sbase

commit 6edcf9948848793f67f04458a72c7825fe9e4138
parent 26cc48e028bd53f8cdc7ba7c564babcc7958aa4b
Author: Roberto E. Vargas Caballero <k0ga@shike2.net>
Date:   Thu, 27 Nov 2025 19:02:33 +0100

bc: Don't reuse ids from functions

When a function has control flow structures they live forever
because the function can be called at any moment. But when
they are in the top level context (in home) then we can reuse
the ids because they cannot be used after being added to the
system.

Diffstat:
M
bc.y
 | 
67
+++++++++++++++++++++++++++++++++++++++++++++++++------------------

1 file changed, 49 insertions(+), 18 deletions(-)
diff --git a/bc.y b/bc.y
@@ -42,7 +42,7 @@ static char *funcode(Macro *, char *, char *, char *);
 static Macro *define(char *, char *);
 static char *retcode(char *);
 static char *brkcode(void);
-static Macro *macro(int, int);
+static Macro *macro(int);
 
 static char *ftn(char *);
 static char *var(char *);
@@ -52,9 +52,9 @@ static void writeout(char *);
 static char *yytext, *buff;
 static char *filename;
 static FILE *filep;
-static int lineno, nerr;
+static int lineno, nerr, flowid;
 static jmp_buf recover;
-static int nested;
+static int nested, inhome;
 static Macro macros[NESTED_MAX];
 int cflag, dflag, lflag, sflag;
 
@@ -146,16 +146,16 @@ stat    : exprstat
         | for '(' expr ';' rel ';' expr ')' stat  {$$ = forcode($1, $3, $5, $7, $9);}
         ;
 
-while   : WHILE                 {$$ = macro(LOOP, 0);}
+while   : WHILE                 {$$ = macro(LOOP);}
         ;
 
-if      : IF                    {$$ = macro(IF, 0);}
+if      : IF                    {$$ = macro(IF);}
         ;
 
-for     : FOR                   {$$ = macro(LOOP, 0);}
+for     : FOR                   {$$ = macro(LOOP);}
         ;
 
-def     : DEF ID                {$$ = macro(DEF, funid($2));}
+def     : DEF ID                {$$ = macro(DEF);}
         ;
 
 parlst  : '(' ')'               {$$ = code("%%s");}
@@ -333,19 +333,48 @@ err:
 }
 
 static Macro *
-macro(int op, int id)
+macro(int op)
 {
-	Macro *d;
+	int preop;
+	Macro *d, *p;
 
 	if (nested == NESTED_MAX)
 		yyerror("too much nesting");
 
 	d = &macros[nested];
-	d->flowid = (op == HOME) ? '0' - 1: d[-1].flowid + 1;
-	d->id = (id != 0) ? id : d->flowid;
 	d->op = op;
 	d->nested = nested++;
 
+	switch (op) {
+	case HOME:
+		d->id = 0;
+		d->flowid = flowid;
+		inhome = 1;
+		break;
+	case DEF:
+		inhome = 0;
+		d->id = funid(yytext);
+		d->flowid = macros[0].flowid;
+		break;
+	default:
+		assert(nested > 1);
+		preop = d[-1].op;
+		d->flowid = d[-1].flowid;
+		if (preop != HOME && preop != DEF) {
+			if (d->flowid == 255)
+				eprintf("too many control flow structures");
+			d->flowid++;
+		}
+		d->id = d->flowid;
+		if (!inhome) {
+			/* populate reserved id */
+			flowid = d->flowid;
+			for (p = d; p != macros; --p)
+				p[-1].flowid++;
+		}
+		break;
+	}
+
 	return d;
 }
 
@@ -358,6 +387,7 @@ funcode(Macro *d, char *params, char *vars, char *body)
 	t2 = code(t1, body);
 
 	nested--;
+	inhome = 0;
 	free(vars);
 	free(t1);
 
@@ -385,10 +415,10 @@ forcode(Macro *d, char *init, char *cmp, char *inc, char *body)
 	         body,
 	         inc,
 	         estrdup(cmp),
-	         d->flowid, d->flowid);
+	         d->flowid, d->id);
 	writeout(s);
 
-	s = code("%ss.%s%c", init, cmp, d->flowid);
+	s = code("%ss.%s%c", init, cmp, d->id);
 	nested--;
 
 	return s;
@@ -402,10 +432,10 @@ whilecode(Macro *d, char *cmp, char *body)
 	s = code("[%ss.%s%c]s%c",
 	         body,
 	         estrdup(cmp),
-	         d->flowid, d->flowid);
+	         d->flowid, d->id);
 	writeout(s);
 
-	s = code("%s%c", cmp, d->flowid);
+	s = code("%s%c", cmp, d->id);
 	nested--;
 
 	return s;
@@ -416,10 +446,10 @@ ifcode(Macro *d, char *cmp, char *body)
 {
 	char *s;
 
-	s = code("[%s]s%c", body, d->flowid);
+	s = code("[%s]s%c", body, d->id);
 	writeout(s);
 
-	s = code("%s%c", cmp, d->flowid);
+	s = code("%s%c", cmp, d->id);
 	nested--;
 
 	return s;
@@ -761,7 +791,7 @@ bc(char *fname)
 	lineno = 1;
 	nested = 0;
 
-	macro(HOME, 0);
+	macro(HOME);
 	if (!fname) {
 		filename = "<stdin>";
 		filep = stdin;
@@ -841,6 +871,7 @@ main(int argc, char *argv[])
 	buff = malloc(BUFSIZ);
 	if (!yytext || !buff)
 		eprintf("out of memory\n");
+	flowid = 128;
 
 	if (!cflag)
 		spawn();