Golang Function.String方法代码示例

// callSSA interprets a call to function fn with arguments args,
// and lexical environment env, returning its result.
// callpos is the position of the callsite.
//
func callSSA(i *interpreter, caller *frame, callpos token.Pos, fn *ssa.Function, args []value, env []value) value {
	if i.mode&EnableTracing != 0 {
		fset := fn.Prog.Fset
		// TODO(adonovan): fix: loc() lies for external functions.
		fmt.Fprintf(os.Stderr, "Entering %s%s.\n", fn, loc(fset, fn.Pos()))
		suffix := ""
		if caller != nil {
			suffix = ", resuming " + caller.fn.String() + loc(fset, callpos)
		}
		defer fmt.Fprintf(os.Stderr, "Leaving %s%s.\n", fn, suffix)
	}
	fr := &frame{
		i:      i,
		caller: caller, // for panic/recover
		fn:     fn,
	}
	if fn.Enclosing == nil {
		name := fn.String()
		if ext := externals[name]; ext != nil {
			if i.mode&EnableTracing != 0 {
				fmt.Fprintln(os.Stderr, "\t(external)")
			}
			return ext(fr, args)
		}
		if fn.Blocks == nil {
			panic("no code for function: " + name)
		}
	}
	fr.env = make(map[ssa.Value]value)
	fr.block = fn.Blocks[0]
	fr.locals = make([]value, len(fn.Locals))
	for i, l := range fn.Locals {
		fr.locals[i] = zero(deref(l.Type()))
		fr.env[l] = &fr.locals[i]
	}
	for i, p := range fn.Params {
		fr.env[p] = args[i]
	}
	for i, fv := range fn.FreeVars {
		fr.env[fv] = env[i]
	}
	for fr.block != nil {
		runFrame(fr)
	}
	// Destroy the locals to avoid accidental use after return.
	for i := range fn.Locals {
		fr.locals[i] = bad{}
	}
	return fr.result
}

// findIntrinsic returns the constraint generation function for an
// intrinsic function fn, or nil if the function should be handled normally.
//
func (a *analysis) findIntrinsic(fn *ssa.Function) intrinsic {
	// Consult the *Function-keyed cache.
	// A cached nil indicates a normal non-intrinsic function.
	impl, ok := a.intrinsics[fn]
	if !ok {
		impl = intrinsicsByName[fn.String()] // may be nil

		if a.isReflect(fn) {
			if !a.config.Reflection {
				impl = ext۰NoEffect // reflection disabled
			} else if impl == nil {
				// Ensure all "reflect" code is treated intrinsically.
				impl = ext۰NotYetImplemented
			}
		}

		a.intrinsics[fn] = impl
	}
	return impl
}

func (u *unit) resolveFunction(f *ssa.Function) *LLVMValue {
	if v, ok := u.globals[f]; ok {
		return v
	}
	name := f.String()
	if f.Enclosing != nil {
		// Anonymous functions are not guaranteed to
		// have unique identifiers at the global scope.
		name = f.Enclosing.String() + ":" + name
	}
	// It's possible that the function already exists in the module;
	// for example, if it's a runtime intrinsic that the compiler
	// has already referenced.
	llvmFunction := u.module.Module.NamedFunction(name)
	if llvmFunction.IsNil() {
		llvmType := u.llvmtypes.ToLLVM(f.Signature)
		llvmType = llvmType.StructElementTypes()[0].ElementType()
		if len(f.FreeVars) > 0 {
			// Add an implicit first argument.
			returnType := llvmType.ReturnType()
			paramTypes := llvmType.ParamTypes()
			vararg := llvmType.IsFunctionVarArg()
			blockElementTypes := make([]llvm.Type, len(f.FreeVars))
			for i, fv := range f.FreeVars {
				blockElementTypes[i] = u.llvmtypes.ToLLVM(fv.Type())
			}
			blockType := llvm.StructType(blockElementTypes, false)
			blockPtrType := llvm.PointerType(blockType, 0)
			paramTypes = append([]llvm.Type{blockPtrType}, paramTypes...)
			llvmType = llvm.FunctionType(returnType, paramTypes, vararg)
		}
		llvmFunction = llvm.AddFunction(u.module.Module, name, llvmType)
		if f.Enclosing != nil {
			llvmFunction.SetLinkage(llvm.PrivateLinkage)
		}
		u.undefinedFuncs[f] = true
	}
	v := u.NewValue(llvmFunction, f.Signature)
	u.globals[f] = v
	return v
}

func (u *unit) defineFunction(f *ssa.Function) {
	// Nothing to do for functions without bodies.
	if len(f.Blocks) == 0 {
		return
	}

