Merge pull request #40063 from amcasey/ChromeTracing

Trace key operations

src/compiler/binder.ts

@@ -174,12 +174,14 @@ namespace ts {
     const binder = createBinder();
 
     export function bindSourceFile(file: SourceFile, options: CompilerOptions) {
+        tracing.begin(tracing.Phase.Bind, "bindSourceFile", { path: file.path });
         performance.mark("beforeBind");
         perfLogger.logStartBindFile("" + file.fileName);
         binder(file, options);
         perfLogger.logStopBindFile();
         performance.mark("afterBind");
         performance.measure("Bind", "beforeBind", "afterBind");
+        tracing.end();
     }
 
     function createBinder(): (file: SourceFile, options: CompilerOptions) => void {

src/compiler/checker.ts

@@ -323,6 +323,8 @@ namespace ts {
         let constraintDepth = 0;
         let currentNode: Node | undefined;
 
+        const typeCatalog: Type[] = []; // NB: id is index + 1
+
         const emptySymbols = createSymbolTable();
         const arrayVariances = [VarianceFlags.Covariant];
 
@@ -366,6 +368,7 @@ namespace ts {
             getNodeCount: () => sum(host.getSourceFiles(), "nodeCount"),
             getIdentifierCount: () => sum(host.getSourceFiles(), "identifierCount"),
             getSymbolCount: () => sum(host.getSourceFiles(), "symbolCount") + symbolCount,
+            getTypeCatalog: () => typeCatalog,
             getTypeCount: () => typeCount,
             getInstantiationCount: () => totalInstantiationCount,
             getRelationCacheSizes: () => ({
@@ -380,6 +383,7 @@ namespace ts {
             getMergedSymbol,
             getDiagnostics,
             getGlobalDiagnostics,
+            getRecursionIdentity,
             getTypeOfSymbolAtLocation: (symbol, locationIn) => {
                 const location = getParseTreeNode(locationIn);
                 return location ? getTypeOfSymbolAtLocation(symbol, location) : errorType;
@@ -3674,6 +3678,7 @@ namespace ts {
             const result = new Type(checker, flags);
             typeCount++;
             result.id = typeCount;
+            typeCatalog.push(result);
             return result;
         }
 
@@ -10847,6 +10852,7 @@ namespace ts {
                         // very high likelihood we're dealing with an infinite generic type that perpetually generates
                         // new type identities as we descend into it. We stop the recursion here and mark this type
                         // and the outer types as having circular constraints.
+                        tracing.instant(tracing.Phase.Check, "getImmediateBaseConstraint_DepthLimit", { typeId: t.id, originalTypeId: type.id, depth: constraintDepth });
                         error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite);
                         nonTerminating = true;
                         return t.immediateBaseConstraint = noConstraintType;
@@ -12936,6 +12942,7 @@ namespace ts {
                             // caps union types at 5000 unique literal types and 1000 unique object types.
                             const estimatedCount = (count / (len - i)) * len;
                             if (estimatedCount > (primitivesOnly ? 25000000 : 1000000)) {
+                                tracing.instant(tracing.Phase.Check, "removeSubtypes_DepthLimit", { typeIds: types.map(t => t.id) });
                                 error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent);
                                 return false;
                             }
@@ -15096,6 +15103,7 @@ namespace ts {
                 // We have reached 50 recursive type instantiations and there is a very high likelyhood we're dealing
                 // with a combination of infinite generic types that perpetually generate new type identities. We stop
                 // the recursion here by yielding the error type.
+                tracing.instant(tracing.Phase.Check, "instantiateType_DepthLimit", { typeId: type.id, instantiationDepth, instantiationCount });
                 error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite);
                 return errorType;
             }
@@ -16195,6 +16203,7 @@ namespace ts {
             containingMessageChain?: () => DiagnosticMessageChain | undefined,
             errorOutputContainer?: { errors?: Diagnostic[], skipLogging?: boolean },
         ): boolean {
+
             let errorInfo: DiagnosticMessageChain | undefined;
             let relatedInfo: [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined;
             let maybeKeys: string[];
@@ -16216,6 +16225,7 @@ namespace ts {
                 reportIncompatibleStack();
             }
             if (overflow) {
+                tracing.instant(tracing.Phase.Check, "checkTypeRelatedTo_DepthLimit", { sourceId: source.id, targetId: target.id, depth });
                 const diag = error(errorNode || currentNode, Diagnostics.Excessive_stack_depth_comparing_types_0_and_1, typeToString(source), typeToString(target));
                 if (errorOutputContainer) {
                     (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag);
@@ -16257,6 +16267,8 @@ namespace ts {
             if (errorNode && errorOutputContainer && errorOutputContainer.skipLogging && result === Ternary.False) {
                 Debug.assert(!!errorOutputContainer.errors, "missed opportunity to interact with error.");
             }
+
+
             return result !== Ternary.False;
 
