src/cmd/6c/cgen.c

// Inferno utils/6c/cgen.c
// http://code.google.com/p/inferno-os/source/browse/utils/6c/cgen.c
//
//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
//	Portions Copyright © 1997-1999 Vita Nuova Limited
//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
//	Portions Copyright © 2004,2006 Bruce Ellis
//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
//	Portions Copyright © 2009 The Go Authors.  All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#include "gc.h"
#include "../../runtime/funcdata.h"

/* ,x/^(print|prtree)\(/i/\/\/ */
int castup(Type*, Type*);
int vaddr(Node *n, int a);

void
cgen(Node *n, Node *nn)
{
	Node *l, *r, *t;
	Prog *p1;
	Node nod, nod1, nod2, nod3, nod4;
	int o, hardleft;
	int32 v, curs;
	vlong c;

	if(debug['g']) {
		prtree(nn, "cgen lhs");
		prtree(n, "cgen");
	}
	if(n == Z || n->type == T)
		return;
	if(typesu[n->type->etype] && (n->op != OFUNC || nn != Z)) {
		sugen(n, nn, n->type->width);
		return;
	}
	l = n->left;
	r = n->right;
	o = n->op;
	
	if(n->op == OEXREG || (nn != Z && nn->op == OEXREG)) {
		gmove(n, nn);
		return;
	}

	if(n->addable >= INDEXED) {
		if(nn == Z) {
			switch(o) {
			default:
				nullwarn(Z, Z);
				break;
			case OINDEX:
				nullwarn(l, r);
				break;
			}
			return;
		}
		gmove(n, nn);
		return;
	}
	curs = cursafe;

	if(l->complex >= FNX)
	if(r != Z && r->complex >= FNX)
	switch(o) {
	default:
		if(cond(o) && typesu[l->type->etype])
			break;

		regret(&nod, r, 0, 0);
		cgen(r, &nod);

		regsalloc(&nod1, r);
		gmove(&nod, &nod1);

		regfree(&nod);
		nod = *n;
		nod.right = &nod1;

		cgen(&nod, nn);
		return;

	case OFUNC:
	case OCOMMA:
	case OANDAND:
	case OOROR:
	case OCOND:
	case ODOT:
		break;
	}

	hardleft = l->addable < INDEXED || l->complex >= FNX;
	switch(o) {
	default:
		diag(n, "unknown op in cgen: %O", o);
		break;

	case ONEG:
	case OCOM:
		if(nn == Z) {
			nullwarn(l, Z);
			break;
		}
		regalloc(&nod, l, nn);
		cgen(l, &nod);
		gopcode(o, n->type, Z, &nod);
		gmove(&nod, nn);
		regfree(&nod);
		break;

	case OAS:
		if(l->op == OBIT)
			goto bitas;
		if(!hardleft) {
			if(nn != Z || r->addable < INDEXED || hardconst(r)) {
				if(r->complex >= FNX && nn == Z)
					regret(&nod, r, 0, 0);
				else
					regalloc(&nod, r, nn);
				cgen(r, &nod);
				gmove(&nod, l);
				if(nn != Z)
					gmove(&nod, nn);
				regfree(&nod);
			} else
				gmove(r, l);
			break;
		}
		if(l->complex >= r->complex) {
			if(l->op == OINDEX && immconst(r)) {
				gmove(r, l);
				break;
			}
			reglcgen(&nod1, l, Z);
			if(r->addable >= INDEXED && !hardconst(r)) {
				gmove(r, &nod1);
				if(nn != Z)
					gmove(r, nn);
				regfree(&nod1);
				break;
			}
			regalloc(&nod, r, nn);
			cgen(r, &nod);
		} else {
			regalloc(&nod, r, nn);
			cgen(r, &nod);
			reglcgen(&nod1, l, Z);
		}
		gmove(&nod, &nod1);
		regfree(&nod);
		regfree(&nod1);
		break;

	bitas:
		n = l->left;
		regalloc(&nod, r, nn);
		if(l->complex >= r->complex) {
			reglcgen(&nod1, n, Z);
			cgen(r, &nod);
		} else {
			cgen(r, &nod);
			reglcgen(&nod1, n, Z);
		}
		regalloc(&nod2, n, Z);
		gmove(&nod1, &nod2);
		bitstore(l, &nod, &nod1, &nod2, nn);
		break;

	case OBIT:
		if(nn == Z) {
			nullwarn(l, Z);
			break;
		}
		bitload(n, &nod, Z, Z, nn);
		gmove(&nod, nn);
		regfree(&nod);
		break;

	case OLSHR:
	case OASHL:
	case OASHR:
		if(nn == Z) {
			nullwarn(l, r);
			break;
		}
		if(r->op == OCONST) {
			if(r->vconst == 0) {
				cgen(l, nn);
				break;
			}
			regalloc(&nod, l, nn);
			cgen(l, &nod);
			if(o == OASHL && r->vconst == 1)
				gopcode(OADD, n->type, &nod, &nod);
			else
				gopcode(o, n->type, r, &nod);
			gmove(&nod, nn);
			regfree(&nod);
			break;
		}

		/*
		 * get nod to be D_CX
		 */
		if(nodreg(&nod, nn, D_CX)) {
			regsalloc(&nod1, n);
			gmove(&nod, &nod1);
			cgen(n, &nod);		/* probably a bug */
			gmove(&nod, nn);
			gmove(&nod1, &nod);
			break;
		}
		reg[D_CX]++;
		if(nn->op == OREGISTER && nn->reg == D_CX)
			regalloc(&nod1, l, Z);
		else
			regalloc(&nod1, l, nn);
		if(r->complex >= l->complex) {
			cgen(r, &nod);
			cgen(l, &nod1);
		} else {
			cgen(l, &nod1);
			cgen(r, &nod);
		}
		gopcode(o, n->type, &nod, &nod1);
		gmove(&nod1, nn);
		regfree(&nod);
		regfree(&nod1);
		break;

