sub.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

	TIND,		0,	"IND",
	TFUNC,		0,	"FUNC",
	TARRAY,		0,	"ARRAY",
	TVOID,		0,	"VOID",
	TSTRUCT,	0,	"STRUCT",
	TUNION,		0,	"UNION",
	TENUM,		0,	"ENUM",

	TAUTO,		0,	"AUTO",
	TEXTERN,	0,	"EXTERN",
	TSTATIC,	0,	"STATIC",
	TTYPEDEF,	0,	"TYPEDEF",
	TTYPESTR,	0,	"TYPESTR",
	TREGISTER,	0,	"REGISTER",
	TCONSTNT,	0,	"CONSTNT",
	TVOLATILE,	0,	"VOLATILE",
	TUNSIGNED,	0,	"UNSIGNED",
	TSIGNED,	0,	"SIGNED",
	TDOT,		0,	"DOT",
	TFILE,		0,	"FILE",
	TOLD,		0,	"OLD",
	-1,		0,	0,
};
char*	cnames[NCTYPES];
Init	cnamesinit[] =
{
	CXXX,		0,	"CXXX",
	CAUTO,		0,	"AUTO",
	CEXTERN,	0,	"EXTERN",
	CGLOBL,		0,	"GLOBL",
	CSTATIC,	0,	"STATIC",
	CLOCAL,		0,	"LOCAL",
	CTYPEDEF,	0,	"TYPEDEF",
	CTYPESTR,	0,	"TYPESTR",
	CPARAM,		0,	"PARAM",
	CSELEM,		0,	"SELEM",
	CLABEL,		0,	"LABEL",
	CEXREG,		0,	"EXREG",
	-1,		0,	0,
};

char*	onames[OEND+1];
Init	onamesinit[] =
{
	OXXX,		0,	"OXXX",
	OADD,		0,	"ADD",
	OADDR,		0,	"ADDR",
	OAND,		0,	"AND",
	OANDAND,	0,	"ANDAND",
	OARRAY,		0,	"ARRAY",
	OAS,		0,	"AS",
	OASI,		0,	"ASI",
	OASADD,		0,	"ASADD",
	OASAND,		0,	"ASAND",
	OASASHL,	0,	"ASASHL",
	OASASHR,	0,	"ASASHR",
	OASDIV,		0,	"ASDIV",
	OASHL,		0,	"ASHL",
	OASHR,		0,	"ASHR",
	OASLDIV,	0,	"ASLDIV",
	OASLMOD,	0,	"ASLMOD",
	OASLMUL,	0,	"ASLMUL",
	OASLSHR,	0,	"ASLSHR",
	OASMOD,		0,	"ASMOD",
	OASMUL,		0,	"ASMUL",
	OASOR,		0,	"ASOR",
	OASSUB,		0,	"ASSUB",
	OASXOR,		0,	"ASXOR",
	OBIT,		0,	"BIT",
	OBREAK,		0,	"BREAK",
	OCASE,		0,	"CASE",
	OCAST,		0,	"CAST",
	OCOMMA,		0,	"COMMA",
	OCOND,		0,	"COND",
	OCONST,		0,	"CONST",
	OCONTINUE,	0,	"CONTINUE",
	ODIV,		0,	"DIV",
	ODOT,		0,	"DOT",
	ODOTDOT,	0,	"DOTDOT",
	ODWHILE,	0,	"DWHILE",
	OENUM,		0,	"ENUM",
	OEQ,		0,	"EQ",
	OFOR,		0,	"FOR",
	OFUNC,		0,	"FUNC",
	OGE,		0,	"GE",
	OGOTO,		0,	"GOTO",
	OGT,		0,	"GT",
	OHI,		0,	"HI",
	OHS,		0,	"HS",
	OIF,		0,	"IF",
	OIND,		0,	"IND",
	OINDREG,	0,	"INDREG",
	OINIT,		0,	"INIT",
	OLABEL,		0,	"LABEL",
	OLDIV,		0,	"LDIV",
	OLE,		0,	"LE",
	OLIST,		0,	"LIST",
	OLMOD,		0,	"LMOD",
	OLMUL,		0,	"LMUL",
	OLO,		0,	"LO",
	OLS,		0,	"LS",
	OLSHR,		0,	"LSHR",
	OLT,		0,	"LT",
	OMOD,		0,	"MOD",
	OMUL,		0,	"MUL",
	ONAME,		0,	"NAME",
	ONE,		0,	"NE",
	ONOT,		0,	"NOT",
	OOR,		0,	"OR",
	OOROR,		0,	"OROR",
	OPOSTDEC,	0,	"POSTDEC",
	OPOSTINC,	0,	"POSTINC",
	OPREDEC,	0,	"PREDEC",
	OPREINC,	0,	"PREINC",
	OPROTO,		0,	"PROTO",
	OREGISTER,	0,	"REGISTER",
	ORETURN,	0,	"RETURN",
	OSET,		0,	"SET",
	OSIGN,		0,	"SIGN",
	OSIZE,		0,	"SIZE",
	OSTRING,	0,	"STRING",
	OLSTRING,	0,	"LSTRING",
	OSTRUCT,	0,	"STRUCT",
	OSUB,		0,	"SUB",
	OSWITCH,	0,	"SWITCH",
	OUNION,		0,	"UNION",
	OUSED,		0,	"USED",
	OWHILE,		0,	"WHILE",
	OXOR,		0,	"XOR",
	OPOS,		0,	"POS",
	ONEG,		0,	"NEG",
	OCOM,		0,	"COM",
	OELEM,		0,	"ELEM",
	OTST,		0,	"TST",
	OINDEX,		0,	"INDEX",
	OFAS,		0,	"FAS",
	OREGPAIR,	0,	"REGPAIR",
	OEND,		0,	"END",
	-1,		0,	0,
};

