4.1cBSD/usr/src/ucb/dbx/eval.c
/* Copyright (c) 1982 Regents of the University of California */
static char sccsid[] = "@(#)eval.c 1.4 2/20/83";
/*
* Tree evaluation.
*/
#include "defs.h"
#include "tree.h"
#include "operators.h"
#include "eval.h"
#include "events.h"
#include "symbols.h"
#include "scanner.h"
#include "source.h"
#include "object.h"
#include "mappings.h"
#include "process.h"
#include "machine.h"
#include <signal.h>
#ifndef public
#include "machine.h"
#define STACKSIZE 2000
typedef Char Stack;
#define push(type, value) { \
((type *) (sp += sizeof(type)))[-1] = (value); \
}
#define pop(type) ( \
(*((type *) (sp -= sizeof(type)))) \
)
#define alignstack() { \
sp = (Stack *) (( ((int) sp) + sizeof(int) - 1)&~(sizeof(int) - 1)); \
}
#endif
public Stack stack[STACKSIZE];
public Stack *sp = &stack[0];
#define chksp() \
{ \
if (sp < &stack[0]) { \
panic("stack underflow"); \
} \
}
#define poparg(n, r, fr) { \
eval(p->value.arg[n]); \
if (isreal(p->op)) { \
fr = pop(double); \
} else if (isint(p->op)) { \
r = popsmall(p->value.arg[n]->nodetype); \
} \
}
#define Boolrep char /* underlying representation type for booleans */
/*
* Evaluate a parse tree leaving the value on the top of the stack.
*/
public eval(p)
register Node p;
{
long r0, r1;
double fr0, fr1;
Address addr;
long i, n;
int len;
Symbol s, f;
Node n1, n2;
Boolean b;
File file;
checkref(p);
switch (degree(p->op)) {
case BINARY:
poparg(1, r1, fr1);
poparg(0, r0, fr0);
break;
case UNARY:
poparg(0, r0, fr0);
break;
default:
/* do nothing */;
}
switch (p->op) {
case O_SYM:
s = p->value.sym;
if (s == retaddrsym) {
push(long, return_addr());
} else {
if (isvariable(s)) {
if (s != program and not isactive(container(s))) {
error("\"%s\" is not active", symname(s));
}
push(long, address(s, nil));
} else if (isblock(s)) {
push(Symbol, s);
} else {
error("can't evaluate a %s", classname(s));
}
}
break;
case O_LCON:
r0 = p->value.lcon;
pushsmall(p->nodetype, r0);
break;
case O_FCON:
push(double, p->value.fcon);
break;
case O_SCON:
len = size(p->nodetype);
mov(p->value.scon, sp, len);
sp += len;
break;
case O_INDEX:
n = pop(long);
i = evalindex(p->value.arg[0]->nodetype,
popsmall(p->value.arg[1]->nodetype));
push(long, n + i*size(p->nodetype));
break;
case O_DOT:
s = p->value.arg[1]->value.sym;
n = lval(p->value.arg[0]);
push(long, n + (s->symvalue.field.offset div 8));
break;
/*
* Get the value of the expression addressed by the top of the stack.
* Push the result back on the stack.
*/
case O_INDIR:
case O_RVAL:
addr = pop(long);
if (addr == 0) {
error("reference through nil pointer");
}
if (p->op == O_INDIR) {
len = sizeof(long);
} else {
len = size(p->nodetype);
}
rpush(addr, len);
break;
/*
* Effectively, we want to pop n bytes off for the evaluated subtree
* and push len bytes on for the new type of the same tree.
