@samitouri / QOS-React-2 / commits / 4837e21de3

[HIR] add `for` terminal

The changes here are pretty significant and there's a bunch more left: - support for with any of `<init>`, `<test>` or `<update>` empty. - support for with `<init>` as `Expression` instead of VariableDeclaration` node - support assignment expressions in `<update>`, this seems like it might require further new abstractions to allow something like a block to codegen into a single expression.

Jan Kassens committed Dec 6, 2022 at 12:01 UTC 4837e21de37098dc16fa78ad2f24495524f3aa90

12 files changed +310 -92

compiler/forget/src/HIR/BuildHIR.ts

+64 -61

@@ -317,90 +317,77 @@ function lowerStatement(

317 }

318 case "ForStatement": {

319 const stmt = stmtPath as NodePath<t.ForStatement>;

320 - /**

321 - * The initializer is evaluated once prior to entering the loop.

322 - * here we are not concerned about scoping, so we can push the

323 - * initializer to the end of of the block leading up to the loop

324 - */

325 - const init = stmt.get("init");

326 - if (init.hasNode()) {

327 - // builder.push(init);

328 - throw new Error("todo: lower initializer in ForStatement");

329 - }

330 - // Block used to evaluate whether to (re)enter or exit the loop

331 - const conditionalBlock = builder.reserve();

320 +

321 + const testBlock = builder.reserve();

322 // Block for code following the loop

323 const continuationBlock = builder.reserve();

334 - /**

335 - * Block for the updater, which runs after each iteration (including upon `continue`)

336 - * Generally this would increment or decrement the loop index variable

337 - */

338 - const updateBlock = builder.reserve();

339 - const update = stmt.get("update");

340 - if (update.hasNode()) {

341 - // updateBlock[1].push(stmt.get("update") as any as NodePath<t.Statement>);

342 - throw new Error("todo: lower updater for ForStatement");

343 - }

344 - builder.complete(updateBlock, {

345 - kind: "goto",

346 - block: conditionalBlock.id,

347 - variant: GotoVariant.Break,

348 - id: makeInstructionId(0),

324 +

325 + const initBlock = builder.enter((blockId) => {

326 + const init = stmt.get("init") as NodePath<t.VariableDeclaration>;

327 + todoInvariant(

328 + t.isVariableDeclaration(init.node),

329 + "handle non variable initialization in for"

330 + );

331 + lowerStatement(builder, init);

332 + return {

333 + kind: "goto",

334 + block: testBlock.id,

335 + variant: GotoVariant.Break,

336 + id: makeInstructionId(0),

337 + };

338 });

350 - /**

351 - * Construct the loop itself: the loop body wraps around to the update block

352 - * and the update block is also set as the `continue` target

353 - */

354 - const loopBlock = builder.enter((blockId) => {

355 - return builder.loop(label, updateBlock.id, continuationBlock.id, () => {

339 +

340 + const updateBlock = builder.enter((blockId) => {

341 + const update = stmt.get("update");

342 + if (update.hasNode()) {

343 + lowerExpressionToVoid(builder, update);

344 + }

345 + return {

346 + kind: "goto",

347 + block: testBlock.id,

348 + variant: GotoVariant.Break,

349 + id: makeInstructionId(0),

350 + };

351 + });

352 +

353 + const bodyBlock = builder.enter((blockId) => {

354 + return builder.loop(label, updateBlock, continuationBlock.id, () => {

355 lowerStatement(builder, stmt.get("body"));

356 return {

357 kind: "goto",

359 - block: updateBlock.id,

358 + block: updateBlock,

359 variant: GotoVariant.Continue,

360 id: makeInstructionId(0),

361 };

362 });

363 });

