diff --git a/src/compiler/compile/render_dom/Renderer.ts b/src/compiler/compile/render_dom/Renderer.ts
index 058746d4e9..262297bd16 100644
--- a/src/compiler/compile/render_dom/Renderer.ts
+++ b/src/compiler/compile/render_dom/Renderer.ts
@@ -199,10 +199,10 @@ export default class Renderer {
 			? x`$$self.$$.dirty`
 			: x`#dirty`) as Identifier | MemberExpression;
 
-		const get_bitmask = () => names.reduce((bits, name) => {
+		const get_bitmask = () => names.reduce((bitmask, name) => {
 			const member = renderer.context_lookup.get(name);
 
-			if (!member) return bits;
+			if (!member) return bitmask;
 
 			if (member.index.value === -1) {
 				throw new Error(`unset index`);
@@ -210,12 +210,15 @@ export default class Renderer {
 
 			const value = member.index.value as number;
 			const i = (value / 31) | 0;
-			const j = 1 << (value % 31);
+			const n = 1 << (value % 31);
 
-			bits[i] |= j;
+			if (!bitmask[i]) bitmask[i] = { n: 0, names: [] };
 
-			return bits;
-		}, Array((this.context.length / 31) | 0).fill(0));
+			bitmask[i].n |= n;
+			bitmask[i].names.push(name);
+
+			return bitmask;
+		}, Array((this.context.length / 31) | 0).fill(null));
 
 		let operator;
 		let left;
@@ -233,14 +236,14 @@ export default class Renderer {
 
 				if (renderer.context_overflow) {
 					const expression = bitmask
-						.map((bits, i) => ({ bits, i }))
-						.filter(({ bits }) => bits)
-						.map(({ bits, i }) => x`${dirty}[${i}] & ${bits}`)
+						.map((b, i) => ({ b, i }))
+						.filter(({ b }) => b)
+						.map(({ b, i }) => x`${dirty}[${i}] & /* ${b.names.join(', ')} */ ${b.n}`)
 						.reduce((lhs, rhs) => x`${lhs} | ${rhs}`);
 
 					({ operator, left, right } = expression);
 				} else {
-					({ operator, left, right } = x`${dirty} & ${bitmask[0] || 0}` as BinaryExpression); // TODO the `|| 0` case should never apply
+					({ operator, left, right } = x`${dirty} & /* ${names.join(', ')} */ ${bitmask[0] ? bitmask[0].n : 0}` as BinaryExpression); // TODO the `: 0` case should never apply
 				}
 
 				return 'BinaryExpression';
diff --git a/test/js/samples/action-custom-event-handler/expected.js b/test/js/samples/action-custom-event-handler/expected.js
index d21b16571d..2f863217b6 100644
--- a/test/js/samples/action-custom-event-handler/expected.js
+++ b/test/js/samples/action-custom-event-handler/expected.js
@@ -24,7 +24,7 @@ function create_fragment(ctx) {
 			foo_action = foo.call(null, button, ctx[1]) || ({});
 		},
 		p(ctx, [dirty]) {
-			if (is_function(foo_action.update) && dirty & 1) foo_action.update.call(null, ctx[1]);
+			if (is_function(foo_action.update) && dirty & /* _id9uocqrtmw00_1_ */ 1) foo_action.update.call(null, ctx[1]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/bind-open/expected.js b/test/js/samples/bind-open/expected.js
index e99c3bbd6b..a2bc78f5d9 100644
--- a/test/js/samples/bind-open/expected.js
+++ b/test/js/samples/bind-open/expected.js
@@ -28,7 +28,7 @@ function create_fragment(ctx) {
 			details.open = ctx[0];
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				details.open = ctx[0];
 			}
 		},
diff --git a/test/js/samples/capture-inject-dev-only/expected.js b/test/js/samples/capture-inject-dev-only/expected.js
index d3b175862d..fd5ee97ce3 100644
--- a/test/js/samples/capture-inject-dev-only/expected.js
+++ b/test/js/samples/capture-inject-dev-only/expected.js
@@ -38,9 +38,9 @@ function create_fragment(ctx) {
 			set_input_value(input, ctx[0]);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) set_data(t0, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data(t0, ctx[0]);
 