*/
case O_TYPERENAME:
n = size(p->value.arg[0]->nodetype);
len = size(p->nodetype);
sp = sp - n + len;
break;
case O_COMMA:
break;
case O_ITOF:
push(double, (double) r0);
break;
case O_ADD:
push(long, r0+r1);
break;
case O_ADDF:
push(double, fr0+fr1);
break;
case O_SUB:
push(long, r0-r1);
break;
case O_SUBF:
push(double, fr0-fr1);
break;
case O_NEG:
push(long, -r0);
break;
case O_NEGF:
push(double, -fr0);
break;
case O_MUL:
push(long, r0*r1);
break;
case O_MULF:
push(double, fr0*fr1);
break;
case O_DIVF:
if (fr1 == 0) {
error("error: division by 0");
}
push(double, fr0 / fr1);
break;
case O_DIV:
if (r1 == 0) {
error("error: div by 0");
}
push(long, r0 div r1);
break;
case O_MOD:
if (r1 == 0) {
error("error: mod by 0");
}
push(long, r0 mod r1);
break;
case O_LT:
push(Boolrep, r0 < r1);
break;
case O_LTF:
push(Boolrep, fr0 < fr1);
break;
case O_LE:
push(Boolrep, r0 <= r1);
break;
case O_LEF:
push(Boolrep, fr0 <= fr1);
break;
case O_GT:
push(Boolrep, r0 > r1);
break;
case O_GTF:
push(Boolrep, fr0 > fr1);
break;
case O_EQ:
push(Boolrep, r0 == r1);
break;
case O_EQF:
push(Boolrep, fr0 == fr1);
break;
case O_NE:
push(Boolrep, r0 != r1);
break;
case O_NEF:
push(Boolrep, fr0 != fr1);
break;
case O_AND:
push(Boolrep, r0 and r1);
break;
case O_OR:
push(Boolrep, r0 or r1);
break;
case O_ASSIGN:
assign(p->value.arg[0], p->value.arg[1]);
break;
case O_CHFILE:
if (p->value.scon == nil) {
printf("%s\n", cursource);
} else {
file = opensource(p->value.scon);
if (file == nil) {
error("can't read \"%s\"", p->value.scon);
} else {
fclose(file);
setsource(p->value.scon);
}
}
break;
case O_CONT:
cont();
printnews();
break;
case O_LIST:
if (p->value.arg[0]->op == O_SYM) {
f = p->value.arg[0]->value.sym;
addr = firstline(f);
if (addr == NOADDR) {
error("no source lines for \"%s\"", symname(f));
}
setsource(srcfilename(addr));
r0 = srcline(addr) - 5;
r1 = r0 + 10;
if (r0 < 1) {
r0 = 1;
}
} else {
eval(p->value.arg[0]);
r0 = pop(long);
eval(p->value.arg[1]);
r1 = pop(long);
}
printlines((Lineno) r0, (Lineno) r1);
break;
case O_FUNC:
if (p->value.arg[0] == nil) {
printname(stdout, curfunc);
putchar('\n');
} else {
curfunc = p->value.arg[0]->value.sym;
addr = codeloc(curfunc);
if (addr != NOADDR) {
setsource(srcfilename(addr));
cursrcline = srcline(addr) - 5;
if (cursrcline < 1) {
cursrcline = 1;
}
}
}
break;
case O_EXAMINE:
eval(p->value.examine.beginaddr);
r0 = pop(long);
if (p->value.examine.endaddr == nil) {
n = p->value.examine.count;
if (n == 0) {
printvalue(r0, p->value.examine.mode);
} else if (streq(p->value.examine.mode, "i")) {
printninst(n, (Address) r0);
} else {
printndata(n, (Address) r0, p->value.examine.mode);
}
} else {
eval(p->value.examine.endaddr);
r1 = pop(long);
if (streq(p->value.examine.mode, "i")) {
printinst((Address)r0, (Address)r1);
} else {
printdata((Address)r0, (Address)r1, p->value.examine.mode);
}
}
break;
case O_PRINT:
for (n1 = p->value.arg[0]; n1 != nil; n1 = n1->value.arg[1]) {
eval(n1->value.arg[0]);
printval(n1->value.arg[0]->nodetype);
putchar(' ');
}
putchar('\n');
break;
case O_PSYM:
if (p->value.arg[0]->op == O_SYM) {