	case OADD:
	case OSUB:
	case OOR:
	case OXOR:
	case OAND:
		if(nn == Z) {
			nullwarn(l, r);
			break;
		}
		if(typefd[n->type->etype])
			goto fop;
		if(r->op == OCONST) {
			if(r->vconst == 0 && o != OAND) {
				cgen(l, nn);
				break;
			}
		}
		if(n->op == OOR && l->op == OASHL && r->op == OLSHR
		&& l->right->op == OCONST && r->right->op == OCONST
		&& l->left->op == ONAME && r->left->op == ONAME
		&& l->left->sym == r->left->sym
		&& l->right->vconst + r->right->vconst == 8 * l->left->type->width) {
			regalloc(&nod, l->left, nn);
			cgen(l->left, &nod);
			gopcode(OROTL, n->type, l->right, &nod);
			gmove(&nod, nn);
			regfree(&nod);
			break;
		}
		if(n->op == OADD && l->op == OASHL && l->right->op == OCONST
		&& (r->op != OCONST || r->vconst < -128 || r->vconst > 127)) {
			c = l->right->vconst;
			if(c > 0 && c <= 3) {
				if(l->left->complex >= r->complex) {
					regalloc(&nod, l->left, nn);
					cgen(l->left, &nod);
					if(r->addable < INDEXED) {
						regalloc(&nod1, r, Z);
						cgen(r, &nod1);
						genmuladd(&nod, &nod, 1 << c, &nod1);
						regfree(&nod1);
					}
					else
						genmuladd(&nod, &nod, 1 << c, r);
				}
				else {
					regalloc(&nod, r, nn);
					cgen(r, &nod);
					regalloc(&nod1, l->left, Z);
					cgen(l->left, &nod1);
					genmuladd(&nod, &nod1, 1 << c, &nod);
					regfree(&nod1);
				}
				gmove(&nod, nn);
				regfree(&nod);
				break;
			}
		}
		if(r->addable >= INDEXED && !hardconst(r)) {
			regalloc(&nod, l, nn);
			cgen(l, &nod);
			gopcode(o, n->type, r, &nod);
			gmove(&nod, nn);
			regfree(&nod);
			break;
		}
		if(l->complex >= r->complex) {
			regalloc(&nod, l, nn);
			cgen(l, &nod);
			regalloc(&nod1, r, Z);
			cgen(r, &nod1);
			gopcode(o, n->type, &nod1, &nod);
		} else {
			regalloc(&nod1, r, nn);
			cgen(r, &nod1);
			regalloc(&nod, l, Z);
			cgen(l, &nod);
			gopcode(o, n->type, &nod1, &nod);
		}
		gmove(&nod, nn);
		regfree(&nod);
		regfree(&nod1);
		break;

	case OLMOD:
	case OMOD:
	case OLMUL:
	case OLDIV:
	case OMUL:
	case ODIV:
		if(nn == Z) {
			nullwarn(l, r);
			break;
		}
		if(typefd[n->type->etype])
			goto fop;
		if(r->op == OCONST && typechl[n->type->etype]) {	/* TO DO */
			SET(v);
			switch(o) {
			case ODIV:
			case OMOD:
				c = r->vconst;
				if(c < 0)
					c = -c;
				v = xlog2(c);
				if(v < 0)
					break;
				/* fall thru */
			case OMUL:
			case OLMUL:
				regalloc(&nod, l, nn);
				cgen(l, &nod);
				switch(o) {
				case OMUL:
				case OLMUL:
					mulgen(n->type, r, &nod);
					break;
				case ODIV:
					sdiv2(r->vconst, v, l, &nod);
					break;
				case OMOD:
					smod2(r->vconst, v, l, &nod);
					break;
				}
				gmove(&nod, nn);
				regfree(&nod);
				goto done;
			case OLDIV:
				c = r->vconst;
				if((c & 0x80000000) == 0)
					break;
				regalloc(&nod1, l, Z);
				cgen(l, &nod1);
				regalloc(&nod, l, nn);
				zeroregm(&nod);
				gins(ACMPL, &nod1, nodconst(c));
				gins(ASBBL, nodconst(-1), &nod);
				regfree(&nod1);
				gmove(&nod, nn);
				regfree(&nod);
				goto done;
			}
		}

		if(o == OMUL || o == OLMUL) {
			if(l->addable >= INDEXED) {
				t = l;
				l = r;
				r = t;
			}
			reg[D_DX]++; // for gopcode case OMUL
			regalloc(&nod, l, nn);
			cgen(l, &nod);
			if(r->addable < INDEXED || hardconst(r)) {
				regalloc(&nod1, r, Z);
				cgen(r, &nod1);
				gopcode(OMUL, n->type, &nod1, &nod);
				regfree(&nod1);
			}else
				gopcode(OMUL, n->type, r, &nod);	/* addressible */
			gmove(&nod, nn);
			regfree(&nod);
			reg[D_DX]--;
			break;
		}

		/*
		 * get nod to be D_AX
		 * get nod1 to be D_DX
		 */
		if(nodreg(&nod, nn, D_AX)) {
			regsalloc(&nod2, n);
			gmove(&nod, &nod2);
			v = reg[D_AX];
			reg[D_AX] = 0;

			if(isreg(l, D_AX)) {
				nod3 = *n;
				nod3.left = &nod2;
				cgen(&nod3, nn);
			} else
			if(isreg(r, D_AX)) {
				nod3 = *n;
				nod3.right = &nod2;
				cgen(&nod3, nn);
			} else
				cgen(n, nn);

			gmove(&nod2, &nod);
			reg[D_AX] = v;
			break;
		}
		if(nodreg(&nod1, nn, D_DX)) {
			regsalloc(&nod2, n);
			gmove(&nod1, &nod2);
			v = reg[D_DX];
			reg[D_DX] = 0;

			if(isreg(l, D_DX)) {
				nod3 = *n;
				nod3.left = &nod2;
				cgen(&nod3, nn);
			} else
			if(isreg(r, D_DX)) {
				nod3 = *n;
				nod3.right = &nod2;
				cgen(&nod3, nn);
			} else
				cgen(n, nn);

			gmove(&nod2, &nod1);
			reg[D_DX] = v;
			break;
		}
		reg[D_AX]++;

		if(r->op == OCONST && (o == ODIV || o == OLDIV) && immconst(r) && typechl[r->type->etype]) {
			reg[D_DX]++;
			if(l->addable < INDEXED) {
				regalloc(&nod2, l, Z);
				cgen(l, &nod2);
				l = &nod2;
			}
			if(o == ODIV)
				sdivgen(l, r, &nod, &nod1);
			else
				udivgen(l, r, &nod, &nod1);
			gmove(&nod1, nn);
			if(l == &nod2)
				regfree(l);
			goto freeaxdx;
		}

		if(l->complex >= r->complex) {
			cgen(l, &nod);
			reg[D_DX]++;
			if(o == ODIV || o == OMOD)
				gins(typechl[l->type->etype]? ACDQ: ACQO, Z, Z);
			if(o == OLDIV || o == OLMOD)
				zeroregm(&nod1);
			if(r->addable < INDEXED || r->op == OCONST) {
				regsalloc(&nod3, r);
				cgen(r, &nod3);
				gopcode(o, n->type, &nod3, Z);
			} else
				gopcode(o, n->type, r, Z);
		} else {
			regsalloc(&nod3, r);
			cgen(r, &nod3);
			cgen(l, &nod);
			reg[D_DX]++;
			if(o == ODIV || o == OMOD)
				gins(typechl[l->type->etype]? ACDQ: ACQO, Z, Z);
			if(o == OLDIV || o == OLMOD)
				zeroregm(&nod1);
			gopcode(o, n->type, &nod3, Z);
		}
		if(o == OMOD || o == OLMOD)
			gmove(&nod1, nn);
		else
			gmove(&nod, nn);
	freeaxdx:
		regfree(&nod);
		regfree(&nod1);
		break;

	case OASLSHR:
	case OASASHL:
	case OASASHR:
		if(r->op == OCONST)
			goto asand;
		if(l->op == OBIT)
			goto asbitop;
		if(typefd[n->type->etype])
			goto asand;	/* can this happen? */

