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[compiler] Add fallthrough to branch terminal #30814

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merged 4 commits into from
Aug 28, 2024
Merged

[compiler] Add fallthrough to branch terminal #30814

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1846220
[compiler] Add fallthrough to branch terminal
josephsavona Aug 26, 2024
01b9791
Update on "[compiler] Add fallthrough to branch terminal"
josephsavona Aug 27, 2024
fed48b4
Update on "[compiler] Add fallthrough to branch terminal"
josephsavona Aug 28, 2024
00d44be
Update on "[compiler] Add fallthrough to branch terminal"
josephsavona Aug 28, 2024
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14 changes: 10 additions & 4 deletions compiler/packages/babel-plugin-react-compiler/src/HIR/BuildHIR.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -607,6 +607,7 @@ function lowerStatement(
),
consequent: bodyBlock,
alternate: continuationBlock.id,
fallthrough: continuationBlock.id,
id: makeInstructionId(0),
loc: stmt.node.loc ?? GeneratedSource,
},
Expand Down Expand Up @@ -656,16 +657,13 @@ function lowerStatement(
},
conditionalBlock,
);
/*
* The conditional block is empty and exists solely as conditional for
* (re)entering or exiting the loop
*/
const test = lowerExpressionToTemporary(builder, stmt.get('test'));
const terminal: BranchTerminal = {
kind: 'branch',
test,
consequent: loopBlock,
alternate: continuationBlock.id,
fallthrough: conditionalBlock.id,
id: makeInstructionId(0),
loc: stmt.node.loc ?? GeneratedSource,
};
Expand Down Expand Up @@ -975,6 +973,7 @@ function lowerStatement(
test,
consequent: loopBlock,
alternate: continuationBlock.id,
fallthrough: conditionalBlock.id,
id: makeInstructionId(0),
loc,
};
Expand Down Expand Up @@ -1118,6 +1117,7 @@ function lowerStatement(
consequent: loopBlock,
alternate: continuationBlock.id,
loc: stmt.node.loc ?? GeneratedSource,
fallthrough: continuationBlock.id,
},
continuationBlock,
);
Expand Down Expand Up @@ -1203,6 +1203,7 @@ function lowerStatement(
test,
consequent: loopBlock,
alternate: continuationBlock.id,
fallthrough: continuationBlock.id,
loc: stmt.node.loc ?? GeneratedSource,
},
continuationBlock,
Expand Down Expand Up @@ -1800,6 +1801,7 @@ function lowerExpression(
test: {...testPlace},
consequent: consequentBlock,
alternate: alternateBlock,
fallthrough: continuationBlock.id,
id: makeInstructionId(0),
loc: exprLoc,
},
Expand Down Expand Up @@ -1878,6 +1880,7 @@ function lowerExpression(
test: {...leftPlace},
consequent,
alternate,
fallthrough: continuationBlock.id,
id: makeInstructionId(0),
loc: exprLoc,
},
Expand Down Expand Up @@ -2611,6 +2614,7 @@ function lowerOptionalMemberExpression(
test: {...object},
consequent: consequent.id,
alternate,
fallthrough: continuationBlock.id,
id: makeInstructionId(0),
loc,
};
Expand Down Expand Up @@ -2750,6 +2754,7 @@ function lowerOptionalCallExpression(
test: {...testPlace},
consequent: consequent.id,
alternate,
fallthrough: continuationBlock.id,
id: makeInstructionId(0),
loc,
};
Expand Down Expand Up @@ -4025,6 +4030,7 @@ function lowerAssignment(
test: {...test},
consequent,
alternate,
fallthrough: continuationBlock.id,
id: makeInstructionId(0),
loc,
},
Expand Down
2 changes: 1 addition & 1 deletion compiler/packages/babel-plugin-react-compiler/src/HIR/HIR.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -491,7 +491,7 @@ export type BranchTerminal = {
alternate: BlockId;
id: InstructionId;
loc: SourceLocation;
fallthrough?: never;
fallthrough: BlockId;
};

export type SwitchTerminal = {
Expand Down
4 changes: 3 additions & 1 deletion compiler/packages/babel-plugin-react-compiler/src/HIR/visitors.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -660,11 +660,13 @@ export function mapTerminalSuccessors(
case 'branch': {
const consequent = fn(terminal.consequent);
const alternate = fn(terminal.alternate);
const fallthrough = fn(terminal.fallthrough);
return {
kind: 'branch',
test: terminal.test,
consequent,
alternate,
fallthrough,
id: makeInstructionId(0),
loc: terminal.loc,
};
Expand Down Expand Up @@ -883,7 +885,6 @@ export function terminalHasFallthrough<
>(terminal: T): terminal is U {
switch (terminal.kind) {
case 'maybe-throw':
case 'branch':
case 'goto':
case 'return':
case 'throw':
Expand All @@ -892,6 +893,7 @@ export function terminalHasFallthrough<
const _: undefined = terminal.fallthrough;
return false;
}
case 'branch':
case 'try':
case 'do-while':
case 'for-of':
Expand Down
55 changes: 53 additions & 2 deletions compiler/packages/babel-plugin-react-compiler/src/Inference/DropManualMemoization.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ type IdentifierSidemap = {
react: Set<IdentifierId>;
maybeDepsLists: Map<IdentifierId, Array<Place>>;
maybeDeps: Map<IdentifierId, ManualMemoDependency>;
optionals: Set<IdentifierId>;
};

