FreeVars []*FreeVar // free variables whose values must be supplied by closure |
320 | Locals []*Alloc // local variables of this function |
321 | Blocks []*BasicBlock // basic blocks of the function; nil => external |
322 | Recover *BasicBlock // optional; control transfers here after recovered panic |
323 | AnonFuncs []*Function // anonymous functions directly beneath this one |
324 | referrers []Instruction // referring instructions (iff Parent() != nil) |
325 | built bool // function has completed both CREATE and BUILD phase. |
326 | anonIdx int32 // position of a nested function in parent's AnonFuncs. fn.Parent()!=nil => fn.Parent().AnonFunc[fn.anonIdx] == fn. |
327 | |
328 | typeparams *typeparams.TypeParamList // type parameters of this function. typeparams.Len() > 0 => generic or instance of generic function |
329 | typeargs []types.Type // type arguments that instantiated typeparams. len(typeargs) > 0 => instance of generic function |
330 | topLevelOrigin *Function // the origin function if this is an instance of a source function. nil if Parent()!=nil. |
331 | |
332 | // The following fields are set transiently during building, |
333 | // then cleared. |
334 | currentBlock *BasicBlock // where to emit code |
335 | objects map[types.Object]Value // addresses of local variables |
336 | namedResults []*Alloc // tuple of named results |
337 | targets *targets // linked stack of branch targets |
338 | lblocks map[types.Object]*lblock // labelled blocks |
339 | info *types.Info // *types.Info to build from. nil for wrappers. |
340 | subst *subster // non-nil => expand generic body using this type substitution of ground types |
341 | } |
342 | |
343 | // BasicBlock represents an SSA basic block. |
344 | // |
345 | // The final element of Instrs is always an explicit transfer of |
346 | // control (If, Jump, Return, or Panic). |
347 | // |
348 | // A block may contain no Instructions only if it is unreachable, |
349 | // i.e., Preds is nil. Empty blocks are typically pruned. |
350 | // |
351 | // BasicBlocks and their Preds/Succs relation form a (possibly cyclic) |
352 | // graph independent of the SSA Value graph: the control-flow graph or |
353 | // CFG. It is illegal for multiple edges to exist between the same |
354 | // pair of blocks. |
355 | // |
356 | // Each BasicBlock is also a node in the dominator tree of the CFG. |
357 | // The tree may be navigated using Idom()/Dominees() and queried using |
358 | // Dominates(). |
359 | // |
360 | // The order of Preds and Succs is significant (to Phi and If |
361 | // instructions, respectively). |
362 | type BasicBlock struct { |
363 | Index int // index of this block within Parent().Blocks |
364 | Comment string // optional label; no semantic significance |
365 | parent *Function // parent function |
366 | Instrs []Instruction // instructions in order |
367 | Preds, Succs []*BasicBlock // predecessors and successors |
368 | succs2 [2]*BasicBlock // initial space for Succs |
369 | dom domInfo // dominator tree info |
370 | gaps int // number of nil Instrs (transient) |
371 | rundefers int // number of rundefers (transient) |
372 | } |
373 | |
374 | // Pure values ---------------------------------------- |
375 | |
376 | // A FreeVar represents a free variable of the function to which it |
377 | // belongs. |
378 | // |
379 | // FreeVars are used to implement anonymous functions, whose free |
380 | // variables are lexically captured in a closure formed by |
381 | // MakeClosure. The value of such a free var is an Alloc or another |
382 | // FreeVar and is considered a potentially escaping heap address, with |
383 | // pointer type. |
384 | // |
385 | // FreeVars are also used to implement bound method closures. Such a |
386 | // free var represents the receiver value and may be of any type that |
387 | // has concrete methods. |
388 | // |
389 | // Pos() returns the position of the value that was captured, which |
390 | // belongs to an enclosing function. |
391 | type FreeVar struct { |
392 | name string |
393 | typ types.Type |
394 | pos token.Pos |
395 | parent *Function |
396 | referrers []Instruction |
397 | |
398 | // Transiently needed during building. |
399 | outer Value // the Value captured from the enclosing context. |
400 | } |
401 | |
402 | // A Parameter represents an input parameter of a function. |
403 | type Parameter struct { |
404 | name string |
405 | object types.Object // a *types.Var; nil for non-source locals |
406 | typ types.Type |
407 | pos token.Pos |
408 | parent *Function |
409 | referrers []Instruction |
410 | } |
411 | |
412 | // A Const represents a value known at build time. |
413 | // |
414 | // Consts include true constants of boolean, numeric, and string types, as |
415 | // defined by the Go spec; these are represented by a non-nil Value field. |
416 | // |
417 | // Consts also include the "zero" value of any type, of which the nil values |
418 | // of various pointer-like types are a special case; these are represented |
419 | // by a nil Value field. |
420 | // |
421 | // Pos() returns token.NoPos. |
422 | // |
423 | // Example printed forms: |
424 | // |
425 | // 42:int |
426 | // "hello":untyped string |
427 | // 3+4i:MyComplex |
428 | // nil:*int |
429 | // nil:[]string |
430 | // [3]int{}:[3]int |
431 | // struct{x string}{}:struct{x string} |
432 | // 0:interface{int|int64} |
433 | // nil:interface{bool|int} // no go/constant representation |
434 | type Const struct { |
435 | typ types.Type |
436 | Value constant.Value |
437 | } |
438 | |
439 | // A Global is a named Value holding the address of a package-level |
440 | // variable. |
441 | // |
442 | // Pos() returns the position of the ast.ValueSpec.Names[*] |
443 | // identifier. |
444 | type Global struct { |
445 | name string |
446 | object types.Object // a *types.Var; may be nil for synthetics e.g. init$guard |
447 | typ types.Type |
448 | pos token.Pos |
449 | |
450 | Pkg *Package |
451 | } |
452 | |
453 | // A Builtin represents a specific use of a built-in function, e.g. len. |
454 | // |
455 | // Builtins are immutable values. Builtins do not have addresses. |
456 | // Builtins can only appear in CallCommon.Value. |
457 | // |
458 | // Name() indicates the function: one of the built-in functions from the |
459 | // Go spec (excluding "make" and "new") or one of these ssa-defined |
460 | // intrinsics: |
461 | // |
462 | // // wrapnilchk returns ptr if non-nil, panics otherwise. |
463 | // // (For use in indirection wrappers.) |
464 | // func ssa:wrapnilchk(ptr *T, recvType, methodName string) *T |
465 | // |
466 | // Object() returns a *types.Builtin for built-ins defined by the spec, |
467 | // nil for others. |
468 | // |
469 | // Type() returns a *types.Signature representing the effective |
470 | // signature of the built-in for this call. |
471 | type Builtin struct { |
472 | name string |
473 | sig *types.Signature |
474 | } |
475 | |
476 | // Value-defining instructions ---------------------------------------- |
477 | |
478 | // The Alloc instruction reserves space for a variable of the given type, |
479 | // zero-initializes it, and yields its address. |
480 | // |
481 | // Alloc values are always addresses, and have pointer types, so the |
482 | // type of the allocated variable is actually |