/*	OEQ, ONE, OLE, OLS, OLT, OLO, OGE, OHS, OGT, OHI */
char	comrel[12] =
{
	ONE, OEQ, OGT, OHI, OGE, OHS, OLT, OLO, OLE, OLS,
};
char	invrel[12] =
{
	OEQ, ONE, OGE, OHS, OGT, OHI, OLE, OLS, OLT, OLO,
};
char	logrel[12] =
{
	OEQ, ONE, OLS, OLS, OLO, OLO, OHS, OHS, OHI, OHI,
};

char	typei[NTYPE];
int	typeiinit[] =
{
	TCHAR, TUCHAR, TSHORT, TUSHORT, TINT, TUINT, TLONG, TULONG, TVLONG, TUVLONG, -1,
};
char	typeu[NTYPE];
int	typeuinit[] =
{
	TUCHAR, TUSHORT, TUINT, TULONG, TUVLONG, TIND, -1,
};

char	typesuv[NTYPE];
int	typesuvinit[] =
{
	TVLONG, TUVLONG, TSTRUCT, TUNION, -1,
};

char	typeilp[NTYPE];
int	typeilpinit[] =
{
	TINT, TUINT, TLONG, TULONG, TIND, -1
};

char	typechl[NTYPE];
char	typechlv[NTYPE];
char typechlvp[NTYPE];
int	typechlinit[] =
{
	TCHAR, TUCHAR, TSHORT, TUSHORT, TINT, TUINT, TLONG, TULONG, -1,
};

char	typechlp[NTYPE];
int	typechlpinit[] =
{
	TCHAR, TUCHAR, TSHORT, TUSHORT, TINT, TUINT, TLONG, TULONG, TIND, -1,
};

char	typechlpfd[NTYPE];
int	typechlpfdinit[] =
{
	TCHAR, TUCHAR, TSHORT, TUSHORT, TINT, TUINT, TLONG, TULONG, TFLOAT, TDOUBLE, TIND, -1,
};

char	typec[NTYPE];
int	typecinit[] =
{
	TCHAR, TUCHAR, -1
};

char	typeh[NTYPE];
int	typehinit[] =
{
	TSHORT, TUSHORT, -1,
};