365 - // End the block leading up to the loop, jumping to the conditional block

364 +

365 builder.terminateWithContinuation(

366 {

368 - kind: "goto",

369 - block: conditionalBlock.id,

370 - variant: GotoVariant.Break,

367 + kind: "for",

368 + init: initBlock,

369 + test: testBlock.id,

370 + update: updateBlock,

371 + loop: bodyBlock,

372 + fallthrough: continuationBlock.id,

373 id: makeInstructionId(0),

374 },

373 - conditionalBlock

375 + testBlock

376 );

377

376 - let terminal: Terminal;

378 const test = stmt.get("test");

378 - if (test.hasNode()) {

379 - /**

380 - * Terminate the conditional block with the test conditional of the for statement:

381 - * if the condition is true enter the loop block, else exit to the continuation

382 - */

383 - terminal = {

379 + todoInvariant(test.hasNode(), "ForStatement without test");

380 + builder.terminateWithContinuation(

381 + {

382 kind: "if",

383 test: lowerExpressionToPlace(builder, test),

386 - consequent: loopBlock,

384 + consequent: bodyBlock,

385 alternate: continuationBlock.id,

386 fallthrough: continuationBlock.id,

387 id: makeInstructionId(0),

390 - };

391 - } else {

392 - /**

393 - * If there is no test, then the "conditional" block unconditionally re-enters the loop.

394 - * this will create an indirection, but `shrink()` will eliminate this in post-processing.

395 - */

396 - terminal = {

397 - kind: "goto",

398 - block: loopBlock,

399 - variant: GotoVariant.Break,

400 - id: makeInstructionId(0),

401 - };

402 - }

403 - builder.terminateWithContinuation(terminal, continuationBlock);

388 + },

389 + continuationBlock

390 + );

391 return;

392 }

393 case "DoWhileStatement": {

@@ -1278,6 +1265,22 @@ function lowerExpressionToPlace(

1265 return place;

1266 }

1267

1268 +function lowerExpressionToVoid(

1269 + builder: HIRBuilder,

1270 + exprPath: NodePath<t.Expression>

1271 +): void {

1272 + const instr = lowerExpression(builder, exprPath);

1273 + if (instr.kind !== "Identifier") {

1274 + const exprLoc = exprPath.node.loc ?? GeneratedSource;

1275 + builder.push({

1276 + id: makeInstructionId(0),

1277 + value: instr,

1278 + loc: exprLoc,

1279 + lvalue: null,

1280 + });

1281 + }

1282 +}

1283 +

1284 function lowerLVal(builder: HIRBuilder, exprPath: NodePath<t.LVal>): Place {

1285 const exprNode = exprPath.node;

1286 const exprLoc = exprNode.loc ?? GeneratedSource;

compiler/forget/src/HIR/Codegen.ts

@@ -190,6 +190,14 @@ class CodegenVisitor

190 case "while": {

191 return createWhileStatement(terminal.loc, terminal.test, terminal.loop);

192 }

193 + case "for": {

194 + return t.forStatement(

195 + terminal.init as any, // TODO: make sure it's a variable declaration

196 + terminal.test,

197 + terminal.update,

198 + terminal.loop

199 + );

200 + }

201 case "return": {

202 const createReturnStatement = withLoc(t.returnStatement);

203 if (terminal.value !== null) {

compiler/forget/src/HIR/HIR.ts

+11

@@ -109,6 +109,7 @@ export type Terminal =

109 | GotoTerminal

110 | IfTerminal

111 | SwitchTerminal

112 + | ForTerminal

113 | WhileTerminal;

114

115 export type ThrowTerminal = { kind: "throw"; value: Place; id: InstructionId };

@@ -158,6 +159,16 @@ export type WhileTerminal = {

159 id: InstructionId;

160 };

161

162 +export type ForTerminal = {

163 + kind: "for";

164 + init: BlockId;

165 + test: BlockId;

166 + update: BlockId;

167 + loop: BlockId;

168 + fallthrough: BlockId;

169 + id: InstructionId;

170 +};

171 +

172 /**

173 * Instructions generally represent expressions but with all nesting flattened away,

