Golang Node.Convconst方法代碼示例

/*
 * n is a 64-bit value.  fill in lo and hi to refer to its 32-bit halves.
 */
func split64(n *gc.Node, lo *gc.Node, hi *gc.Node) {
	if !gc.Is64(n.Type) {
		gc.Fatalf("split64 %v", n.Type)
	}

	if nsclean >= len(sclean) {
		gc.Fatalf("split64 clean")
	}
	sclean[nsclean].Op = gc.OEMPTY
	nsclean++
	switch n.Op {
	default:
		switch n.Op {
		default:
			var n1 gc.Node
			if !dotaddable(n, &n1) {
				gc.Igen(n, &n1, nil)
				sclean[nsclean-1] = n1
			}

			n = &n1

		case gc.ONAME, gc.OINDREG:
			// nothing
		}

		*lo = *n
		*hi = *n
		lo.Type = gc.Types[gc.TUINT32]
		if n.Type.Etype == gc.TINT64 {
			hi.Type = gc.Types[gc.TINT32]
		} else {
			hi.Type = gc.Types[gc.TUINT32]
		}
		hi.Xoffset += 4

	case gc.OLITERAL:
		var n1 gc.Node
		n.Convconst(&n1, n.Type)
		i := n1.Int64()
		gc.Nodconst(lo, gc.Types[gc.TUINT32], int64(uint32(i)))
		i >>= 32
		if n.Type.Etype == gc.TINT64 {
			gc.Nodconst(hi, gc.Types[gc.TINT32], int64(int32(i)))
		} else {
			gc.Nodconst(hi, gc.Types[gc.TUINT32], int64(uint32(i)))
		}
	}
}

func bignodes() {
	if bignodes_did {
		return
	}
	bignodes_did = true

	gc.Nodconst(&zerof, gc.Types[gc.TINT64], 0)
	zerof.Convconst(&zerof, gc.Types[gc.TFLOAT64])

	var i big.Int
	i.SetInt64(1)
	i.Lsh(&i, 63)
	var bigi gc.Node

	gc.Nodconst(&bigi, gc.Types[gc.TUINT64], 0)
	bigi.SetBigInt(&i)
	bigi.Convconst(&two63f, gc.Types[gc.TFLOAT64])

	gc.Nodconst(&bigi, gc.Types[gc.TUINT64], 0)
	i.Lsh(&i, 1)
	bigi.SetBigInt(&i)
	bigi.Convconst(&two64f, gc.Types[gc.TFLOAT64])
}

func gmove(f *gc.Node, t *gc.Node) {
	if gc.Debug['M'] != 0 {
		fmt.Printf("gmove %v -> %v\n", f, t)
	}

	ft := gc.Simsimtype(f.Type)
	tt := gc.Simsimtype(t.Type)
	cvt := t.Type

	if gc.Iscomplex[ft] || gc.Iscomplex[tt] {
		gc.Complexmove(f, t)
		return
	}

	// cannot have two memory operands;
	// except 64-bit, which always copies via registers anyway.
	var a obj.As
	var r1 gc.Node
	if !gc.Is64(f.Type) && !gc.Is64(t.Type) && gc.Ismem(f) && gc.Ismem(t) {
		goto hard
	}

	// convert constant to desired type
	if f.Op == gc.OLITERAL {
		var con gc.Node
		switch tt {
		default:
			f.Convconst(&con, t.Type)

		case gc.TINT16,
			gc.TINT8:
			var con gc.Node
			f.Convconst(&con, gc.Types[gc.TINT32])
			var r1 gc.Node
			gc.Regalloc(&r1, con.Type, t)
			gins(arm.AMOVW, &con, &r1)
			gmove(&r1, t)
			gc.Regfree(&r1)
			return

		case gc.TUINT16,
			gc.TUINT8:
			var con gc.Node
			f.Convconst(&con, gc.Types[gc.TUINT32])
			var r1 gc.Node
			gc.Regalloc(&r1, con.Type, t)
			gins(arm.AMOVW, &con, &r1)
			gmove(&r1, t)
			gc.Regfree(&r1)
			return
		}

		f = &con
		ft = gc.Simsimtype(con.Type)

		// constants can't move directly to memory
		if gc.Ismem(t) && !gc.Is64(t.Type) {
			goto hard
		}
	}

	// value -> value copy, only one memory operand.
	// figure out the instruction to use.
	// break out of switch for one-instruction gins.
	// goto rdst for "destination must be register".
	// goto hard for "convert to cvt type first".
	// otherwise handle and return.

