Update on "[compiler] Infer phi types, extend mutable ranges to account for Store effects"

Redo of an earlier (pre-OSS) PR to infer types of phi nodes. There are a few pieces to this:

1. Update InferTypes to infer the type of `phi.id.type`, not the unused `phi.type`.
2. Update the algorithm to verify that all the phi types are actually equal, not just have the same kind.
3. Handle circular types by removing the cycle.

However, that reveals another issue: InferMutableRanges currently infers the results of `Store` effects _after_ its fixpoint loop. That was fine when a Store could never occur on a phi (since they wouldn't have a type to get a function signature from). Now though, we can have Store effects occur on phis, and we need to ensure that this correctly updates the mutable range of the phi operands - recursively. See new test that fails without the fixpoint loop.

[ghstack-poisoned]

Author: josephsavona

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutableRanges.ts

@@ -50,7 +50,28 @@ export function inferMutableRanges(ir: HIRFunction): void {
   // Re-infer mutable ranges for all values
   inferMutableLifetimes(ir, true);
 
-  // Re-infer mutable ranges for aliases, but *not* for stores
+  /**
+   * The second inferMutableLifetimes() call updates mutable ranges
+   * of values to account for Store effects. Now we need to update
+   * all aliases of such values to extend their ranges as well. Note
+   * that the store only mutates the the directly aliased value and
+   * not any of its inner captured references. For example:
+   *
+   * ```
+   * let y;
+   * if (cond) {
+   *   y = [];
+   * } else {
+   *   y = [{}];
+   * }
+   * y.push(z);
+   * ```
+   *
+   * The Store effect from the `y.push` modifies the values that `y`
+   * directly aliases - the two arrays from the if/else branches -
+   * but does not modify values that `y` "contains" such as the
+   * object literal or `z`.
+   */
   prevAliases = aliases.canonicalize();
   while (true) {
     inferMutableRangesForAlias(ir, aliases);