-			if (dirty & 1 && input.value !== ctx[0]) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && input.value !== ctx[0]) {
 				set_input_value(input, ctx[0]);
 			}
 		},
diff --git a/test/js/samples/collapses-text-around-comments/expected.js b/test/js/samples/collapses-text-around-comments/expected.js
index 9f2ab90797..59bf38e900 100644
--- a/test/js/samples/collapses-text-around-comments/expected.js
+++ b/test/js/samples/collapses-text-around-comments/expected.js
@@ -35,7 +35,7 @@ function create_fragment(ctx) {
 			append(p, t);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) set_data(t, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data(t, ctx[0]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/component-static-var/expected.js b/test/js/samples/component-static-var/expected.js
index 4785fc9527..f5ec221c02 100644
--- a/test/js/samples/component-static-var/expected.js
+++ b/test/js/samples/component-static-var/expected.js
@@ -48,10 +48,10 @@ function create_fragment(ctx) {
 		},
 		p(ctx, [dirty]) {
 			const bar_changes = {};
-			if (dirty & 1) bar_changes.x = ctx[0];
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) bar_changes.x = ctx[0];
 			bar.$set(bar_changes);
 
-			if (dirty & 1 && input.value !== ctx[0]) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && input.value !== ctx[0]) {
 				set_input_value(input, ctx[0]);
 			}
 		},
diff --git a/test/js/samples/component-store-access-invalidate/expected.js b/test/js/samples/component-store-access-invalidate/expected.js
index 639404b4bb..e1dae76e89 100644
--- a/test/js/samples/component-store-access-invalidate/expected.js
+++ b/test/js/samples/component-store-access-invalidate/expected.js
@@ -29,7 +29,7 @@ function create_fragment(ctx) {
 			append(h1, t);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) set_data(t, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data(t, ctx[0]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/component-store-reassign-invalidate/expected.js b/test/js/samples/component-store-reassign-invalidate/expected.js
index 9876626cf9..ff30f3a2a8 100644
--- a/test/js/samples/component-store-reassign-invalidate/expected.js
+++ b/test/js/samples/component-store-reassign-invalidate/expected.js
@@ -40,7 +40,7 @@ function create_fragment(ctx) {
 			insert(target, button, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 2) set_data(t0, ctx[1]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 2) set_data(t0, ctx[1]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/data-attribute/expected.js b/test/js/samples/data-attribute/expected.js
index d7edc739e8..424799fdf3 100644
--- a/test/js/samples/data-attribute/expected.js
+++ b/test/js/samples/data-attribute/expected.js
@@ -30,7 +30,7 @@ function create_fragment(ctx) {
 			insert(target, div1, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				attr(div1, "data-foo", ctx[0]);
 			}
 		},
diff --git a/test/js/samples/debug-empty/expected.js b/test/js/samples/debug-empty/expected.js
index 0f55de4df9..8865fb332e 100644
--- a/test/js/samples/debug-empty/expected.js
+++ b/test/js/samples/debug-empty/expected.js
@@ -45,7 +45,7 @@ function create_fragment(ctx) {
 			insert_dev(target, t3, anchor);
 		},
 		p: function update(ctx, [dirty]) {
-			if (dirty & 1) set_data_dev(t1, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data_dev(t1, ctx[0]);
 			debugger;
 		},
 		i: noop,
diff --git a/test/js/samples/debug-foo-bar-baz-things/expected.js b/test/js/samples/debug-foo-bar-baz-things/expected.js
index 11ff13bb46..0dfe1a0829 100644
--- a/test/js/samples/debug-foo-bar-baz-things/expected.js
+++ b/test/js/samples/debug-foo-bar-baz-things/expected.js
@@ -54,9 +54,9 @@ function create_each_block(ctx) {
 			insert_dev(target, t1, anchor);
 		},
 		p: function update(ctx, dirty) {
-			if (dirty & 1 && t0_value !== (t0_value = ctx[4].name + "")) set_data_dev(t0, t0_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t0_value !== (t0_value = ctx[4].name + "")) set_data_dev(t0, t0_value);
 