174 * such that all operands to each instruction are either primitive values OR are

compiler/forget/src/HIR/HIRBuilder.ts

+6 -1

@@ -365,7 +365,8 @@ function shrink(func: HIR): HIR {

365 if (target !== null) {

366 return target;

367 }

368 - const block = func.blocks.get(blockId)!;

368 + const block = func.blocks.get(blockId);

369 + invariant(block != null, "expected block %s to exist", blockId);

370 target = getTargetIfIndirection(block);

371 if (target !== null) {

372 // the target might also be a simple goto, recurse

@@ -485,6 +486,10 @@ function reversePostorderBlocks(func: HIR): HIR {

486 visit(terminal.test);

487 break;

488 }

489 + case "for": {

490 + visit(terminal.init);

491 + break;

492 + }

493 default: {

494 assertExhaustive(

495 terminal,

compiler/forget/src/HIR/HIRTreeVisitor.ts

+114

@@ -311,6 +311,113 @@ class Driver<TBlock, TValue, TItem, TCase> {

311 }

312 break;

313 }

314 + case "for": {

315 + const loopId =

316 + !this.cx.isScheduled(terminal.loop) &&

317 + terminal.loop !== terminal.fallthrough

318 + ? terminal.loop

319 + : null;

320 +

321 + const fallthroughId =

322 + terminal.fallthrough !== null &&

323 + !this.cx.isScheduled(terminal.fallthrough)

324 + ? terminal.fallthrough

325 + : null;

326 +

327 + const scheduleId = this.cx.scheduleLoop(

328 + terminal.fallthrough,

329 + terminal.update,

330 + terminal.loop

331 + );

332 + scheduleIds.push(scheduleId);

333 +

334 + const initBlock = this.cx.ir.blocks.get(terminal.init)!;

335 + const initTerminal = initBlock.terminal;

336 + invariant(

337 + initTerminal.kind === "goto",

338 + "Expected for loop init block to end in a goto"

339 + );

340 +

341 + let initItem;

342 + for (const instr of initBlock.instructions) {

343 + const value = this.visitor.visitValue(instr.value, instr.id);

344 + initItem = this.visitor.visitInstruction(instr, value);

345 + }

346 +

347 + const testBlock = this.cx.ir.blocks.get(terminal.test)!;

348 + const testTerminal = testBlock.terminal;

349 + invariant(

350 + testTerminal.kind === "if",

351 + "Expected for loop test block to end in an if"

352 + );

353 + const testValueBlock = this.visitor.enterValueBlock();

354 + for (const instr of testBlock.instructions) {

355 + const value = this.visitor.visitValue(instr.value, instr.id);

356 + const item = this.visitor.visitInstruction(instr, value);

357 + this.visitor.appendBlock(testValueBlock, item);

358 + }

359 + const testValueLast = this.visitor.visitValue(

360 + testTerminal.test,

361 + testTerminal.id

362 + );

363 + const testValue = this.visitor.leaveValueBlock(

364 + testValueBlock,

365 + testValueLast

366 + );

367 +

368 + const updateBlock = this.cx.ir.blocks.get(terminal.update)!;

369 + const updateTerminal = updateBlock.terminal;

370 + invariant(

371 + updateTerminal.kind === "goto",

372 + "Expected for loop update block to end in a goto"

373 + );

374 + let updateValue;

375 + for (const instr of updateBlock.instructions) {

376 + updateValue = this.visitor.visitValue(instr.value, instr.id);

377 + }

378 +

379 + let loopBody: TItem;

380 + if (loopId) {

381 + loopBody = this.traverseBlock(this.cx.ir.blocks.get(loopId)!);

382 + } else {

383 + const break_ = this.visitBreak(terminal.loop);

384 + invariant(

385 + break_ !== null,

386 + "If loop body is already scheduled it must be a break"

387 + );

388 + const body = this.visitor.enterBlock();

389 + this.visitor.appendBlock(body, break_);

