feat: Limited support for the runtime ternary operator

apps/typegpu-docs/tests/individual-example-tests/game-of-life.test.ts

@@ -53,7 +53,7 @@ describe('game of life example', () => {
 
       fn wrappedCallback(x: u32, y: u32, _arg_2: u32) {
         randSeed2(((vec2f(f32(x), f32(y)) / f32(gameSizeUniform)) * timeUniform));
-        textureStore(next, vec2u(x, y), vec4u(u32(select(0, 1, (randFloat01() > 0.5f))), 0u, 0u, 0u));
+        textureStore(next, vec2u(x, y), vec4u(u32(select(0i, 1i, (randFloat01() > 0.5f))), 0u, 0u, 0u));
       }
 
       @compute @workgroup_size(16, 16, 1) fn mainCompute(@builtin(global_invocation_id) id: vec3u) {
@@ -146,7 +146,7 @@ describe('game of life example', () => {
         let current_1 = readTile(lx, ly);
         let neighbors = countNeighborsInTile(lx, ly);
         let nextAlive = golNextState((current_1 != 0u), neighbors);
-        textureStore(next, gid.xy, vec4u(u32(select(0, 1, nextAlive)), 0u, 0u, 0u));
+        textureStore(next, gid.xy, vec4u(u32(select(0i, 1i, nextAlive)), 0u, 0u, 0u));
       }
 
       @group(0) @binding(0) var<uniform> gameSizeUniform: u32;
@@ -199,7 +199,7 @@ describe('game of life example', () => {
         let current_1 = readTile(lx, ly);
         let neighbors = countNeighborsInTile(lx, ly);
         let nextAlive = golNextState((current_1 != 0u), neighbors);
-        textureStore(next, gid.xy, vec4u(u32(select(0, 1, nextAlive)), 0u, 0u, 0u));
+        textureStore(next, gid.xy, vec4u(u32(select(0i, 1i, nextAlive)), 0u, 0u, 0u));
       }
 
       struct fullScreenTriangle_Output {

apps/typegpu-docs/tests/individual-example-tests/jelly-switch.test.ts

@@ -390,7 +390,7 @@ describe('jelly switch example', () => {
         let ndc = vec2f(((_arg_0.uv.x * 2f) - 1f), -(((_arg_0.uv.y * 2f) - 1f)));
         let ray = getRay(ndc);
         let color = rayMarch(ray.origin, ray.direction, _arg_0.uv);
-        let exposure = select(1.5, 2., (darkModeUniform == 1u));
+        let exposure = select(1.5f, 2f, (darkModeUniform == 1u));
         return vec4f(tanh((color.rgb * exposure)), 1f);
       }
 

apps/typegpu-docs/tests/individual-example-tests/probability.test.ts

@@ -251,7 +251,7 @@ describe('probability distribution plot example', () => {
         let face = u32((sample() * 6f));
         let axis = (face % 3u);
         var result = vec3f();
-        result[axis] = f32(select(0, 1, (face > 2u)));
+        result[axis] = f32(select(0i, 1i, (face > 2u)));
         result[((axis + 1u) % 3u)] = sample();
         result[((axis + 2u) % 3u)] = sample();
         return result;

apps/typegpu-docs/tests/individual-example-tests/ripple-cube.test.ts

@@ -262,7 +262,7 @@ describe('ripple-cube example', () => {
         const cellSize = 0.0047169811320754715;
         let p = ((vec3f(f32(x), f32(y), f32(z)) + 0.5f) * cellSize);
         let r = (timeUniform * 0.15f);
-        let iterCount = select(5, 11, (extendedRippleUniform == 1u));
+        let iterCount = select(5i, 11i, (extendedRippleUniform == 1u));
         var shellD = 1e+10f;
         for (var ix = 0; (ix < iterCount); ix++) {
           for (var iy = 0; (iy < iterCount); iy++) {

packages/typegpu/src/core/function/createCallableSchema.ts

@@ -1,4 +1,10 @@
-import { type MapValueToSnippet, type ResolvedSnippet, snip } from '../../data/snippet.ts';
+import {
+  type MapValueToSnippet,
+  noSideEffects,
+  type ResolvedSnippet,
+  snip,
+  type Snippet,
+} from '../../data/snippet.ts';
 import { type BaseData, isPtr } from '../../data/wgslTypes.ts';
 import { setName } from '../../shared/meta.ts';
 import { $gpuCallable } from '../../shared/symbols.ts';
@@ -51,10 +57,11 @@ export function callableSchema<T extends AnyFn>(options: CallableSchemaOptions<T
         return tryConvertSnippet(ctx, s, argType, false);
       }) as MapValueToSnippet<Parameters<T>>;
 