char	typeil[NTYPE];
int	typeilinit[] =
{
	TINT, TUINT, TLONG, TULONG, -1,
};

char	typev[NTYPE];
int	typevinit[] =
{
	TVLONG,	TUVLONG, -1,
};

char	typefd[NTYPE];
int	typefdinit[] =
{
	TFLOAT, TDOUBLE, -1,
};

char	typeaf[NTYPE];
int	typeafinit[] =
{
	TFUNC, TARRAY, -1,
};

char	typesu[NTYPE];
int	typesuinit[] =
{
	TSTRUCT, TUNION, -1,
};

long	tasign[NTYPE];
Init	tasigninit[] =
{
	TCHAR,		BNUMBER,	0,
	TUCHAR,		BNUMBER,	0,
	TSHORT,		BNUMBER,	0,
	TUSHORT,	BNUMBER,	0,
	TINT,		BNUMBER,	0,
	TUINT,		BNUMBER,	0,
	TLONG,		BNUMBER,	0,
	TULONG,		BNUMBER,	0,
	TVLONG,		BNUMBER,	0,
	TUVLONG,	BNUMBER,	0,
	TFLOAT,		BNUMBER,	0,
	TDOUBLE,	BNUMBER,	0,
	TIND,		BIND,		0,
	TSTRUCT,	BSTRUCT,	0,
	TUNION,		BUNION,		0,
	-1,		0,		0,
};

long	tasadd[NTYPE];
Init	tasaddinit[] =
{
	TCHAR,		BNUMBER,	0,
	TUCHAR,		BNUMBER,	0,
	TSHORT,		BNUMBER,	0,
	TUSHORT,	BNUMBER,	0,
	TINT,		BNUMBER,	0,
	TUINT,		BNUMBER,	0,
	TLONG,		BNUMBER,	0,
	TULONG,		BNUMBER,	0,
	TVLONG,		BNUMBER,	0,
	TUVLONG,	BNUMBER,	0,
	TFLOAT,		BNUMBER,	0,
	TDOUBLE,	BNUMBER,	0,
	TIND,		BINTEGER,	0,
	-1,		0,		0,
};

long	tcast[NTYPE];
Init	tcastinit[] =
{
	TCHAR,		BNUMBER|BIND|BVOID,	0,
	TUCHAR,		BNUMBER|BIND|BVOID,	0,
	TSHORT,		BNUMBER|BIND|BVOID,	0,
	TUSHORT,	BNUMBER|BIND|BVOID,	0,
	TINT,		BNUMBER|BIND|BVOID,	0,
	TUINT,		BNUMBER|BIND|BVOID,	0,
	TLONG,		BNUMBER|BIND|BVOID,	0,
	TULONG,		BNUMBER|BIND|BVOID,	0,
	TVLONG,		BNUMBER|BIND|BVOID,	0,
	TUVLONG,	BNUMBER|BIND|BVOID,	0,
	TFLOAT,		BNUMBER|BVOID,		0,
	TDOUBLE,	BNUMBER|BVOID,		0,
	TIND,		BINTEGER|BIND|BVOID,	0,
	TVOID,		BVOID,			0,
	TSTRUCT,	BSTRUCT|BVOID,		0,
	TUNION,		BUNION|BVOID,		0,
	-1,		0,			0,
};

long	tadd[NTYPE];
Init	taddinit[] =
{
	TCHAR,		BNUMBER|BIND,	0,
	TUCHAR,		BNUMBER|BIND,	0,
	TSHORT,		BNUMBER|BIND,	0,
	TUSHORT,	BNUMBER|BIND,	0,
	TINT,		BNUMBER|BIND,	0,
	TUINT,		BNUMBER|BIND,	0,
	TLONG,		BNUMBER|BIND,	0,
	TULONG,		BNUMBER|BIND,	0,
	TVLONG,		BNUMBER|BIND,	0,
	TUVLONG,	BNUMBER|BIND,	0,
	TFLOAT,		BNUMBER,	0,
	TDOUBLE,	BNUMBER,	0,
	TIND,		BINTEGER,	0,
	-1,		0,		0,
};