-			if (dirty & 15) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 15) {
 				const foo = ctx[1];
 				const bar = ctx[2];
 				const baz = ctx[3];
@@ -120,7 +120,7 @@ function create_fragment(ctx) {
 			append_dev(p, t2);
 		},
 		p: function update(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				each_value = ctx[0];
 				let i;
 
@@ -143,7 +143,7 @@ function create_fragment(ctx) {
 				each_blocks.length = each_value.length;
 			}
 
-			if (dirty & 2) set_data_dev(t2, ctx[1]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 2) set_data_dev(t2, ctx[1]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/debug-foo/expected.js b/test/js/samples/debug-foo/expected.js
index a2b19de8cd..21fe13073e 100644
--- a/test/js/samples/debug-foo/expected.js
+++ b/test/js/samples/debug-foo/expected.js
@@ -51,9 +51,9 @@ function create_each_block(ctx) {
 			insert_dev(target, t1, anchor);
 		},
 		p: function update(ctx, dirty) {
-			if (dirty & 1 && t0_value !== (t0_value = ctx[2].name + "")) set_data_dev(t0, t0_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t0_value !== (t0_value = ctx[2].name + "")) set_data_dev(t0, t0_value);
 
-			if (dirty & 2) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 2) {
 				const foo = ctx[1];
 				console.log({ foo });
 				debugger;
@@ -114,7 +114,7 @@ function create_fragment(ctx) {
 			append_dev(p, t2);
 		},
 		p: function update(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				each_value = ctx[0];
 				let i;
 
@@ -137,7 +137,7 @@ function create_fragment(ctx) {
 				each_blocks.length = each_value.length;
 			}
 
-			if (dirty & 2) set_data_dev(t2, ctx[1]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 2) set_data_dev(t2, ctx[1]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/debug-hoisted/expected.js b/test/js/samples/debug-hoisted/expected.js
index 37b983c8cc..324c02e2c5 100644
--- a/test/js/samples/debug-hoisted/expected.js
+++ b/test/js/samples/debug-hoisted/expected.js
@@ -24,7 +24,7 @@ function create_fragment(ctx) {
 		},
 		m: noop,
 		p: function update(ctx, [dirty]) {
-			if (dirty & 3) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 3) {
 				const obj = ctx[0];
 				const kobzol = ctx[1];
 				console.log({ obj, kobzol });
diff --git a/test/js/samples/debug-no-dependencies/expected.js b/test/js/samples/debug-no-dependencies/expected.js
index 28c5b35dc5..1c1835292c 100644
--- a/test/js/samples/debug-no-dependencies/expected.js
+++ b/test/js/samples/debug-no-dependencies/expected.js
@@ -89,7 +89,7 @@ function create_fragment(ctx) {
 			insert_dev(target, each_1_anchor, anchor);
 		},
 		p: function update(ctx, [dirty]) {
-			if (dirty & 0) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 0) {
 				each_value = things;
 				let i;
 
diff --git a/test/js/samples/deconflict-builtins/expected.js b/test/js/samples/deconflict-builtins/expected.js
index 9e4763be65..5436bbefcf 100644
--- a/test/js/samples/deconflict-builtins/expected.js
+++ b/test/js/samples/deconflict-builtins/expected.js
@@ -36,7 +36,7 @@ function create_each_block(ctx) {
 			append(span, t);
 		},
 		p(ctx, dirty) {
-			if (dirty & 1 && t_value !== (t_value = ctx[1] + "")) set_data(t, t_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t_value !== (t_value = ctx[1] + "")) set_data(t, t_value);
 		},
 		d(detaching) {
 			if (detaching) detach(span);
@@ -69,7 +69,7 @@ function create_fragment(ctx) {
 			insert(target, each_1_anchor, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				each_value = ctx[0];
 				let i;
 