             function resetErrorInfo(saved: ReturnType<typeof captureErrorCalculationState>) {
@@ -17034,6 +17046,17 @@ namespace ts {
                         return originalHandler!(onlyUnreliable);
                     };
                 }
+
+                if (expandingFlags === ExpandingFlags.Both) {
+                    tracing.instant(tracing.Phase.Check, "recursiveTypeRelatedTo_DepthLimit", {
+                        sourceId: source.id,
+                        sourceIdStack: sourceStack.map(t => t.id),
+                        targetId: target.id,
+                        targetIdStack: targetStack.map(t => t.id),
+                        depth,
+                    });
+                }
+
                 const result = expandingFlags !== ExpandingFlags.Both ? structuredTypeRelatedTo(source, target, reportErrors, intersectionState) : Ternary.Maybe;
                 if (outofbandVarianceMarkerHandler) {
                     outofbandVarianceMarkerHandler = originalHandler;
@@ -17059,6 +17082,13 @@ namespace ts {
             }
 
             function structuredTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary {
+                tracing.begin(tracing.Phase.Check, "structuredTypeRelatedTo", { sourceId: source.id, targetId: target.id });
+                const result = structuredTypeRelatedToWorker(source, target, reportErrors, intersectionState);
+                tracing.end();
+                return result;
+            }
+
+            function structuredTypeRelatedToWorker(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary {
                 if (intersectionState & IntersectionState.PropertyCheck) {
                     return propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, IntersectionState.None);
                 }
@@ -17517,6 +17547,7 @@ namespace ts {
                     numCombinations *= countTypes(getTypeOfSymbol(sourceProperty));
                     if (numCombinations > 25) {
                         // We've reached the complexity limit.
+                        tracing.instant(tracing.Phase.Check, "typeRelatedToDiscriminatedType_DepthLimit", { sourceId: source.id, targetId: target.id, numCombinations });
                         return Ternary.False;
                     }
                 }
@@ -18267,6 +18298,7 @@ namespace ts {
         function getVariancesWorker<TCache extends { variances?: VarianceFlags[] }>(typeParameters: readonly TypeParameter[] = emptyArray, cache: TCache, createMarkerType: (input: TCache, param: TypeParameter, marker: Type) => Type): VarianceFlags[] {
             let variances = cache.variances;
             if (!variances) {
+                tracing.begin(tracing.Phase.Check, "getVariancesWorker", { arity: typeParameters.length, id: (cache as any).id ?? (cache as any).declaredType?.id ?? -1 });
                 // The emptyArray singleton is used to signal a recursive invocation.
                 cache.variances = emptyArray;
                 variances = [];
@@ -18301,6 +18333,7 @@ namespace ts {
                     variances.push(variance);
                 }
                 cache.variances = variances;
+                tracing.end();
             }
             return variances;
         }
@@ -18449,7 +18482,9 @@ namespace ts {
                     for (let i = 0; i < depth; i++) {
                         if (getRecursionIdentity(stack[i]) === identity) {
                             count++;
-                            if (count >= 5) return true;
+                            if (count >= 5) {
+                                return true;
+                            }
                         }
                     }
                 }
@@ -19554,6 +19589,7 @@ namespace ts {
             inferFromTypes(originalSource, originalTarget);
 
