@samitouri / QOS-React / commits / 0977115440

TryStatement: maybe-throw terminal for per-instruction throw points

Adds a "maybe-throw" terminal which represents the possibility that the block may or may not throw, and can either continue forward or exit to an exception handler (`catch`). Also updates HIRBuilder to track the current mode, and when inside a try block to wrap every instruction inside a basic block that ends in a maybe-throw. So far this code isn't used yet, so doesn't affect output.

Joe Savona committed Sep 7, 2023 at 14:22 UTC 0977115440b53ca505a62e793ab3ec44355f69aa

6 files changed +75 -1

compiler/packages/babel-plugin-react-forget/src/HIR/HIR.ts

+10 -1

@@ -279,7 +279,8 @@ export type Terminal =

279 | TernaryTerminal

280 | OptionalTerminal

281 | LabelTerminal

282 - | SequenceTerminal;

282 + | SequenceTerminal

283 + | MaybeThrowTerminal;

284

285 function _staticInvariantTerminalHasLocation(

286 terminal: Terminal

@@ -444,6 +445,14 @@ export type SequenceTerminal = {

445 loc: SourceLocation;

446 };

447

448 +export type MaybeThrowTerminal = {

449 + kind: "maybe-throw";

450 + continuation: BlockId;

451 + handler: BlockId;

452 + id: InstructionId;

453 + loc: SourceLocation;

454 +};

455 +

456 /**

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

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

compiler/packages/babel-plugin-react-forget/src/HIR/HIRBuilder.ts

+31

@@ -77,6 +77,17 @@ export type Bindings = Map<

77 { node: t.Identifier; identifier: Identifier }

78 >;

80 +// Determines how instructions should be constructed in order to preserve

81 +// exception semantics

82 +type ExceptionsMode =

83 + // Mode used for code not covered by explicit exception handling, any

84 + // errors are assumed to be thrown out of the function

85 + | { kind: "ThrowExceptions" }

86 + // Mode used for code that *is* covered by explicit exception handling

87 + // (ie try/catch), which requires modeling the possibility of control

88 + // flow to the exception handler.

89 + | { kind: "CatchExceptions"; handler: BlockId };

90 +

91 /**

92 * Helper class for constructing a CFG

93 */

@@ -88,6 +99,7 @@ export default class HIRBuilder {

99 #context: t.Identifier[];

100 #bindings: Bindings;

101 #env: Environment;

102 + #mode: ExceptionsMode = { kind: "ThrowExceptions" };

103 parentFunction: NodePath<t.Function>;

104 errors: CompilerError = new CompilerError();

105

@@ -130,6 +142,20 @@ export default class HIRBuilder {

142 */

143 push(instruction: Instruction): void {

144 this.#current.instructions.push(instruction);

145 + if (this.#mode.kind === "CatchExceptions") {

146 + const handler = this.#mode.handler;

147 + const continuationBlock = this.reserve(this.currentBlockKind());

148 + this.terminateWithContinuation(

149 + {

150 + kind: "maybe-throw",

151 + continuation: continuationBlock.id,

152 + handler,

153 + id: makeInstructionId(0),

154 + loc: instruction.loc,

155 + },

156 + continuationBlock

157 + );

158 + }

159 }

160

161 makeTemporary(): Identifier {

@@ -723,6 +749,11 @@ export function reversePostorderBlocks(func: HIR): void {

749 visit(terminal.block);

750 break;

751 }

752 + case "maybe-throw": {

753 + visit(terminal.handler);

754 + visit(terminal.continuation);

755 + break;

756 + }

757 case "unsupported": {

758 break;

759 }

compiler/packages/babel-plugin-react-forget/src/HIR/PrintHIR.ts

@@ -80,6 +80,7 @@ export function printMixedHIR(

80 return printInstruction(value);

81 }

82 switch (value.kind) {

83 + case "maybe-throw":

84 case "sequence":

85 case "label":

86 case "optional":

@@ -230,6 +231,10 @@ export function printTerminal(terminal: Terminal): Array<string> | string {

231 value = `Unsupported`;

232 break;

233 }

234 + case "maybe-throw": {

235 + value = `MaybeThrow continuation=bb${terminal.continuation} handler=bb${terminal.handler}`;

236 + break;

237 + }

238 default: {

239 assertExhaustive(

240 terminal,

compiler/packages/babel-plugin-react-forget/src/HIR/visitors.ts

+20

@@ -731,6 +731,17 @@ export function mapTerminalSuccessors(

731 loc: terminal.loc,

732 };

733 }

734 + case "maybe-throw": {

735 + const continuation = fn(terminal.continuation);

736 + const handler = fn(terminal.handler);

737 + return {

738 + kind: "maybe-throw",

739 + continuation,

740 + handler,

741 + id: makeInstructionId(0),

742 + loc: terminal.loc,

743 + };

744 + }

745 case "unsupported": {

746 return terminal;

747 }

@@ -750,6 +761,7 @@ export function mapTerminalSuccessors(

761 */

762 export function terminalFallthrough(terminal: Terminal): BlockId | null {

763 switch (terminal.kind) {

764 + case "maybe-throw":

765 case "branch":

766 case "goto":

767 case "return":

@@ -784,6 +796,7 @@ export function mapOptionalFallthroughs(

796 fn: (block: BlockId) => BlockId | null

797 ): void {

798 switch (terminal.kind) {

799 + case "maybe-throw":

800 case "branch":

801 case "goto":

802 case "return":

@@ -917,6 +930,11 @@ export function* eachTerminalSuccessor(terminal: Terminal): Iterable<BlockId> {

930 yield terminal.block;

931 break;

932 }

933 + case "maybe-throw": {

934 + yield terminal.continuation;

935 + yield terminal.handler;

936 + break;

937 + }

938 case "unsupported":

939 break;

940 default: {

@@ -956,6 +974,7 @@ export function mapTerminalOperands(

974 terminal.value = fn(terminal.value);

975 break;

976 }

977 + case "maybe-throw":

978 case "sequence":

979 case "label":

980 case "optional":

@@ -1004,6 +1023,7 @@ export function* eachTerminalOperand(terminal: Terminal): Iterable<Place> {

1023 yield terminal.value;

1024 break;

1025 }

1026 + case "maybe-throw":

1027 case "sequence":

1028 case "label":

1029 case "optional":

compiler/packages/babel-plugin-react-forget/src/ReactiveScopes/BuildReactiveFunction.ts

@@ -636,6 +636,13 @@ class Driver {

636 }

637 break;

638 }

639 + case "maybe-throw": {

640 + this.visitBlock(

641 + this.cx.ir.blocks.get(terminal.continuation)!,

642 + blockValue

643 + );

644 + break;

645 + }

646 case "unsupported": {

647 CompilerError.invariant(false, {

648 reason: "Unexpected unsupported terminal",

compiler/packages/babel-plugin-react-forget/src/Utils/VisualizeHIRMermaid.ts

@@ -139,6 +139,7 @@ function printTerminalLabel(terminal: Terminal): string {

139 buffer.push("Sequence");

140 break;

141 }

142 + case "maybe-throw":

143 case "unsupported": {

144 break;

145 }

@@ -246,6 +247,7 @@ function printTerminalArrows(blockId: BlockId, terminal: Terminal): string {

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

248 break;

249 }

250 + case "maybe-throw":

251 case "throw":

252 case "return":

253 case "unsupported": {