+      let result: Snippet;
       if (converted.every((s) => isKnownAtComptime(s))) {
         ctx.pushMode(new NormalState());
         try {
-          return snip(
+          result = snip(
             options.normalImpl(...(converted.map((s) => s.value) as never[])),
             options.schema(),
             // Functions give up ownership of their return value
@@ -63,9 +70,14 @@ export function callableSchema<T extends AnyFn>(options: CallableSchemaOptions<T
         } finally {
           ctx.popMode('normal');
         }
+      } else {
+        result = options.codegenImpl(ctx, converted);
       }
 
-      return options.codegenImpl(ctx, converted);
+      if (!args.some((a) => a.possibleSideEffects)) {
+        return noSideEffects(result);
+      }
+      return result;
     },
   };
 

packages/typegpu/src/core/slot/accessor.ts

@@ -119,7 +119,7 @@ abstract class AccessorBase<
     try {
       // Doing a deep copy each time so that we don't have to deal with refs
       const cloned = schemaCallWrapper(this.schema, value);
-      return snip(cloned, this.schema, 'constant');
+      return snip(cloned, this.schema, 'constant', /* possibleSideEffects */ false);
     } finally {
       ctx.popMode('normal');
     }

packages/typegpu/src/data/snippet.ts

@@ -92,6 +92,7 @@ export interface Snippet {
    */
   readonly dataType: BaseData | UnknownData;
   readonly origin: Origin;
+  readonly possibleSideEffects: boolean;
 }
 
 export interface ResolvedSnippet extends Snippet {
@@ -105,11 +106,18 @@ class SnippetImpl implements Snippet {
   readonly value: unknown;
   readonly dataType: BaseData | UnknownData;
   readonly origin: Origin;
+  readonly possibleSideEffects: boolean;
 
-  constructor(value: unknown, dataType: BaseData | UnknownData, origin: Origin) {
+  constructor(
+    value: unknown,
+    dataType: BaseData | UnknownData,
+    origin: Origin,
+    possibleSideEffects: boolean,
+  ) {
     this.value = value;
     this.dataType = dataType;
     this.origin = origin;
+    this.possibleSideEffects = possibleSideEffects;
   }
 }
 
@@ -121,12 +129,23 @@ export function isSnippetNumeric(snippet: Snippet) {
   return isNumericSchema(snippet.dataType);
 }
 
-export function snip(value: string, dataType: BaseData, origin: Origin): ResolvedSnippet;
-export function snip(value: unknown, dataType: BaseData | UnknownData, origin: Origin): Snippet;
+export function snip(
+  value: string,
+  dataType: BaseData,
+  origin: Origin,
+  possibleSideEffects?: boolean,
+): ResolvedSnippet;
+export function snip(
+  value: unknown,
+  dataType: BaseData | UnknownData,
+  origin: Origin,
+  possibleSideEffects?: boolean,
+): Snippet;
 export function snip(
   value: unknown,
   dataType: BaseData | UnknownData,
   origin: Origin,
+  possibleSideEffects: boolean = true,
 ): Snippet | ResolvedSnippet {
   if (DEV && isSnippet(value)) {
     // An early error, but not worth checking every time in production
@@ -138,5 +157,30 @@ export function snip(
     // We don't care about attributes in snippet land, so we discard that information.
     undecorate(dataType as BaseData),
     origin,
+    possibleSideEffects,
   );
 }
+
+export function withDataType(
+  dataType: BaseData | UnknownData,
+  snippet: ResolvedSnippet,
+): ResolvedSnippet;
+export function withDataType(dataType: BaseData | UnknownData, snippet: Snippet): Snippet;
+export function withDataType(dataType: BaseData | UnknownData, snippet: Snippet): Snippet {
+  return new SnippetImpl(snippet.value, dataType, snippet.origin, snippet.possibleSideEffects);
+}
+
+export function withSideEffects(
+  possibleSideEffects: boolean,
+  snippet: ResolvedSnippet,
+): ResolvedSnippet;
+export function withSideEffects(possibleSideEffects: boolean, snippet: Snippet): Snippet;
+export function withSideEffects(possibleSideEffects: boolean, snippet: Snippet): Snippet {
+  return new SnippetImpl(snippet.value, snippet.dataType, snippet.origin, possibleSideEffects);
+}
+
+export function noSideEffects(snippet: ResolvedSnippet): ResolvedSnippet;
+export function noSideEffects(snippet: Snippet): Snippet;
+export function noSideEffects(snippet: Snippet): Snippet {
+  return withSideEffects(/* possibleSideEffects */ false, snippet);
+}