             function inferFromTypes(source: Type, target: Type): void {
+
                 if (!couldContainTypeVariables(target)) {
                     return;
                 }
@@ -21296,6 +21332,7 @@ namespace ts {
                 if (flowDepth === 2000) {
                     // We have made 2000 recursive invocations. To avoid overflowing the call stack we report an error
                     // and disable further control flow analysis in the containing function or module body.
+                    tracing.instant(tracing.Phase.Check, "getTypeAtFlowNode_DepthLimit", { flowId: flow.id });
                     flowAnalysisDisabled = true;
                     reportFlowControlError(reference);
                     return errorType;
@@ -30504,6 +30541,7 @@ namespace ts {
         }
 
         function checkExpression(node: Expression | QualifiedName, checkMode?: CheckMode, forceTuple?: boolean): Type {
+            tracing.begin(tracing.Phase.Check, "checkExpression", { kind: node.kind, pos: node.pos, end: node.end });
             const saveCurrentNode = currentNode;
             currentNode = node;
             instantiationCount = 0;
@@ -30513,6 +30551,7 @@ namespace ts {
                 checkConstEnumAccess(node, type);
             }
             currentNode = saveCurrentNode;
+            tracing.end();
             return type;
         }
 
@@ -33306,8 +33345,10 @@ namespace ts {
         }
 
         function checkVariableDeclaration(node: VariableDeclaration) {
+            tracing.begin(tracing.Phase.Check, "checkVariableDeclaration", { kind: node.kind, pos: node.pos, end: node.end });
             checkGrammarVariableDeclaration(node);
-            return checkVariableLikeDeclaration(node);
+            checkVariableLikeDeclaration(node);
+            tracing.end();
         }
 
         function checkBindingElement(node: BindingElement) {
@@ -36348,10 +36389,12 @@ namespace ts {
         }
 
         function checkSourceFile(node: SourceFile) {
+            tracing.begin(tracing.Phase.Check, "checkSourceFile", { path: node.path });
             performance.mark("beforeCheck");
             checkSourceFileWorker(node);
             performance.mark("afterCheck");
             performance.measure("Check", "beforeCheck", "afterCheck");
+            tracing.end();
         }
 
         function unusedIsError(kind: UnusedKind, isAmbient: boolean): boolean {

src/compiler/commandLineParser.ts

@@ -197,6 +197,15 @@ namespace ts {
             category: Diagnostics.Advanced_Options,
             description: Diagnostics.Generates_a_CPU_profile
         },
+        {
+            name: "generateTrace",
+            type: "string",
+            isFilePath: true,
+            isCommandLineOnly: true,
+            paramType: Diagnostics.DIRECTORY,
+            category: Diagnostics.Advanced_Options,
+            description: Diagnostics.Generates_an_event_trace_and_a_list_of_types
+        },
         {
             name: "incremental",
             shortName: "i",

src/compiler/diagnosticMessages.json

@@ -4497,6 +4497,10 @@
         "category": "Error",
         "code": 6236
     },
+    "Generates an event trace and a list of types.": {
+        "category": "Message",
+        "code": 6237
+    },
 
     "Projects to reference": {
         "category": "Message",

src/compiler/emitter.ts

@@ -300,9 +300,17 @@ namespace ts {
                     sourceFiles: sourceFileOrBundle.sourceFiles.map(file => relativeToBuildInfo(getNormalizedAbsolutePath(file.fileName, host.getCurrentDirectory())))
                 };
             }
+            tracing.begin(tracing.Phase.Emit, "emitJsFileOrBundle", { jsFilePath });
             emitJsFileOrBundle(sourceFileOrBundle, jsFilePath, sourceMapFilePath, relativeToBuildInfo);
+            tracing.end();
+
+            tracing.begin(tracing.Phase.Emit, "emitDeclarationFileOrBundle", { declarationFilePath });
             emitDeclarationFileOrBundle(sourceFileOrBundle, declarationFilePath, declarationMapPath, relativeToBuildInfo);
+            tracing.end();
+
+            tracing.begin(tracing.Phase.Emit, "emitBuildInfo", { buildInfoPath });
             emitBuildInfo(bundleBuildInfo, buildInfoPath);
+            tracing.end();
 