483 | // Type().Underlying().(*types.Pointer).Elem(). |
484 | // |
485 | // If Heap is false, Alloc allocates space in the function's |
486 | // activation record (frame); we refer to an Alloc(Heap=false) as a |
487 | // "local" alloc. Each local Alloc returns the same address each time |
488 | // it is executed within the same activation; the space is |
489 | // re-initialized to zero. |
490 | // |
491 | // If Heap is true, Alloc allocates space in the heap; we |
492 | // refer to an Alloc(Heap=true) as a "new" alloc. Each new Alloc |
493 | // returns a different address each time it is executed. |
494 | // |
495 | // When Alloc is applied to a channel, map or slice type, it returns |
496 | // the address of an uninitialized (nil) reference of that kind; store |
497 | // the result of MakeSlice, MakeMap or MakeChan in that location to |
498 | // instantiate these types. |
499 | // |
500 | // Pos() returns the ast.CompositeLit.Lbrace for a composite literal, |
501 | // or the ast.CallExpr.Rparen for a call to new() or for a call that |
502 | // allocates a varargs slice. |
503 | // |
504 | // Example printed form: |
505 | // |
506 | // t0 = local int |
507 | // t1 = new int |
508 | type Alloc struct { |
509 | register |
510 | Comment string |
511 | Heap bool |
512 | index int // dense numbering; for lifting |
513 | } |
514 | |
515 | // The Phi instruction represents an SSA φ-node, which combines values |
516 | // that differ across incoming control-flow edges and yields a new |
517 | // value. Within a block, all φ-nodes must appear before all non-φ |
518 | // nodes. |
519 | // |
520 | // Pos() returns the position of the && or || for short-circuit |
521 | // control-flow joins, or that of the *Alloc for φ-nodes inserted |
522 | // during SSA renaming. |
523 | // |
524 | // Example printed form: |
525 | // |
526 | // t2 = phi [0: t0, 1: t1] |
527 | type Phi struct { |
528 | register |
529 | Comment string // a hint as to its purpose |
530 | Edges []Value // Edges[i] is value for Block().Preds[i] |
531 | } |
532 | |
533 | // The Call instruction represents a function or method call. |
534 | // |
535 | // The Call instruction yields the function result if there is exactly |
536 | // one. Otherwise it returns a tuple, the components of which are |
537 | // accessed via Extract. |
538 | // |
539 | // See CallCommon for generic function call documentation. |
540 | // |
541 | // Pos() returns the ast.CallExpr.Lparen, if explicit in the source. |
542 | // |
543 | // Example printed form: |
544 | // |
545 | // t2 = println(t0, t1) |
546 | // t4 = t3() |
547 | // t7 = invoke t5.Println(...t6) |
548 | type Call struct { |
549 | register |
550 | Call CallCommon |
551 | } |
552 | |
553 | // The BinOp instruction yields the result of binary operation X Op Y. |
554 | // |
555 | // Pos() returns the ast.BinaryExpr.OpPos, if explicit in the source. |
556 | // |
557 | // Example printed form: |
558 | // |
559 | // t1 = t0 + 1:int |
560 | type BinOp struct { |
561 | register |
562 | // One of: |
563 | // ADD SUB MUL QUO REM + - * / % |
564 | // AND OR XOR SHL SHR AND_NOT & | ^ << >> &^ |
565 | // EQL NEQ LSS LEQ GTR GEQ == != < <= < >= |
566 | Op token.Token |
567 | X, Y Value |
568 | } |
569 | |
570 | // The UnOp instruction yields the result of Op X. |
571 | // ARROW is channel receive. |
572 | // MUL is pointer indirection (load). |
573 | // XOR is bitwise complement. |
574 | // SUB is negation. |
575 | // NOT is logical negation. |
576 | // |
577 | // If CommaOk and Op=ARROW, the result is a 2-tuple of the value above |
578 | // and a boolean indicating the success of the receive. The |
579 | // components of the tuple are accessed using Extract. |
580 | // |
581 | // Pos() returns the ast.UnaryExpr.OpPos, if explicit in the source. |
582 | // For receive operations (ARROW) implicit in ranging over a channel, |
583 | // Pos() returns the ast.RangeStmt.For. |
584 | // For implicit memory loads (STAR), Pos() returns the position of the |
585 | // most closely associated source-level construct; the details are not |
586 | // specified. |
587 | // |
588 | // Example printed form: |
589 | // |
590 | // t0 = *x |
591 | // t2 = <-t1,ok |
592 | type UnOp struct { |
593 | register |
594 | Op token.Token // One of: NOT SUB ARROW MUL XOR ! - <- * ^ |
595 | X Value |
596 | CommaOk bool |
597 | } |
598 | |
599 | // The ChangeType instruction applies to X a value-preserving type |
600 | // change to Type(). |
601 | // |
602 | // Type changes are permitted: |
603 | // - between a named type and its underlying type. |
604 | // - between two named types of the same underlying type. |
605 | // - between (possibly named) pointers to identical base types. |
606 | // - from a bidirectional channel to a read- or write-channel, |
607 | // optionally adding/removing a name. |
608 | // - between a type (t) and an instance of the type (tσ), i.e. |
609 | // Type() == σ(X.Type()) (or X.Type()== σ(Type())) where |
610 | // σ is the type substitution of Parent().TypeParams by |
611 | // Parent().TypeArgs. |
612 | // |
613 | // This operation cannot fail dynamically. |
614 | // |
615 | // Type changes may to be to or from a type parameter (or both). All |
616 | // types in the type set of X.Type() have a value-preserving type |
617 | // change to all types in the type set of Type(). |
618 | // |
619 | // Pos() returns the ast.CallExpr.Lparen, if the instruction arose |
620 | // from an explicit conversion in the source. |
621 | // |
622 | // Example printed form: |
623 | // |
624 | // t1 = changetype *int <- IntPtr (t0) |
625 | type ChangeType struct { |
626 | register |
627 | X Value |
628 | } |
629 | |
630 | // The Convert instruction yields the conversion of value X to type |
631 | // Type(). One or both of those types is basic (but possibly named). |
632 | // |
633 | // A conversion may change the value and representation of its operand. |
634 | // Conversions are permitted: |
635 | // - between real numeric types. |
636 | // - between complex numeric types. |
637 | // - between string and []byte or []rune. |
638 | // - between pointers and unsafe.Pointer. |
639 | // - between unsafe.Pointer and uintptr. |
640 | // - from (Unicode) integer to (UTF-8) string. |
641 | // |
642 | // A conversion may imply a type name change also. |
643 | // |
644 | // Conversions may to be to or from a type parameter. All types in |
645 | // the type set of X.Type() can be converted to all types in the type |
646 | // set of Type(). |
647 | // |
648 | // This operation cannot fail dynamically. |
649 | // |
650 | // Conversions of untyped string/number/bool constants to a specific |
651 | // representation are eliminated during SSA construction. |
652 | // |
653 | // Pos() returns the ast.CallExpr.Lparen, if the instruction arose |
654 | // from an explicit conversion in the source. |
655 | // |
656 | // Example printed form: |
657 | // |
658 | // t1 = convert []byte <- string (t0) |
659 | type Convert struct { |
660 | register |
661 | X Value |
662 | } |
663 | |
664 | // ChangeInterface constructs a value of one interface type from a |
665 | // value of another interface type known to be assignable to it. |
666 | // This operation cannot fail. |
667 | // |
668 | // Pos() returns the ast.CallExpr.Lparen if the instruction arose from |