packages/typegpu/src/std/boolean.ts

@@ -1,8 +1,24 @@
 import { dualImpl } from '../core/function/dualImpl.ts';
 import { stitch } from '../core/resolve/stitch.ts';
-import { bool, f32 } from '../data/numeric.ts';
+import { bool, f16, f32, i32, u32 } from '../data/numeric.ts';
 import { isSnippetNumeric, snip } from '../data/snippet.ts';
-import { vec2b, vec3b, vec4b } from '../data/vector.ts';
+import {
+  vec2b,
+  vec2f,
+  vec2h,
+  vec2i,
+  vec2u,
+  vec3b,
+  vec3f,
+  vec3h,
+  vec3i,
+  vec3u,
+  vec4b,
+  vec4f,
+  vec4h,
+  vec4i,
+  vec4u,
+} from '../data/vector.ts';
 import { VectorOps } from '../data/vectorOps.ts';
 import {
   type AnyBooleanVecInstance,
@@ -374,6 +390,29 @@ function cpuSelect<T extends number | boolean | AnyVecInstance>(
   );
 }
 
+export const validSelectBranchTypes: AnyWgslData[] = [
+  f32,
+  f16,
+  i32,
+  u32,
+  bool,
+  vec2f,
+  vec3f,
+  vec4f,
+  vec2h,
+  vec3h,
+  vec4h,
+  vec2i,
+  vec3i,
+  vec4i,
+  vec2u,
+  vec3u,
+  vec4u,
+  vec2b,
+  vec3b,
+  vec4b,
+];
+
 /**
  * Returns `t` if `cond` is `true`, and `f` otherwise.
  * Component-wise if `cond` is a vector.
@@ -386,9 +425,27 @@ function cpuSelect<T extends number | boolean | AnyVecInstance>(
 export const select = dualImpl({
   name: 'select',
   signature: (f, t, cond) => {
-    const [uf, ut] = unify([f, t]) ?? ([f, t] as const);
+    const [uf, ut] = unify([f, t], validSelectBranchTypes) ?? ([f, t] as const);
     return { argTypes: [uf, ut, cond], returnType: uf };
   },
   normalImpl: cpuSelect,
-  codegenImpl: (_ctx, [f, t, cond]) => stitch`select(${f}, ${t}, ${cond})`,
+  codegenImpl: (ctx, [f, t, cond]) => {
+    const result = stitch`select(${f}, ${t}, ${cond})`;
+    if (
+      !validSelectBranchTypes.includes(f.dataType as AnyWgslData) ||
+      !validSelectBranchTypes.includes(t.dataType as AnyWgslData)
+    ) {
+      throw new Error(
+        `'${result}' is invalid, std.select requires both branches to be either scalars or vectors.`,
+      );
+    }
+    if (f.dataType !== t.dataType) {
+      const fStr = ctx.resolve(f.dataType);
+      const tStr = ctx.resolve(t.dataType);
+      throw new Error(
+        `'${result}' is invalid, std.select requires both branches to be the same type, got [${fStr.value}, ${tStr.value}].`,
+      );
+    }
+    return result;
+  },
 });

packages/typegpu/src/tgsl/accessIndex.ts

@@ -1,7 +1,8 @@
 import { stitch } from '../core/resolve/stitch.ts';
 import { isDisarray, MatrixColumnsAccess } from '../data/dataTypes.ts';
 import { derefSnippet } from '../data/ref.ts';
-import { type Origin, snip, type Snippet } from '../data/snippet.ts';
+import { snip } from '../data/snippet.ts';
+import type { Origin, Snippet } from '../data/snippet.ts';
 import { vec2f, vec3f, vec4f } from '../data/vector.ts';
 import { type BaseData, isPtr, isVec, isWgslArray, isWgslStruct } from '../data/wgslTypes.ts';
 import { isKnownAtComptime } from '../types.ts';
@@ -51,6 +52,7 @@ export function accessIndex(target: Snippet, indexArg: Snippet | number): Snippe
         : stitch`${target}[${index}]`,
       elementType,
       /* origin */ origin,
+      target.possibleSideEffects || index.possibleSideEffects,
     );
   }
 
@@ -63,6 +65,7 @@ export function accessIndex(target: Snippet, indexArg: Snippet | number): Snippe
         : stitch`${target}[${index}]`,
       target.dataType.primitive,
       /* origin */ target.origin,
+      target.possibleSideEffects || index.possibleSideEffects,
     );
   }
 
@@ -79,7 +82,12 @@ export function accessIndex(target: Snippet, indexArg: Snippet | number): Snippe
         (target.value.matrix.dataType as BaseData).type as keyof typeof indexableTypeToResult
       ];
 
-    return snip(stitch`${target.value.matrix}[${index}]`, propType, /* origin */ target.origin);
+    return snip(
+      stitch`${target.value.matrix}[${index}]`,
+      propType,
+      /* origin */ target.origin,
+      target.possibleSideEffects || index.possibleSideEffects,
+    );
   }
 
   // matrix