long	tsub[NTYPE];
Init	tsubinit[] =
{
	TCHAR,		BNUMBER,	0,
	TUCHAR,		BNUMBER,	0,
	TSHORT,		BNUMBER,	0,
	TUSHORT,	BNUMBER,	0,
	TINT,		BNUMBER,	0,
	TUINT,		BNUMBER,	0,
	TLONG,		BNUMBER,	0,
	TULONG,		BNUMBER,	0,
	TVLONG,		BNUMBER,	0,
	TUVLONG,	BNUMBER,	0,
	TFLOAT,		BNUMBER,	0,
	TDOUBLE,	BNUMBER,	0,
	TIND,		BINTEGER|BIND,	0,
	-1,		0,		0,
};

long	tmul[NTYPE];
Init	tmulinit[] =
{
	TCHAR,		BNUMBER,	0,
	TUCHAR,		BNUMBER,	0,
	TSHORT,		BNUMBER,	0,
	TUSHORT,	BNUMBER,	0,
	TINT,		BNUMBER,	0,
	TUINT,		BNUMBER,	0,
	TLONG,		BNUMBER,	0,
	TULONG,		BNUMBER,	0,
	TVLONG,		BNUMBER,	0,
	TUVLONG,	BNUMBER,	0,
	TFLOAT,		BNUMBER,	0,
	TDOUBLE,	BNUMBER,	0,
	-1,		0,		0,
};

long	tand[NTYPE];
Init	tandinit[] =
{
	TCHAR,		BINTEGER,	0,
	TUCHAR,		BINTEGER,	0,
	TSHORT,		BINTEGER,	0,
	TUSHORT,	BINTEGER,	0,
	TINT,		BNUMBER,	0,
	TUINT,		BNUMBER,	0,
	TLONG,		BINTEGER,	0,
	TULONG,		BINTEGER,	0,
	TVLONG,		BINTEGER,	0,
	TUVLONG,	BINTEGER,	0,
	-1,		0,		0,
};

long	trel[NTYPE];
Init	trelinit[] =
{
	TCHAR,		BNUMBER,	0,
	TUCHAR,		BNUMBER,	0,
	TSHORT,		BNUMBER,	0,
	TUSHORT,	BNUMBER,	0,
	TINT,		BNUMBER,	0,
	TUINT,		BNUMBER,	0,
	TLONG,		BNUMBER,	0,
	TULONG,		BNUMBER,	0,
	TVLONG,		BNUMBER,	0,
	TUVLONG,	BNUMBER,	0,
	TFLOAT,		BNUMBER,	0,
	TDOUBLE,	BNUMBER,	0,
	TIND,		BIND,		0,
	-1,		0,		0,
};

long	tfunct[1] =
{
	BFUNC,
};

long	tindir[1] =
{
	BIND,
};

long	tdot[1] =
{
	BSTRUCT|BUNION,
};

long	tnot[1] =
{
	BNUMBER|BIND,
};

long	targ[1] =
{
	BNUMBER|BIND|BSTRUCT|BUNION,
};