390 + loopBody = this.visitor.leaveBlock(body);

391 + }

392 +

393 + this.cx.unscheduleAll(scheduleIds);

394 + if (fallthroughId !== null) {

395 + this.visitor.appendBlock(

396 + blockValue,

397 + this.visitor.visitTerminal({

398 + kind: "for",

399 + init: initItem as any,

400 + test: testValue,

401 + update: updateValue as any,

402 + loop: loopBody,

403 + }),

404 + fallthroughId

405 + );

406 + this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue);

407 + } else {

408 + this.visitor.appendBlock(

409 + blockValue,

410 + this.visitor.visitTerminal({

411 + kind: "for",

412 + init: initItem as any,

413 + test: testValue,

414 + update: updateValue as any,

415 + loop: loopBody,

416 + })

417 + );

418 + }

419 + break;

420 + }

421 case "goto": {

422 this.visitor.visitTerminalId(terminal.id);

423 switch (terminal.variant) {

@@ -722,5 +829,12 @@ export type BlockTerminal<TBlock, TValue, TItem, TCase> =

829 test: TValue;

830 loop: TItem;

831 }

832 + | {

833 + kind: "for";

834 + init: TItem;

835 + test: TValue;

836 + update: TValue;

837 + loop: TItem;

838 + }

839 | { kind: "break"; label: BlockId | null }

840 | { kind: "continue"; label: BlockId | null };

compiler/forget/src/HIR/InferReactiveScopeDependencies.ts

@@ -102,6 +102,7 @@ class ScopeDependenciesVisitor

102 switch (terminal.kind) {

103 case "if":

104 case "switch":

105 + case "for":

106 case "while": {

107 for (const operand of eachInstructionValueOperand(terminal.test)) {

108 this.#addTerminalDependency(operand);

compiler/forget/src/HIR/PrintHIR.ts

@@ -82,6 +82,7 @@ export function printMixedHIR(

82 case "switch":

83 case "throw":

84 case "while":

85 + case "for":

86 case "goto": {

87 const terminal = printTerminal(value);

88 if (Array.isArray(terminal)) {

@@ -165,6 +166,10 @@ export function printTerminal(terminal: Terminal): Array<string> | string {

166 } fallthrough=${terminal.fallthrough ? `bb${terminal.fallthrough}` : ""}`;

167 break;

168 }

169 + case "for": {

170 + value = `[${terminal.id}] For init=bb${terminal.init} test=bb${terminal.test} loop=bb${terminal.loop} update=bb${terminal.update} fallthrough=bb${terminal.fallthrough}`;

171 + break;

172 + }

173 default: {

174 assertExhaustive(

175 terminal,

compiler/forget/src/HIR/PrintHIRTree.ts

@@ -94,6 +94,12 @@ class PrintVisitor implements Visitor<Array<string>, string, string, string> {

94 value = `While (${terminal.test}) ${terminal.loop.trimStart()}`;

95 break;

96 }

97 + case "for": {

98 + value = `For (TODO) (${

99 + terminal.test

100 + }) (TODO) ${terminal.loop.trimStart()}`;

101 + break;

102 + }

103 case "return": {

104 if (terminal.value !== null) {

105 value = `Return ${terminal.value}`;

compiler/forget/src/HIR/VisualizeHIRMermaid.ts

+11

@@ -98,6 +98,9 @@ function printTerminalLabel(terminal: Terminal): string {

98 case "while":

99 buffer.push("While");

100 break;

101 + case "for":

102 + buffer.push("For");

103 + break;

104 default:

105 assertExhaustive(terminal, `unhandled terminal ${terminal}`);

106 }

@@ -147,6 +150,14 @@ function printTerminalArrows(blockId: BlockId, terminal: Terminal): string {

150 buffer.push(printJumpArrow(blockId, terminal.fallthrough, "fallthrough"));

151 break;

152 }

153 + case "for": {

154 + buffer.push(printJumpArrow(blockId, terminal.init, "init"));