	// Only define functions from this package.
	if f.Pkg == nil {
		if r := f.Signature.Recv(); r != nil {
			if r.Pkg() != nil && r.Pkg() != u.pkg.Object {
				return
			} else if named, ok := r.Type().(*types.Named); ok && named.Obj().Parent() == types.Universe {
				// This condition is true iff f is error.Error.
				if u.pkg.Object.Path() != "runtime" {
					return
				}
			}
		}
	} else if f.Pkg != u.pkg {
		return
	}

	fr := frame{
		unit:   u,
		blocks: make([]llvm.BasicBlock, len(f.Blocks)),
		env:    make(map[ssa.Value]*LLVMValue),
	}

	fr.logf("Define function: %s", f.String())
	llvmFunction := fr.resolveFunction(f).LLVMValue()
	delete(u.undefinedFuncs, f)

	// Push the function onto the debug context.
	// TODO(axw) create a fake CU for synthetic functions
	if u.GenerateDebug && f.Synthetic == "" {
		u.debug.pushFunctionContext(llvmFunction, f.Signature, f.Pos())
		defer u.debug.popFunctionContext()
		u.debug.setLocation(u.builder, f.Pos())
	}

	// Functions that call recover must not be inlined, or we
	// can't tell whether the recover call is valid at runtime.
	if f.Recover != nil {
		llvmFunction.AddFunctionAttr(llvm.NoInlineAttribute)
	}

	for i, block := range f.Blocks {
		fr.blocks[i] = llvm.AddBasicBlock(llvmFunction, fmt.Sprintf(".%d.%s", i, block.Comment))
	}
	fr.builder.SetInsertPointAtEnd(fr.blocks[0])

	var paramOffset int
	if len(f.FreeVars) > 0 {
		// Extract captures from the first implicit parameter.
		arg0 := llvmFunction.Param(0)
		for i, fv := range f.FreeVars {
			addressPtr := fr.builder.CreateStructGEP(arg0, i, "")
			address := fr.builder.CreateLoad(addressPtr, "")
			fr.env[fv] = fr.NewValue(address, fv.Type())
		}
		paramOffset++
	}
	// Map parameter positions to indices. We use this
	// when processing locals to map back to parameters
	// when generating debug metadata.
	paramPos := make(map[token.Pos]int)
	for i, param := range f.Params {
		paramPos[param.Pos()] = i + paramOffset
		llparam := llvmFunction.Param(i + paramOffset)
		fr.env[param] = fr.NewValue(llparam, param.Type())
	}

	// Allocate stack space for locals in the prologue block.
	prologueBlock := llvm.InsertBasicBlock(fr.blocks[0], "prologue")
	fr.builder.SetInsertPointAtEnd(prologueBlock)
	for _, local := range f.Locals {
		typ := fr.llvmtypes.ToLLVM(deref(local.Type()))
		alloca := fr.builder.CreateAlloca(typ, local.Comment)
		u.memsetZero(alloca, llvm.SizeOf(typ))
		value := fr.NewValue(alloca, local.Type())
		fr.env[local] = value
		if fr.GenerateDebug {
			paramIndex, ok := paramPos[local.Pos()]
			if !ok {
				paramIndex = -1
			}
			fr.debug.declare(fr.builder, local, alloca, paramIndex)
		}
	}

	// Move any allocs relating to named results from the entry block
	// to the prologue block, so they dominate the rundefers and recover
	// blocks.
	//
	// TODO(axw) ask adonovan for a cleaner way of doing this, e.g.
	// have ssa generate an entry block that defines Allocs and related
	// stores, and then a separate block for function body instructions.
	if f.Synthetic == "" {
		if results := f.Signature.Results(); results != nil {
			for i := 0; i < results.Len(); i++ {
//.........这里部分代码省略.........