char	tab[NTYPE][NTYPE] =
{
/*TXXX*/	{ 0,
		},

/*TCHAR*/	{ 0,	TCHAR, TUCHAR, TSHORT, TUSHORT, TINT, TUINT, TLONG,
			TULONG, TVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TUCHAR*/	{ 0,	TUCHAR, TUCHAR, TUSHORT, TUSHORT, TUINT, TUINT, TULONG,
			TULONG, TUVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TSHORT*/	{ 0,	TSHORT, TUSHORT, TSHORT, TUSHORT, TINT, TUINT, TLONG,
			TULONG, TVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TUSHORT*/	{ 0,	TUSHORT, TUSHORT, TUSHORT, TUSHORT, TUINT, TUINT, TULONG,
			TULONG, TUVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TINT*/	{ 0,	TINT, TUINT, TINT, TUINT, TINT, TUINT, TLONG,
			TULONG, TVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TUINT*/	{ 0,	TUINT, TUINT, TUINT, TUINT, TUINT, TUINT, TULONG,
			TULONG, TUVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TLONG*/	{ 0,	TLONG, TULONG, TLONG, TULONG, TLONG, TULONG, TLONG,
			TULONG, TVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TULONG*/	{ 0,	TULONG, TULONG, TULONG, TULONG, TULONG, TULONG, TULONG,
			TULONG, TUVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TVLONG*/	{ 0,	TVLONG, TUVLONG, TVLONG, TUVLONG, TVLONG, TUVLONG, TVLONG,
			TUVLONG, TVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TUVLONG*/	{ 0,	TUVLONG, TUVLONG, TUVLONG, TUVLONG, TUVLONG, TUVLONG, TUVLONG,
			TUVLONG, TUVLONG, TUVLONG, TFLOAT, TDOUBLE, TIND,
		},
/*TFLOAT*/	{ 0,	TFLOAT, TFLOAT, TFLOAT, TFLOAT, TFLOAT, TFLOAT, TFLOAT,
			TFLOAT, TFLOAT, TFLOAT, TFLOAT, TDOUBLE, TIND,
		},
/*TDOUBLE*/	{ 0,	TDOUBLE, TDOUBLE, TDOUBLE, TDOUBLE, TDOUBLE, TDOUBLE, TDOUBLE,
			TDOUBLE, TDOUBLE, TDOUBLE, TFLOAT, TDOUBLE, TIND,
		},
/*TIND*/	{ 0,	TIND, TIND, TIND, TIND, TIND, TIND, TIND,
			 TIND, TIND, TIND, TIND, TIND, TIND,
		},
};

void
urk(char *name, int max, int i)
{
	if(i >= max) {
		fprint(2, "bad tinit: %s %d>=%d\n", name, i, max);
		exits("init");
	}
}

void
tinit(void)
{
	int *ip;
	Init *p;