		/*
		 * get nod to be D_CX
		 */
		if(nodreg(&nod, nn, D_CX)) {
			regsalloc(&nod1, n);
			gmove(&nod, &nod1);
			cgen(n, &nod);
			if(nn != Z)
				gmove(&nod, nn);
			gmove(&nod1, &nod);
			break;
		}
		reg[D_CX]++;

		if(r->complex >= l->complex) {
			cgen(r, &nod);
			if(hardleft)
				reglcgen(&nod1, l, Z);
			else
				nod1 = *l;
		} else {
			if(hardleft)
				reglcgen(&nod1, l, Z);
			else
				nod1 = *l;
			cgen(r, &nod);
		}

		gopcode(o, l->type, &nod, &nod1);
		regfree(&nod);
		if(nn != Z)
			gmove(&nod1, nn);
		if(hardleft)
			regfree(&nod1);
		break;

	case OASAND:
	case OASADD:
	case OASSUB:
	case OASXOR:
	case OASOR:
	asand:
		if(l->op == OBIT)
			goto asbitop;
		if(typefd[l->type->etype] || typefd[r->type->etype])
			goto asfop;
		if(l->complex >= r->complex) {
			if(hardleft)
				reglcgen(&nod, l, Z);
			else
				nod = *l;
			if(!immconst(r)) {
				regalloc(&nod1, r, nn);
				cgen(r, &nod1);
				gopcode(o, l->type, &nod1, &nod);
				regfree(&nod1);
			} else
				gopcode(o, l->type, r, &nod);
		} else {
			regalloc(&nod1, r, nn);
			cgen(r, &nod1);
			if(hardleft)
				reglcgen(&nod, l, Z);
			else
				nod = *l;
			gopcode(o, l->type, &nod1, &nod);
			regfree(&nod1);
		}
		if(nn != Z)
			gmove(&nod, nn);
		if(hardleft)
			regfree(&nod);
		break;

	asfop:
		if(l->complex >= r->complex) {
			if(hardleft)
				reglcgen(&nod, l, Z);
			else
				nod = *l;
			if(r->addable < INDEXED){
				regalloc(&nod1, r, nn);
				cgen(r, &nod1);
			}else
				nod1 = *r;
			regalloc(&nod2, r, Z);
			gmove(&nod, &nod2);
			gopcode(o, r->type, &nod1, &nod2);
			gmove(&nod2, &nod);
			regfree(&nod2);
			if(r->addable < INDEXED)
				regfree(&nod1);
		} else {
			regalloc(&nod1, r, nn);
			cgen(r, &nod1);
			if(hardleft)
				reglcgen(&nod, l, Z);
			else
				nod = *l;
			if(o != OASMUL && o != OASADD) {
				regalloc(&nod2, r, Z);
				gmove(&nod, &nod2);
				gopcode(o, r->type, &nod1, &nod2);
				regfree(&nod1);
				gmove(&nod2, &nod);
				regfree(&nod2);
			} else {
				gopcode(o, r->type, &nod, &nod1);
				gmove(&nod1, &nod);
				regfree(&nod1);
			}
		}
		if(nn != Z)
			gmove(&nod, nn);
		if(hardleft)
			regfree(&nod);
		break;

	case OASLMUL:
	case OASLDIV:
	case OASLMOD:
	case OASMUL:
	case OASDIV:
	case OASMOD:
		if(l->op == OBIT)
			goto asbitop;
		if(typefd[n->type->etype] || typefd[r->type->etype])
			goto asfop;
		if(r->op == OCONST && typechl[n->type->etype]) {
			SET(v);
			switch(o) {
			case OASDIV:
			case OASMOD:
				c = r->vconst;
				if(c < 0)
					c = -c;
				v = xlog2(c);
				if(v < 0)
					break;
				/* fall thru */
			case OASMUL:
			case OASLMUL:
				if(hardleft)
					reglcgen(&nod2, l, Z);
				else
					nod2 = *l;
				regalloc(&nod, l, nn);
				cgen(&nod2, &nod);
				switch(o) {
				case OASMUL:
				case OASLMUL:
					mulgen(n->type, r, &nod);
					break;
				case OASDIV:
					sdiv2(r->vconst, v, l, &nod);
					break;
				case OASMOD:
					smod2(r->vconst, v, l, &nod);
					break;
				}
			havev:
				gmove(&nod, &nod2);
				if(nn != Z)
					gmove(&nod, nn);
				if(hardleft)
					regfree(&nod2);
				regfree(&nod);
				goto done;
			case OASLDIV:
				c = r->vconst;
				if((c & 0x80000000) == 0)
					break;
				if(hardleft)
					reglcgen(&nod2, l, Z);
				else
					nod2 = *l;
				regalloc(&nod1, l, nn);
				cgen(&nod2, &nod1);
				regalloc(&nod, l, nn);
				zeroregm(&nod);
				gins(ACMPL, &nod1, nodconst(c));
				gins(ASBBL, nodconst(-1), &nod);
				regfree(&nod1);
				goto havev;
			}
		}

		if(o == OASMUL) {
			/* should favour AX */
			regalloc(&nod, l, nn);
			if(r->complex >= FNX) {
				regalloc(&nod1, r, Z);
				cgen(r, &nod1);
				r = &nod1;
			}
			if(hardleft)
				reglcgen(&nod2, l, Z);
			else
				nod2 = *l;
			cgen(&nod2, &nod);
			if(r->addable < INDEXED || hardconst(r)) {
				if(r->complex < FNX) {
					regalloc(&nod1, r, Z);
					cgen(r, &nod1);
				}
				gopcode(OASMUL, n->type, &nod1, &nod);
				regfree(&nod1);
			}
			else
				gopcode(OASMUL, n->type, r, &nod);
			if(r == &nod1)
				regfree(r);
			gmove(&nod, &nod2);
			if(nn != Z)
				gmove(&nod, nn);
			regfree(&nod);
			if(hardleft)
				regfree(&nod2);
			break;
		}