psym(p->value.arg[0]->value.sym);
} else {
psym(p->value.arg[0]->nodetype);
}
break;
case O_QLINE:
eval(p->value.arg[1]);
break;
case O_STEP:
b = inst_tracing;
inst_tracing = (Boolean) (not p->value.step.source);
if (p->value.step.skipcalls) {
next();
} else {
stepc();
}
inst_tracing = b;
printnews();
break;
case O_WHATIS:
if (p->value.arg[0]->op == O_SYM) {
printdecl(p->value.arg[0]->value.sym);
} else {
printdecl(p->value.arg[0]->nodetype);
}
break;
case O_WHERE:
wherecmd();
break;
case O_WHEREIS:
printwhereis(stdout, p->value.arg[0]->value.sym);
break;
case O_WHICH:
printwhich(stdout, p->value.arg[0]->value.sym);
putchar('\n');
break;
case O_ALIAS:
n1 = p->value.arg[0];
n2 = p->value.arg[1];
if (n1 == nil) {
print_alias(nil);
} else if (n2 == nil) {
print_alias(n1->value.name);
} else {
enter_alias(n1->value.name, n2->value.name);
}
break;
case O_CALL:
callproc(p->value.arg[0], p->value.arg[1]);
break;
case O_CATCH:
psigtrace(process, p->value.lcon, true);
break;
case O_EDIT:
edit(p->value.scon);
break;
case O_DUMP:
dump();
break;
case O_GRIPE:
gripe();
break;
case O_HELP:
help();
break;
case O_IGNORE:
psigtrace(process, p->value.lcon, false);
break;
case O_RUN:
run();
break;
case O_SOURCE:
setinput(p->value.scon);
break;
case O_STATUS:
status();
break;
case O_TRACE:
case O_TRACEI:
trace(p);
if (isstdin()) {
status();
}
break;
case O_STOP:
case O_STOPI:
stop(p);
if (isstdin()) {
status();
}
break;
case O_ADDEVENT:
addevent(p->value.event.cond, p->value.event.actions);
break;
case O_DELETE:
delevent((unsigned int) p->value.lcon);
break;
case O_ENDX:
endprogram();
break;
case O_IF:
if (cond(p->value.event.cond)) {
evalcmdlist(p->value.event.actions);
}
break;
case O_ONCE:
event_once(p->value.event.cond, p->value.event.actions);
break;
case O_PRINTCALL:
printcall(p->value.sym, whatblock(return_addr()));
break;
case O_PRINTIFCHANGED:
printifchanged(p->value.arg[0]);
break;
case O_PRINTRTN:
printrtn(p->value.sym);
break;
case O_PRINTSRCPOS:
getsrcpos();
if (p->value.arg[0] == nil) {
printsrcpos();
putchar('\n');
printlines(curline, curline);
} else if (p->value.arg[0]->op == O_QLINE) {
if (p->value.arg[0]->value.arg[1]->value.lcon == 0) {
printf("tracei: ");
printinst(pc, pc);
} else {
printf("trace: ");
printlines(curline, curline);
}
} else {
printsrcpos();
printf(": ");
eval(p->value.arg[0]);
prtree(stdout, p->value.arg[0]);
printf(" = ");
printval(p->value.arg[0]->nodetype);
putchar('\n');
}
break;
case O_PROCRTN:
procreturn(p->value.sym);
break;
case O_STOPIFCHANGED:
stopifchanged(p->value.arg[0]);
break;
case O_STOPX:
isstopped = true;
break;
case O_TRACEON:
traceon(p->value.trace.inst, p->value.trace.event,
p->value.trace.actions);
break;
case O_TRACEOFF:
traceoff(p->value.lcon);
break;
default:
panic("eval: bad op %d", p->op);
}
}
/*
* Evaluate a list of commands.
*/
public evalcmdlist(cl)
Cmdlist cl;
{
Command c;
foreach (Command, c, cl)
evalcmd(c);
endfor
}
/*
* Push "len" bytes onto the expression stack from address "addr"
* in the process. If there isn't room on the stack, print an error message.