diff --git a/test/js/samples/dev-warning-missing-data-computed/expected.js b/test/js/samples/dev-warning-missing-data-computed/expected.js
index c18817c812..c5050dc4b6 100644
--- a/test/js/samples/dev-warning-missing-data-computed/expected.js
+++ b/test/js/samples/dev-warning-missing-data-computed/expected.js
@@ -42,8 +42,8 @@ function create_fragment(ctx) {
 			append_dev(p, t2);
 		},
 		p: function update(ctx, [dirty]) {
-			if (dirty & 1 && t0_value !== (t0_value = Math.max(0, ctx[0]) + "")) set_data_dev(t0, t0_value);
-			if (dirty & 2) set_data_dev(t2, ctx[1]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t0_value !== (t0_value = Math.max(0, ctx[0]) + "")) set_data_dev(t0, t0_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 2) set_data_dev(t2, ctx[1]);
 		},
 		i: noop,
 		o: noop,
@@ -86,7 +86,7 @@ function instance($$self, $$props, $$invalidate) {
 	};
 
 	$$self.$$.update = () => {
-		if ($$self.$$.dirty & 1) {
+		if ($$self.$$.dirty & /* _id9uocqrtmw00_1_ */ 1) {
 			$: $$invalidate(1, bar = foo * 2);
 		}
 	};
diff --git a/test/js/samples/each-block-array-literal/expected.js b/test/js/samples/each-block-array-literal/expected.js
index b47b1cca95..ee0c9a3b4e 100644
--- a/test/js/samples/each-block-array-literal/expected.js
+++ b/test/js/samples/each-block-array-literal/expected.js
@@ -36,7 +36,7 @@ function create_each_block(ctx) {
 			append(span, t);
 		},
 		p(ctx, dirty) {
-			if (dirty & 31 && t_value !== (t_value = ctx[5] + "")) set_data(t, t_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 31 && t_value !== (t_value = ctx[5] + "")) set_data(t, t_value);
 		},
 		d(detaching) {
 			if (detaching) detach(span);
@@ -69,7 +69,7 @@ function create_fragment(ctx) {
 			insert(target, each_1_anchor, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 31) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 31) {
 				each_value = [ctx[0], ctx[1], ctx[2], ctx[3], ctx[4]];
 				let i;
 
diff --git a/test/js/samples/each-block-changed-check/expected.js b/test/js/samples/each-block-changed-check/expected.js
index f98c738203..aed0fae12a 100644
--- a/test/js/samples/each-block-changed-check/expected.js
+++ b/test/js/samples/each-block-changed-check/expected.js
@@ -70,9 +70,9 @@ function create_each_block(ctx) {
 			html_tag.m(div);
 		},
 		p(ctx, dirty) {
-			if (dirty & 1 && t2_value !== (t2_value = ctx[4].author + "")) set_data(t2, t2_value);
-			if (dirty & 7 && t4_value !== (t4_value = ctx[1](ctx[4].time, ctx[2]) + "")) set_data(t4, t4_value);
-			if (dirty & 1 && raw_value !== (raw_value = ctx[4].html + "")) html_tag.p(raw_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t2_value !== (t2_value = ctx[4].author + "")) set_data(t2, t2_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 7 && t4_value !== (t4_value = ctx[1](ctx[4].time, ctx[2]) + "")) set_data(t4, t4_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && raw_value !== (raw_value = ctx[4].html + "")) html_tag.p(raw_value);
 		},
 		d(detaching) {
 			if (detaching) detach(div);
@@ -111,7 +111,7 @@ function create_fragment(ctx) {
 			append(p, t1);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 7) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 7) {
 				each_value = ctx[0];
 				let i;
 
@@ -134,7 +134,7 @@ function create_fragment(ctx) {
 				each_blocks.length = each_value.length;
 			}
 