	for(p=thashinit; p->code >= 0; p++) {
		urk("thash", nelem(thash), p->code);
		thash[p->code] = p->value;
	}
	for(p=bnamesinit; p->code >= 0; p++) {
		urk("bnames", nelem(bnames), p->code);
		bnames[p->code] = p->s;
	}
	for(p=tnamesinit; p->code >= 0; p++) {
		urk("tnames", nelem(tnames), p->code);
		tnames[p->code] = p->s;
	}
	for(p=gnamesinit; p->code >= 0; p++) {
		urk("gnames", nelem(gnames), p->code);
		gnames[p->code] = p->s;
	}
	for(p=qnamesinit; p->code >= 0; p++) {
		urk("qnames", nelem(qnames), p->code);
		qnames[p->code] = p->s;
	}
	for(p=cnamesinit; p->code >= 0; p++) {
		urk("cnames", nelem(cnames), p->code);
		cnames[p->code] = p->s;
	}
	for(p=onamesinit; p->code >= 0; p++) {
		urk("onames", nelem(onames), p->code);
		onames[p->code] = p->s;
	}
	for(ip=typeiinit; *ip>=0; ip++) {
		urk("typei", nelem(typei), *ip);
		typei[*ip] = 1;
	}
	for(ip=typeuinit; *ip>=0; ip++) {
		urk("typeu", nelem(typeu), *ip);
		typeu[*ip] = 1;
	}
	for(ip=typesuvinit; *ip>=0; ip++) {
		urk("typesuv", nelem(typesuv), *ip);
		typesuv[*ip] = 1;
	}
	for(ip=typeilpinit; *ip>=0; ip++) {
		urk("typeilp", nelem(typeilp), *ip);
		typeilp[*ip] = 1;
	}
	for(ip=typechlinit; *ip>=0; ip++) {
		urk("typechl", nelem(typechl), *ip);
		typechl[*ip] = 1;
		typechlv[*ip] = 1;
		typechlvp[*ip] = 1;
	}
	for(ip=typechlpinit; *ip>=0; ip++) {
		urk("typechlp", nelem(typechlp), *ip);
		typechlp[*ip] = 1;
		typechlvp[*ip] = 1;
	}
	for(ip=typechlpfdinit; *ip>=0; ip++) {
		urk("typechlpfd", nelem(typechlpfd), *ip);
		typechlpfd[*ip] = 1;
	}
	for(ip=typecinit; *ip>=0; ip++) {
		urk("typec", nelem(typec), *ip);
		typec[*ip] = 1;
	}
	for(ip=typehinit; *ip>=0; ip++) {
		urk("typeh", nelem(typeh), *ip);
		typeh[*ip] = 1;
	}
	for(ip=typeilinit; *ip>=0; ip++) {
		urk("typeil", nelem(typeil), *ip);
		typeil[*ip] = 1;
	}
	for(ip=typevinit; *ip>=0; ip++) {
		urk("typev", nelem(typev), *ip);
		typev[*ip] = 1;
		typechlv[*ip] = 1;
		typechlvp[*ip] = 1;
	}
	for(ip=typefdinit; *ip>=0; ip++) {
		urk("typefd", nelem(typefd), *ip);
		typefd[*ip] = 1;
	}
	for(ip=typeafinit; *ip>=0; ip++) {
		urk("typeaf", nelem(typeaf), *ip);
		typeaf[*ip] = 1;
	}
	for(ip=typesuinit; *ip >= 0; ip++) {
		urk("typesu", nelem(typesu), *ip);
		typesu[*ip] = 1;
	}
	for(p=tasigninit; p->code >= 0; p++) {
		urk("tasign", nelem(tasign), p->code);
		tasign[p->code] = p->value;
	}
	for(p=tasaddinit; p->code >= 0; p++) {
		urk("tasadd", nelem(tasadd), p->code);
		tasadd[p->code] = p->value;
	}
	for(p=tcastinit; p->code >= 0; p++) {
		urk("tcast", nelem(tcast), p->code);
		tcast[p->code] = p->value;
	}
	for(p=taddinit; p->code >= 0; p++) {
		urk("tadd", nelem(tadd), p->code);
		tadd[p->code] = p->value;
	}
	for(p=tsubinit; p->code >= 0; p++) {
		urk("tsub", nelem(tsub), p->code);
		tsub[p->code] = p->value;
	}
	for(p=tmulinit; p->code >= 0; p++) {
		urk("tmul", nelem(tmul), p->code);
		tmul[p->code] = p->value;
	}
	for(p=tandinit; p->code >= 0; p++) {
		urk("tand", nelem(tand), p->code);
		tand[p->code] = p->value;
	}
	for(p=trelinit; p->code >= 0; p++) {
		urk("trel", nelem(trel), p->code);
		trel[p->code] = p->value;
	}
	
	/* 32-bit defaults */
	typeword = typechlp;
	typecmplx = typesuv;
}

/*
 * return 1 if it is impossible to jump into the middle of n.
 */
static int
deadhead(Node *n, int caseok)
{
loop:
	if(n == Z)
		return 1;
	switch(n->op) {
	case OLIST:
		if(!deadhead(n->left, caseok))
			return 0;
	rloop:
		n = n->right;
		goto loop;

	case ORETURN:
		break;

	case OLABEL:
		return 0;

	case OGOTO:
		break;

	case OCASE:
		if(!caseok)
			return 0;
		goto rloop;

	case OSWITCH:
		return deadhead(n->right, 1);

	case OWHILE:
	case ODWHILE:
		goto rloop;

	case OFOR:
		goto rloop;

	case OCONTINUE:
		break;

	case OBREAK:
		break;

	case OIF:
		return deadhead(n->right->left, caseok) && deadhead(n->right->right, caseok);

	case OSET:
	case OUSED:
		break;
	}
	return 1;
}

int
deadheads(Node *c)
{
	return deadhead(c->left, 0) && deadhead(c->right, 0);
}

int
mixedasop(Type *l, Type *r)
{
	return !typefd[l->etype] && typefd[r->etype];
}