diff --git a/core/math.odin b/core/math.odin
index 7ff245651..dc8b26b3b 100644
--- a/core/math.odin
+++ b/core/math.odin
@@ -319,15 +319,14 @@ look_at :: proc(eye, centre, up: Vec3) -> Mat4 {
 	s := norm(cross(f, up));
 	u := cross(s, f);
 
-	m: Mat4;
-
-	m[0] = [4]f32{+s.x, +s.y, +s.z, 0};
-	m[1] = [4]f32{+u.x, +u.y, +u.z, 0};
-	m[2] = [4]f32{-f.x, -f.y, -f.z, 0};
-	m[3] = [4]f32{dot(s, eye), dot(u, eye), dot(f, eye), 1};
-
-	return m;
+	return Mat4{
+		{+s.x, +u.x, -f.x, 0},
+		{+s.y, +u.y, -f.y, 0},
+		{+s.z, +u.z, -f.z, 0},
+		{-dot(s, eye), -dot(u, eye), dot(f, eye), 1},
+	};
 }
+
 perspective :: proc(fovy, aspect, near, far: f32) -> Mat4 {
 	m: Mat4;
 	tan_half_fovy := tan(0.5 * fovy);
diff --git a/src/check_expr.c b/src/check_expr.c
index db31c25ec..dc98b1bc7 100644
--- a/src/check_expr.c
+++ b/src/check_expr.c
@@ -3345,10 +3345,15 @@ bool check_builtin_procedure(Checker *c, Operand *operand, AstNode *call, i32 id
 		}
 	}
 
+	bool vari_expand = (ce->ellipsis.pos.line != 0);
+	if (vari_expand && id != BuiltinProc_append) {
+		error(ce->ellipsis, "Invalid use of `..` with built-in procedure `append`");
+		return false;
+	}
+
 
 	switch (id) {
 	case BuiltinProc_new:
-	// case BuiltinProc_new_slice:
 	case BuiltinProc_make:
 	case BuiltinProc_size_of:
 	case BuiltinProc_align_of:
@@ -4083,50 +4088,34 @@ bool check_builtin_procedure(Checker *c, Operand *operand, AstNode *call, i32 id
 		check_expr(c, &z, ce->args.e[2]); if (z.mode == Addressing_Invalid) return false;
 		check_expr(c, &w, ce->args.e[3]); if (w.mode == Addressing_Invalid) return false;
 
-		convert_to_typed(c, &x, y.type, 0); if (x.mode == Addressing_Invalid) return false;
-		convert_to_typed(c, &x, z.type, 0); if (x.mode == Addressing_Invalid) return false;
-		convert_to_typed(c, &x, w.type, 0); if (x.mode == Addressing_Invalid) return false;
-
-		convert_to_typed(c, &y, z.type, 0); if (y.mode == Addressing_Invalid) return false;
-		convert_to_typed(c, &y, w.type, 0); if (y.mode == Addressing_Invalid) return false;
-		convert_to_typed(c, &y, x.type, 0); if (y.mode == Addressing_Invalid) return false;
-
-		convert_to_typed(c, &z, y.type, 0); if (z.mode == Addressing_Invalid) return false;
-		convert_to_typed(c, &z, w.type, 0); if (z.mode == Addressing_Invalid) return false;
-		convert_to_typed(c, &z, x.type, 0); if (z.mode == Addressing_Invalid) return false;
-
-		convert_to_typed(c, &w, x.type, 0); if (w.mode == Addressing_Invalid) return false;
-		convert_to_typed(c, &w, y.type, 0); if (w.mode == Addressing_Invalid) return false;
-		convert_to_typed(c, &w, z.type, 0); if (w.mode == Addressing_Invalid) return false;
+#define _QUAT_CTT(x, y, z, w) do { \
+		convert_to_typed(c, &(x), (y).type, 0); if ((x).mode == Addressing_Invalid) return false; \
+		convert_to_typed(c, &(x), (z).type, 0); if ((x).mode == Addressing_Invalid) return false; \
+		convert_to_typed(c, &(x), (w).type, 0); if ((x).mode == Addressing_Invalid) return false; \
+	} while (0)
+		_QUAT_CTT(x, y, z, w);
+		_QUAT_CTT(y, z, w, x);
+		_QUAT_CTT(z, w, x, y);
+		_QUAT_CTT(w, x, y, z);
+#undef _QUAT_CTT
 