-			if (dirty & 8) set_data(t1, ctx[3]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 8) set_data(t1, ctx[3]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/each-block-keyed-animated/expected.js b/test/js/samples/each-block-keyed-animated/expected.js
index 4aa238963f..7ffde4a8b8 100644
--- a/test/js/samples/each-block-keyed-animated/expected.js
+++ b/test/js/samples/each-block-keyed-animated/expected.js
@@ -44,7 +44,7 @@ function create_each_block(key_1, ctx) {
 			append(div, t);
 		},
 		p(ctx, dirty) {
-			if (dirty & 1 && t_value !== (t_value = ctx[1].name + "")) set_data(t, t_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t_value !== (t_value = ctx[1].name + "")) set_data(t, t_value);
 		},
 		r() {
 			rect = div.getBoundingClientRect();
diff --git a/test/js/samples/each-block-keyed/expected.js b/test/js/samples/each-block-keyed/expected.js
index aa949e95b9..23b294afd9 100644
--- a/test/js/samples/each-block-keyed/expected.js
+++ b/test/js/samples/each-block-keyed/expected.js
@@ -40,7 +40,7 @@ function create_each_block(key_1, ctx) {
 			append(div, t);
 		},
 		p(ctx, dirty) {
-			if (dirty & 1 && t_value !== (t_value = ctx[1].name + "")) set_data(t, t_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t_value !== (t_value = ctx[1].name + "")) set_data(t, t_value);
 		},
 		d(detaching) {
 			if (detaching) detach(div);
diff --git a/test/js/samples/event-handler-dynamic/expected.js b/test/js/samples/event-handler-dynamic/expected.js
index adf88c5e08..4d1e9eb6b6 100644
--- a/test/js/samples/event-handler-dynamic/expected.js
+++ b/test/js/samples/event-handler-dynamic/expected.js
@@ -63,7 +63,7 @@ function create_fragment(ctx) {
 		},
 		p(new_ctx, [dirty]) {
 			ctx = new_ctx;
-			if (dirty & 2) set_data(t4, ctx[1]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 2) set_data(t4, ctx[1]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/inline-style-optimized-multiple/expected.js b/test/js/samples/inline-style-optimized-multiple/expected.js
index f9ff9721ba..6af193263a 100644
--- a/test/js/samples/inline-style-optimized-multiple/expected.js
+++ b/test/js/samples/inline-style-optimized-multiple/expected.js
@@ -23,11 +23,11 @@ function create_fragment(ctx) {
 			insert(target, div, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				set_style(div, "color", ctx[0]);
 			}
 
-			if (dirty & 6) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 6) {
 				set_style(div, "transform", "translate(" + ctx[1] + "px," + ctx[2] + "px)");
 			}
 		},
diff --git a/test/js/samples/inline-style-optimized-url/expected.js b/test/js/samples/inline-style-optimized-url/expected.js
index 806ced193f..627f22d693 100644
--- a/test/js/samples/inline-style-optimized-url/expected.js
+++ b/test/js/samples/inline-style-optimized-url/expected.js
@@ -22,7 +22,7 @@ function create_fragment(ctx) {
 			insert(target, div, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				set_style(div, "background", "url(data:image/png;base64," + ctx[0] + ")");
 			}
 		},
diff --git a/test/js/samples/inline-style-optimized/expected.js b/test/js/samples/inline-style-optimized/expected.js
index d3f8e789be..948735aace 100644
--- a/test/js/samples/inline-style-optimized/expected.js
+++ b/test/js/samples/inline-style-optimized/expected.js
@@ -22,7 +22,7 @@ function create_fragment(ctx) {
 			insert(target, div, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				set_style(div, "color", ctx[0]);
 			}
 		},
diff --git a/test/js/samples/inline-style-unoptimized/expected.js b/test/js/samples/inline-style-unoptimized/expected.js
index 48da85ede9..5d55aa84f2 100644
--- a/test/js/samples/inline-style-unoptimized/expected.js
+++ b/test/js/samples/inline-style-unoptimized/expected.js
@@ -31,11 +31,11 @@ function create_fragment(ctx) {
 			insert(target, div1, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				attr(div0, "style", ctx[0]);
 			}
 