*/
public rpush(addr, len)
Address addr;
int len;
{
if (not canpush(len)) {
error("expression too large to evaluate");
} else {
chksp();
dread(sp, addr, len);
sp += len;
}
}
/*
* Check if the stack has n bytes available.
*/
public Boolean canpush(n)
Integer n;
{
return (Boolean) (sp + n < &stack[STACKSIZE]);
}
/*
* Push a small scalar of the given type onto the stack.
*/
public pushsmall(t, v)
Symbol t;
long v;
{
register Integer s;
s = size(t);
switch (s) {
case sizeof(char):
push(char, v);
break;
case sizeof(short):
push(short, v);
break;
case sizeof(long):
push(long, v);
break;
default:
panic("bad size %d in popsmall", s);
}
}
/*
* Pop an item of the given type which is assumed to be no larger
* than a long and return it expanded into a long.
*/
public long popsmall(t)
Symbol t;
{
long r;
switch (size(t)) {
case sizeof(char):
r = (long) pop(char);
break;
case sizeof(short):
r = (long) pop(short);
break;
case sizeof(long):
r = pop(long);
break;
default:
panic("popsmall: size is %d", size(t));
}
return r;
}
/*
* Evaluate a conditional expression.
*/
public Boolean cond(p)
Node p;
{
register Boolean b;
if (p == nil) {
b = true;
} else {
eval(p);
b = pop(Boolean);
}
return b;
}
/*
* Return the address corresponding to a given tree.
*/
public Address lval(p)
Node p;
{
if (p->op == O_RVAL) {
eval(p->value.arg[0]);
} else {
eval(p);
}
return (Address) (pop(long));
}
/*
* Process a trace command, translating into the appropriate events
* and associated actions.
*/
public trace(p)
Node p;
{
Node exp, place, cond;
Node left;
exp = p->value.arg[0];
place = p->value.arg[1];
cond = p->value.arg[2];
if (exp == nil) {
traceall(p->op, place, cond);
} else if (exp->op == O_QLINE) {
traceinst(p->op, exp, cond);
} else if (place != nil and place->op == O_QLINE) {
traceat(p->op, exp, place, cond);
} else {
left = exp;
if (left->op == O_RVAL or left->op == O_CALL) {
left = left->value.arg[0];
}
if (left->op == O_SYM and isblock(left->value.sym)) {
traceproc(p->op, left->value.sym, place, cond);
} else {
tracedata(p->op, exp, place, cond);
}
}
}
/*
* Set a breakpoint that will turn on tracing.
*/
private traceall(op, place, cond)
Operator op;
Node place;
Node cond;
{
Symbol s;
Node event;
Command action;
if (place == nil) {
s = program;
} else {
s = place->value.sym;
}
event = build(O_EQ, build(O_SYM, procsym), build(O_SYM, s));
action = build(O_PRINTSRCPOS,
build(O_QLINE, nil, build(O_LCON, (op == O_TRACE) ? 1 : 0)));
if (cond != nil) {
action = build(O_IF, cond, buildcmdlist(action));
}
action = build(O_TRACEON, (op == O_TRACEI), buildcmdlist(action));
action->value.trace.event = addevent(event, buildcmdlist(action));
}
/*
* Set up the appropriate breakpoint for tracing an instruction.
*/
private traceinst(op, exp, cond)
Operator op;
Node exp;
Node cond;
{
Node event;
Command action;
if (op == O_TRACEI) {
event = build(O_EQ, build(O_SYM, pcsym), exp);
} else {
event = build(O_EQ, build(O_SYM, linesym), exp);
}
action = build(O_PRINTSRCPOS, exp);
if (cond) {
action = build(O_IF, cond, buildcmdlist(action));
}
addevent(event, buildcmdlist(action));
}
/*
* Set a breakpoint to print an expression at a given line or address.
*/
private traceat(op, exp, place, cond)
Operator op;
Node exp;
Node place;
Node cond;
{
Node event;
Command action;
if (op == O_TRACEI) {
event = build(O_EQ, build(O_SYM, pcsym), place);
} else {
event = build(O_EQ, build(O_SYM, linesym), place);
}
action = build(O_PRINTSRCPOS, exp);
if (cond != nil) {
action = build(O_IF, cond, buildcmdlist(action));
}
addevent(event, buildcmdlist(action));
}
/*
* Construct event for tracing a procedure.