             if (!emitSkipped && emittedFilesList) {
                 if (!emitOnlyDtsFiles) {

src/compiler/parser.ts

@@ -614,6 +614,7 @@ namespace ts {
     }
 
     export function createSourceFile(fileName: string, sourceText: string, languageVersion: ScriptTarget, setParentNodes = false, scriptKind?: ScriptKind): SourceFile {
+        tracing.begin(tracing.Phase.Parse, "createSourceFile", { path: fileName });
         performance.mark("beforeParse");
         let result: SourceFile;
 
@@ -628,6 +629,7 @@ namespace ts {
 
         performance.mark("afterParse");
         performance.measure("Parse", "beforeParse", "afterParse");
+        tracing.end();
         return result;
     }
 

src/compiler/program.ts

@@ -734,6 +734,7 @@ namespace ts {
         // Track source files that are source files found by searching under node_modules, as these shouldn't be compiled.
         const sourceFilesFoundSearchingNodeModules = new Map<string, boolean>();
 
+        tracing.begin(tracing.Phase.Program, "createProgram", {});
         performance.mark("beforeProgram");
 
         const host = createProgramOptions.host || createCompilerHost(options);
@@ -948,6 +949,7 @@ namespace ts {
             getNodeCount: () => getDiagnosticsProducingTypeChecker().getNodeCount(),
             getIdentifierCount: () => getDiagnosticsProducingTypeChecker().getIdentifierCount(),
             getSymbolCount: () => getDiagnosticsProducingTypeChecker().getSymbolCount(),
+            getTypeCatalog: () => getDiagnosticsProducingTypeChecker().getTypeCatalog(),
             getTypeCount: () => getDiagnosticsProducingTypeChecker().getTypeCount(),
             getInstantiationCount: () => getDiagnosticsProducingTypeChecker().getInstantiationCount(),
             getRelationCacheSizes: () => getDiagnosticsProducingTypeChecker().getRelationCacheSizes(),
@@ -982,6 +984,7 @@ namespace ts {
         verifyCompilerOptions();
         performance.mark("afterProgram");
         performance.measure("Program", "beforeProgram", "afterProgram");
+        tracing.end();
 
         return program;
 
@@ -1505,6 +1508,7 @@ namespace ts {
 
         function emitBuildInfo(writeFileCallback?: WriteFileCallback): EmitResult {
             Debug.assert(!outFile(options));
+            tracing.begin(tracing.Phase.Emit, "emitBuildInfo", {});
             performance.mark("beforeEmit");
             const emitResult = emitFiles(
                 notImplementedResolver,
@@ -1517,6 +1521,7 @@ namespace ts {
 
             performance.mark("afterEmit");
             performance.measure("Emit", "beforeEmit", "afterEmit");
+            tracing.end();
             return emitResult;
         }
 
@@ -1577,7 +1582,10 @@ namespace ts {
         }
 
         function emit(sourceFile?: SourceFile, writeFileCallback?: WriteFileCallback, cancellationToken?: CancellationToken, emitOnlyDtsFiles?: boolean, transformers?: CustomTransformers, forceDtsEmit?: boolean): EmitResult {
-            return runWithCancellationToken(() => emitWorker(program, sourceFile, writeFileCallback, cancellationToken, emitOnlyDtsFiles, transformers, forceDtsEmit));
+            tracing.begin(tracing.Phase.Emit, "emit", { path: sourceFile?.path });
+            const result = runWithCancellationToken(() => emitWorker(program, sourceFile, writeFileCallback, cancellationToken, emitOnlyDtsFiles, transformers, forceDtsEmit));
+            tracing.end();
+            return result;
         }
 