-			if (dirty & 6 && div1_style_value !== (div1_style_value = "" + (ctx[1] + ": " + ctx[2]))) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 6 && div1_style_value !== (div1_style_value = "" + (ctx[1] + ": " + ctx[2]))) {
 				attr(div1, "style", div1_style_value);
 			}
 		},
diff --git a/test/js/samples/input-no-initial-value/expected.js b/test/js/samples/input-no-initial-value/expected.js
index 0ac875a15a..24e2ede21f 100644
--- a/test/js/samples/input-no-initial-value/expected.js
+++ b/test/js/samples/input-no-initial-value/expected.js
@@ -41,7 +41,7 @@ function create_fragment(ctx) {
 			append(form, button);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1 && input.value !== ctx[0]) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && input.value !== ctx[0]) {
 				set_input_value(input, ctx[0]);
 			}
 		},
diff --git a/test/js/samples/input-range/expected.js b/test/js/samples/input-range/expected.js
index 4693a0b707..38ce1087dc 100644
--- a/test/js/samples/input-range/expected.js
+++ b/test/js/samples/input-range/expected.js
@@ -29,7 +29,7 @@ function create_fragment(ctx) {
 			set_input_value(input, ctx[0]);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				set_input_value(input, ctx[0]);
 			}
 		},
diff --git a/test/js/samples/input-without-blowback-guard/expected.js b/test/js/samples/input-without-blowback-guard/expected.js
index 5a730a6973..02b3463be1 100644
--- a/test/js/samples/input-without-blowback-guard/expected.js
+++ b/test/js/samples/input-without-blowback-guard/expected.js
@@ -26,7 +26,7 @@ function create_fragment(ctx) {
 			input.checked = ctx[0];
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) {
 				input.checked = ctx[0];
 			}
 		},
diff --git a/test/js/samples/instrumentation-script-if-no-block/expected.js b/test/js/samples/instrumentation-script-if-no-block/expected.js
index 74d9ab46b8..893c331b44 100644
--- a/test/js/samples/instrumentation-script-if-no-block/expected.js
+++ b/test/js/samples/instrumentation-script-if-no-block/expected.js
@@ -40,7 +40,7 @@ function create_fragment(ctx) {
 			append(p, t3);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) set_data(t3, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data(t3, ctx[0]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/instrumentation-script-x-equals-x/expected.js b/test/js/samples/instrumentation-script-x-equals-x/expected.js
index 0a1e271cbe..4b3f7a2c2d 100644
--- a/test/js/samples/instrumentation-script-x-equals-x/expected.js
+++ b/test/js/samples/instrumentation-script-x-equals-x/expected.js
@@ -41,7 +41,7 @@ function create_fragment(ctx) {
 			append(p, t3);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1 && t3_value !== (t3_value = ctx[0].length + "")) set_data(t3, t3_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t3_value !== (t3_value = ctx[0].length + "")) set_data(t3, t3_value);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/instrumentation-template-if-no-block/expected.js b/test/js/samples/instrumentation-template-if-no-block/expected.js
index 4452b54aac..291fc9aa33 100644
--- a/test/js/samples/instrumentation-template-if-no-block/expected.js
+++ b/test/js/samples/instrumentation-template-if-no-block/expected.js
@@ -40,7 +40,7 @@ function create_fragment(ctx) {
 			append(p, t3);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) set_data(t3, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data(t3, ctx[0]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/instrumentation-template-x-equals-x/expected.js b/test/js/samples/instrumentation-template-x-equals-x/expected.js
index 474d78ca7c..b3e5f59ea3 100644
--- a/test/js/samples/instrumentation-template-x-equals-x/expected.js
+++ b/test/js/samples/instrumentation-template-x-equals-x/expected.js
@@ -41,7 +41,7 @@ function create_fragment(ctx) {
 			append(p, t3);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1 && t3_value !== (t3_value = ctx[0].length + "")) set_data(t3, t3_value);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && t3_value !== (t3_value = ctx[0].length + "")) set_data(t3, t3_value);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/media-bindings/expected.js b/test/js/samples/media-bindings/expected.js
index dcca20b248..b5b8450216 100644
--- a/test/js/samples/media-bindings/expected.js
+++ b/test/js/samples/media-bindings/expected.js
@@ -68,19 +68,19 @@ function create_fragment(ctx) {
 			}
 		},
 		p(ctx, [dirty]) {
-			if (!audio_updating && dirty & 8 && !isNaN(ctx[3])) {
+			if (!audio_updating && dirty & /* _id9uocqrtmw00_1_ */ 8 && !isNaN(ctx[3])) {
 				audio.currentTime = ctx[3];
 			}
 