		/*
		 * get nod to be D_AX
		 * get nod1 to be D_DX
		 */
		if(nodreg(&nod, nn, D_AX)) {
			regsalloc(&nod2, n);
			gmove(&nod, &nod2);
			v = reg[D_AX];
			reg[D_AX] = 0;

			if(isreg(l, D_AX)) {
				nod3 = *n;
				nod3.left = &nod2;
				cgen(&nod3, nn);
			} else
			if(isreg(r, D_AX)) {
				nod3 = *n;
				nod3.right = &nod2;
				cgen(&nod3, nn);
			} else
				cgen(n, nn);

			gmove(&nod2, &nod);
			reg[D_AX] = v;
			break;
		}
		if(nodreg(&nod1, nn, D_DX)) {
			regsalloc(&nod2, n);
			gmove(&nod1, &nod2);
			v = reg[D_DX];
			reg[D_DX] = 0;

			if(isreg(l, D_DX)) {
				nod3 = *n;
				nod3.left = &nod2;
				cgen(&nod3, nn);
			} else
			if(isreg(r, D_DX)) {
				nod3 = *n;
				nod3.right = &nod2;
				cgen(&nod3, nn);
			} else
				cgen(n, nn);

			gmove(&nod2, &nod1);
			reg[D_DX] = v;
			break;
		}
		reg[D_AX]++;
		reg[D_DX]++;

		if(l->complex >= r->complex) {
			if(hardleft)
				reglcgen(&nod2, l, Z);
			else
				nod2 = *l;
			cgen(&nod2, &nod);
			if(r->op == OCONST && typechl[r->type->etype]) {
				switch(o) {
				case OASDIV:
					sdivgen(&nod2, r, &nod, &nod1);
					goto divdone;
				case OASLDIV:
					udivgen(&nod2, r, &nod, &nod1);
				divdone:
					gmove(&nod1, &nod2);
					if(nn != Z)
						gmove(&nod1, nn);
					goto freelxaxdx;
				}
			}
			if(o == OASDIV || o == OASMOD)
				gins(typechl[l->type->etype]? ACDQ: ACQO, Z, Z);
			if(o == OASLDIV || o == OASLMOD)
				zeroregm(&nod1);
			if(r->addable < INDEXED || r->op == OCONST ||
			   !typeil[r->type->etype]) {
				regalloc(&nod3, r, Z);
				cgen(r, &nod3);
				gopcode(o, l->type, &nod3, Z);
				regfree(&nod3);
			} else
				gopcode(o, n->type, r, Z);
		} else {
			regalloc(&nod3, r, Z);
			cgen(r, &nod3);
			if(hardleft)
				reglcgen(&nod2, l, Z);
			else
				nod2 = *l;
			cgen(&nod2, &nod);
			if(o == OASDIV || o == OASMOD)
				gins(typechl[l->type->etype]? ACDQ: ACQO, Z, Z);
			if(o == OASLDIV || o == OASLMOD)
				zeroregm(&nod1);
			gopcode(o, l->type, &nod3, Z);
			regfree(&nod3);
		}
		if(o == OASMOD || o == OASLMOD) {
			gmove(&nod1, &nod2);
			if(nn != Z)
				gmove(&nod1, nn);
		} else {
			gmove(&nod, &nod2);
			if(nn != Z)
				gmove(&nod, nn);
		}
	freelxaxdx:
		if(hardleft)
			regfree(&nod2);
		regfree(&nod);
		regfree(&nod1);
		break;

	fop:
		if(l->complex >= r->complex) {
			regalloc(&nod, l, nn);
			cgen(l, &nod);
			if(r->addable < INDEXED) {
				regalloc(&nod1, r, Z);
				cgen(r, &nod1);
				gopcode(o, n->type, &nod1, &nod);
				regfree(&nod1);
			} else
				gopcode(o, n->type, r, &nod);
		} else {
			/* TO DO: could do better with r->addable >= INDEXED */
			regalloc(&nod1, r, Z);
			cgen(r, &nod1);
			regalloc(&nod, l, nn);
			cgen(l, &nod);
			gopcode(o, n->type, &nod1, &nod);
			regfree(&nod1);
		}
		gmove(&nod, nn);
		regfree(&nod);
		break;

	asbitop:
		regalloc(&nod4, n, nn);
		if(l->complex >= r->complex) {
			bitload(l, &nod, &nod1, &nod2, &nod4);
			regalloc(&nod3, r, Z);
			cgen(r, &nod3);
		} else {
			regalloc(&nod3, r, Z);
			cgen(r, &nod3);
			bitload(l, &nod, &nod1, &nod2, &nod4);
		}
		gmove(&nod, &nod4);

		{	/* TO DO: check floating point source */
			Node onod;

			/* incredible grot ... */
			onod = nod3;
			onod.op = o;
			onod.complex = 2;
			onod.addable = 0;
			onod.type = tfield;
			onod.left = &nod4;
			onod.right = &nod3;
			cgen(&onod, Z);
		}
		regfree(&nod3);
		gmove(&nod4, &nod);
		regfree(&nod4);
		bitstore(l, &nod, &nod1, &nod2, nn);
		break;

	case OADDR:
		if(nn == Z) {
			nullwarn(l, Z);
			break;
		}
		lcgen(l, nn);
		break;

	case OFUNC:
		if(l->complex >= FNX) {
			if(l->op != OIND)
				diag(n, "bad function call");

			regret(&nod, l->left, 0, 0);
			cgen(l->left, &nod);
			regsalloc(&nod1, l->left);
			gmove(&nod, &nod1);
			regfree(&nod);

			nod = *n;
			nod.left = &nod2;
			nod2 = *l;
			nod2.left = &nod1;
			nod2.complex = 1;
			cgen(&nod, nn);

			return;
		}
		gargs(r, &nod, &nod1);
		if(l->addable < INDEXED) {
			reglcgen(&nod, l, nn);
			nod.op = OREGISTER;
			gopcode(OFUNC, n->type, Z, &nod);
			regfree(&nod);
		} else
			gopcode(OFUNC, n->type, Z, l);
		if(REGARG >= 0 && reg[REGARG])
			reg[REGARG]--;
		regret(&nod, n, l->type, 1); // update maxarg if nothing else
		if(nn != Z)
			gmove(&nod, nn);
		if(nod.op == OREGISTER)
			regfree(&nod);
		break;