*
* What we want here is
*
* when $proc = p do
* if <condition> then
* printcall;
* once $pc = $retaddr do
* printrtn;
* end;
* end if;
* end;
*
* Note that "once" is like "when" except that the event
* deletes itself as part of its associated action.
*/
private traceproc(op, p, place, cond)
Operator op;
Symbol p;
Node place;
Node cond;
{
Node event;
Command action;
Cmdlist actionlist;
action = build(O_PRINTCALL, p);
actionlist = list_alloc();
cmdlist_append(action, actionlist);
event = build(O_EQ, build(O_SYM, pcsym), build(O_SYM, retaddrsym));
action = build(O_ONCE, event, buildcmdlist(build(O_PRINTRTN, p)));
cmdlist_append(action, actionlist);
if (cond != nil) {
actionlist = buildcmdlist(build(O_IF, cond, actionlist));
}
event = build(O_EQ, build(O_SYM, procsym), build(O_SYM, p));
addevent(event, actionlist);
}
/*
* Set up breakpoint for tracing data.
*/
private tracedata(op, exp, place, cond)
Operator op;
Node exp;
Node place;
Node cond;
{
Symbol p;
Node event;
Command action;
p = (place == nil) ? tcontainer(exp) : place->value.sym;
if (p == nil) {
p = program;
}
action = build(O_PRINTIFCHANGED, exp);
if (cond != nil) {
action = build(O_IF, cond, buildcmdlist(action));
}
action = build(O_TRACEON, (op == O_TRACEI), buildcmdlist(action));
event = build(O_EQ, build(O_SYM, procsym), build(O_SYM, p));
action->value.trace.event = addevent(event, buildcmdlist(action));
}
/*
* Setting and unsetting of stops.
*/
public stop(p)
Node p;
{
Node exp, place, cond;
Symbol s;
Command action;
exp = p->value.arg[0];
place = p->value.arg[1];
cond = p->value.arg[2];
if (exp != nil) {
stopvar(p->op, exp, place, cond);
} else if (cond != nil) {
s = (place == nil) ? program : place->value.sym;
action = build(O_IF, cond, buildcmdlist(build(O_STOPX)));
action = build(O_TRACEON, (p->op == O_STOPI), buildcmdlist(action));
cond = build(O_EQ, build(O_SYM, procsym), build(O_SYM, s));
action->value.trace.event = addevent(cond, buildcmdlist(action));
} else if (place->op == O_SYM) {
s = place->value.sym;
cond = build(O_EQ, build(O_SYM, procsym), build(O_SYM, s));
addevent(cond, buildcmdlist(build(O_STOPX)));
} else {
stopinst(p->op, place, cond);
}
}
private stopinst(op, place, cond)
Operator op;
Node place;
Node cond;
{
Node event;
if (op == O_STOP) {
event = build(O_EQ, build(O_SYM, linesym), place);
} else {
event = build(O_EQ, build(O_SYM, pcsym), place);
}
addevent(event, buildcmdlist(build(O_STOPX)));
}
/*
* Implement stopping on assignment to a variable by adding it to
* the variable list.
*/
private stopvar(op, exp, place, cond)
Operator op;
Node exp;
Node place;
Node cond;
{
Symbol p;
Node event;
Command action;
p = (place == nil) ? tcontainer(exp) : place->value.sym;
if (p == nil) {
p = program;
}
action = build(O_IF, cond, buildcmdlist(build(O_STOPIFCHANGED, exp)));
action = build(O_TRACEON, (op == O_STOPI), buildcmdlist(action));
event = build(O_EQ, build(O_SYM, procsym), build(O_SYM, p));
action->value.trace.event = addevent(event, buildcmdlist(action));
}
/*
* Assign the value of an expression to a variable (or term).