155 + buffer.push(printJumpArrow(blockId, terminal.test, "test"));

156 + buffer.push(printJumpArrow(blockId, terminal.update, "update"));

157 + buffer.push(printJumpArrow(blockId, terminal.loop, "loop"));

158 + buffer.push(printJumpArrow(blockId, terminal.fallthrough, "fallthrough"));

159 + break;

160 + }

161 case "throw":

162 case "return": {

163 break;

compiler/forget/src/HIR/visitors.ts

+22

@@ -214,6 +214,22 @@ export function mapTerminalSuccessors(

214 id: makeInstructionId(0),

215 };

216 }

217 + case "for": {

218 + const init = fn(terminal.init);

219 + const test = fn(terminal.test);

220 + const update = fn(terminal.update);

221 + const loop = fn(terminal.loop);

222 + const fallthrough = fn(terminal.fallthrough);

223 + return {

224 + kind: "for",

225 + init,

226 + test,

227 + update,

228 + loop,

229 + fallthrough,

230 + id: makeInstructionId(0),

231 + };

232 + }

233 default: {

234 assertExhaustive(

235 terminal,

@@ -255,6 +271,10 @@ export function* eachTerminalSuccessor(terminal: Terminal): Iterable<BlockId> {

271 yield terminal.test;

272 break;

273 }

274 + case "for": {

275 + yield terminal.init;

276 + break;

277 + }

278 default: {

279 assertExhaustive(

280 terminal,

@@ -291,6 +311,7 @@ export function mapTerminalOperands(

311 break;

312 }

313 case "while":

314 + case "for":

315 case "goto": {

316 // no-op

317 break;

@@ -328,6 +349,7 @@ export function* eachTerminalOperand(terminal: Terminal): Iterable<Place> {

349 break;

350 }

351 case "while":

352 + case "for":

353 case "goto": {

354 // no-op

355 break;

compiler/forget/src/__tests__/fixtures/hir/ssa-for.expect.md

+59 -27

@@ -3,9 +3,9 @@

4 ```javascript

5 function foo() {

6 - let x = 0;

7 - for (; x < 10; ) {

8 - x = x + 1;

6 + let x = 1;

7 + for (let i = 0; i < 10; update()) {

8 + x += 1;

9 }

10 return x;

11 }

@@ -16,23 +16,32 @@ function foo() {

17 ```

18 bb0:

19 - [1] Let mutate x$5_@0[0:8] = 0

20 - [2] Goto bb1

19 + [1] Let mutate x$7_@0[0:13] = 1

20 + [2] For init=bb3 test=bb1 loop=bb5 update=bb4 fallthrough=bb2

21 +bb3:

22 + predecessor blocks: bb0

23 + [3] Let mutate i$8_@1[3:13] = 0

24 + [4] Goto bb1

25 bb1:

22 - predecessor blocks: bb0 bb4

23 - x$7_@0[0:8]: phi(bb0: x$5_@0, bb4: x$10_@0)

24 - [3] Const mutate $6_@1 = 10

25 - [4] Const mutate $8_@2 = Binary read x$7_@0 < read $6_@1

26 - [5] If (read $8_@2) then:bb4 else:bb2

27 -bb4:

26 + predecessor blocks: bb3 bb4

27 + x$13_@0[0:13]: phi(bb3: x$7_@0, bb4: x$14_@0)

28 + [5] Const mutate $9_@2 = 10

29 + [6] Const mutate $11_@3[6:8] = Binary read i$8_@1 < read $9_@2

30 + [7] If (read $11_@3) then:bb5 else:bb2

31 +bb5:

32 predecessor blocks: bb1

29 - [6] Const mutate $9_@3 = 1

30 - [7] Reassign mutate x$10_@0[0:8] = Binary read x$7_@0 + read $9_@3

31 - [8] Goto(Continue) bb1

33 + [8] Const mutate $12_@4 = 1

34 + [9] Reassign mutate x$14_@0[0:13] = Binary read x$13_@0 + read $12_@4

35 + [10] Goto(Continue) bb4

36 +bb4:

