[Compiler]: Type inference information does not propagate past phi nodes #29907
Description
What kind of issue is this?
- React Compiler core (the JS output is incorrect, or your app works incorrectly after optimization)
- babel-plugin-react-compiler (build issue installing or using the Babel plugin)
- eslint-plugin-react-compiler (build issue installing or using the eslint plugin)
- react-compiler-healthcheck (build issue installing or using the healthcheck script)
Link to repro
Repro steps
The following output is obtained after the InferTypes pass.
...
bb1 (block):
predecessor blocks: bb2 bb3
someVar$51:TFunction<BuiltInSetState>: phi(bb2: someVar$46, bb3: someVar$49)
[19] <unknown> $52 = LoadLocal <unknown> someVar$51
[20] <unknown> $54 = StoreLocal Let <unknown> res$53 = <unknown> $52
[21] <unknown> $55 = LoadLocal <unknown> res$53
[22] Return <unknown> $55I would expect the type (TFunction<BuiltInSetState>) of someVar$51 phi node to propagate at instruction 19 but it does not happen.
I was able to figure out why it happens. During SSA generation the phi node's identifier has a typeId which is different than the identifier at instruction 19.
I tried to fix this by adding the following patch (to be run right after enterSSA pass) which just makes sure in such cases we always use the same typeId:
// Ensure PHI node types are the same as their uses
let ssaTypeRemap: Map<IdentifierId, Type> = new Map()
for (const [_, block] of func.body.blocks) {
block.phis.forEach(p => {
ssaTypeRemap.set(p.id.id, p.type);
})
}
for (const [_, block] of func.body.blocks) {
for (const instr of block.instructions) {
mapInstructionOperands(instr, (place) => {
if (ssaTypeRemap.has(place.identifier.id)) {
place.identifier.type = ssaTypeRemap.get(place.identifier.id)!;
}
return place;
});
}
mapTerminalOperands(block.terminal, (place) => {
if (ssaTypeRemap.has(place.identifier.id)) {
place.identifier.type = ssaTypeRemap.get(place.identifier.id)!;
}
return place;
});
}With this patch however 6 testcases fail:
Failures:
FAIL: phi-type-inference-property-store
>> Unexpected error during test:
Expected fixture `phi-type-inference-property-store` to succeed but it failed with error:
Invariant: Invalid mutable range for scope. Scope @3 has range [0:18] but the valid range is [1:22]
FAIL: phi-type-inference-array-push
>> Unexpected error during test:
Expected fixture `phi-type-inference-array-push` to succeed but it failed with error:
Invariant: Invalid mutable range for scope. Scope @3 has range [0:19] but the valid range is [1:23]
FAIL: obj-literal-mutated-after-if-else
>> Unexpected error during test:
Expected fixture `obj-literal-mutated-after-if-else` to succeed but it failed with error:
Invariant: Invalid mutable range for scope. Scope @2 has range [0:16] but the valid range is [1:18]
FAIL: mutable-lifetime-loops
>> Unexpected error during test:
Expected fixture `mutable-lifetime-loops` to succeed but it failed with error:
/mutable-lifetime-loops.ts: cycle detected
FAIL: for-in-statement-continue
>> Unexpected error during test:
Expected fixture `for-in-statement-continue` to succeed but it failed with error:
/for-in-statement-continue.ts: cycle detected
FAIL: alias-while
>> Unexpected error during test:
Expected fixture `alias-while` to succeed but it failed with error:
/alias-while.ts: cycle detected
FAIL: meta-isms/repro-cx-assigned-to-temporary-
The mutable range inference pass gets a weird range (I am not sure how starting location can be zero, I guessed that the mutable range must start at atleast instruction idx + 1).
-
inference fails with a cycle detected.
I would appreciate some insights, thank you.
How often does this bug happen?
Every time
What version of React are you using?
19