669 | // an explicit T(e) conversion; the ast.TypeAssertExpr.Lparen if the |
670 | // instruction arose from an explicit e.(T) operation; or token.NoPos |
671 | // otherwise. |
672 | // |
673 | // Example printed form: |
674 | // |
675 | // t1 = change interface interface{} <- I (t0) |
676 | type ChangeInterface struct { |
677 | register |
678 | X Value |
679 | } |
680 | |
681 | // The SliceToArrayPointer instruction yields the conversion of slice X to |
682 | // array pointer. |
683 | // |
684 | // Pos() returns the ast.CallExpr.Lparen, if the instruction arose |
685 | // from an explicit conversion in the source. |
686 | // |
687 | // Conversion may to be to or from a type parameter. All types in |
688 | // the type set of X.Type() must be a slice types that can be converted to |
689 | // all types in the type set of Type() which must all be pointer to array |
690 | // types. |
691 | // |
692 | // Example printed form: |
693 | // |
694 | // t1 = slice to array pointer *[4]byte <- []byte (t0) |
695 | type SliceToArrayPointer struct { |
696 | register |
697 | X Value |
698 | } |
699 | |
700 | // MakeInterface constructs an instance of an interface type from a |
701 | // value of a concrete type. |
702 | // |
703 | // Use Program.MethodSets.MethodSet(X.Type()) to find the method-set |
704 | // of X, and Program.MethodValue(m) to find the implementation of a method. |
705 | // |
706 | // To construct the zero value of an interface type T, use: |
707 | // |
708 | // NewConst(constant.MakeNil(), T, pos) |
709 | // |
710 | // Pos() returns the ast.CallExpr.Lparen, if the instruction arose |
711 | // from an explicit conversion in the source. |
712 | // |
713 | // Example printed form: |
714 | // |
715 | // t1 = make interface{} <- int (42:int) |
716 | // t2 = make Stringer <- t0 |
717 | type MakeInterface struct { |
718 | register |
719 | X Value |
720 | } |
721 | |
722 | // The MakeClosure instruction yields a closure value whose code is |
723 | // Fn and whose free variables' values are supplied by Bindings. |
724 | // |
725 | // Type() returns a (possibly named) *types.Signature. |
726 | // |
727 | // Pos() returns the ast.FuncLit.Type.Func for a function literal |
728 | // closure or the ast.SelectorExpr.Sel for a bound method closure. |
729 | // |
730 | // Example printed form: |
731 | // |
732 | // t0 = make closure anon@1.2 [x y z] |
733 | // t1 = make closure bound$(main.I).add [i] |
734 | type MakeClosure struct { |
735 | register |
736 | Fn Value // always a *Function |
737 | Bindings []Value // values for each free variable in Fn.FreeVars |
738 | } |
739 | |
740 | // The MakeMap instruction creates a new hash-table-based map object |
741 | // and yields a value of kind map. |
742 | // |
743 | // Type() returns a (possibly named) *types.Map. |
744 | // |
745 | // Pos() returns the ast.CallExpr.Lparen, if created by make(map), or |
746 | // the ast.CompositeLit.Lbrack if created by a literal. |
747 | // |
748 | // Example printed form: |
749 | // |
750 | // t1 = make map[string]int t0 |
751 | // t1 = make StringIntMap t0 |
752 | type MakeMap struct { |
753 | register |
754 | Reserve Value // initial space reservation; nil => default |
755 | } |
756 | |
757 | // The MakeChan instruction creates a new channel object and yields a |
758 | // value of kind chan. |
759 | // |
760 | // Type() returns a (possibly named) *types.Chan. |
761 | // |
762 | // Pos() returns the ast.CallExpr.Lparen for the make(chan) that |
763 | // created it. |
764 | // |
765 | // Example printed form: |
766 | // |
767 | // t0 = make chan int 0 |
768 | // t0 = make IntChan 0 |
769 | type MakeChan struct { |
770 | register |
771 | Size Value // int; size of buffer; zero => synchronous. |
772 | } |
773 | |
774 | // The MakeSlice instruction yields a slice of length Len backed by a |
775 | // newly allocated array of length Cap. |
776 | // |
777 | // Both Len and Cap must be non-nil Values of integer type. |
778 | // |
779 | // (Alloc(types.Array) followed by Slice will not suffice because |
780 | // Alloc can only create arrays of constant length.) |
781 | // |
782 | // Type() returns a (possibly named) *types.Slice. |
783 | // |
784 | // Pos() returns the ast.CallExpr.Lparen for the make([]T) that |
785 | // created it. |
786 | // |
787 | // Example printed form: |
788 | // |
789 | // t1 = make []string 1:int t0 |
790 | // t1 = make StringSlice 1:int t0 |
791 | type MakeSlice struct { |
792 | register |
793 | Len Value |
794 | Cap Value |
795 | } |
796 | |
797 | // The Slice instruction yields a slice of an existing string, slice |
798 | // or *array X between optional integer bounds Low and High. |
799 | // |
800 | // Dynamically, this instruction panics if X evaluates to a nil *array |
801 | // pointer. |
802 | // |
803 | // Type() returns string if the type of X was string, otherwise a |
804 | // *types.Slice with the same element type as X. |
805 | // |
806 | // Pos() returns the ast.SliceExpr.Lbrack if created by a x[:] slice |
807 | // operation, the ast.CompositeLit.Lbrace if created by a literal, or |
808 | // NoPos if not explicit in the source (e.g. a variadic argument slice). |
809 | // |
810 | // Example printed form: |
811 | // |
812 | // t1 = slice t0[1:] |
813 | type Slice struct { |
814 | register |
815 | X Value // slice, string, or *array |
816 | Low, High, Max Value // each may be nil |
817 | } |
818 | |
819 | // The FieldAddr instruction yields the address of Field of *struct X. |
820 | // |
821 | // The field is identified by its index within the field list of the |
822 | // struct type of X. |
823 | // |
824 | // Dynamically, this instruction panics if X evaluates to a nil |
825 | // pointer. |
826 | // |
827 | // Type() returns a (possibly named) *types.Pointer. |
828 | // |
829 | // Pos() returns the position of the ast.SelectorExpr.Sel for the |
830 | // field, if explicit in the source. For implicit selections, returns |
831 | // the position of the inducing explicit selection. If produced for a |
832 | // struct literal S{f: e}, it returns the position of the colon; for |
833 | // S{e} it returns the start of expression e. |
834 | // |
835 | // Example printed form: |
836 | // |
837 | // t1 = &t0.name [#1] |
838 | type FieldAddr struct { |
839 | register |
840 | X Value // *struct |
841 | Field int // field is typeparams.CoreType(X.Type().Underlying().(*types.Pointer).Elem()).(*types.Struct).Field(Field) |
842 | } |
843 | |
844 | // The Field instruction yields the Field of struct X. |
845 | // |
846 | // The field is identified by its index within the field list of the |
847 | // struct type of X; by using numeric indices we avoid ambiguity of |
848 | // package-local identifiers and permit compact representations. |
849 | // |
850 | // Pos() returns the position of the ast.SelectorExpr.Sel for the |
851 | // field, if explicit in the source. For implicit selections, returns |
852 | // the position of the inducing explicit selection. |
853 | |
854 | // Example printed form: |
855 | // |
856 | // t1 = t0.name [#1] |
857 | type Field struct { |
858 | register |
859 | X Value // struct |
860 | Field int // index into typeparams.CoreType(X.Type()).(*types.Struct).Fields |
861 | } |
862 | |
863 | // The IndexAddr instruction yields the address of the element at |