 		if (x.mode == Addressing_Constant &&
 		    y.mode == Addressing_Constant &&
 		    z.mode == Addressing_Constant &&
 		    w.mode == Addressing_Constant) {
-			if (is_type_numeric(x.type) &&
-			    exact_value_imag(x.value).value_float == 0 &&
-			    exact_value_jmag(x.value).value_float == 0 &&
-			    exact_value_kmag(x.value).value_float == 0) {
-				x.type = t_untyped_float;
-			}
-			if (is_type_numeric(y.type) &&
-			    exact_value_imag(y.value).value_float == 0 &&
-			    exact_value_jmag(y.value).value_float == 0 &&
-			    exact_value_kmag(y.value).value_float == 0) {
-				y.type = t_untyped_float;
-			}
-			if (is_type_numeric(z.type) &&
-			    exact_value_imag(z.value).value_float == 0 &&
-			    exact_value_jmag(z.value).value_float == 0 &&
-			    exact_value_kmag(z.value).value_float == 0) {
-				z.type = t_untyped_float;
-			}
-			if (is_type_numeric(w.type) &&
-			    exact_value_imag(w.value).value_float == 0 &&
-			    exact_value_jmag(w.value).value_float == 0 &&
-			    exact_value_kmag(w.value).value_float == 0) {
-				w.type = t_untyped_float;
-			}
+#define _QUAT_EXACT_VAL(x) do { \
+			if (is_type_numeric((x).type) && \
+			    exact_value_imag((x).value).value_float == 0 && \
+			    exact_value_jmag((x).value).value_float == 0 && \
+			    exact_value_kmag((x).value).value_float == 0) { \
+				(x).type = t_untyped_float; \
+			} \
+		} while (0)
+		_QUAT_EXACT_VAL(x);
+		_QUAT_EXACT_VAL(y);
+		_QUAT_EXACT_VAL(z);
+		_QUAT_EXACT_VAL(w);
+#undef _QUAT_EXACT_VAL
 		}
 
 		if (!are_types_identical(x.type, y.type)) {
diff --git a/src/check_stmt.c b/src/check_stmt.c
index 2d25e88a9..619431907 100644
--- a/src/check_stmt.c
+++ b/src/check_stmt.c
@@ -918,6 +918,14 @@ void check_stmt_internal(Checker *c, AstNode *node, u32 flags) {
 				}
 			}
 
+			if (x.mode != Addressing_Constant) {
+				x.value = (ExactValue){0};
+			}
+			if (y.mode != Addressing_Constant) {
+				y.value = (ExactValue){0};
+			}
+
+
 			add_type_and_value(&c->info, ie->left,  x.mode, x.type, x.value);
 			add_type_and_value(&c->info, ie->right, y.mode, y.type, y.value);
 			val = type;
diff --git a/src/ir.c b/src/ir.c
index 54d193b2f..ab1321bb4 100644
--- a/src/ir.c
+++ b/src/ir.c
@@ -673,8 +673,11 @@ bool ir_is_instr_terminating(irInstr *i) {
 
 
 void ir_add_edge(irBlock *from, irBlock *to) {
-	array_add(&from->succs, to);
-	array_add(&to->preds, from);
+	GB_ASSERT(from->instrs.count > 0);
+	if (!ir_is_instr_terminating(ir_get_last_instr(from))) {
+		array_add(&from->succs, to);
+		array_add(&to->preds, from);
+	}
 }
 
 void ir_set_instr_parent(irValue *instr, irBlock *parent) {
@@ -1812,14 +1815,15 @@ irValue *ir_emit_unary_arith(irProcedure *proc, TokenKind op, irValue *x, Type *
 	return ir_emit(proc, ir_instr_unary_op(proc, op, x, type));
 }
 