         function isEmitBlocked(emitFileName: string): boolean {

src/compiler/tracing.ts

@@ -0,0 +1,256 @@
+/*@internal*/
+/** Tracing events for the compiler. */
+namespace ts.tracing {
+    let fs: typeof import("fs") | false | undefined;
+
+    let traceCount = 0;
+    let traceFd: number | undefined;
+
+    let legendPath: string | undefined;
+    const legend: TraceRecord[] = [];
+
+    /** Starts tracing for the given project (unless the `fs` module is unavailable). */
+    export function startTracing(configFilePath: string | undefined, traceDir: string, isBuildMode: boolean) {
+        Debug.assert(!traceFd, "Tracing already started");
+
+        if (fs === undefined) {
+            try {
+                fs = require("fs");
+            }
+            catch {
+                fs = false;
+            }
+        }
+
+        if (!fs) {
+            return;
+        }
+
+        if (legendPath === undefined) {
+            legendPath = combinePaths(traceDir, "legend.json");
+        }
+
+        // Note that writing will fail later on if it exists and is not a directory
+        if (!fs.existsSync(traceDir)) {
+            fs.mkdirSync(traceDir, { recursive: true });
+        }
+
+        const countPart = isBuildMode ? `.${++traceCount}` : ``;
+        const tracePath = combinePaths(traceDir, `trace${countPart}.json`);
+        const typesPath = combinePaths(traceDir, `types${countPart}.json`);
+
+        legend.push({
+            configFilePath,
+            tracePath,
+            typesPath,
+        });
+
+        traceFd = fs.openSync(tracePath, "w");
+        fs.writeSync(traceFd, `[\n`);
+    }
+
+    /** Stops tracing for the in-progress project and dumps the type catalog (unless the `fs` module is unavailable). */
+    export function stopTracing(typeCatalog: readonly Type[]) {
+        if (!traceFd) {
+            Debug.assert(!fs, "Tracing is not in progress");
+            return;
+        }
+
+        Debug.assert(fs);
+
+        // This both indicates that the trace is untruncated and conveniently
+        // ensures that the last array element won't have a trailing comma.
+        fs.writeSync(traceFd, `{"pid":1,"tid":1,"ph":"i","ts":${1000 * timestamp()},"name":"done","s":"g"}\n`);
+        fs.writeSync(traceFd, `]\n`);
+
+        fs.closeSync(traceFd);
+        traceFd = undefined;
+
+        if (typeCatalog) {
+            dumpTypes(typeCatalog);
+        }
+        else {
+            // We pre-computed this path for convenience, but clear it
+            // now that the file won't be created.
+            legend[legend.length - 1].typesPath = undefined;
+        }
+    }
+
+    export function isTracing() {
+        return !!traceFd;
+    }
+
+    export const enum Phase {
+        Parse = "parse",
+        Program = "program",
+        Bind = "bind",
+        Check = "check",
+        Emit = "emit",
+    }
+
+    export function begin(phase: Phase, name: string, args: object) {
+        if (!traceFd) {
+            return;
+        }
+        Debug.assert(fs);
+
+        performance.mark("beginTracing");
+        fs.writeSync(traceFd, `{"pid":1,"tid":1,"ph":"B","cat":"${phase}","ts":${1000 * timestamp()},"name":"${name}","args":{ "ts": ${JSON.stringify(args)} }},\n`);
+        performance.mark("endTracing");
+        performance.measure("Tracing", "beginTracing", "endTracing");
+    }
+
+    export function end() {
+        if (!traceFd) {
+            return;
+        }
+        Debug.assert(fs);
+
+        performance.mark("beginTracing");
+        fs.writeSync(traceFd, `{"pid":1,"tid":1,"ph":"E","ts":${1000 * timestamp()}},\n`);
+        performance.mark("endTracing");
+        performance.measure("Tracing", "beginTracing", "endTracing");
+    }
+
+    export function instant(phase: Phase, name: string, args: object) {
+        if (!traceFd) {
+            return;
+        }
+        Debug.assert(fs);
+
+        performance.mark("beginTracing");