864 | // index Index of collection X. Index is an integer expression. |
865 | // |
866 | // The elements of maps and strings are not addressable; use Lookup (map), |
867 | // Index (string), or MapUpdate instead. |
868 | // |
869 | // Dynamically, this instruction panics if X evaluates to a nil *array |
870 | // pointer. |
871 | // |
872 | // Type() returns a (possibly named) *types.Pointer. |
873 | // |
874 | // Pos() returns the ast.IndexExpr.Lbrack for the index operation, if |
875 | // explicit in the source. |
876 | // |
877 | // Example printed form: |
878 | // |
879 | // t2 = &t0[t1] |
880 | type IndexAddr struct { |
881 | register |
882 | X Value // *array, slice or type parameter with types array, *array, or slice. |
883 | Index Value // numeric index |
884 | } |
885 | |
886 | // The Index instruction yields element Index of collection X, an array, |
887 | // string or type parameter containing an array, a string, a pointer to an, |
888 | // array or a slice. |
889 | // |
890 | // Pos() returns the ast.IndexExpr.Lbrack for the index operation, if |
891 | // explicit in the source. |
892 | // |
893 | // Example printed form: |
894 | // |
895 | // t2 = t0[t1] |
896 | type Index struct { |
897 | register |
898 | X Value // array, string or type parameter with types array, *array, slice, or string. |
899 | Index Value // integer index |
900 | } |
901 | |
902 | // The Lookup instruction yields element Index of collection map X. |
903 | // Index is the appropriate key type. |
904 | // |
905 | // If CommaOk, the result is a 2-tuple of the value above and a |
906 | // boolean indicating the result of a map membership test for the key. |
907 | // The components of the tuple are accessed using Extract. |
908 | // |
909 | // Pos() returns the ast.IndexExpr.Lbrack, if explicit in the source. |
910 | // |
911 | // Example printed form: |
912 | // |
913 | // t2 = t0[t1] |
914 | // t5 = t3[t4],ok |
915 | type Lookup struct { |
916 | register |
917 | X Value // map |
918 | Index Value // key-typed index |
919 | CommaOk bool // return a value,ok pair |
920 | } |
921 | |
922 | // SelectState is a helper for Select. |
923 | // It represents one goal state and its corresponding communication. |
924 | type SelectState struct { |
925 | Dir types.ChanDir // direction of case (SendOnly or RecvOnly) |
926 | Chan Value // channel to use (for send or receive) |
927 | Send Value // value to send (for send) |
928 | Pos token.Pos // position of token.ARROW |
929 | DebugNode ast.Node // ast.SendStmt or ast.UnaryExpr(<-) [debug mode] |
930 | } |
931 | |
932 | // The Select instruction tests whether (or blocks until) one |
933 | // of the specified sent or received states is entered. |
934 | // |
935 | // Let n be the number of States for which Dir==RECV and T_i (0<=i<n) |
936 | // be the element type of each such state's Chan. |
937 | // Select returns an n+2-tuple |
938 | // |
939 | // (index int, recvOk bool, r_0 T_0, ... r_n-1 T_n-1) |
940 | // |
941 | // The tuple's components, described below, must be accessed via the |
942 | // Extract instruction. |
943 | // |
944 | // If Blocking, select waits until exactly one state holds, i.e. a |
945 | // channel becomes ready for the designated operation of sending or |
946 | // receiving; select chooses one among the ready states |
947 | // pseudorandomly, performs the send or receive operation, and sets |
948 | // 'index' to the index of the chosen channel. |
949 | // |
950 | // If !Blocking, select doesn't block if no states hold; instead it |
951 | // returns immediately with index equal to -1. |
952 | // |
953 | // If the chosen channel was used for a receive, the r_i component is |
954 | // set to the received value, where i is the index of that state among |
955 | // all n receive states; otherwise r_i has the zero value of type T_i. |
956 | // Note that the receive index i is not the same as the state |
957 | // index index. |
958 | // |
959 | // The second component of the triple, recvOk, is a boolean whose value |
960 | // is true iff the selected operation was a receive and the receive |
961 | // successfully yielded a value. |
962 | // |
963 | // Pos() returns the ast.SelectStmt.Select. |
964 | // |
965 | // Example printed form: |
966 | // |
967 | // t3 = select nonblocking [<-t0, t1<-t2] |
968 | // t4 = select blocking [] |
969 | type Select struct { |
970 | register |
971 | States []*SelectState |
972 | Blocking bool |
973 | } |
974 | |
975 | // The Range instruction yields an iterator over the domain and range |
976 | // of X, which must be a string or map. |
977 | // |
978 | // Elements are accessed via Next. |
979 | // |
980 | // Type() returns an opaque and degenerate "rangeIter" type. |
981 | // |
982 | // Pos() returns the ast.RangeStmt.For. |
983 | // |
984 | // Example printed form: |
985 | // |
986 | // t0 = range "hello":string |
987 | type Range struct { |
988 | register |
989 | X Value // string or map |
990 | } |
991 | |
992 | // The Next instruction reads and advances the (map or string) |
993 | // iterator Iter and returns a 3-tuple value (ok, k, v). If the |
994 | // iterator is not exhausted, ok is true and k and v are the next |
995 | // elements of the domain and range, respectively. Otherwise ok is |
996 | // false and k and v are undefined. |
997 | // |
998 | // Components of the tuple are accessed using Extract. |
999 | // |
1000 | // The IsString field distinguishes iterators over strings from those |
1001 | // over maps, as the Type() alone is insufficient: consider |
1002 | // map[int]rune. |
1003 | // |
1004 | // Type() returns a *types.Tuple for the triple (ok, k, v). |
1005 | // The types of k and/or v may be types.Invalid. |
1006 | // |
1007 | // Example printed form: |
1008 | // |
1009 | // t1 = next t0 |
1010 | type Next struct { |
1011 | register |
1012 | Iter Value |
1013 | IsString bool // true => string iterator; false => map iterator. |
1014 | } |
1015 | |
1016 | // The TypeAssert instruction tests whether interface value X has type |
1017 | // AssertedType. |
1018 | // |
1019 | // If !CommaOk, on success it returns v, the result of the conversion |
1020 | // (defined below); on failure it panics. |
1021 | // |
1022 | // If CommaOk: on success it returns a pair (v, true) where v is the |
1023 | // result of the conversion; on failure it returns (z, false) where z |
1024 | // is AssertedType's zero value. The components of the pair must be |
1025 | // accessed using the Extract instruction. |
1026 | // |
1027 | // If AssertedType is a concrete type, TypeAssert checks whether the |
1028 | // dynamic type in interface X is equal to it, and if so, the result |
1029 | // of the conversion is a copy of the value in the interface. |
1030 | // |
1031 | // If AssertedType is an interface, TypeAssert checks whether the |
1032 | // dynamic type of the interface is assignable to it, and if so, the |
1033 | // result of the conversion is a copy of the interface value X. |
1034 | // If AssertedType is a superinterface of X.Type(), the operation will |
1035 | // fail iff the operand is nil. (Contrast with ChangeInterface, which |
1036 | // performs no nil-check.) |
1037 | // |
1038 | // Type() reflects the actual type of the result, possibly a |
1039 | // 2-types.Tuple; AssertedType is the asserted type. |