+
+
 irValue *ir_emit_arith(irProcedure *proc, TokenKind op, irValue *left, irValue *right, Type *type) {
 	Type *t_left = ir_type(left);
 	Type *t_right = ir_type(right);
 
-	if (is_type_vector(t_left)) {
+	if (is_type_vector(t_left) || is_type_vector(t_right)) {
 		ir_emit_comment(proc, str_lit("vector.arith.begin"));
 		// IMPORTANT TODO(bill): This is very wasteful with regards to stack memory
-		Type *tl = base_type(t_left);
 		left  = ir_emit_conv(proc, left, type);
 		right = ir_emit_conv(proc, right, type);
 		irValue *lhs = ir_address_from_load_or_generate_local(proc, left);
@@ -1828,7 +1832,8 @@ irValue *ir_emit_arith(irProcedure *proc, TokenKind op, irValue *left, irValue *
 		Type *elem_type = base_type(type)->Vector.elem;
 
 		irValue *res = ir_add_local_generated(proc, type);
-		for (i32 i = 0; i < tl->Vector.count; i++) {
+		i64 count = base_type(type)->Vector.count;
+		for (i32 i = 0; i < count; i++) {
 			irValue *x = ir_emit_load(proc, ir_emit_array_epi(proc, lhs, i));
 			irValue *y = ir_emit_load(proc, ir_emit_array_epi(proc, rhs, i));
 			irValue *z = ir_emit_arith(proc, op, x, y, elem_type);
@@ -5640,7 +5645,6 @@ void ir_build_range_string(irProcedure *proc, irValue *expr, Type *val_type,
 	done = ir_new_block(proc, NULL, "for.string.done");
 
 	irValue *offset = ir_emit_load(proc, offset_);
-
 	irValue *cond = ir_emit_comp(proc, Token_Lt, offset, count);
 	ir_emit_if(proc, cond, body, done);
 	ir_start_block(proc, body);
@@ -5696,7 +5700,6 @@ void ir_build_range_interval(irProcedure *proc, AstNodeBinaryExpr *node, Type *v
 	body = ir_new_block(proc, NULL, "for.interval.body");
 	done = ir_new_block(proc, NULL, "for.interval.done");
 
-	upper = ir_build_expr(proc, node->right);
 
 	TokenKind op = Token_Lt;
 	switch (node->op.kind) {
@@ -5704,6 +5707,9 @@ void ir_build_range_interval(irProcedure *proc, AstNodeBinaryExpr *node, Type *v
 	case Token_HalfClosed: op = Token_Lt;   break;
 	default: GB_PANIC("Invalid interval operator"); break;
 	}
+
+	upper = ir_build_expr(proc, node->right);
+
 	irValue *cond = ir_emit_comp(proc, op, ir_emit_load(proc, value), upper);
 	ir_emit_if(proc, cond, body, done);
 	ir_start_block(proc, body);
@@ -6222,7 +6228,6 @@ void ir_build_stmt_internal(irProcedure *proc, AstNode *node) {
 					GB_PANIC("TODO(bill): enum core type %s", type_to_string(core_elem));
 				}
 			}
-
 		} else {
 			Type *expr_type = type_of_expr(proc->module->info, rs->expr);
 			Type *et = base_type(type_deref(expr_type));
diff --git a/src/ir_print.c b/src/ir_print.c
index 237d50773..3d7b2e9d6 100644
--- a/src/ir_print.c
+++ b/src/ir_print.c
@@ -1060,7 +1060,7 @@ void ir_print_instr(irFileBuffer *f, irModule *m, irValue *value) {
 		irInstrBinaryOp *bo = &value->Instr.BinaryOp;
 		Type *type = base_type(ir_type(bo->left));
 		Type *elem_type = type;
-		GB_ASSERT(!is_type_vector(elem_type));
+		GB_ASSERT_MSG(!is_type_vector(elem_type), type_to_string(elem_type));
 
 		ir_fprintf(f, "%%%d = ", value->index);