*/
public assign(var, exp)
Node var;
Node exp;
{
Address addr;
int varsize;
char cvalue;
short svalue;
long lvalue;
if (not compatible(var->nodetype, exp->nodetype)) {
error("incompatible types");
}
addr = lval(var);
eval(exp);
varsize = size(var->nodetype);
if (varsize < sizeof(long)) {
lvalue = pop(long);
switch (varsize) {
case sizeof(char):
cvalue = lvalue;
dwrite(&cvalue, addr, varsize);
break;
case sizeof(short):
svalue = lvalue;
dwrite(&svalue, addr, varsize);
break;
default:
panic("bad size %d", varsize);
}
} else {
sp -= varsize;
dwrite(sp, addr, varsize);
}
}
#define DEF_EDITOR "vi"
/*
* Invoke an editor on the given file. Which editor to use might change
* installation to installation. For now, we use "vi". In any event,
* the environment variable "EDITOR" overrides any default.
*/
public edit(filename)
String filename;
{
extern String getenv();
String ed, src;
File f;
Symbol s;
Address addr;
char buff[10];
ed = getenv("EDITOR");
if (ed == nil) {
ed = DEF_EDITOR;
}
if (filename == nil) {
call(ed, stdin, stdout, cursource, nil);
} else {
f = fopen(filename, "r");
if (f == nil) {
s = which(identname(filename, true));
if (not isblock(s)) {
error("can't read \"%s\"", filename);
}
addr = firstline(s);
if (addr == NOADDR) {
error("no source for \"%s\"", filename);
}
src = srcfilename(addr);
sprintf(buff, "+%d", srcline(addr));
call(ed, stdin, stdout, buff, src, nil);
} else {
fclose(f);
call(ed, stdin, stdout, filename, nil);
}
}
}
/*
* Send some nasty mail to the current support person.
*/
public gripe()
{
typedef Operation();
Operation *old;
char *maintainer = "linton@ucbarpa";
puts("Type control-D to end your message. Be sure to include");
puts("your name and the name of the file you are debugging.");
putchar('\n');
old = signal(SIGINT, SIG_DFL);
call("Mail", stdin, stdout, maintainer, nil);
signal(SIGINT, old);
puts("Thank you.");
}
/*
* Give the user some help.
*/
public help()
{
puts("run - begin execution of the program");
puts("cont - continue execution");
puts("step - single step one line");
puts("next - step to next line (skip over calls)");
puts("trace <line#> - trace execution of the line");
puts("trace <proc> - trace calls to the procedure");
puts("trace <var> - trace changes to the variable");
puts("trace <exp> at <line#> - print <exp> when <line> is reached");
puts("stop at <line> - suspend execution at the line");
puts("stop in <proc> - suspend execution when <proc> is called");
puts("status - print trace/stop's in effect");
puts("delete <number> - remove trace or stop of given number");
puts("call <proc> - call the procedure");
puts("where - print currently active procedures");
puts("print <exp> - print the value of the expression");
puts("whatis <name> - print the declaration of the name");
puts("list <line>, <line> - list source lines");
puts("edit <proc> - edit file containing <proc>");
puts("gripe - send mail to the person in charge of dbx");
puts("quit - exit dbx");
}
/*
* Divert output to the given file name.
* Cannot redirect to an existing file.
*/
private int so_fd;
private Boolean notstdout;
public setout(filename)
String filename;
{
File f;
f = fopen(filename, "r");
if (f != nil) {
fclose(f);
error("%s: file already exists", filename);
} else {
so_fd = dup(1);
close(1);
if (creat(filename, 0666) == nil) {
unsetout();
error("can't create %s", filename);
}
notstdout = true;
}
}
/*
* Revert output to standard output.
*/
public unsetout()
{
fflush(stdout);
close(1);
if (dup(so_fd) != 1) {
panic("standard out dup failed");
}
close(so_fd);
notstdout = false;
}
/*
* Determine is standard output is currently being redirected
* to a file (as far as we know).
*/
public Boolean isredirected()
{
return notstdout;
}