1040 | // |
1041 | // Pos() returns the ast.CallExpr.Lparen if the instruction arose from |
1042 | // an explicit T(e) conversion; the ast.TypeAssertExpr.Lparen if the |
1043 | // instruction arose from an explicit e.(T) operation; or the |
1044 | // ast.CaseClause.Case if the instruction arose from a case of a |
1045 | // type-switch statement. |
1046 | // |
1047 | // Example printed form: |
1048 | // |
1049 | // t1 = typeassert t0.(int) |
1050 | // t3 = typeassert,ok t2.(T) |
1051 | type TypeAssert struct { |
1052 | register |
1053 | X Value |
1054 | AssertedType types.Type |
1055 | CommaOk bool |
1056 | } |
1057 | |
1058 | // The Extract instruction yields component Index of Tuple. |
1059 | // |
1060 | // This is used to access the results of instructions with multiple |
1061 | // return values, such as Call, TypeAssert, Next, UnOp(ARROW) and |
1062 | // IndexExpr(Map). |
1063 | // |
1064 | // Example printed form: |
1065 | // |
1066 | // t1 = extract t0 #1 |
1067 | type Extract struct { |
1068 | register |
1069 | Tuple Value |
1070 | Index int |
1071 | } |
1072 | |
1073 | // Instructions executed for effect. They do not yield a value. -------------------- |
1074 | |
1075 | // The Jump instruction transfers control to the sole successor of its |
1076 | // owning block. |
1077 | // |
1078 | // A Jump must be the last instruction of its containing BasicBlock. |
1079 | // |
1080 | // Pos() returns NoPos. |
1081 | // |
1082 | // Example printed form: |
1083 | // |
1084 | // jump done |
1085 | type Jump struct { |
1086 | anInstruction |
1087 | } |
1088 | |
1089 | // The If instruction transfers control to one of the two successors |
1090 | // of its owning block, depending on the boolean Cond: the first if |
1091 | // true, the second if false. |
1092 | // |
1093 | // An If instruction must be the last instruction of its containing |
1094 | // BasicBlock. |
1095 | // |
1096 | // Pos() returns NoPos. |
1097 | // |
1098 | // Example printed form: |
1099 | // |
1100 | // if t0 goto done else body |
1101 | type If struct { |
1102 | anInstruction |
1103 | Cond Value |
1104 | } |
1105 | |
1106 | // The Return instruction returns values and control back to the calling |
1107 | // function. |
1108 | // |
1109 | // len(Results) is always equal to the number of results in the |
1110 | // function's signature. |
1111 | // |
1112 | // If len(Results) > 1, Return returns a tuple value with the specified |
1113 | // components which the caller must access using Extract instructions. |
1114 | // |
1115 | // There is no instruction to return a ready-made tuple like those |
1116 | // returned by a "value,ok"-mode TypeAssert, Lookup or UnOp(ARROW) or |
1117 | // a tail-call to a function with multiple result parameters. |
1118 | // |
1119 | // Return must be the last instruction of its containing BasicBlock. |
1120 | // Such a block has no successors. |
1121 | // |
1122 | // Pos() returns the ast.ReturnStmt.Return, if explicit in the source. |
1123 | // |
1124 | // Example printed form: |
1125 | // |
1126 | // return |
1127 | // return nil:I, 2:int |
1128 | type Return struct { |
1129 | anInstruction |
1130 | Results []Value |
1131 | pos token.Pos |
1132 | } |
1133 | |
1134 | // The RunDefers instruction pops and invokes the entire stack of |
1135 | // procedure calls pushed by Defer instructions in this function. |
1136 | // |
1137 | // It is legal to encounter multiple 'rundefers' instructions in a |
1138 | // single control-flow path through a function; this is useful in |
1139 | // the combined init() function, for example. |
1140 | // |
1141 | // Pos() returns NoPos. |
1142 | // |
1143 | // Example printed form: |
1144 | // |
1145 | // rundefers |
1146 | type RunDefers struct { |
1147 | anInstruction |
1148 | } |
1149 | |
1150 | // The Panic instruction initiates a panic with value X. |
1151 | // |
1152 | // A Panic instruction must be the last instruction of its containing |
1153 | // BasicBlock, which must have no successors. |
1154 | // |
1155 | // NB: 'go panic(x)' and 'defer panic(x)' do not use this instruction; |
1156 | // they are treated as calls to a built-in function. |
1157 | // |
1158 | // Pos() returns the ast.CallExpr.Lparen if this panic was explicit |
1159 | // in the source. |
1160 | // |
1161 | // Example printed form: |
1162 | // |
1163 | // panic t0 |
1164 | type Panic struct { |
1165 | anInstruction |
1166 | X Value // an interface{} |
1167 | pos token.Pos |
1168 | } |
1169 | |
1170 | // The Go instruction creates a new goroutine and calls the specified |
1171 | // function within it. |
1172 | // |
1173 | // See CallCommon for generic function call documentation. |
1174 | // |
1175 | // Pos() returns the ast.GoStmt.Go. |
1176 | // |
1177 | // Example printed form: |
1178 | // |
1179 | // go println(t0, t1) |
1180 | // go t3() |
1181 | // go invoke t5.Println(...t6) |
1182 | type Go struct { |
1183 | anInstruction |
1184 | Call CallCommon |
1185 | pos token.Pos |
1186 | } |
1187 | |
1188 | // The Defer instruction pushes the specified call onto a stack of |
1189 | // functions to be called by a RunDefers instruction or by a panic. |
1190 | // |
1191 | // See CallCommon for generic function call documentation. |
1192 | // |
1193 | // Pos() returns the ast.DeferStmt.Defer. |
1194 | // |
1195 | // Example printed form: |
1196 | // |
1197 | // defer println(t0, t1) |
1198 | // defer t3() |
1199 | // defer invoke t5.Println(...t6) |
1200 | type Defer struct { |
1201 | anInstruction |
1202 | Call CallCommon |
1203 | pos token.Pos |
1204 | } |
1205 | |
1206 | // The Send instruction sends X on channel Chan. |
1207 | // |
1208 | // Pos() returns the ast.SendStmt.Arrow, if explicit in the source. |
1209 | // |
1210 | // Example printed form: |
1211 | // |
1212 | // send t0 <- t1 |
1213 | type Send struct { |
1214 | anInstruction |
1215 | Chan, X Value |
1216 | pos token.Pos |
1217 | } |
1218 | |
1219 | // The Store instruction stores Val at address Addr. |
1220 | // Stores can be of arbitrary types. |
1221 | // |
1222 | // Pos() returns the position of the source-level construct most closely |
1223 | // associated with the memory store operation. |
1224 | // Since implicit memory stores are numerous and varied and depend upon |
1225 | // implementation choices, the details are not specified. |
1226 | // |
1227 | // Example printed form: |
1228 | // |
1229 | // *x = y |
1230 | type Store struct { |
1231 | anInstruction |
1232 | Addr Value |
1233 | Val Value |
1234 | pos token.Pos |
1235 | } |
1236 | |
1237 | // The MapUpdate instruction updates the association of Map[Key] to |
1238 | // Value. |
1239 | // |
1240 | // Pos() returns the ast.KeyValueExpr.Colon or ast.IndexExpr.Lbrack, |
1241 | // if explicit in the source. |
1242 | // |
1243 | // Example printed form: |
1244 | // |
1245 | // t0[t1] = t2 |
1246 | type MapUpdate struct { |
1247 | anInstruction |
1248 | Map Value |
1249 | Key Value |
1250 | Value Value |
1251 | pos token.Pos |
1252 | } |
1253 | |
1254 | // A DebugRef instruction maps a source-level expression Expr to the |
1255 | // SSA value X that represents the value (!IsAddr) or address (IsAddr) |
1256 | // of that expression. |
1257 | // |
1258 | // DebugRef is a pseudo-instruction: it has no dynamic effect. |
1259 | // |