-			if (dirty & 32 && audio_is_paused !== (audio_is_paused = ctx[5])) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 32 && audio_is_paused !== (audio_is_paused = ctx[5])) {
 				audio[audio_is_paused ? "pause" : "play"]();
 			}
 
-			if (dirty & 64 && !isNaN(ctx[6])) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 64 && !isNaN(ctx[6])) {
 				audio.volume = ctx[6];
 			}
 
-			if (dirty & 128 && !isNaN(ctx[7])) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 128 && !isNaN(ctx[7])) {
 				audio.playbackRate = ctx[7];
 			}
 
diff --git a/test/js/samples/reactive-values-non-topologically-ordered/expected.js b/test/js/samples/reactive-values-non-topologically-ordered/expected.js
index a98e81293f..2c1f2ace9f 100644
--- a/test/js/samples/reactive-values-non-topologically-ordered/expected.js
+++ b/test/js/samples/reactive-values-non-topologically-ordered/expected.js
@@ -11,11 +11,11 @@ function instance($$self, $$props, $$invalidate) {
 	};
 
 	$$self.$$.update = () => {
-		if ($$self.$$.dirty & 1) {
+		if ($$self.$$.dirty & /* _id9uocqrtmw00_1_ */ 1) {
 			$: $$invalidate(2, b = x);
 		}
 
-		if ($$self.$$.dirty & 4) {
+		if ($$self.$$.dirty & /* _id9uocqrtmw00_1_ */ 4) {
 			$: a = b;
 		}
 	};
diff --git a/test/js/samples/reactive-values-non-writable-dependencies/expected.js b/test/js/samples/reactive-values-non-writable-dependencies/expected.js
index 9c29f8510e..a12d9cb697 100644
--- a/test/js/samples/reactive-values-non-writable-dependencies/expected.js
+++ b/test/js/samples/reactive-values-non-writable-dependencies/expected.js
@@ -11,7 +11,7 @@ function instance($$self, $$props, $$invalidate) {
 	};
 
 	$$self.$$.update = () => {
-		if ($$self.$$.dirty & 3) {
+		if ($$self.$$.dirty & /* _id9uocqrtmw00_1_ */ 3) {
 			$: console.log("max", Math.max(a, b));
 		}
 	};
diff --git a/test/js/samples/select-dynamic-value/expected.js b/test/js/samples/select-dynamic-value/expected.js
index 8f309aaed2..44e343c5ef 100644
--- a/test/js/samples/select-dynamic-value/expected.js
+++ b/test/js/samples/select-dynamic-value/expected.js
@@ -44,7 +44,7 @@ function create_fragment(ctx) {
 			}
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1 && select_value_value !== (select_value_value = ctx[0])) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && select_value_value !== (select_value_value = ctx[0])) {
 				for (var i = 0; i < select.options.length; i += 1) {
 					var option = select.options[i];
 
diff --git a/test/js/samples/src-attribute-check/expected.js b/test/js/samples/src-attribute-check/expected.js
index ab73564ab3..7d04c4a350 100644
--- a/test/js/samples/src-attribute-check/expected.js
+++ b/test/js/samples/src-attribute-check/expected.js
@@ -45,11 +45,11 @@ function create_fragment(ctx) {
 			insert(target, img1, anchor);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1 && img0.src !== (img0_src_value = ctx[0])) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && img0.src !== (img0_src_value = ctx[0])) {
 				attr(img0, "src", img0_src_value);
 			}
 
