compiler: count local variables on the go

Create local variables as they are needed and remove `INITSLOT`
if there were no locals. This helps to eliminate a whole class
of bugs when calculated and real amount mismatched.

pkg/compiler/func_scope.go

@@ -2,7 +2,6 @@ package compiler
 
 import (
 	"go/ast"
-	"go/token"
 	"go/types"
 )
 
@@ -104,113 +103,6 @@ func (c *funcScope) analyzeVoidCalls(node ast.Node) bool {
 	return true
 }
 
-func (c *codegen) countLocalsCall(n ast.Expr, pkg *types.Package) int {
-	ce, ok := n.(*ast.CallExpr)
-	if !ok {
-		return -1
-	}
-
-	var size int
-	var name string
-	switch fun := ce.Fun.(type) {
-	case *ast.Ident:
-		var pkgName string
-		if pkg != nil {
-			pkgName = pkg.Path()
-		}
-		name = c.getIdentName(pkgName, fun.Name)
-	case *ast.SelectorExpr:
-		name, _ = c.getFuncNameFromSelector(fun)
-	default:
-		return 0
-	}
-	if inner, ok := c.funcs[name]; ok && canInline(name) {
-		sig, ok := c.typeOf(ce.Fun).(*types.Signature)
-		if !ok {
-			info := c.buildInfo.program.Package(pkg.Path())
-			sig = info.Types[ce.Fun].Type.(*types.Signature)
-		}
-		for i := range ce.Args {
-			switch ce.Args[i].(type) {
-			case *ast.Ident:
-			case *ast.BasicLit:
-			default:
-				size++
-			}
-		}
-		// Variadic with direct var args.
-		if sig.Variadic() && !ce.Ellipsis.IsValid() {
-			size++
-		}
-		innerSz, _ := c.countLocalsInline(inner.decl, inner.pkg, inner)
-		size += innerSz
-	}
-	return size
-}
-
-func (c *codegen) countLocals(decl *ast.FuncDecl) (int, bool) {
-	return c.countLocalsInline(decl, nil, nil)
-}
-
-func (c *codegen) countLocalsInline(decl *ast.FuncDecl, pkg *types.Package, f *funcScope) (int, bool) {
-	oldMap := c.importMap
-	if pkg != nil {
-		c.fillImportMap(f.file, pkg)
-	}
-
-	size := 0
-	hasDefer := false
-	ast.Inspect(decl, func(n ast.Node) bool {
-		switch n := n.(type) {
-		case *ast.CallExpr:
-			size += c.countLocalsCall(n, pkg)
-		case *ast.FuncType:
-			num := n.Results.NumFields()
-			if num != 0 && len(n.Results.List[0].Names) != 0 {
-				size += num
-			}
-		case *ast.AssignStmt:
-			if n.Tok == token.DEFINE {
-				size += len(n.Lhs)
-			}
-		case *ast.DeferStmt:
-			hasDefer = true
-			return false
-		case *ast.ReturnStmt:
-			if pkg == nil {
-				size++
-			}
-		case *ast.IfStmt:
-			size++
-		// This handles the inline GenDecl like "var x = 2"
-		case *ast.ValueSpec:
-			size += len(n.Names)
-		case *ast.RangeStmt:
-			if n.Tok == token.DEFINE {
-				if n.Key != nil {
-					size++
-				}
-				if n.Value != nil {
-					size++
-				}
-			}
-		}
-		return true
-	})
-	if pkg != nil {
-		c.importMap = oldMap
-	}
-	return size, hasDefer
-}
-
-func (c *codegen) countLocalsWithDefer(f *funcScope) int {
-	size, hasDefer := c.countLocals(f.decl)
-	if hasDefer {
-		size++
-	}
-	return size
-}
-
 func (c *funcScope) countArgs() int {
 	n := c.decl.Type.Params.NumFields()
 	if c.decl.Recv != nil {