1260 | // Pos() returns Expr.Pos(), the start position of the source-level |
1261 | // expression. This is not the same as the "designated" token as |
1262 | // documented at Value.Pos(). e.g. CallExpr.Pos() does not return the |
1263 | // position of the ("designated") Lparen token. |
1264 | // |
1265 | // If Expr is an *ast.Ident denoting a var or func, Object() returns |
1266 | // the object; though this information can be obtained from the type |
1267 | // checker, including it here greatly facilitates debugging. |
1268 | // For non-Ident expressions, Object() returns nil. |
1269 | // |
1270 | // DebugRefs are generated only for functions built with debugging |
1271 | // enabled; see Package.SetDebugMode() and the GlobalDebug builder |
1272 | // mode flag. |
1273 | // |
1274 | // DebugRefs are not emitted for ast.Idents referring to constants or |
1275 | // predeclared identifiers, since they are trivial and numerous. |
1276 | // Nor are they emitted for ast.ParenExprs. |
1277 | // |
1278 | // (By representing these as instructions, rather than out-of-band, |
1279 | // consistency is maintained during transformation passes by the |
1280 | // ordinary SSA renaming machinery.) |
1281 | // |
1282 | // Example printed form: |
1283 | // |
1284 | // ; *ast.CallExpr @ 102:9 is t5 |
1285 | // ; var x float64 @ 109:72 is x |
1286 | // ; address of *ast.CompositeLit @ 216:10 is t0 |
1287 | type DebugRef struct { |
1288 | // TODO(generics): Reconsider what DebugRefs are for generics. |
1289 | anInstruction |
1290 | Expr ast.Expr // the referring expression (never *ast.ParenExpr) |
1291 | object types.Object // the identity of the source var/func |
1292 | IsAddr bool // Expr is addressable and X is the address it denotes |
1293 | X Value // the value or address of Expr |
1294 | } |
1295 | |
1296 | // Embeddable mix-ins and helpers for common parts of other structs. ----------- |
1297 | |
1298 | // register is a mix-in embedded by all SSA values that are also |
1299 | // instructions, i.e. virtual registers, and provides a uniform |
1300 | // implementation of most of the Value interface: Value.Name() is a |
1301 | // numbered register (e.g. "t0"); the other methods are field accessors. |
1302 | // |
1303 | // Temporary names are automatically assigned to each register on |
1304 | // completion of building a function in SSA form. |
1305 | // |
1306 | // Clients must not assume that the 'id' value (and the Name() derived |
1307 | // from it) is unique within a function. As always in this API, |
1308 | // semantics are determined only by identity; names exist only to |
1309 | // facilitate debugging. |
1310 | type register struct { |
1311 | anInstruction |
1312 | num int // "name" of virtual register, e.g. "t0". Not guaranteed unique. |
1313 | typ types.Type // type of virtual register |
1314 | pos token.Pos // position of source expression, or NoPos |
1315 | referrers []Instruction |
1316 | } |
1317 | |
1318 | // anInstruction is a mix-in embedded by all Instructions. |
1319 | // It provides the implementations of the Block and setBlock methods. |
1320 | type anInstruction struct { |
1321 | block *BasicBlock // the basic block of this instruction |
1322 | } |
1323 | |
1324 | // CallCommon is contained by Go, Defer and Call to hold the |
1325 | // common parts of a function or method call. |
1326 | // |
1327 | // Each CallCommon exists in one of two modes, function call and |
1328 | // interface method invocation, or "call" and "invoke" for short. |
1329 | // |
1330 | // 1. "call" mode: when Method is nil (!IsInvoke), a CallCommon |
1331 | // represents an ordinary function call of the value in Value, |
1332 | // which may be a *Builtin, a *Function or any other value of kind |
1333 | // 'func'. |
1334 | // |
1335 | // Value may be one of: |
1336 | // |
1337 | // (a) a *Function, indicating a statically dispatched call |
1338 | // to a package-level function, an anonymous function, or |
1339 | // a method of a named type. |
1340 | // (b) a *MakeClosure, indicating an immediately applied |
1341 | // function literal with free variables. |
1342 | // (c) a *Builtin, indicating a statically dispatched call |
1343 | // to a built-in function. |
1344 | // (d) any other value, indicating a dynamically dispatched |
1345 | // function call. |
1346 | // |
1347 | // StaticCallee returns the identity of the callee in cases |
1348 | // (a) and (b), nil otherwise. |
1349 | // |
1350 | // Args contains the arguments to the call. If Value is a method, |
1351 | // Args[0] contains the receiver parameter. |
1352 | // |
1353 | // Example printed form: |
1354 | // |
1355 | // t2 = println(t0, t1) |
1356 | // go t3() |
1357 | // defer t5(...t6) |
1358 | // |
1359 | // 2. "invoke" mode: when Method is non-nil (IsInvoke), a CallCommon |
1360 | // represents a dynamically dispatched call to an interface method. |
1361 | // In this mode, Value is the interface value and Method is the |
1362 | // interface's abstract method. The interface value may be a type |
1363 | // parameter. Note: an abstract method may be shared by multiple |
1364 | // interfaces due to embedding; Value.Type() provides the specific |
1365 | // interface used for this call. |
1366 | // |
1367 | // Value is implicitly supplied to the concrete method implementation |
1368 | // as the receiver parameter; in other words, Args[0] holds not the |
1369 | // receiver but the first true argument. |
1370 | // |
1371 | // Example printed form: |
1372 | // |
1373 | // t1 = invoke t0.String() |
1374 | // go invoke t3.Run(t2) |
1375 | // defer invoke t4.Handle(...t5) |
1376 | // |
1377 | // For all calls to variadic functions (Signature().Variadic()), |
1378 | // the last element of Args is a slice. |
1379 | type CallCommon struct { |
1380 | Value Value // receiver (invoke mode) or func value (call mode) |
1381 | Method *types.Func // abstract method (invoke mode) |
1382 | Args []Value // actual parameters (in static method call, includes receiver) |
1383 | pos token.Pos // position of CallExpr.Lparen, iff explicit in source |
1384 | } |
1385 | |
1386 | // IsInvoke returns true if this call has "invoke" (not "call") mode. |
1387 | func (c *CallCommon) IsInvoke() bool { |
1388 | return c.Method != nil |
1389 | } |
1390 | |
1391 | func (c *CallCommon) Pos() token.Pos { return c.pos } |
1392 | |
1393 | // Signature returns the signature of the called function. |
1394 | // |
1395 | // For an "invoke"-mode call, the signature of the interface method is |
1396 | // returned. |
1397 | // |
1398 | // In either "call" or "invoke" mode, if the callee is a method, its |
1399 | // receiver is represented by sig.Recv, not sig.Params().At(0). |
1400 | func (c *CallCommon) Signature() *types.Signature { |
1401 | if c.Method != nil { |
1402 | return c.Method.Type().(*types.Signature) |
1403 | } |
1404 | return typeparams.CoreType(c.Value.Type()).(*types.Signature) |
1405 | } |
1406 | |
1407 | // StaticCallee returns the callee if this is a trivially static |
1408 | // "call"-mode call to a function. |
1409 | func (c *CallCommon) StaticCallee() *Function { |
1410 | switch fn := c.Value.(type) { |
1411 | case *Function: |
1412 | return fn |
1413 | case *MakeClosure: |
1414 | return fn.Fn.(*Function) |
1415 | } |
1416 | return nil |
1417 | } |
1418 | |
1419 | // Description returns a description of the mode of this call suitable |
