Copy lvalues on multi-valued assignments to allow for `a, b = b, a` on large types (minor bodge)

1 files changed, 30 insertions, 2 deletions

diff --git a/src/tilde_stmt.cpp b/src/tilde_stmt.cpp
index c5aaa9161..6aa906288 100644
--- a/src/tilde_stmt.cpp
+++ b/src/tilde_stmt.cpp
@@ -850,11 +850,39 @@ gb_internal void cg_build_assignment(cgProcedure *p, Array<cgAddr> const &lvals,
 	p->in_multi_assignment = lval_count > 1;
 
 	GB_ASSERT(lvals.count == inits.count);
-	for_array(i, inits) {
+
+
+	if (inits.count > 1) for_array(i, inits) {
 		cgAddr lval = lvals[i];
+		cgValue init = cg_flatten_value(p, inits[i]);
+
+		GB_ASSERT(init.kind != cgValue_Multi);
+		if (init.type == nullptr) {
+			continue;
+		}
+
+	    	Type *type = cg_addr_type(lval);
+		GB_ASSERT(are_types_identical(type, init.type));
+		if (init.kind == cgValue_Addr &&
+		    !cg_addr_is_empty(lval)) {
+		    	// NOTE(bill): This is needed for certain constructs such as this:
+		    	// a, b = b, a
+		    	// NOTE(bill): This is a bodge and not necessarily a good way of doing things whatsoever
+		    	TB_CharUnits size  = cast(TB_CharUnits)type_size_of(type);
+		    	TB_CharUnits align = cast(TB_CharUnits)type_align_of(type);
+		    	TB_Node *copy = tb_inst_local(p->func, size, align);
+		    	tb_inst_memcpy(p->func, copy, init.node, tb_inst_uint(p->func, TB_TYPE_INT, size), align, false);
+		    	// use the copy instead
+		    	init.node = copy;
+		}
+		inits[i] = init;
+	}
+
+	for_array(i, inits) {
+		cgAddr  lval = lvals[i];
 		cgValue init = inits[i];
+		GB_ASSERT(init.kind != cgValue_Multi);
 		if (init.type == nullptr) {
-			// TODO(bill): figure out how to do this
 			continue;
 		}
 		cg_addr_store(p, lval, init);