	case OIND:
		if(nn == Z) {
			nullwarn(l, Z);
			break;
		}
		regialloc(&nod, n, nn);
		r = l;
		while(r->op == OADD)
			r = r->right;
		if(sconst(r)) {
			v = r->vconst;
			r->vconst = 0;
			cgen(l, &nod);
			nod.xoffset += v;
			r->vconst = v;
		} else
			cgen(l, &nod);
		regind(&nod, n);
		gmove(&nod, nn);
		regfree(&nod);
		break;

	case OEQ:
	case ONE:
	case OLE:
	case OLT:
	case OGE:
	case OGT:
	case OLO:
	case OLS:
	case OHI:
	case OHS:
		if(nn == Z) {
			nullwarn(l, r);
			break;
		}
		boolgen(n, 1, nn);
		break;

	case OANDAND:
	case OOROR:
		boolgen(n, 1, nn);
		if(nn == Z)
			patch(p, pc);
		break;

	case ONOT:
		if(nn == Z) {
			nullwarn(l, Z);
			break;
		}
		boolgen(n, 1, nn);
		break;

	case OCOMMA:
		cgen(l, Z);
		cgen(r, nn);
		break;

	case OCAST:
		if(nn == Z) {
			nullwarn(l, Z);
			break;
		}
		/*
		 * convert from types l->n->nn
		 */
		if(nocast(l->type, n->type) && nocast(n->type, nn->type)) {
			/* both null, gen l->nn */
			cgen(l, nn);
			break;
		}
		if(ewidth[n->type->etype] < ewidth[l->type->etype]){
			if(l->type->etype == TIND && typechlp[n->type->etype])
				warn(n, "conversion of pointer to shorter integer");
		}else if(0){
			if(nocast(n->type, nn->type) || castup(n->type, nn->type)){
				if(typefd[l->type->etype] != typefd[nn->type->etype])
					regalloc(&nod, l, nn);
				else
					regalloc(&nod, nn, nn);
				cgen(l, &nod);
				gmove(&nod, nn);
				regfree(&nod);
				break;
			}
		}
		regalloc(&nod, l, nn);
		cgen(l, &nod);
		regalloc(&nod1, n, &nod);
		gmove(&nod, &nod1);
		gmove(&nod1, nn);
		regfree(&nod1);
		regfree(&nod);
		break;

	case ODOT:
		sugen(l, nodrat, l->type->width);
		if(nn == Z)
			break;
		warn(n, "non-interruptable temporary");
		nod = *nodrat;
		if(!r || r->op != OCONST) {
			diag(n, "DOT and no offset");
			break;
		}
		nod.xoffset += (int32)r->vconst;
		nod.type = n->type;
		cgen(&nod, nn);
		break;

	case OCOND:
		bcgen(l, 1);
		p1 = p;
		cgen(r->left, nn);
		gbranch(OGOTO);
		patch(p1, pc);
		p1 = p;
		cgen(r->right, nn);
		patch(p1, pc);
		break;

	case OPOSTINC:
	case OPOSTDEC:
		v = 1;
		if(l->type->etype == TIND)
			v = l->type->link->width;
		if(o == OPOSTDEC)
			v = -v;
		if(l->op == OBIT)
			goto bitinc;
		if(nn == Z)
			goto pre;

		if(hardleft)
			reglcgen(&nod, l, Z);
		else
			nod = *l;

		gmove(&nod, nn);
		if(typefd[n->type->etype]) {
			regalloc(&nod1, l, Z);
			gmove(&nod, &nod1);
			if(v < 0)
				gopcode(OSUB, n->type, nodfconst(-v), &nod1);
			else
				gopcode(OADD, n->type, nodfconst(v), &nod1);
			gmove(&nod1, &nod);
			regfree(&nod1);
		} else
			gopcode(OADD, n->type, nodconst(v), &nod);
		if(hardleft)
			regfree(&nod);
		break;

	case OPREINC:
	case OPREDEC:
		v = 1;
		if(l->type->etype == TIND)
			v = l->type->link->width;
		if(o == OPREDEC)
			v = -v;
		if(l->op == OBIT)
			goto bitinc;

	pre:
		if(hardleft)
			reglcgen(&nod, l, Z);
		else
			nod = *l;
		if(typefd[n->type->etype]) {
			regalloc(&nod1, l, Z);
			gmove(&nod, &nod1);
			if(v < 0)
				gopcode(OSUB, n->type, nodfconst(-v), &nod1);
			else
				gopcode(OADD, n->type, nodfconst(v), &nod1);
			gmove(&nod1, &nod);
			regfree(&nod1);
		} else
			gopcode(OADD, n->type, nodconst(v), &nod);
		if(nn != Z)
			gmove(&nod, nn);
		if(hardleft)
			regfree(&nod);
		break;

	bitinc:
		if(nn != Z && (o == OPOSTINC || o == OPOSTDEC)) {
			bitload(l, &nod, &nod1, &nod2, Z);
			gmove(&nod, nn);
			gopcode(OADD, tfield, nodconst(v), &nod);
			bitstore(l, &nod, &nod1, &nod2, Z);
			break;
		}
		bitload(l, &nod, &nod1, &nod2, nn);
		gopcode(OADD, tfield, nodconst(v), &nod);
		bitstore(l, &nod, &nod1, &nod2, nn);
		break;
	}
done:
	cursafe = curs;
}

void
reglcgen(Node *t, Node *n, Node *nn)
{
	Node *r;
	int32 v;

	regialloc(t, n, nn);
	if(n->op == OIND) {
		r = n->left;
		while(r->op == OADD)
			r = r->right;
		if(sconst(r)) {
			v = r->vconst;
			r->vconst = 0;
			lcgen(n, t);
			t->xoffset += v;
			r->vconst = v;
			regind(t, n);
			return;
		}
	}
	lcgen(n, t);
	regind(t, n);
}

void
lcgen(Node *n, Node *nn)
{
	Prog *p1;
	Node nod;

	if(debug['g']) {
		prtree(nn, "lcgen lhs");
		prtree(n, "lcgen");
	}
	if(n == Z || n->type == T)
		return;
	if(nn == Z) {
		nn = &nod;
		regalloc(&nod, n, Z);
	}
	switch(n->op) {
	default:
		if(n->addable < INDEXED) {
			diag(n, "unknown op in lcgen: %O", n->op);
			break;
		}
		gopcode(OADDR, n->type, n, nn);
		break;

	case OCOMMA:
		cgen(n->left, n->left);
		lcgen(n->right, nn);
		break;

	case OIND:
		cgen(n->left, nn);
		break;

	case OCOND:
		bcgen(n->left, 1);
		p1 = p;
		lcgen(n->right->left, nn);
		gbranch(OGOTO);
		patch(p1, pc);
		p1 = p;
		lcgen(n->right->right, nn);
		patch(p1, pc);
		break;
	}
}