1420 | // for a user interface, e.g., "static method call". |
1421 | func (c *CallCommon) Description() string { |
1422 | switch fn := c.Value.(type) { |
1423 | case *Builtin: |
1424 | return "built-in function call" |
1425 | case *MakeClosure: |
1426 | return "static function closure call" |
1427 | case *Function: |
1428 | if fn.Signature.Recv() != nil { |
1429 | return "static method call" |
1430 | } |
1431 | return "static function call" |
1432 | } |
1433 | if c.IsInvoke() { |
1434 | return "dynamic method call" // ("invoke" mode) |
1435 | } |
1436 | return "dynamic function call" |
1437 | } |
1438 | |
1439 | // The CallInstruction interface, implemented by *Go, *Defer and *Call, |
1440 | // exposes the common parts of function-calling instructions, |
1441 | // yet provides a way back to the Value defined by *Call alone. |
1442 | type CallInstruction interface { |
1443 | Instruction |
1444 | Common() *CallCommon // returns the common parts of the call |
1445 | Value() *Call // returns the result value of the call (*Call) or nil (*Go, *Defer) |
1446 | } |
1447 | |
1448 | func (s *Call) Common() *CallCommon { return &s.Call } |
1449 | func (s *Defer) Common() *CallCommon { return &s.Call } |
1450 | func (s *Go) Common() *CallCommon { return &s.Call } |
1451 | |
1452 | func (s *Call) Value() *Call { return s } |
1453 | func (s *Defer) Value() *Call { return nil } |
1454 | func (s *Go) Value() *Call { return nil } |
1455 | |
1456 | func (v *Builtin) Type() types.Type { return v.sig } |
1457 | func (v *Builtin) Name() string { return v.name } |
1458 | func (*Builtin) Referrers() *[]Instruction { return nil } |
1459 | func (v *Builtin) Pos() token.Pos { return token.NoPos } |
1460 | func (v *Builtin) Object() types.Object { return types.Universe.Lookup(v.name) } |
1461 | func (v *Builtin) Parent() *Function { return nil } |
1462 | |
1463 | func (v *FreeVar) Type() types.Type { return v.typ } |
1464 | func (v *FreeVar) Name() string { return v.name } |
1465 | func (v *FreeVar) Referrers() *[]Instruction { return &v.referrers } |
1466 | func (v *FreeVar) Pos() token.Pos { return v.pos } |
1467 | func (v *FreeVar) Parent() *Function { return v.parent } |
1468 | |
1469 | func (v *Global) Type() types.Type { return v.typ } |
1470 | func (v *Global) Name() string { return v.name } |
1471 | func (v *Global) Parent() *Function { return nil } |
1472 | func (v *Global) Pos() token.Pos { return v.pos } |
1473 | func (v *Global) Referrers() *[]Instruction { return nil } |
1474 | func (v *Global) Token() token.Token { return token.VAR } |
1475 | func (v *Global) Object() types.Object { return v.object } |
1476 | func (v *Global) String() string { return v.RelString(nil) } |
1477 | func (v *Global) Package() *Package { return v.Pkg } |
1478 | func (v *Global) RelString(from *types.Package) string { return relString(v, from) } |
1479 | |
1480 | func (v *Function) Name() string { return v.name } |
1481 | func (v *Function) Type() types.Type { return v.Signature } |
1482 | func (v *Function) Pos() token.Pos { return v.pos } |
1483 | func (v *Function) Token() token.Token { return token.FUNC } |
1484 | func (v *Function) Object() types.Object { return v.object } |
1485 | func (v *Function) String() string { return v.RelString(nil) } |
1486 | func (v *Function) Package() *Package { return v.Pkg } |
1487 | func (v *Function) Parent() *Function { return v.parent } |
1488 | func (v *Function) Referrers() *[]Instruction { |
1489 | if v.parent != nil { |
1490 | return &v.referrers |
1491 | } |
1492 | return nil |
1493 | } |
1494 | |
1495 | // TypeParams are the function's type parameters if generic or the |
1496 | // type parameters that were instantiated if fn is an instantiation. |
1497 | // |
1498 | // TODO(taking): declare result type as *types.TypeParamList |
1499 | // after we drop support for go1.17. |
1500 | func (fn *Function) TypeParams() *typeparams.TypeParamList { |
1501 | return fn.typeparams |
1502 | } |
1503 | |
1504 | // TypeArgs are the types that TypeParams() were instantiated by to create fn |
1505 | // from fn.Origin(). |
1506 | func (fn *Function) TypeArgs() []types.Type { return fn.typeargs } |
1507 | |
1508 | // Origin is the function fn is an instantiation of. Returns nil if fn is not |
1509 | // an instantiation. |
1510 | func (fn *Function) Origin() *Function { |
1511 | if fn.parent != nil && len(fn.typeargs) > 0 { |
1512 | // Nested functions are BUILT at a different time than there instances. |
1513 | return fn.parent.Origin().AnonFuncs[fn.anonIdx] |
1514 | } |
1515 | return fn.topLevelOrigin |
1516 | } |
1517 | |
1518 | func (v *Parameter) Type() types.Type { return v.typ } |
1519 | func (v *Parameter) Name() string { return v.name } |
1520 | func (v *Parameter) Object() types.Object { return v.object } |
1521 | func (v *Parameter) Referrers() *[]Instruction { return &v.referrers } |
1522 | func (v *Parameter) Pos() token.Pos { return v.pos } |
1523 | func (v *Parameter) Parent() *Function { return v.parent } |
1524 | |
1525 | func (v *Alloc) Type() types.Type { return v.typ } |
1526 | func (v *Alloc) Referrers() *[]Instruction { return &v.referrers } |
1527 | func (v *Alloc) Pos() token.Pos { return v.pos } |
1528 | |
1529 | func (v *register) Type() types.Type { return v.typ } |
1530 | func (v *register) setType(typ types.Type) { v.typ = typ } |
1531 | func (v *register) Name() string { return fmt.Sprintf("t%d", v.num) } |
1532 | func (v *register) setNum(num int) { v.num = num } |
1533 | func (v *register) Referrers() *[]Instruction { return &v.referrers } |
1534 | func (v *register) Pos() token.Pos { return v.pos } |
1535 | func (v *register) setPos(pos token.Pos) { v.pos = pos } |
1536 | |
1537 | func (v *anInstruction) Parent() *Function { return v.block.parent } |
1538 | func (v *anInstruction) Block() *BasicBlock { return v.block } |
1539 | func (v *anInstruction) setBlock(block *BasicBlock) { v.block = block } |
1540 | func (v *anInstruction) Referrers() *[]Instruction { return nil } |
1541 | |
1542 | func (t *Type) Name() string { return t.object.Name() } |
1543 | func (t *Type) Pos() token.Pos { return t.object.Pos() } |
1544 | func (t *Type) Type() types.Type { return t.object.Type() } |
1545 | func (t *Type) Token() token.Token { return token.TYPE } |
1546 | func (t *Type) Object() types.Object { return t.object } |
1547 | func (t *Type) String() string { return t.RelString(nil) } |
1548 | func (t *Type) Package() *Package { return t.pkg } |
1549 | func (t *Type) RelString(from *types.Package) string { return relString(t, from) } |
1550 | |
1551 | func (c *NamedConst) Name() string { return c.object.Name() } |
1552 | func (c *NamedConst) Pos() token.Pos { return c.object.Pos() } |
1553 | func (c *NamedConst) String() string { return c.RelString(nil) } |
1554 | func (c *NamedConst) Type() types.Type { return c.object.Type() } |
1555 | func (c *NamedConst) Token() token.Token { return token.CONST } |
1556 | func (c *NamedConst) Object() types.Object { return c.object } |
1557 | func (c *NamedConst) Package() *Package { return c.pkg } |
1558 | func (c *NamedConst) RelString(from *types.Package) string { return relString(c, from) } |
1559 | |
1560 | func (d *DebugRef) Object() types.Object { return d.object } |
1561 | |