	switch uint32(ft)<<16 | uint32(tt) {
	default:
		// should not happen
		gc.Fatalf("gmove %v -> %v", f, t)
		return

		/*
		 * integer copy and truncate
		 */
	case gc.TINT8<<16 | gc.TINT8: // same size
		if !gc.Ismem(f) {
			a = arm.AMOVB
			break
		}
		fallthrough

	case gc.TUINT8<<16 | gc.TINT8,
		gc.TINT16<<16 | gc.TINT8, // truncate
		gc.TUINT16<<16 | gc.TINT8,
		gc.TINT32<<16 | gc.TINT8,
		gc.TUINT32<<16 | gc.TINT8:
		a = arm.AMOVBS

	case gc.TUINT8<<16 | gc.TUINT8:
		if !gc.Ismem(f) {
			a = arm.AMOVB
			break
		}
		fallthrough

	case gc.TINT8<<16 | gc.TUINT8,
		gc.TINT16<<16 | gc.TUINT8,
//.........這裏部分代碼省略.........

func floatmove(f *gc.Node, t *gc.Node) {
	var r1 gc.Node

	ft := gc.Simsimtype(f.Type)
	tt := gc.Simsimtype(t.Type)
	cvt := t.Type

	// cannot have two floating point memory operands.
	if gc.Isfloat[ft] && gc.Isfloat[tt] && gc.Ismem(f) && gc.Ismem(t) {
		goto hard
	}

	// convert constant to desired type
	if f.Op == gc.OLITERAL {
		var con gc.Node
		f.Convconst(&con, t.Type)
		f = &con
		ft = gc.Simsimtype(con.Type)

		// some constants can't move directly to memory.
		if gc.Ismem(t) {
			// float constants come from memory.
			if gc.Isfloat[tt] {
				goto hard
			}
		}
	}

	// value -> value copy, only one memory operand.
	// figure out the instruction to use.
	// break out of switch for one-instruction gins.
	// goto rdst for "destination must be register".
	// goto hard for "convert to cvt type first".
	// otherwise handle and return.

	switch uint32(ft)<<16 | uint32(tt) {
	default:
		if gc.Thearch.Use387 {
			floatmove_387(f, t)
		} else {
			floatmove_sse(f, t)
		}
		return

		// float to very long integer.
	case gc.TFLOAT32<<16 | gc.TINT64,
		gc.TFLOAT64<<16 | gc.TINT64:
		if f.Op == gc.OREGISTER {
			cvt = f.Type
			goto hardmem
		}

		var r1 gc.Node
		gc.Nodreg(&r1, gc.Types[ft], x86.REG_F0)
		if ft == gc.TFLOAT32 {
			gins(x86.AFMOVF, f, &r1)
		} else {
			gins(x86.AFMOVD, f, &r1)
		}

		// set round to zero mode during conversion
		var t1 gc.Node
		memname(&t1, gc.Types[gc.TUINT16])

		var t2 gc.Node
		memname(&t2, gc.Types[gc.TUINT16])
		gins(x86.AFSTCW, nil, &t1)
		gins(x86.AMOVW, ncon(0xf7f), &t2)
		gins(x86.AFLDCW, &t2, nil)
		if tt == gc.TINT16 {
			gins(x86.AFMOVWP, &r1, t)
		} else if tt == gc.TINT32 {
			gins(x86.AFMOVLP, &r1, t)
		} else {
			gins(x86.AFMOVVP, &r1, t)
		}
		gins(x86.AFLDCW, &t1, nil)
		return

	case gc.TFLOAT32<<16 | gc.TUINT64,
		gc.TFLOAT64<<16 | gc.TUINT64:
		if !gc.Ismem(f) {
			cvt = f.Type
			goto hardmem
		}

		bignodes()
		var f0 gc.Node
		gc.Nodreg(&f0, gc.Types[ft], x86.REG_F0)
		var f1 gc.Node
		gc.Nodreg(&f1, gc.Types[ft], x86.REG_F0+1)
		var ax gc.Node
		gc.Nodreg(&ax, gc.Types[gc.TUINT16], x86.REG_AX)

		if ft == gc.TFLOAT32 {
			gins(x86.AFMOVF, f, &f0)
		} else {
			gins(x86.AFMOVD, f, &f0)
		}

//.........這裏部分代碼省略.........