void
bcgen(Node *n, int true)
{

	if(n->type == T)
		gbranch(OGOTO);
	else
		boolgen(n, true, Z);
}

void
boolgen(Node *n, int true, Node *nn)
{
	int o;
	Prog *p1, *p2, *p3;
	Node *l, *r, nod, nod1;
	int32 curs;

	if(debug['g']) {
		print("boolgen %d\n", true);
		prtree(nn, "boolgen lhs");
		prtree(n, "boolgen");
	}
	curs = cursafe;
	l = n->left;
	r = n->right;
	switch(n->op) {

	default:
		o = ONE;
		if(true)
			o = OEQ;
		/* bad, 13 is address of external that becomes constant */
		if(n->addable >= INDEXED && n->addable != 13) {
			if(typefd[n->type->etype]) {
				regalloc(&nod1, n, Z);
				gmove(nodfconst(0.0), &nod1);	/* TO DO: FREGZERO */
				gopcode(o, n->type, n, &nod1);
				regfree(&nod1);
			} else
				gopcode(o, n->type, n, nodconst(0));
			goto com;
		}
		regalloc(&nod, n, nn);
		cgen(n, &nod);
		if(typefd[n->type->etype]) {
			regalloc(&nod1, n, Z);
			gmove(nodfconst(0.0), &nod1);	/* TO DO: FREGZERO */
			gopcode(o, n->type, &nod, &nod1);
			regfree(&nod1);
		} else
			gopcode(o, n->type, &nod, nodconst(0));
		regfree(&nod);
		goto com;

	case OCONST:
		o = vconst(n);
		if(!true)
			o = !o;
		gbranch(OGOTO);
		if(o) {
			p1 = p;
			gbranch(OGOTO);
			patch(p1, pc);
		}
		goto com;

	case OCOMMA:
		cgen(l, Z);
		boolgen(r, true, nn);
		break;

	case ONOT:
		boolgen(l, !true, nn);
		break;

	case OCOND:
		bcgen(l, 1);
		p1 = p;
		bcgen(r->left, true);
		p2 = p;
		gbranch(OGOTO);
		patch(p1, pc);
		p1 = p;
		bcgen(r->right, !true);
		patch(p2, pc);
		p2 = p;
		gbranch(OGOTO);
		patch(p1, pc);
		patch(p2, pc);
		goto com;

	case OANDAND:
		if(!true)
			goto caseor;

	caseand:
		bcgen(l, true);
		p1 = p;
		bcgen(r, !true);
		p2 = p;
		patch(p1, pc);
		gbranch(OGOTO);
		patch(p2, pc);
		goto com;

	case OOROR:
		if(!true)
			goto caseand;

	caseor:
		bcgen(l, !true);
		p1 = p;
		bcgen(r, !true);
		p2 = p;
		gbranch(OGOTO);
		patch(p1, pc);
		patch(p2, pc);
		goto com;

	case OEQ:
	case ONE:
	case OLE:
	case OLT:
	case OGE:
	case OGT:
	case OHI:
	case OHS:
	case OLO:
	case OLS:
		o = n->op;
		if(true && typefd[l->type->etype] && (o == OEQ || o == ONE)) {
			// Cannot rewrite !(l == r) into l != r with float64; it breaks NaNs.
			// Jump around instead.
			boolgen(n, 0, Z);
			p1 = p;
			gbranch(OGOTO);
			patch(p1, pc);
			goto com;
		}
		if(true)
			o = comrel[relindex(o)];
		if(l->complex >= FNX && r->complex >= FNX) {
			regret(&nod, r, 0, 0);
			cgen(r, &nod);
			regsalloc(&nod1, r);
			gmove(&nod, &nod1);
			regfree(&nod);
			nod = *n;
			nod.right = &nod1;
			boolgen(&nod, true, nn);
			break;
		}
		if(immconst(l)) {
			// NOTE: Reversing the comparison here is wrong
			// for floating point ordering comparisons involving NaN,
			// but we don't have any of those yet so we don't
			// bother worrying about it.
			o = invrel[relindex(o)];
			/* bad, 13 is address of external that becomes constant */
			if(r->addable < INDEXED || r->addable == 13) {
				regalloc(&nod, r, nn);
				cgen(r, &nod);
				gopcode(o, l->type, &nod, l);
				regfree(&nod);
			} else
				gopcode(o, l->type, r, l);
			goto com;
		}
		if(typefd[l->type->etype])
			o = invrel[relindex(logrel[relindex(o)])];
		if(l->complex >= r->complex) {
			regalloc(&nod, l, nn);
			cgen(l, &nod);
			if(r->addable < INDEXED || hardconst(r) || typefd[l->type->etype]) {
				regalloc(&nod1, r, Z);
				cgen(r, &nod1);
				gopcode(o, l->type, &nod, &nod1);
				regfree(&nod1);
			} else {
				gopcode(o, l->type, &nod, r);
			}
			regfree(&nod);
			goto fixfloat;
		}
		regalloc(&nod, r, nn);
		cgen(r, &nod);
		if(l->addable < INDEXED || l->addable == 13 || hardconst(l)) {
			regalloc(&nod1, l, Z);
			cgen(l, &nod1);
			if(typechl[l->type->etype] && ewidth[l->type->etype] <= ewidth[TINT])
				gopcode(o, types[TINT], &nod1, &nod);
			else
				gopcode(o, l->type, &nod1, &nod);
			regfree(&nod1);
		} else
			gopcode(o, l->type, l, &nod);
		regfree(&nod);
	fixfloat:
		if(typefd[l->type->etype]) {
			switch(o) {
			case OEQ:
				// Already emitted AJEQ; want AJEQ and AJPC.
				p1 = p;
				gbranch(OGOTO);
				p2 = p;
				patch(p1, pc);
				gins(AJPC, Z, Z);
				patch(p2, pc);
				break;

			case ONE:
				// Already emitted AJNE; want AJNE or AJPS.
				p1 = p;
				gins(AJPS, Z, Z);
				p2 = p;
				gbranch(OGOTO);
				p3 = p;
				patch(p1, pc);
				patch(p2, pc);
				gbranch(OGOTO);
				patch(p3, pc);
				break;
			}
		}

	com:
		if(nn != Z) {
			p1 = p;
			gmove(nodconst(1L), nn);
			gbranch(OGOTO);
			p2 = p;
			patch(p1, pc);
			gmove(nodconst(0L), nn);
			patch(p2, pc);
		}
		break;
	}
	cursafe = curs;
}

void
sugen(Node *n, Node *nn, int32 w)
{
	Prog *p1;
	Node nod0, nod1, nod2, nod3, nod4, *l, *r;
	Type *t;
	int c, mt, mo;
	vlong o0, o1;