1562 | // Func returns the package-level function of the specified name, |
1563 | // or nil if not found. |
1564 | func (p *Package) Func(name string) (f *Function) { |
1565 | f, _ = p.Members[name].(*Function) |
1566 | return |
1567 | } |
1568 | |
1569 | // Var returns the package-level variable of the specified name, |
1570 | // or nil if not found. |
1571 | func (p *Package) Var(name string) (g *Global) { |
1572 | g, _ = p.Members[name].(*Global) |
1573 | return |
1574 | } |
1575 | |
1576 | // Const returns the package-level constant of the specified name, |
1577 | // or nil if not found. |
1578 | func (p *Package) Const(name string) (c *NamedConst) { |
1579 | c, _ = p.Members[name].(*NamedConst) |
1580 | return |
1581 | } |
1582 | |
1583 | // Type returns the package-level type of the specified name, |
1584 | // or nil if not found. |
1585 | func (p *Package) Type(name string) (t *Type) { |
1586 | t, _ = p.Members[name].(*Type) |
1587 | return |
1588 | } |
1589 | |
1590 | func (v *Call) Pos() token.Pos { return v.Call.pos } |
1591 | func (s *Defer) Pos() token.Pos { return s.pos } |
1592 | func (s *Go) Pos() token.Pos { return s.pos } |
1593 | func (s *MapUpdate) Pos() token.Pos { return s.pos } |
1594 | func (s *Panic) Pos() token.Pos { return s.pos } |
1595 | func (s *Return) Pos() token.Pos { return s.pos } |
1596 | func (s *Send) Pos() token.Pos { return s.pos } |
1597 | func (s *Store) Pos() token.Pos { return s.pos } |
1598 | func (s *If) Pos() token.Pos { return token.NoPos } |
1599 | func (s *Jump) Pos() token.Pos { return token.NoPos } |
1600 | func (s *RunDefers) Pos() token.Pos { return token.NoPos } |
1601 | func (s *DebugRef) Pos() token.Pos { return s.Expr.Pos() } |
1602 | |
1603 | // Operands. |
1604 | |
1605 | func (v *Alloc) Operands(rands []*Value) []*Value { |
1606 | return rands |
1607 | } |
1608 | |
1609 | func (v *BinOp) Operands(rands []*Value) []*Value { |
1610 | return append(rands, &v.X, &v.Y) |
1611 | } |
1612 | |
1613 | func (c *CallCommon) Operands(rands []*Value) []*Value { |
1614 | rands = append(rands, &c.Value) |
1615 | for i := range c.Args { |
1616 | rands = append(rands, &c.Args[i]) |
1617 | } |
1618 | return rands |
1619 | } |
1620 | |
1621 | func (s *Go) Operands(rands []*Value) []*Value { |
1622 | return s.Call.Operands(rands) |
1623 | } |
1624 | |
1625 | func (s *Call) Operands(rands []*Value) []*Value { |
1626 | return s.Call.Operands(rands) |
1627 | } |
1628 | |
1629 | func (s *Defer) Operands(rands []*Value) []*Value { |
1630 | return s.Call.Operands(rands) |
1631 | } |
1632 | |
1633 | func (v *ChangeInterface) Operands(rands []*Value) []*Value { |
1634 | return append(rands, &v.X) |
1635 | } |
1636 | |
1637 | func (v *ChangeType) Operands(rands []*Value) []*Value { |
1638 | return append(rands, &v.X) |
1639 | } |
1640 | |
1641 | func (v *Convert) Operands(rands []*Value) []*Value { |
1642 | return append(rands, &v.X) |
1643 | } |
1644 | |
1645 | func (v *SliceToArrayPointer) Operands(rands []*Value) []*Value { |
1646 | return append(rands, &v.X) |
1647 | } |
1648 | |
1649 | func (s *DebugRef) Operands(rands []*Value) []*Value { |
1650 | return append(rands, &s.X) |
1651 | } |
1652 | |
1653 | func (v *Extract) Operands(rands []*Value) []*Value { |
1654 | return append(rands, &v.Tuple) |
1655 | } |
1656 | |
1657 | func (v *Field) Operands(rands []*Value) []*Value { |
1658 | return append(rands, &v.X) |
1659 | } |
1660 | |
1661 | func (v *FieldAddr) Operands(rands []*Value) []*Value { |
1662 | return append(rands, &v.X) |
1663 | } |
1664 | |
1665 | func (s *If) Operands(rands []*Value) []*Value { |
1666 | return append(rands, &s.Cond) |
1667 | } |
1668 | |
1669 | func (v *Index) Operands(rands []*Value) []*Value { |
1670 | return append(rands, &v.X, &v.Index) |
1671 | } |
1672 | |
1673 | func (v *IndexAddr) Operands(rands []*Value) []*Value { |
1674 | return append(rands, &v.X, &v.Index) |
1675 | } |
1676 | |
1677 | func (*Jump) Operands(rands []*Value) []*Value { |
1678 | return rands |
1679 | } |
1680 | |
1681 | func (v *Lookup) Operands(rands []*Value) []*Value { |
1682 | return append(rands, &v.X, &v.Index) |
1683 | } |
1684 | |
1685 | func (v *MakeChan) Operands(rands []*Value) []*Value { |
1686 | return append(rands, &v.Size) |
1687 | } |
1688 | |
1689 | func (v *MakeClosure) Operands(rands []*Value) []*Value { |
1690 | rands = append(rands, &v.Fn) |
1691 | for i := range v.Bindings { |
1692 | rands = append(rands, &v.Bindings[i]) |
1693 | } |
1694 | return rands |
1695 | } |
1696 | |
1697 | func (v *MakeInterface) Operands(rands []*Value) []*Value { |
1698 | return append(rands, &v.X) |
1699 | } |
1700 | |
1701 | func (v *MakeMap) Operands(rands []*Value) []*Value { |
1702 | return append(rands, &v.Reserve) |
1703 | } |
1704 | |
1705 | func (v *MakeSlice) Operands(rands []*Value) []*Value { |
1706 | return append(rands, &v.Len, &v.Cap) |
1707 | } |
1708 | |
1709 | func (v *MapUpdate) Operands(rands []*Value) []*Value { |
1710 | return append(rands, &v.Map, &v.Key, &v.Value) |
1711 | } |
1712 | |
1713 | func (v *Next) Operands(rands []*Value) []*Value { |
1714 | return append(rands, &v.Iter) |
1715 | } |
1716 | |
1717 | func (s *Panic) Operands(rands []*Value) []*Value { |
1718 | return append(rands, &s.X) |
1719 | } |
1720 | |
1721 | func (v *Phi) Operands(rands []*Value) []*Value { |
1722 | for i := range v.Edges { |
1723 | rands = append(rands, &v.Edges[i]) |
1724 | } |
1725 | return rands |
1726 | } |
1727 | |
1728 | func (v *Range) Operands(rands []*Value) []*Value { |
1729 | return append(rands, &v.X) |
1730 | } |
1731 | |
1732 | func (s *Return) Operands(rands []*Value) []*Value { |
1733 | for i := range s.Results { |
1734 | rands = append(rands, &s.Results[i]) |
1735 | } |
1736 | return rands |
1737 | } |
1738 | |
1739 | func (*RunDefers) Operands(rands []*Value) []*Value { |
1740 | return rands |
1741 | } |
1742 | |
1743 | func (v *Select) Operands(rands []*Value) []*Value { |
1744 | for i := range v.States { |
1745 | rands = append(rands, &v.States[i].Chan, &v.States[i].Send) |
1746 | } |
1747 | return rands |
1748 | } |
1749 | |
1750 | func (s *Send) Operands(rands []*Value) []*Value { |
1751 | return append(rands, &s.Chan, &s.X) |
1752 | } |
1753 | |
1754 | func (v *Slice) Operands(rands []*Value) []*Value { |
1755 | return append(rands, &v.X, &v.Low, &v.High, &v.Max) |
1756 | } |
1757 | |
1758 | func (s *Store) Operands(rands []*Value) []*Value { |
1759 | return append(rands, &s.Addr, &s.Val) |
1760 | } |
1761 | |
1762 | func (v *TypeAssert) Operands(rands []*Value) []*Value { |
1763 | return append(rands, &v.X) |
1764 | } |
1765 | |
1766 | func (v *UnOp) Operands(rands []*Value) []*Value { |
1767 | return append(rands, &v.X) |
1768 | } |
1769 | |
1770 | // Non-Instruction Values: |
1771 | func (v *Builtin) Operands(rands []*Value) []*Value { return rands } |
1772 | func (v *FreeVar) Operands(rands []*Value) []*Value { return rands } |
1773 | func (v *Const) Operands(rands []*Value) []*Value { return rands } |
1774 | func (v *Function) Operands(rands []*Value) []*Value { return rands } |
1775 | func (v *Global) Operands(rands []*Value) []*Value { return rands } |
1776 | func (v *Parameter) Operands(rands []*Value) []*Value { return rands } |
1777 |
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