Files
avo/printer/goasm.go
2018-12-27 13:48:31 -08:00

104 lines
2.2 KiB
Go

package printer
import (
"strconv"
"strings"
"github.com/mmcloughlin/avo"
"github.com/mmcloughlin/avo/internal/prnt"
"github.com/mmcloughlin/avo/operand"
)
// dot is the pesky unicode dot used in Go assembly.
const dot = "\u00b7"
type goasm struct {
cfg Config
prnt.Generator
}
func NewGoAsm(cfg Config) Printer {
return &goasm{cfg: cfg}
}
func (p *goasm) Print(f *avo.File) ([]byte, error) {
p.header()
for _, s := range f.Sections {
switch s := s.(type) {
case *avo.Function:
p.function(s)
case *avo.Global:
p.global(s)
default:
panic("unknown section type")
}
}
return p.Result()
}
func (p *goasm) header() {
p.Comment(p.cfg.GeneratedWarning())
p.NL()
p.include("textflag.h")
}
func (p *goasm) include(path string) {
p.Printf("#include \"%s\"\n", path)
}
func (p *goasm) function(f *avo.Function) {
p.NL()
p.Comment(f.Stub())
p.Printf("TEXT %s%s(SB), 0, %s\n", dot, f.Name, textsize(f))
for _, node := range f.Nodes {
switch n := node.(type) {
case *avo.Instruction:
if len(n.Operands) > 0 {
p.Printf("\t%s\t%s\n", n.Opcode, joinOperands(n.Operands))
} else {
p.Printf("\t%s\n", n.Opcode)
}
case avo.Label:
p.Printf("%s:\n", n)
default:
panic("unexpected node type")
}
}
}
func (p *goasm) global(g *avo.Global) {
p.NL()
for _, d := range g.Data {
a := operand.NewDataAddr(g.Symbol, d.Offset)
p.Printf("DATA %s/%d, %s\n", a.Asm(), d.Value.Bytes(), d.Value.Asm())
}
// TODO(mbm): replace hardcoded RODATA with an attributes list
p.Printf("GLOBL %s(SB), RODATA, $%d\n", g.Symbol, g.Size)
}
func textsize(f *avo.Function) string {
// Reference: https://github.com/golang/go/blob/b115207baf6c2decc3820ada4574ef4e5ad940ec/src/cmd/internal/obj/util.go#L260-L265
//
// case TYPE_TEXTSIZE:
// if a.Val.(int32) == objabi.ArgsSizeUnknown {
// str = fmt.Sprintf("$%d", a.Offset)
// } else {
// str = fmt.Sprintf("$%d-%d", a.Offset, a.Val.(int32))
// }
//
s := "$" + strconv.Itoa(f.FrameBytes())
if argsize := f.ArgumentBytes(); argsize > 0 {
return s + "-" + strconv.Itoa(argsize)
}
return s
}
func joinOperands(operands []operand.Op) string {
asm := make([]string, len(operands))
for i, op := range operands {
asm[i] = op.Asm()
}
return strings.Join(asm, ", ")
}