Begin work on the static analyzer

1 files changed, 211 insertions, 0 deletions

diff --git a/src/analyzer.c b/src/analyzer.c
new file mode 100644
index 0000000..6687856
--- /dev/null
+++ b/src/analyzer.c
@@ -0,0 +1,211 @@
+#include <assert.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "alloc.h"
+#include "analyzer.h"
+#include "common.h"
+#include "errors.h"
+#include "parser.h"
+#include "types.h"
+
+struct environ {
+	idx_t_ up;
+	struct constdecl {
+		struct type type;
+		idx_t_ astidx;
+	} *buf;
+	size_t len, cap;
+};
+
+struct environs {
+	struct environ *buf;
+	size_t len, cap;
+};
+
+static struct environ *create_environments(struct ast, struct lexemes,
+                                           struct environs *, idx_t_, idx_t_,
+                                           arena *)
+	__attribute__((nonnull));
+static void typecheck_environment(struct environs, struct ast, struct lexemes,
+                                  idx_t_);
+
+/* Defined in primitives.gperf */
+const struct type *typelookup(const uchar *, size_t)
+	__attribute__((nonnull));
+
+void
+analyzeast(struct ast ast, struct lexemes toks)
+{
+	arena a = NULL;
+	struct environs evs = {0};
+
+	create_environments(ast, toks, &evs, 0, ast.len - 1, &a);
+	for (size_t i = 0; i < evs.len; i++)
+		typecheck_environment(evs, ast, toks, i);
+
+	arena_free(&a);
+	free(evs.buf);
+}
+
+struct environ *
+create_environments(struct ast ast, struct lexemes toks, struct environs *evs,
+                    idx_t_ beg, idx_t_ end, arena *a)
+{
+	assert(evs != NULL);
+
+	if (evs->len == evs->cap) {
+		evs->cap = evs->cap == 0 ? 8 : evs->cap * 2;
+		evs->buf = bufalloc(evs->buf, evs->cap, sizeof(*evs->buf));
+	}
+
+	struct environ *ev = evs->buf + evs->len++;
+	*ev = (struct environ){.cap = 16};
+	ev->buf = arena_new(a, struct constdecl, ev->cap);
+
+	for (idx_t_ i = beg; likely(i <= end); i++) {
+		switch (ast.kinds[i]) {
+		case ASTCDECL: {
+			struct constdecl cd = {.astidx = i};
+			struct strview sv = toks.strs[ast.lexemes[i]];
+
+			/* TODO: Sorted insert and existence check */
+			for (size_t i = 0; i < ev->len; i++) {
+				struct strview sv2 = toks.strs[ast.lexemes[ev->buf[i].astidx]];
+				if (sv.len == sv2.len && memcmp(sv.p, sv2.p, sv.len) == 0) {
+					err("analyzer: Constant ‘%.*s’ declared multiple times",
+					    (int)sv.len, sv.p);
+				}
+			}
+
+			if (ev->len == ev->cap) {
+				ev->buf = arena_grow(a, ev->buf, struct constdecl, ev->cap,
+				                     ev->cap * 2);
+				ev->cap *= 2;
+			}
+			ev->buf[ev->len++] = cd;
+			break;
+		}
+		case ASTBLK: {
+			idx_t_ lhs, rhs, up;
+			lhs = ast.kids[i].lhs;
+			rhs = ast.kids[i].rhs;
+			up = ev - evs->buf;
+			create_environments(ast, toks, evs, lhs, rhs, a)->up = up;
+			i = rhs;
+			break;
+		}
+		}
+	}
+
+	return ev;
+}
+
+static struct type typegrab(struct ast, struct lexemes, idx_t_);
+static struct type typecheck_constdecl(struct environs, struct ast,
+                                       struct lexemes, idx_t_, idx_t_);
+static struct type typecheck_expr(struct environs, struct ast, struct lexemes,
+                                  idx_t_, idx_t_);
+static bool typecompat(struct type, struct type);
+
+void
+typecheck_environment(struct environs evs, struct ast ast, struct lexemes toks,
+                      idx_t_ i)
+{
+	struct environ ev = evs.buf[i];
+	for (size_t j = 0; j < ev.len; j++)
+		typecheck_constdecl(evs, ast, toks, j, i);
+}
+
+struct type
+typegrab(struct ast ast, struct lexemes toks, idx_t_ i)
+{
+	struct strview sv = toks.strs[ast.lexemes[i]];
+	const struct type *tp = typelookup(sv.p, sv.len);
+	if (tp == NULL)
+		err("analyzer: Unknown type ‘%.*s’", (int)sv.len, sv.p);
+	return *tp;
+}
+
+struct type
+typecheck_constdecl(struct environs evs, struct ast ast, struct lexemes toks,
+                    idx_t_ i, idx_t_ evi)
+{
+	struct environ ev = evs.buf[evi];
+	struct constdecl cd = ev.buf[i];
+	if (cd.type.kind != TYPE_UNSET)
+		return cd.type;
+	ev.buf[i].type.kind = TYPE_CHECKING;
+
+	struct pair p = ast.kids[cd.astidx];
+	struct type ltype, rtype;
+	ltype.kind = TYPE_UNSET;
+
+	assert(p.rhs != AST_EMPTY);
+
+	if (p.lhs != AST_EMPTY)
+		ltype = typegrab(ast, toks, p.lhs);
+	rtype = typecheck_expr(evs, ast, toks, p.rhs, evi);
+
+	if (ltype.kind == TYPE_UNSET)
+		ltype = rtype;
+	else if (!typecompat(ltype, rtype))
+		err("analyzer: Type mismatch");
+
+	return ev.buf[i].type = ltype;
+}
+
+struct type
+typecheck_expr(struct environs evs, struct ast ast, struct lexemes toks,
+               idx_t_ i, idx_t_ evi)
+{
+	switch (ast.kinds[i]) {
+	case ASTNUMLIT:
+		return (struct type){.kind = TYPE_INT_UNTYPED, .issigned = true};
+	case ASTIDENT: {
+		struct environ ev = evs.buf[evi];
+		struct strview sv = toks.strs[ast.lexemes[i]];
+
+		for (;;) {
+			for (size_t i = 0; i < ev.len; i++) {
+				struct strview sv2 = toks.strs[ast.lexemes[ev.buf[i].astidx]];
+				if (sv.len != sv2.len || memcmp(sv.p, sv2.p, sv.len) != 0)
+					continue;
+				struct type t = typecheck_constdecl(evs, ast, toks, i, evi);
+				if (t.kind == TYPE_CHECKING) {
+					err("analyzer: Circular dependency for type ‘%.*s’",
+					    (int)sv2.len, sv2.p);
+				}
+				return t;
+			}
+			if (evi == 0)
+				err("analyzer: Unknown constant ‘%.*s’", (int)sv.len, sv.p);
+			evi = ev.up;
+		}
+	}
+	case ASTFN:
+		assert(!"not implemented");
+	default:
+		err("analyzer: Unexpected AST kind %u", ast.kinds[i]);
+		__builtin_unreachable();
+	}
+}
+
+bool
+typecompat(struct type lhs, struct type rhs)
+{
+	if (lhs.kind == rhs.kind)
+		return true;
+
+	/* TODO: Need to actually parse it!  256 should not coerce to i8. */
+	if (rhs.kind == TYPE_INT_UNTYPED)
+		return true;
+
+	if (lhs.issigned != rhs.issigned)
+		return false;
+
+	return lhs.size >= rhs.size;
+}