commit e0240d896dfaec528f2a78953cedded2d717355c
parent baae29bff5e6bf792eee373a4a53931b9fe7f2a3
Author: Drew DeVault <sir@cmpwn.com>
Date: Tue, 29 Dec 2020 10:38:49 -0500
Implement aggregate type assignments
This is still a bit messy and I think there's room for simplificaiton. I
choose to copy via qbe instructions, which gives qbe an opportunity to
optimize it out if we're not using it - something which the memcpy
approach would not have been able to do.
One change this makes is to function call parameters - and one possible
improvement would be to add some kind of "alloc if necssary" flag to
qbe_value, which gen_store would read and allocate the appropriate
amount of space if necessary before copying the data in. This would
remove one useless stack allocation when not passing array literals
directly into function parameters. However, I suspect that a simpler
approach to aggregate types in general is possible, and would save us
the trouble.
Diffstat:
3 files changed, 71 insertions(+), 7 deletions(-)
diff --git a/include/qbe.h b/include/qbe.h
@@ -26,6 +26,7 @@ struct qbe_field {
struct qbe_type {
enum qbe_stype stype;
+ size_t size;
// Aggregate types only:
char *name;
size_t align;
diff --git a/src/gen.c b/src/gen.c
@@ -108,7 +108,7 @@ qval_for_object(struct gen_context *ctx,
}
if (type_is_aggregate(obj->type)) {
- val->type = &qbe_aggregate; // TODO: Lookup actual type
+ val->type = qtype_for_type(ctx, obj->type, true);
val->indirect = false;
} else {
val->type = &qbe_long; // XXX: ARCH
@@ -130,6 +130,60 @@ qval_address(struct qbe_value *val)
}
static void
+gen_copy(struct gen_context *ctx,
+ const struct qbe_value *dest,
+ const struct qbe_value *src)
+{
+ assert(!dest->indirect && !src->indirect);
+ assert(dest->type == src->type);
+ const struct qbe_field *field = &dest->type->fields;
+
+ struct qbe_value temp = {0}, destp = {0}, srcp = {0}, size = {0};
+ gen_temp(ctx, &temp, &qbe_long, "temp.%d");
+ gen_temp(ctx, &destp, &qbe_long, "dest.%d");
+ gen_temp(ctx, &srcp, &qbe_long, "src.%d");
+ pushi(ctx->current, &destp, Q_COPY, dest, NULL);
+ pushi(ctx->current, &srcp, Q_COPY, src, NULL);
+
+ while (field) {
+ temp.type = field->type;
+
+ for (size_t i = field->count; i > 0; --i) {
+ switch (field->type->stype) {
+ case Q_BYTE:
+ case Q_HALF:
+ case Q_WORD:
+ case Q_LONG:
+ case Q_SINGLE:
+ case Q_DOUBLE:
+ // XXX: This may be broken for unsigned types b
+ // and h
+ pushi(ctx->current, &temp,
+ load_for_type(field->type->stype, true),
+ &srcp, NULL);
+ pushi(ctx->current, NULL,
+ store_for_type(field->type->stype),
+ &temp, &destp, NULL);
+ break;
+ case Q__AGGREGATE:
+ assert(0); // TODO
+ case Q__VOID:
+ assert(0); // Invariant
+ }
+
+ if (i > 1) {
+ assert(field->type->size != 0);
+ constl(&size, field->type->size);
+ pushi(ctx->current, &destp, Q_ADD, &destp, &size, NULL);
+ pushi(ctx->current, &srcp, Q_ADD, &srcp, &size, NULL);
+ }
+ }
+
+ field = field->next;
+ }
+}
+
+static void
gen_store(struct gen_context *ctx,
const struct qbe_value *dest,
const struct qbe_value *src)
@@ -142,13 +196,13 @@ gen_store(struct gen_context *ctx,
assert(src->type->stype != Q__VOID
&& dest->type->stype != Q__VOID); // Invariant
+ // TODO: Revisit me (again)
if (src->type->stype == Q__AGGREGATE) {
if (src->indirect) {
assert(dest->indirect);
- // XXX: ARCH
- pushi(ctx->current, NULL, Q_STOREL, src, dest, NULL);
+ pushi(ctx->current, NULL, Q_STOREL, src, dest, NULL); // XXX: ARCH
} else if (!dest->indirect && dest->type->stype == Q__AGGREGATE) {
- assert(0); // TODO: memcpy
+ gen_copy(ctx, dest, src);
} else {
pushi(ctx->current, dest, Q_COPY, src, NULL);
}
@@ -389,11 +443,14 @@ gen_expr_call(struct gen_context *ctx,
while (carg) {
assert(!carg->variadic); // TODO
arg = *next = xcalloc(1, sizeof(struct qbe_arguments));
- gen_temp(ctx, &arg->value,
- qtype_for_type(ctx, carg->value->result, true),
- "arg.%d");
if (type_is_aggregate(carg->value->result)) {
+ alloc_temp(ctx, &arg->value,
+ carg->value->result, "arg.%d");
qval_address(&arg->value);
+ } else {
+ gen_temp(ctx, &arg->value,
+ qtype_for_type(ctx, carg->value->result, true),
+ "arg.%d");
}
gen_expression(ctx, carg->value, &arg->value);
carg = carg->next;
diff --git a/src/qbe.c b/src/qbe.c
@@ -10,21 +10,27 @@
const struct qbe_type
qbe_byte = {
.stype = Q_BYTE,
+ .size = 1,
},
qbe_half = {
.stype = Q_HALF,
+ .size = 2,
},
qbe_word = {
.stype = Q_WORD,
+ .size = 4,
},
qbe_long = {
.stype = Q_LONG,
+ .size = 8,
},
qbe_single = {
.stype = Q_SINGLE,
+ .size = 4,
},
qbe_double = {
.stype = Q_DOUBLE,
+ .size = 8,
},
qbe_void = {
.stype = Q__VOID,
