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[cc2-qbe] Begin to emit instructions

This code is totally unstested, but it defines how we can emit
instructions for QBE. Comparisions instructions and divisions
even emit incorrect text strings, but after this point is easy
to begin hacking.

--- a/cc2/arch/qbe/cgen.c

+++ b/cc2/arch/qbe/cgen.c

@@ -46,7 +46,6 @@

 	case OCONST:

 	case OLABEL:

 		np->flags |= ISCONS;

-	case OPAR:

 	case OMEM:

 	case OAUTO:

 		return np;

@@ -82,6 +81,7 @@

 	case OBLOOP:

 	case OELOOP:

 		return NULL;

+	case OPAR:

 	case ONEG:

 	case OADDR:

 	case OPTR:

--- a/cc2/arch/qbe/code.c

+++ b/cc2/arch/qbe/code.c

@@ -6,6 +6,30 @@

 #include "../../cc2.h"

 #include "../../../inc/sizes.h"

+static void inst3(void);

+

+static struct opdata {

+	void (*fun)(void);

+	char *txt;

+} optbl [] = {

+	[OADD]  = {.fun = inst3, .txt = "add"},

+	[OSUB]  = {.fun = inst3, .txt = "sub"},

+	[OMUL]  = {.fun = inst3, .txt = "mul"},

+	[OMOD]  = {.fun = inst3, .txt = "rem"},

+	[ODIV]  = {.fun = inst3, .txt = "div"},

+	[OSHL]  = {.fun = inst3, .txt = "shl"},

+	[OSHR]  = {.fun = inst3, .txt = "shr"},

+	[OLT]   = {.fun = inst3, .txt = "clt"},

+	[OGT]   = {.fun = inst3, .txt = "cgt"},

+	[OLE]   = {.fun = inst3, .txt = "cle"},

+	[OGE]   = {.fun = inst3, .txt = "cge"},

+	[OEQ]   = {.fun = inst3, .txt = "ceq"},

+	[ONE]   = {.fun = inst3, .txt = "cne"},

+	[OBAND] = {.fun = inst3, .txt = "and"},

+	[OBOR]  = {.fun = inst3, .txt = "or"},

+	[OBXOR] = {.fun = inst3, .txt = "xor"}

+};

+

 /*

  * : is for user-defined Aggregate Types

  * $ is for globals (represented by a pointer)

@@ -181,8 +205,36 @@

 		       symname(p), size2asm(tp), tp->size, tp->align);

 	}

+	for (pc = prog; pc; pc = pc->next) {

+		if (pc->label)

+			printf("%s:\n", symname(pc->label));

+		(*optbl[pc->op].fun)();

+	}

 	puts("}");

+}

+

+static char *

+addr2txt(Addr *a)

+{

+	static char buff[40];

+

+	switch (a->kind) {

+	case AUTO:

+	case LABEL:

+		return symname(a->u.sym);

+	default:

+		abort();

+	}

+}

+

+static void

+inst3(void)

+{

+	printf("\t%s %c= %s\t%s,%s\n",

+	       addr2txt(&pc->to),

+	       optbl[pc->op].txt,

+	       addr2txt(&pc->from1), addr2txt(&pc->from2));

 }

 void

--- a/cc2/cc2.h

+++ b/cc2/cc2.h

@@ -138,7 +138,8 @@

 	char kind;

 	union {

 		TSIZE off;

-		Node *label;

+		Node *nlabel;

+		Inst *ilabel;

 	} u;

 	Symbol *next;

 	Symbol *h_next;

@@ -173,6 +174,7 @@

 struct inst {

         char op;

+	Symbol *label;

         Addr from1, from2, to;

         Inst *next, *prev;

 };

@@ -216,3 +218,4 @@

 /* globals */

 extern Symbol *locals;

+extern Inst *pc, *prog;

--- a/cc2/code.c

+++ b/cc2/code.c

@@ -4,7 +4,7 @@

 #include "arch.h"

 #include "cc2.h"

-static Inst *pc, *prog;

+Inst *pc, *prog;

 static void

 nextpc(void)

--- a/cc2/node.c

+++ b/cc2/node.c

@@ -80,6 +80,6 @@

 	if (!curfun)

 		return;

-	for (np = curfun->u.label; np; np = np->stmt)

+	for (np = curfun->u.nlabel; np; np = np->stmt)

 		(*fun)(np);

 }

--- a/cc2/parser.c

+++ b/cc2/parser.c

@@ -587,14 +587,14 @@

 	delnode(np);

 	nextline();

 	stmtp->label = sym;

-	sym->u.label = stmtp;

+	sym->u.nlabel = stmtp;

 }

 static void

 addstmt(Node *np)

 {

-	if (!curfun->u.label)

-		curfun->u.label = np;

+	if (!curfun->u.nlabel)

+		curfun->u.nlabel = np;

 	else

 		stmtp->stmt = np;

 	stmtp = np;