package ssautil

import "golang.org/x/tools/go/ssa/ssautil"

Index ¶

Package Files ¶

load.go switch.go visit.go

func AllFunctions ¶

func AllFunctions(prog *ssa.Program) map[*ssa.Function]bool

AllFunctions finds and returns the set of functions potentially needed by program prog, as determined by a simple linker-style reachability algorithm starting from the members and method-sets of each package. The result may include anonymous functions and synthetic wrappers.

Precondition: all packages are built.

func BuildPackage ¶

func BuildPackage(tc *types.Config, fset *token.FileSet, pkg *types.Package, files []*ast.File, mode ssa.BuilderMode) (*ssa.Package, *types.Info, error)

BuildPackage builds an SSA program with IR for a single package.

It populates pkg by type-checking the specified file ASTs. All dependencies are loaded using the importer specified by tc, which typically loads compiler export data; SSA code cannot be built for those packages. BuildPackage then constructs an ssa.Program with all dependency packages created, and builds and returns the SSA package corresponding to pkg.

The caller must have set pkg.Path() to the import path.

The operation fails if there were any type-checking or import errors.

See ../ssa/example_test.go for an example.

func CreateProgram ¶

func CreateProgram(lprog *loader.Program, mode ssa.BuilderMode) *ssa.Program

CreateProgram returns a new program in SSA form, given a program loaded from source. An SSA package is created for each transitively error-free package of lprog.

Code for bodies of functions is not built until BuildAll() is called on the result.

mode controls diagnostics and checking during SSA construction.

func Switches ¶

func Switches(fn *ssa.Function) []Switch

Switches examines the control-flow graph of fn and returns the set of inferred value and type switches. A value switch tests an ssa.Value for equality against two or more compile-time constant values. Switches involving link-time constants (addresses) are ignored. A type switch type-asserts an ssa.Value against two or more types.

The switches are returned in dominance order.

The resulting switches do not necessarily correspond to uses of the 'switch' keyword in the source: for example, a single source-level switch statement with non-constant cases may result in zero, one or many Switches, one per plural sequence of constant cases. Switches may even be inferred from if/else- or goto-based control flow. (In general, the control flow constructs of the source program cannot be faithfully reproduced from the SSA representation.)

type ConstCase ¶

type ConstCase struct {
    Block *ssa.BasicBlock // block performing the comparison
    Body  *ssa.BasicBlock // body of the case
    Value *ssa.Const      // case comparand
}

A ConstCase represents a single constant comparison. It is part of a Switch.

type Switch ¶

type Switch struct {
    Start      *ssa.BasicBlock // block containing start of if/else chain
    X          ssa.Value       // the switch operand
    ConstCases []ConstCase     // ordered list of constant comparisons
    TypeCases  []TypeCase      // ordered list of type assertions
    Default    *ssa.BasicBlock // successor if all comparisons fail
}

A Switch is a logical high-level control flow operation (a multiway branch) discovered by analysis of a CFG containing only if/else chains. It is not part of the ssa.Instruction set.

One of ConstCases and TypeCases has length >= 2; the other is nil.

In a value switch, the list of cases may contain duplicate constants. A type switch may contain duplicate types, or types assignable to an interface type also in the list. TODO(adonovan): eliminate such duplicates.

func (*Switch) String ¶

func (sw *Switch) String() string

type TypeCase ¶

type TypeCase struct {
    Block   *ssa.BasicBlock // block performing the type assert
    Body    *ssa.BasicBlock // body of the case
    Type    types.Type      // case type
    Binding ssa.Value       // value bound by this case
}

A TypeCase represents a single type assertion. It is part of a Switch.