/**
Expand All @@ -52,6 +53,7 @@ type IdentifierSidemap = {
export function collectMaybeMemoDependencies(
value: InstructionValue,
maybeDeps: Map<IdentifierId, ManualMemoDependency>,
optional: boolean,
): ManualMemoDependency | null {
switch (value.kind) {
case 'LoadGlobal': {
Expand All @@ -69,7 +71,7 @@ export function collectMaybeMemoDependencies(
return {
root: object.root,
// TODO: determine if the access is optional
path: [...object.path, {property: value.property, optional: false}],
path: [...object.path, {property: value.property, optional}],
};
}
break;
Expand Down Expand Up @@ -162,7 +164,11 @@ function collectTemporaries(
break;
}
}
const maybeDep = collectMaybeMemoDependencies(value, sidemap.maybeDeps);
const maybeDep = collectMaybeMemoDependencies(
value,
sidemap.maybeDeps,
sidemap.optionals.has(lvalue.identifier.id),
);
// We don't expect named lvalues during this pass (unlike ValidatePreservingManualMemo)
if (maybeDep != null) {
sidemap.maybeDeps.set(lvalue.identifier.id, maybeDep);
Expand Down Expand Up @@ -338,12 +344,14 @@ export function dropManualMemoization(func: HIRFunction): void {
func.env.config.validatePreserveExistingMemoizationGuarantees ||
func.env.config.validateNoSetStateInRender ||
func.env.config.enablePreserveExistingMemoizationGuarantees;
const optionals = findOptionalPlaces(func);
const sidemap: IdentifierSidemap = {
functions: new Map(),
manualMemos: new Map(),
react: new Set(),
maybeDeps: new Map(),
maybeDepsLists: new Map(),
optionals,
};
let nextManualMemoId = 0;

Expand Down Expand Up @@ -476,3 +484,46 @@ export function dropManualMemoization(func: HIRFunction): void {
}
}
}

function findOptionalPlaces(fn: HIRFunction): Set<IdentifierId> {
const optionals = new Set<IdentifierId>();
for (const [, block] of fn.body.blocks) {
if (block.terminal.kind === 'optional') {
const optionalTerminal = block.terminal;
let testBlock = fn.body.blocks.get(block.terminal.test)!;
loop: while (true) {
const terminal = testBlock.terminal;
switch (terminal.kind) {
case 'branch': {
if (terminal.fallthrough === optionalTerminal.fallthrough) {
// found it
const consequent = fn.body.blocks.get(terminal.consequent)!;
const last = consequent.instructions.at(-1);
if (last !== undefined && last.value.kind === 'StoreLocal') {
optionals.add(last.value.value.identifier.id);
}
Comment on lines +502 to +504
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This feels slightly weird since DropManualMemo runs before we enter ssa, so both consequent (the optional read) and alternate (undefined) write to the same identifier ID. There is also no phi join, so reads to the OptionalExpression rvalue is also guaranteed to use the same identifier ID (and this works)

(I'm guessing that passes after SSA will need to track phis as well -- reading the rest of the stack now)

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Yeah I looked at using the phi to figure out which values is optional. First, as you noted we aren't in SSA so we don't have phis yet. Second, the phis end up in weird places for nested optionals, because with nested optionals the alternate actually goes to the outermost fallthrough. So we just look at where the consequent assigns to in order to figure out what the optional value was.

break loop;
} else {
testBlock = fn.body.blocks.get(terminal.fallthrough)!;
}
break;
}
case 'optional':
case 'logical':
case 'sequence':
case 'ternary': {
Comment on lines +512 to +514
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Ah I see, I'm guessing that this is to support something like useMemo(..., [(a ?? b)?.c]). Not technically necessary for DropManualMemo as we're only tracking named variables, but this makes sense to have in a utility function

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yup exactly

testBlock = fn.body.blocks.get(terminal.fallthrough)!;
break;
}
default: {
CompilerError.invariant(false, {
reason: `Unexpected terminal in optional`,
loc: terminal.loc,
});
}
}
}
}
}
return optionals;
}
2 changes: 1 addition & 1 deletion ...ges/babel-plugin-react-compiler/src/ReactiveScopes/AlignReactiveScopesToBlockScopesHIR.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -140,7 +140,7 @@ export function alignReactiveScopesToBlockScopesHIR(fn: HIRFunction): void {
}

const fallthrough = terminalFallthrough(terminal);
if (fallthrough !== null) {
if (fallthrough !== null && terminal.kind !== 'branch') {
/*
* Any currently active scopes that overlaps the block-fallthrough range
* need their range extended to at least the first instruction of the
Expand Down
11 changes: 9 additions & 2 deletions ...packages/babel-plugin-react-compiler/src/Validation/ValidatePreservedManualMemoization.ts
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Expand Up @@ -167,7 +167,10 @@ function compareDeps(

let isSubpath = true;
for (let i = 0; i < Math.min(inferred.path.length, source.path.length); i++) {
if (inferred.path[i].property !== source.path[i].property) {
if (
inferred.path[i].property !== source.path[i].property ||
inferred.path[i].optional !== source.path[i].optional
) {
isSubpath = false;
break;
}
Expand Down Expand Up @@ -339,7 +342,11 @@ class Visitor extends ReactiveFunctionVisitor<VisitorState> {
return null;
}
default: {
const dep = collectMaybeMemoDependencies(value, this.temporaries);
const dep = collectMaybeMemoDependencies(
value,
this.temporaries,
false,
);
if (value.kind === 'StoreLocal' || value.kind === 'StoreContext') {
const storeTarget = value.lvalue.place;
state.manualMemoState?.decls.add(
Expand Down