compiler: allow to use local variables in init()

Because body of multiple `init()` functions constitute single
method in contract, we initialize slot with maximum amount of
locals encounterered in any of `init()` functions and clear them
before emitting body of each instance of `init()`.
This commit is contained in:
Evgenii Stratonikov 2020-10-06 18:25:40 +03:00
parent 2d9ef9219a
commit 6701e8cda0
4 changed files with 58 additions and 27 deletions

View file

@ -37,20 +37,24 @@ func (c *codegen) getIdentName(pkg string, name string) string {
}
// traverseGlobals visits and initializes global variables.
// and returns number of variables initialized and
// true if any init functions were encountered.
func (c *codegen) traverseGlobals() (int, bool) {
// and returns number of variables initialized.
// Second return value is -1 if no `init()` functions were encountered
// and number of maximum amount of locals in any of init functions otherwise.
func (c *codegen) traverseGlobals() (int, int) {
var hasDefer bool
var n int
var hasInit bool
initLocals := -1
c.ForEachFile(func(f *ast.File, _ *types.Package) {
n += countGlobals(f)
if !hasInit || !hasDefer {
if initLocals == -1 || !hasDefer {
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.FuncDecl:
if isInitFunc(n) {
hasInit = true
c, _ := countLocals(n)
if c > initLocals {
initLocals = c
}
}
return !hasDefer
case *ast.DeferStmt:
@ -64,14 +68,18 @@ func (c *codegen) traverseGlobals() (int, bool) {
if hasDefer {
n++
}
if n != 0 || hasInit {
if n != 0 || initLocals > -1 {
if n > 255 {
c.prog.BinWriter.Err = errors.New("too many global variables")
return 0, hasInit
return 0, initLocals
}
if n != 0 {
emit.Instruction(c.prog.BinWriter, opcode.INITSSLOT, []byte{byte(n)})
}
if initLocals > 0 {
emit.Instruction(c.prog.BinWriter, opcode.INITSLOT, []byte{byte(initLocals), 0})
}
seenBefore := false
c.ForEachPackage(func(pkg *loader.PackageInfo) {
if n > 0 {
for _, f := range pkg.Files {
@ -79,10 +87,10 @@ func (c *codegen) traverseGlobals() (int, bool) {
c.convertGlobals(f, pkg.Pkg)
}
}
if hasInit {
if initLocals > -1 {
for _, f := range pkg.Files {
c.fillImportMap(f, pkg.Pkg)
c.convertInitFuncs(f, pkg.Pkg)
seenBefore = c.convertInitFuncs(f, pkg.Pkg, seenBefore) || seenBefore
}
}
// because we reuse `convertFuncDecl` for init funcs,
@ -96,7 +104,7 @@ func (c *codegen) traverseGlobals() (int, bool) {
c.globals["<exception>"] = c.exceptionIndex
}
}
return n, hasInit
return n, initLocals
}
// countGlobals counts the global variables in the program to add

View file

@ -301,11 +301,23 @@ func isInitFunc(decl *ast.FuncDecl) bool {
decl.Type.Results.NumFields() == 0
}
func (c *codegen) convertInitFuncs(f *ast.File, pkg *types.Package) {
func (c *codegen) clearSlots(n int) {
for i := 0; i < n; i++ {
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
c.emitStoreByIndex(varLocal, i)
}
}
func (c *codegen) convertInitFuncs(f *ast.File, pkg *types.Package, seenBefore bool) bool {
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.FuncDecl:
if isInitFunc(n) {
if seenBefore {
cnt, _ := countLocals(n)
c.clearSlots(cnt)
seenBefore = true
}
c.convertFuncDecl(f, n, pkg)
}
case *ast.GenDecl:
@ -313,6 +325,7 @@ func (c *codegen) convertInitFuncs(f *ast.File, pkg *types.Package) {
}
return true
})
return seenBefore
}
func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl, pkg *types.Package) {
@ -345,6 +358,7 @@ func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl, pkg *types.
// All globals copied into the scope of the function need to be added
// to the stack size of the function.
if !isInit {
sizeLoc := f.countLocals()
if sizeLoc > 255 {
c.prog.Err = errors.New("maximum of 255 local variables is allowed")
@ -356,6 +370,7 @@ func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl, pkg *types.
if sizeLoc != 0 || sizeArg != 0 {
emit.Instruction(c.prog.BinWriter, opcode.INITSLOT, []byte{byte(sizeLoc), byte(sizeArg)})
}
}
f.vars.newScope()
defer f.vars.dropScope()
@ -1777,7 +1792,8 @@ func (c *codegen) compile(info *buildInfo, pkg *loader.PackageInfo) error {
// Bring all imported functions into scope.
c.ForEachFile(c.resolveFuncDecls)
n, hasInit := c.traverseGlobals()
n, initLocals := c.traverseGlobals()
hasInit := initLocals > -1
if n > 0 || hasInit {
emit.Opcodes(c.prog.BinWriter, opcode.RET)
c.initEndOffset = c.prog.Len()

View file

@ -152,10 +152,10 @@ func (c *funcScope) analyzeVoidCalls(node ast.Node) bool {
return true
}
func (c *funcScope) countLocals() int {
func countLocals(decl *ast.FuncDecl) (int, bool) {
size := 0
hasDefer := false
ast.Inspect(c.decl, func(n ast.Node) bool {
ast.Inspect(decl, func(n ast.Node) bool {
switch n := n.(type) {
case *ast.FuncType:
num := n.Results.NumFields()
@ -186,6 +186,11 @@ func (c *funcScope) countLocals() int {
}
return true
})
return size, hasDefer
}
func (c *funcScope) countLocals() int {
size, hasDefer := countLocals(c.decl)
if hasDefer {
c.finallyProcessedIndex = size
size++

View file

@ -24,11 +24,13 @@ func TestInit(t *testing.T) {
var m = map[int]int{}
var a = 2
func init() {
m[1] = 11
b := 11
m[1] = b
}
func init() {
a = 1
m[3] = 30
var b int
m[3] = 30 + b
}
func Main() int {
return m[1] + m[3] + a