harec

commit 2a6711b038d44577cd1aca66ea666260cbecc34b
parent 8376c3d205dffff25aa6294fde4c8e57f39af613
Author: Drew DeVault <sir@cmpwn.com>
Date:   Sun, 31 Jan 2021 11:01:14 -0500

gen: rig up new tagged rules

Diffstat:
M
include/types.h
 | 
4
++++
M
src/gen.c
 | 
32
+++++++++++++++++++++-----------
M
src/types.c
 | 
4
++--

3 files changed, 27 insertions(+), 13 deletions(-)
diff --git a/include/types.h b/include/types.h
@@ -145,6 +145,10 @@ const struct type *type_dealias(const struct type *type);
 const struct struct_field *type_get_field(
 	const struct type *type, const char *name);
 
+const struct type *tagged_select_subtype(
+	const struct type *tagged, const struct type *subtype);
+bool tagged_subset_compat(const struct type *to, const struct type *from);
+
 const char *type_storage_unparse(enum type_storage storage);
 bool type_is_signed(const struct type *type);
 bool type_is_integer(const struct type *type);
diff --git a/src/gen.c b/src/gen.c
@@ -916,17 +916,25 @@ gen_cast_to_tagged(struct gen_context *ctx,
 	const struct qbe_value *out,
 	const struct type *from)
 {
+	const struct type *tagged = expr->result;
+	const struct type *subtype = tagged_select_subtype(tagged, from);
+
 	struct qbe_value tag = {0}, ptr = {0}, offs = {0};
-	gen_temp(ctx, &ptr, &qbe_long, "ptr.%d");
+	gen_temp(ctx, &ptr, &qbe_long, "to_tagged.from.%d");
 	constl(&offs, expr->result->align);
 
-	if (type_dealias(from)->storage == TYPE_STORAGE_TAGGED) {
+	if (!subtype) {
+		pushc(ctx->current, "to_tagged; no subtype");
 		gen_expression(ctx, expr->cast.value, &ptr);
 		gen_copy(ctx, out, &ptr);
 		return;
-
 	}
-	constw(&tag, expr->cast.value->result->id);
+
+	pushc(ctx->current, "to_tagged; valid subtype");
+	// TODO: check should lower this to multiple casts:
+	assert(subtype->id == from->id);
+
+	constw(&tag, subtype->id);
 	pushi(ctx->current, &ptr, Q_COPY, out, NULL);
 	pushi(ctx->current, NULL, Q_STOREW, &tag, &ptr, NULL);
 
@@ -1048,19 +1056,21 @@ gen_expr_cast(struct gen_context *ctx,
 		return;
 	}
 
-	const struct type *to = type_dealias(expr->result),
-	      *from = type_dealias(expr->cast.value->result);
-	if (to->storage == from->storage && to->size == from->size) {
-		gen_expression(ctx, expr->cast.value, out);
-		return;
-	} else if (to->storage == TYPE_STORAGE_TAGGED) {
+	const struct type *to = expr->result, *from = expr->cast.value->result;
+	if (type_dealias(to)->storage == TYPE_STORAGE_TAGGED) {
 		gen_cast_to_tagged(ctx, expr, out, from);
 		return;
-	} else if (from->storage == TYPE_STORAGE_TAGGED) {
+	} else if (type_dealias(from)->storage == TYPE_STORAGE_TAGGED) {
 		gen_cast_from_tagged(ctx, expr, out, to);
 		return;
 	}
 
+	to = type_dealias(to), from = type_dealias(from);
+	if (to->storage == from->storage && to->size == from->size) {
+		gen_expression(ctx, expr->cast.value, out);
+		return;
+	}
+
 	bool is_signed = type_is_signed(from);
 
 	struct qbe_value in = {0}, result = {0};
diff --git a/src/types.c b/src/types.c
@@ -346,7 +346,7 @@ strip_flags(const struct type *t, struct type *secondary)
 	return secondary;
 }
 
-static const struct type *
+const struct type *
 tagged_select_subtype(const struct type *tagged, const struct type *subtype)
 {
 	tagged = type_dealias(tagged);
@@ -375,7 +375,7 @@ tagged_select_subtype(const struct type *tagged, const struct type *subtype)
 	return NULL;
 }
 
-static bool
+bool
 tagged_subset_compat(const struct type *to, const struct type *from)
 {
 	// Note: this implementation depends on the invariant that tagged union