visit.go

Documentation: golang.org/x/tools/go/ssa/ssautil

     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 ssautil // import "golang.org/x/tools/go/ssa/ssautil"
     6  
     7  import "golang.org/x/tools/go/ssa"
     8  
     9  // This file defines utilities for visiting the SSA representation of
    10  // a Program.
    11  //
    12  // TODO(adonovan): test coverage.
    13  
    14  // AllFunctions finds and returns the set of functions potentially
    15  // needed by program prog, as determined by a simple linker-style
    16  // reachability algorithm starting from the members and method-sets of
    17  // each package.  The result may include anonymous functions and
    18  // synthetic wrappers.
    19  //
    20  // Precondition: all packages are built.
    21  func AllFunctions(prog *ssa.Program) map[*ssa.Function]bool {
    22  	visit := visitor{
    23  		prog: prog,
    24  		seen: make(map[*ssa.Function]bool),
    25  	}
    26  	visit.program()
    27  	return visit.seen
    28  }
    29  
    30  type visitor struct {
    31  	prog *ssa.Program
    32  	seen map[*ssa.Function]bool
    33  }
    34  
    35  func (visit *visitor) program() {
    36  	for _, pkg := range visit.prog.AllPackages() {
    37  		for _, mem := range pkg.Members {
    38  			if fn, ok := mem.(*ssa.Function); ok {
    39  				visit.function(fn)
    40  			}
    41  		}
    42  	}
    43  	for _, T := range visit.prog.RuntimeTypes() {
    44  		mset := visit.prog.MethodSets.MethodSet(T)
    45  		for i, n := 0, mset.Len(); i < n; i++ {
    46  			visit.function(visit.prog.MethodValue(mset.At(i)))
    47  		}
    48  	}
    49  }
    50  
    51  func (visit *visitor) function(fn *ssa.Function) {
    52  	if !visit.seen[fn] {
    53  		visit.seen[fn] = true
    54  		var buf [10]*ssa.Value // avoid alloc in common case
    55  		for _, b := range fn.Blocks {
    56  			for _, instr := range b.Instrs {
    57  				for _, op := range instr.Operands(buf[:0]) {
    58  					if fn, ok := (*op).(*ssa.Function); ok {
    59  						visit.function(fn)
    60  					}
    61  				}
    62  			}
    63  		}
    64  	}
    65  }
    66  
    67  // MainPackages returns the subset of the specified packages
    68  // named "main" that define a main function.
    69  // The result may include synthetic "testmain" packages.
    70  func MainPackages(pkgs []*ssa.Package) []*ssa.Package {
    71  	var mains []*ssa.Package
    72  	for _, pkg := range pkgs {
    73  		if pkg.Pkg.Name() == "main" && pkg.Func("main") != nil {
    74  			mains = append(mains, pkg)
    75  		}
    76  	}
    77  	return mains
    78  }
    79
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