	if(n == Z || n->type == T)
		return;
	if(debug['g']) {
		prtree(nn, "sugen lhs");
		prtree(n, "sugen");
	}
	if(nn == nodrat)
		if(w > nrathole)
			nrathole = w;
	switch(n->op) {
	case OIND:
		if(nn == Z) {
			nullwarn(n->left, Z);
			break;
		}

	default:
		goto copy;

	case OCONST:
		goto copy;

	case ODOT:
		l = n->left;
		sugen(l, nodrat, l->type->width);
		if(nn == Z)
			break;
		warn(n, "non-interruptable temporary");
		nod1 = *nodrat;
		r = n->right;
		if(!r || r->op != OCONST) {
			diag(n, "DOT and no offset");
			break;
		}
		nod1.xoffset += (int32)r->vconst;
		nod1.type = n->type;
		sugen(&nod1, nn, w);
		break;

	case OSTRUCT:
		/*
		 * rewrite so lhs has no fn call
		 */
		if(nn != Z && side(nn)) {
			nod1 = *n;
			nod1.type = typ(TIND, n->type);
			regret(&nod2, &nod1, 0, 0);
			lcgen(nn, &nod2);
			regsalloc(&nod0, &nod1);
			cgen(&nod2, &nod0);
			regfree(&nod2);

			nod1 = *n;
			nod1.op = OIND;
			nod1.left = &nod0;
			nod1.right = Z;
			nod1.complex = 1;

			sugen(n, &nod1, w);
			return;
		}

		r = n->left;
		for(t = n->type->link; t != T; t = t->down) {
			l = r;
			if(r->op == OLIST) {
				l = r->left;
				r = r->right;
			}
			if(nn == Z) {
				cgen(l, nn);
				continue;
			}
			/*
			 * hand craft *(&nn + o) = l
			 */
			nod0 = znode;
			nod0.op = OAS;
			nod0.type = t;
			nod0.left = &nod1;
			nod0.right = nil;

			nod1 = znode;
			nod1.op = OIND;
			nod1.type = t;
			nod1.left = &nod2;

			nod2 = znode;
			nod2.op = OADD;
			nod2.type = typ(TIND, t);
			nod2.left = &nod3;
			nod2.right = &nod4;

			nod3 = znode;
			nod3.op = OADDR;
			nod3.type = nod2.type;
			nod3.left = nn;

			nod4 = znode;
			nod4.op = OCONST;
			nod4.type = nod2.type;
			nod4.vconst = t->offset;

			ccom(&nod0);
			acom(&nod0);
			xcom(&nod0);
			nod0.addable = 0;
			nod0.right = l;

			// prtree(&nod0, "hand craft");
			cgen(&nod0, Z);
		}
		break;

	case OAS:
		if(nn == Z) {
			if(n->addable < INDEXED)
				sugen(n->right, n->left, w);
			break;
		}

		sugen(n->right, nodrat, w);
		warn(n, "non-interruptable temporary");
		sugen(nodrat, n->left, w);
		sugen(nodrat, nn, w);
		break;

	case OFUNC:
		if(!hasdotdotdot(n->left->type)) {
			cgen(n, Z);
			if(nn != Z) {
				curarg -= n->type->width;
				regret(&nod1, n, n->left->type, 1);
				if(nn->complex >= FNX) {
					regsalloc(&nod2, n);
					cgen(&nod1, &nod2);
					nod1 = nod2;
				}
				cgen(&nod1, nn);
			}
			break;
		}
		if(nn == Z) {
			sugen(n, nodrat, w);
			break;
		}
		if(nn->op != OIND) {
			nn = new1(OADDR, nn, Z);
			nn->type = types[TIND];
			nn->addable = 0;
		} else
			nn = nn->left;
		n = new(OFUNC, n->left, new(OLIST, nn, n->right));
		n->type = types[TVOID];
		n->left->type = types[TVOID];
		cgen(n, Z);
		break;

	case OCOND:
		bcgen(n->left, 1);
		p1 = p;
		sugen(n->right->left, nn, w);
		gbranch(OGOTO);
		patch(p1, pc);
		p1 = p;
		sugen(n->right->right, nn, w);
		patch(p1, pc);
		break;

	case OCOMMA:
		cgen(n->left, Z);
		sugen(n->right, nn, w);
		break;
	}
	return;

copy:
	if(nn == Z) {
		switch(n->op) {
		case OASADD:
		case OASSUB:
		case OASAND:
		case OASOR:
		case OASXOR:

		case OASMUL:
		case OASLMUL:


		case OASASHL:
		case OASASHR:
		case OASLSHR:
			break;

		case OPOSTINC:
		case OPOSTDEC:
		case OPREINC:
		case OPREDEC:
			break;

		default:
			return;
		}
	}

	if(n->complex >= FNX && nn != nil && nn->complex >= FNX) {
		t = nn->type;
		nn->type = types[TIND];
		regialloc(&nod1, nn, Z);
		lcgen(nn, &nod1);
		regsalloc(&nod2, nn);
		nn->type = t;

		gins(AMOVQ, &nod1, &nod2);
		regfree(&nod1);

		nod2.type = typ(TIND, t);

		nod1 = nod2;
		nod1.op = OIND;
		nod1.left = &nod2;
		nod1.right = Z;
		nod1.complex = 1;
		nod1.type = t;

		sugen(n, &nod1, w);
		return;
	}

	if(w <= 32) {
		c = cursafe;
		if(n->left != Z && n->left->complex >= FNX
		&& n->right != Z && n->right->complex >= FNX) {
			regsalloc(&nod1, n->right);
			cgen(n->right, &nod1);
			nod2 = *n;
			nod2.right = &nod1;
			cgen(&nod2, nn);
			cursafe = c;
			return;
		}
		if(w & 7) {
			mt = TLONG;
			mo = AMOVL;
		} else {
			mt = TVLONG;
			mo = AMOVQ;
		}
		if(n->complex > nn->complex) {
			t = n->type;
			n->type = types[mt];
			regalloc(&nod0, n, Z);
			if(!vaddr(n, 0)) {
				reglcgen(&nod1, n, Z);
				n->type = t;
				n = &nod1;
			}
			else
				n->type = t;

			t = nn->type;
			nn->type = types[mt];
			if(!vaddr(nn, 0)) {
				reglcgen(&nod2, nn, Z);
				nn->type = t;
				nn = &nod2;
			}
			else
				nn->type = t;
		} else {
			t = nn->type;
			nn->type = types[mt];
			regalloc(&nod0, nn, Z);
			if(!vaddr(nn, 0)) {
				reglcgen(&nod2, nn, Z);
				nn->type = t;
				nn = &nod2;
			}
			else
				nn->type = t;

			t = n->type;
			n->type = types[mt];
			if(!vaddr(n, 0)) {
				reglcgen(&nod1, n, Z);
				n->type = t;
				n = &nod1;
			}
			else
				n->type = t;
		}
		o0 = n->xoffset;
		o1 = nn->xoffset;
		w /= ewidth[mt];
		while(--w >= 0) {
			gins(mo, n, &nod0);
			gins(mo, &nod0, nn);
			n->xoffset += ewidth[mt];
			nn->xoffset += ewidth[mt];
		}
		n->xoffset = o0;
		nn->xoffset = o1;
		if(nn == &nod2)
			regfree(&nod2);
		if(n == &nod1)
			regfree(&nod1);
		regfree(&nod0);
		return;
	}

