shithub: scc

ref: 643e8a40e46be15008645eecbeac019d7796552b
dir: /src/cmd/cc/cc2/symbol.c/

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <scc/scc.h>

#include "cc2.h"

#define NR_SYMHASH  64

Symbol *locals;
static Symbol *tail;

static Symbol *symtab[NR_SYMHASH];
static int infunction;


void
freesym(Symbol *sym)
{
	free(sym->name);
	free(sym);
}

void
pushctx(void)
{
	infunction = 1;
}

void
popctx(void)
{
	Symbol *sym, *prev;

	infunction = 0;
	for (sym = tail; sym; sym = prev) {
		prev = sym->prev;
		/*
		 * Symbols are inserted in the hash in the inverted
		 * order they are found in locals and it is impossible
		 * to have a global over a local, because a local is
		 * any symbol defined in the body of a function,
		 * even if it has extern linkage.
		 * For this reason when we reach a symbol in the
		 * locals list we know that it is the head of it
		 * collision list and we can remove it assigning
		 * it h_next to the hash table position
		 */
		if (sym->id != TMPSYM)
			symtab[sym->id & NR_SYMHASH-1] = sym->h_next;
		freesym(sym);
	}
	locals = tail = NULL;
}

Symbol *
getsym(unsigned id)
{
	Symbol **htab, *sym;
	static unsigned short num;

	if (id >= USHRT_MAX)
		error(EBADID);

	if (id != TMPSYM) {
		htab = &symtab[id & NR_SYMHASH-1];
		for (sym = *htab; sym; sym = sym->h_next) {
			if (sym->id == id)
				return sym;
		}
	}

	sym = xcalloc(1, sizeof(*sym));
	sym->id = id;
	if (infunction) {
		sym->next = NULL;
		sym->prev = tail;
		if (tail)
			tail->next = sym;
		tail = sym;
		if (!locals)
			locals = sym;
	}
	if (id != TMPSYM) {
		sym->h_next = *htab;
		*htab = sym;
	}
	if ((sym->numid = ++num) == 0)
		error(EIDOVER);

	return sym;
}