func gnuArg()

in x86/x86asm/gnu.go [520:683]

• 160 lines of code
• 63 McCabe index (conditional complexity)

func gnuArg(inst *Inst, pc uint64, symname SymLookup, x Arg, usedPrefixes *bool) string {
	if x == nil {
		return "<nil>"
	}
	switch x := x.(type) {
	case Reg:
		switch inst.Op {
		case CVTSI2SS, CVTSI2SD, CVTSS2SI, CVTSD2SI, CVTTSD2SI, CVTTSS2SI:
			if inst.DataSize == 16 && EAX <= x && x <= R15L {
				x -= EAX - AX
			}

		case IN, INSB, INSW, INSD, OUT, OUTSB, OUTSW, OUTSD:
			// DX is the port, but libopcodes prints it as if it were a memory reference.
			if x == DX {
				return "(%dx)"
			}
		case VMOVDQA, VMOVDQU, VMOVNTDQA, VMOVNTDQ:
			return strings.Replace(gccRegName[x], "xmm", "ymm", -1)
		}
		return gccRegName[x]
	case Mem:
		if s, disp := memArgToSymbol(x, pc, inst.Len, symname); s != "" {
			suffix := ""
			if disp != 0 {
				suffix = fmt.Sprintf("%+d", disp)
			}
			return fmt.Sprintf("%s%s", s, suffix)
		}
		seg := ""
		var haveCS, haveDS, haveES, haveFS, haveGS, haveSS bool
		switch x.Segment {
		case CS:
			haveCS = true
		case DS:
			haveDS = true
		case ES:
			haveES = true
		case FS:
			haveFS = true
		case GS:
			haveGS = true
		case SS:
			haveSS = true
		}
		switch inst.Op {
		case INSB, INSW, INSD, STOSB, STOSW, STOSD, STOSQ, SCASB, SCASW, SCASD, SCASQ:
			// These do not accept segment prefixes, at least in the GNU rendering.
		default:
			if *usedPrefixes {
				break
			}
			for i := len(inst.Prefix) - 1; i >= 0; i-- {
				p := inst.Prefix[i] &^ PrefixIgnored
				if p == 0 {
					continue
				}
				switch p {
				case PrefixCS:
					if !haveCS {
						haveCS = true
						inst.Prefix[i] |= PrefixImplicit
					}
				case PrefixDS:
					if !haveDS {
						haveDS = true
						inst.Prefix[i] |= PrefixImplicit
					}
				case PrefixES:
					if !haveES {
						haveES = true
						inst.Prefix[i] |= PrefixImplicit
					}
				case PrefixFS:
					if !haveFS {
						haveFS = true
						inst.Prefix[i] |= PrefixImplicit
					}
				case PrefixGS:
					if !haveGS {
						haveGS = true
						inst.Prefix[i] |= PrefixImplicit
					}
				case PrefixSS:
					if !haveSS {
						haveSS = true
						inst.Prefix[i] |= PrefixImplicit
					}
				}
			}
			*usedPrefixes = true
		}
		if haveCS {
			seg += "%cs:"
		}
		if haveDS {
			seg += "%ds:"
		}
		if haveSS {
			seg += "%ss:"
		}
		if haveES {
			seg += "%es:"
		}
		if haveFS {
			seg += "%fs:"
		}
		if haveGS {
			seg += "%gs:"
		}
		disp := ""
		if x.Disp != 0 {
			disp = fmt.Sprintf("%#x", x.Disp)
		}
		if x.Scale == 0 || x.Index == 0 && x.Scale == 1 && (x.Base == ESP || x.Base == RSP || x.Base == 0 && inst.Mode == 64) {
			if x.Base == 0 {
				return seg + disp
			}
			return fmt.Sprintf("%s%s(%s)", seg, disp, gccRegName[x.Base])
		}
		base := gccRegName[x.Base]
		if x.Base == 0 {
			base = ""
		}
		index := gccRegName[x.Index]
		if x.Index == 0 {
			if inst.AddrSize == 64 {
				index = "%riz"
			} else {
				index = "%eiz"
			}
		}
		if AX <= x.Base && x.Base <= DI {
			// 16-bit addressing - no scale
			return fmt.Sprintf("%s%s(%s,%s)", seg, disp, base, index)
		}
		return fmt.Sprintf("%s%s(%s,%s,%d)", seg, disp, base, index, x.Scale)
	case Rel:
		if pc == 0 {
			return fmt.Sprintf(".%+#x", int64(x))
		} else {
			addr := pc + uint64(inst.Len) + uint64(x)
			if s, base := symname(addr); s != "" && addr == base {
				return fmt.Sprintf("%s", s)
			} else {
				addr := pc + uint64(inst.Len) + uint64(x)
				return fmt.Sprintf("%#x", addr)
			}
		}
	case Imm:
		if s, base := symname(uint64(x)); s != "" {
			suffix := ""
			if uint64(x) != base {
				suffix = fmt.Sprintf("%+d", uint64(x)-base)
			}
			return fmt.Sprintf("$%s%s", s, suffix)
		}
		if inst.Mode == 32 {
			return fmt.Sprintf("$%#x", uint32(x))
		}
		return fmt.Sprintf("$%#x", int64(x))
	}
	return x.String()
}