	/* botch, need to save in .safe */
	c = 0;
	if(n->complex > nn->complex) {
		t = n->type;
		n->type = types[TIND];
		nodreg(&nod1, n, D_SI);
		if(reg[D_SI]) {
			gins(APUSHQ, &nod1, Z);
			c |= 1;
			reg[D_SI]++;
		}
		lcgen(n, &nod1);
		n->type = t;

		t = nn->type;
		nn->type = types[TIND];
		nodreg(&nod2, nn, D_DI);
		if(reg[D_DI]) {
warn(Z, "DI botch");
			gins(APUSHQ, &nod2, Z);
			c |= 2;
			reg[D_DI]++;
		}
		lcgen(nn, &nod2);
		nn->type = t;
	} else {
		t = nn->type;
		nn->type = types[TIND];
		nodreg(&nod2, nn, D_DI);
		if(reg[D_DI]) {
warn(Z, "DI botch");
			gins(APUSHQ, &nod2, Z);
			c |= 2;
			reg[D_DI]++;
		}
		lcgen(nn, &nod2);
		nn->type = t;

		t = n->type;
		n->type = types[TIND];
		nodreg(&nod1, n, D_SI);
		if(reg[D_SI]) {
			gins(APUSHQ, &nod1, Z);
			c |= 1;
			reg[D_SI]++;
		}
		lcgen(n, &nod1);
		n->type = t;
	}
	nodreg(&nod3, n, D_CX);
	if(reg[D_CX]) {
		gins(APUSHQ, &nod3, Z);
		c |= 4;
		reg[D_CX]++;
	}
	gins(AMOVL, nodconst(w/SZ_INT), &nod3);
	gins(ACLD, Z, Z);
	gins(AREP, Z, Z);
	gins(AMOVSL, Z, Z);
	if(c & 4) {
		gins(APOPQ, Z, &nod3);
		reg[D_CX]--;
	}
	if(c & 2) {
		gins(APOPQ, Z, &nod2);
		reg[nod2.reg]--;
	}
	if(c & 1) {
		gins(APOPQ, Z, &nod1);
		reg[nod1.reg]--;
	}
}

/*
 * TO DO
 */
void
layout(Node *f, Node *t, int c, int cv, Node *cn)
{
	Node t1, t2;

	while(c > 3) {
		layout(f, t, 2, 0, Z);
		c -= 2;
	}

	regalloc(&t1, &lregnode, Z);
	regalloc(&t2, &lregnode, Z);
	if(c > 0) {
		gmove(f, &t1);
		f->xoffset += SZ_INT;
	}
	if(cn != Z)
		gmove(nodconst(cv), cn);
	if(c > 1) {
		gmove(f, &t2);
		f->xoffset += SZ_INT;
	}
	if(c > 0) {
		gmove(&t1, t);
		t->xoffset += SZ_INT;
	}
	if(c > 2) {
		gmove(f, &t1);
		f->xoffset += SZ_INT;
	}
	if(c > 1) {
		gmove(&t2, t);
		t->xoffset += SZ_INT;
	}
	if(c > 2) {
		gmove(&t1, t);
		t->xoffset += SZ_INT;
	}
	regfree(&t1);
	regfree(&t2);
}

/*
 * constant is not vlong or fits as 32-bit signed immediate
 */
int
immconst(Node *n)
{
	int32 v;

	if(n->op != OCONST || !typechlpv[n->type->etype])
		return 0;
	if(typechl[n->type->etype])
		return 1;
	v = n->vconst;
	return n->vconst == (vlong)v;
}

/*
 * if a constant and vlong, doesn't fit as 32-bit signed immediate
 */
int
hardconst(Node *n)
{
	return n->op == OCONST && !immconst(n);
}

/*
 * casting up to t2 covers an intermediate cast to t1
 */
int
castup(Type *t1, Type *t2)
{
	int ft;

	if(!nilcast(t1, t2))
		return 0;
	/* known to be small to large */
	ft = t1->etype;
	switch(t2->etype){
	case TINT:
	case TLONG:
		return ft == TLONG || ft == TINT || ft == TSHORT || ft == TCHAR;
	case TUINT:
	case TULONG:
		return ft == TULONG || ft == TUINT || ft == TUSHORT || ft == TUCHAR;
	case TVLONG:
		return ft == TLONG || ft == TINT || ft == TSHORT;
	case TUVLONG:
		return ft == TULONG || ft == TUINT || ft == TUSHORT;
	}
	return 0;
}

void
zeroregm(Node *n)
{
	gins(AMOVL, nodconst(0), n);
}

/* do we need to load the address of a vlong? */
int
vaddr(Node *n, int a)
{
	switch(n->op) {
	case ONAME:
		if(a)
			return 1;
		return !(n->class == CEXTERN || n->class == CGLOBL || n->class == CSTATIC);

	case OCONST:
	case OREGISTER:
	case OINDREG:
		return 1;
	}
	return 0;
}

int32
hi64v(Node *n)
{
	if(align(0, types[TCHAR], Aarg1, nil))	/* isbigendian */
		return (int32)(n->vconst) & ~0L;
	else
		return (int32)((uvlong)n->vconst>>32) & ~0L;
}

int32
lo64v(Node *n)
{
	if(align(0, types[TCHAR], Aarg1, nil))	/* isbigendian */
		return (int32)((uvlong)n->vconst>>32) & ~0L;
	else
		return (int32)(n->vconst) & ~0L;
}

Node *
hi64(Node *n)
{
	return nodconst(hi64v(n));
}

Node *
lo64(Node *n)
{
	return nodconst(lo64v(n));
}

int
cond(int op)
{
	switch(op) {
	case OANDAND:
	case OOROR:
	case ONOT:
		return 1;

	case OEQ:
	case ONE:
	case OLE:
	case OLT:
	case OGE:
	case OGT:
	case OHI:
	case OHS:
	case OLO:
	case OLS:
		return 1;
	}
	return 0;
}