-			if (dirty & 2 && img1.src !== (img1_src_value = "" + (ctx[1] + ".jpg"))) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 2 && img1.src !== (img1_src_value = "" + (ctx[1] + ".jpg"))) {
 				attr(img1, "src", img1_src_value);
 			}
 		},
diff --git a/test/js/samples/title/expected.js b/test/js/samples/title/expected.js
index 3d29c496a4..3bc02f60c6 100644
--- a/test/js/samples/title/expected.js
+++ b/test/js/samples/title/expected.js
@@ -9,7 +9,7 @@ function create_fragment(ctx) {
 		c: noop,
 		m: noop,
 		p(ctx, [dirty]) {
-			if (dirty & 1 && title_value !== (title_value = "a " + ctx[0] + " title")) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && title_value !== (title_value = "a " + ctx[0] + " title")) {
 				document.title = title_value;
 			}
 		},
diff --git a/test/js/samples/unchanged-expression/expected.js b/test/js/samples/unchanged-expression/expected.js
index eee0079a71..0c0b779270 100644
--- a/test/js/samples/unchanged-expression/expected.js
+++ b/test/js/samples/unchanged-expression/expected.js
@@ -57,7 +57,7 @@ function create_fragment(ctx) {
 			append(p3, t9);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) set_data(t9, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data(t9, ctx[0]);
 		},
 		i: noop,
 		o: noop,
diff --git a/test/js/samples/unreferenced-state-not-invalidated/expected.js b/test/js/samples/unreferenced-state-not-invalidated/expected.js
index 5fa679aecf..c0f6da2928 100644
--- a/test/js/samples/unreferenced-state-not-invalidated/expected.js
+++ b/test/js/samples/unreferenced-state-not-invalidated/expected.js
@@ -28,7 +28,7 @@ function create_fragment(ctx) {
 			append(p, t);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1) set_data(t, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data(t, ctx[0]);
 		},
 		i: noop,
 		o: noop,
@@ -58,7 +58,7 @@ function instance($$self, $$props, $$invalidate) {
 	let y;
 
 	$$self.$$.update = () => {
-		if ($$self.$$.dirty & 2) {
+		if ($$self.$$.dirty & /* _id9uocqrtmw00_1_ */ 2) {
 			$: $$invalidate(0, y = b * 2);
 		}
 	};
diff --git a/test/js/samples/video-bindings/expected.js b/test/js/samples/video-bindings/expected.js
index 4149d95059..71ab2c545d 100644
--- a/test/js/samples/video-bindings/expected.js
+++ b/test/js/samples/video-bindings/expected.js
@@ -48,7 +48,7 @@ function create_fragment(ctx) {
 			video_resize_listener = add_resize_listener(video, ctx[4].bind(video));
 		},
 		p(ctx, [dirty]) {
-			if (!video_updating && dirty & 1 && !isNaN(ctx[0])) {
+			if (!video_updating && dirty & /* _id9uocqrtmw00_1_ */ 1 && !isNaN(ctx[0])) {
 				video.currentTime = ctx[0];
 			}
 
diff --git a/test/js/samples/window-binding-scroll/expected.js b/test/js/samples/window-binding-scroll/expected.js
index 886c065333..11e7160646 100644
--- a/test/js/samples/window-binding-scroll/expected.js
+++ b/test/js/samples/window-binding-scroll/expected.js
@@ -47,14 +47,14 @@ function create_fragment(ctx) {
 			append(p, t1);
 		},
 		p(ctx, [dirty]) {
-			if (dirty & 1 && !scrolling) {
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1 && !scrolling) {
 				scrolling = true;
 				clearTimeout(scrolling_timeout);
 				scrollTo(window.pageXOffset, ctx[0]);
 				scrolling_timeout = setTimeout(clear_scrolling, 100);
 			}
 
-			if (dirty & 1) set_data(t1, ctx[0]);
+			if (dirty & /* _id9uocqrtmw00_1_ */ 1) set_data(t1, ctx[0]);
 		},
 		i: noop,
 		o: noop,