示例#1
0
文件: main.go 项目: 0x7cc/rsc
func fixMemset(prog *cc.Prog, fn *cc.Decl, stmt *cc.Stmt) {
	x := stmt.Expr
	if len(x.List) != 3 || x.List[1].Op != cc.Number || x.List[1].Text != "0" {
		fprintf(x.Span, "unsupported %v - nonzero", x)
		return
	}

	if x.List[2].Op == cc.SizeofExpr || x.List[2].Op == cc.SizeofType {
		obj, objType := objIndir(fn, x.List[0])
		if !matchSize(fn, obj, objType, x.List[2]) {
			fprintf(x.Span, "unsupported %v - wrong size", x)
			return
		}

		x.Op = cc.Eq
		x.Left = obj
		x.Right = zeroFor(objType)
		x.List = nil
		return
	}

	siz := x.List[2]
	var count *cc.Expr
	var objType *cc.Type
	if siz.Op == cc.Mul {
		count = siz.Left
		siz = siz.Right
		if siz.Op != cc.SizeofExpr && siz.Op != cc.SizeofType {
			fprintf(x.Span, "unsupported %v - wrong array size", x)
			return
		}

		switch siz.Op {
		case cc.SizeofExpr:
			p := unparen(siz.Left)
			if p.Op != cc.Indir && p.Op != cc.Index || !sameType(p.Left.XType, x.List[0].XType) {
				fprintf(x.Span, "unsupported %v - wrong size", x)
			}
			objType = fixGoTypesExpr(fn, x.List[0], nil)
		case cc.SizeofType:
			objType = fixGoTypesExpr(fn, x.List[0], nil)
			if !sameType(siz.Type, objType.Base) {
				fprintf(x.Span, "unsupported %v - wrong size", x)
			}
		}
	} else {
		count = siz
		objType = fixGoTypesExpr(fn, x.List[0], nil)
		if !objType.Base.Is(c2go.Byte) && !objType.Base.Is(c2go.Uint8) {
			fprintf(x.Span, "unsupported %v - wrong size form for non-byte type", x)
			return
		}
	}

	// Found it. Replace with zeroing for loop.
	stmt.Op = cc.For
	stmt.Pre = &cc.Expr{
		Op: cc.Eq,
		Left: &cc.Expr{
			Op:    cc.Name,
			Text:  "i",
			XType: intType,
		},
		Right: &cc.Expr{
			Op:    cc.Number,
			Text:  "0",
			XType: intType,
		},
		XType: boolType,
	}
	stmt.Expr = &cc.Expr{
		Op: cc.Lt,
		Left: &cc.Expr{
			Op:    cc.Name,
			Text:  "i",
			XType: intType,
		},
		Right: count,
		XType: boolType,
	}
	stmt.Post = &cc.Expr{
		Op: cc.PostInc,
		Left: &cc.Expr{
			Op:    cc.Name,
			Text:  "i",
			XType: intType,
		},
		XType: intType,
	}
	stmt.Body = &cc.Stmt{
		Op: cc.Block,
		Block: []*cc.Stmt{
			{
				Op: cc.StmtExpr,
				Expr: &cc.Expr{
					Op: cc.Eq,
					Left: &cc.Expr{
						Op:    cc.Index,
						Left:  x.List[0],
						Right: &cc.Expr{Op: cc.Name, Text: "i"},
					},
					Right: zeroFor(objType.Base),
				},
			},
		},
	}
	return
}
示例#2
0
文件: syntax.go 项目: 0x7cc/rsc
func rewriteStmt(stmt *cc.Stmt) {
	// TODO: Double-check stmt.Labels

	switch stmt.Op {
	case cc.ARGBEGIN:
		panic(fmt.Sprintf("unexpected ARGBEGIN"))

	case cc.Do:
		// Rewrite do { ... } while(x)
		// to for(;;) { ... if(!x) break }
		// Since rewriteStmt is called in a preorder traversal,
		// the recursion into the children will clean up x
		// in the if condition as needed.
		stmt.Op = cc.For
		x := stmt.Expr
		stmt.Expr = nil
		stmt.Body = forceBlock(stmt.Body)
		stmt.Body.Block = append(stmt.Body.Block, &cc.Stmt{
			Op:   cc.If,
			Expr: &cc.Expr{Op: cc.Not, Left: x},
			Body: &cc.Stmt{Op: cc.Break},
		})

	case cc.While:
		stmt.Op = cc.For
		fallthrough

	case cc.For:
		before1, _ := extractSideEffects(stmt.Pre, sideStmt|sideNoAfter)
		before2, _ := extractSideEffects(stmt.Expr, sideNoAfter)
		if len(before2) > 0 {
			x := stmt.Expr
			stmt.Expr = nil
			stmt.Body = forceBlock(stmt.Body)
			top := &cc.Stmt{
				Op:   cc.If,
				Expr: &cc.Expr{Op: cc.Not, Left: x},
				Body: &cc.Stmt{Op: cc.Break},
			}
			stmt.Body.Block = append(append(before2, top), stmt.Body.Block...)
		}
		if len(before1) > 0 {
			old := copyStmt(stmt)
			stmt.Pre = nil
			stmt.Expr = nil
			stmt.Post = nil
			stmt.Body = nil
			stmt.Op = c2go.BlockNoBrace
			stmt.Block = append(before1, old)
		}
		before, after := extractSideEffects(stmt.Post, sideStmt)
		if len(before)+len(after) > 0 {
			all := append(append(before, &cc.Stmt{Op: cc.StmtExpr, Expr: stmt.Post}), after...)
			stmt.Post = &cc.Expr{Op: c2go.ExprBlock, Block: all}
		}

	case cc.If, cc.Return:
		before, _ := extractSideEffects(stmt.Expr, sideNoAfter)
		if len(before) > 0 {
			old := copyStmt(stmt)
			stmt.Expr = nil
			stmt.Body = nil
			stmt.Else = nil
			stmt.Op = c2go.BlockNoBrace
			stmt.Block = append(before, old)
		}

	case cc.StmtExpr:
		before, after := extractSideEffects(stmt.Expr, sideStmt)
		if len(before)+len(after) > 0 {
			old := copyStmt(stmt)
			stmt.Expr = nil
			stmt.Op = c2go.BlockNoBrace
			stmt.Block = append(append(before, old), after...)
		}

	case cc.Goto:
		// TODO: Figure out where the goto goes and maybe rewrite
		// to labeled break/continue.
		// Otherwise move code or something.

	case cc.Switch:
		// TODO: Change default fallthrough to default break.
		before, _ := extractSideEffects(stmt.Expr, sideNoAfter)
		rewriteSwitch(stmt)
		if len(before) > 0 {
			old := copyStmt(stmt)
			stmt.Expr = nil
			stmt.Body = nil
			stmt.Else = nil
			stmt.Op = c2go.BlockNoBrace
			stmt.Block = append(before, old)
		}
	}
}