37 + predecessor blocks: bb5

38 + [11] Call mutate update$3_@5()

39 + [12] Goto bb1

40 bb2:

41 predecessor blocks: bb1

34 - [9] Return read x$7_@0

35 -

42 + [13] Return read x$13_@0

43 +scope3 [6:8]:

44 + - read $9_@2

45 ```

47 ### CFG

@@ -42,32 +51,50 @@ flowchart TB

51 %% Basic Blocks

52 subgraph bb0

53 bb0_instrs["

45 - [1] Let mutate x$5_@0[0:8] = 0

54 + [1] Let mutate x$7_@0[0:13] = 1

55 + "]

56 + bb0_instrs --> bb0_terminal(["For"])

57 + end

58 + subgraph bb3

59 + bb3_instrs["

60 + [3] Let mutate i$8_@1[3:13] = 0

61 "]

47 - bb0_instrs --> bb0_terminal(["Goto"])

62 + bb3_instrs --> bb3_terminal(["Goto"])

63 end

64 subgraph bb1

65 bb1_instrs["

51 - [3] Const mutate $6_@1 = 10

52 - [4] Const mutate $8_@2 = Binary read x$7_@0 < read $6_@1

66 + [5] Const mutate $9_@2 = 10

67 + [6] Const mutate $11_@3[6:8] = Binary read i$8_@1 < read $9_@2

68 "]

54 - bb1_instrs --> bb1_terminal(["If (read $8_@2)"])

69 + bb1_instrs --> bb1_terminal(["If (read $11_@3)"])

70 + end

71 + subgraph bb5

72 + bb5_instrs["

73 + [8] Const mutate $12_@4 = 1

74 + [9] Reassign mutate x$14_@0[0:13] = Binary read x$13_@0 + read $12_@4

75 + "]

76 + bb5_instrs --> bb5_terminal(["Goto"])

77 end

78 subgraph bb4

79 bb4_instrs["

58 - [6] Const mutate $9_@3 = 1

59 - [7] Reassign mutate x$10_@0[0:8] = Binary read x$7_@0 + read $9_@3

80 + [11] Call mutate update$3_@5()

81 "]

82 bb4_instrs --> bb4_terminal(["Goto"])

83 end

84 subgraph bb2

64 - bb2_terminal(["Return read x$7_@0"])

85 + bb2_terminal(["Return read x$13_@0"])

86 end

88 %% Jumps

68 - bb0_terminal --> bb1

69 - bb1_terminal -- "then" --> bb4

89 + bb0_terminal -- "init" --> bb3

90 + bb0_terminal -- "test" --> bb1

91 + bb0_terminal -- "update" --> bb4

92 + bb0_terminal -- "loop" --> bb5

93 + bb0_terminal -- "fallthrough" --> bb2

94 + bb3_terminal --> bb1

95 + bb1_terminal -- "then" --> bb5

96 bb1_terminal -- "else" --> bb2

97 + bb5_terminal --> bb4

98 bb4_terminal --> bb1

100 ```

@@ -76,7 +103,12 @@ flowchart TB

103

104 ```javascript

105 function foo$0() {

79 - let x$1 = 0;

106 + let x$1 = 1;

107 + bb2: for (let i$2 = 0; i$2 < 10; update$3()) {

108 + x$1 = x$1 + 1;

109 + }

110 +

111 + return x$1;

112 }

113

114 ```

compiler/forget/src/__tests__/fixtures/hir/ssa-for.js

+3 -3

@@ -1,7 +1,7 @@

1 function foo() {

2 - let x = 0;

3 - for (; x < 10; ) {

4 - x = x + 1;

2 + let x = 1;

3 + for (let i = 0; i < 10; update()) {

4 + x += 1;

5 }

6 return x;

7 }