+        fs.writeSync(traceFd, `{"pid":1,"tid":1,"ph":"i","cat":"${phase}","ts":${1000 * timestamp()},"name":"${name}","s":"g","args":{ "ts": ${JSON.stringify(args)} }},\n`);
+        performance.mark("endTracing");
+        performance.measure("Tracing", "beginTracing", "endTracing");
+    }
+
+    function indexFromOne(lc: LineAndCharacter): LineAndCharacter {
+        return {
+            line: lc.line + 1,
+            character: lc.character + 1,
+        };
+    }
+
+    function dumpTypes(types: readonly Type[]) {
+        Debug.assert(fs);
+
+        performance.mark("beginDumpTypes");
+
+        const typesPath = legend[legend.length - 1].typesPath!;
+        const typesFd = fs.openSync(typesPath, "w");
+
+        const recursionIdentityMap = new Map<object, number>();
+
+        // Cleverness: no line break here so that the type ID will match the line number
+        fs.writeSync(typesFd, "[");
+
+        const numTypes = types.length;
+        for (let i = 0; i < numTypes; i++) {
+            const type = types[i];
+            const objectFlags = (type as any).objectFlags;
+            const symbol = type.aliasSymbol ?? type.symbol;
+            const firstDeclaration = symbol?.declarations?.[0];
+            const firstFile = firstDeclaration && getSourceFileOfNode(firstDeclaration);
+
+            // It's slow to compute the display text, so skip it unless it's really valuable (or cheap)
+            let display: string | undefined;
+            if ((objectFlags & ObjectFlags.Anonymous) | (type.flags & TypeFlags.Literal)) {
+                try {
+                    display = type.checker?.typeToString(type);
+                }
+                catch {
+                    display = undefined;
+                }
+            }
+
+            let indexedAccessProperties: object = {};
+            if (type.flags & TypeFlags.IndexedAccess) {
+                const indexedAccessType = type as IndexedAccessType;
+                indexedAccessProperties = {
+                    indexedAccessObjectType: indexedAccessType.objectType?.id,
+                    indexedAccessIndexType: indexedAccessType.indexType?.id,
+                };
+            }
+
+            let referenceProperties: object = {};
+            if (objectFlags & ObjectFlags.Reference) {
+                const referenceType = type as TypeReference;
+                referenceProperties = {
+                    instantiatedType: referenceType.target?.id,
+                    typeArguments: referenceType.resolvedTypeArguments?.map(t => t.id),
+                };
+            }
+
+            let conditionalProperties: object = {};
+            if (type.flags & TypeFlags.Conditional) {
+                const conditionalType = type as ConditionalType;
+                conditionalProperties = {
+                    conditionalCheckType: conditionalType.checkType?.id,
+                    conditionalExtendsType: conditionalType.extendsType?.id,
+                    conditionalTrueType: conditionalType.resolvedTrueType?.id ?? -1,
+                    conditionalFalseType: conditionalType.resolvedFalseType?.id ?? -1,
+                };
+            }
+
+            // We can't print out an arbitrary object, so just assign each one a unique number.
+            // Don't call it an "id" so people don't treat it as a type id.
+            let recursionToken: number | undefined;
+            const recursionIdentity = type.checker.getRecursionIdentity(type);
+            if (recursionIdentity) {
+                recursionToken = recursionIdentityMap.get(recursionIdentity);
+                if (!recursionToken) {
+                    recursionToken = recursionIdentityMap.size;
+                    recursionIdentityMap.set(recursionIdentity, recursionToken);
+                }
+            }
+
+            const descriptor = {
+                id: type.id,
+                intrinsicName: (type as any).intrinsicName,
+                symbolName: symbol?.escapedName && unescapeLeadingUnderscores(symbol.escapedName),
+                recursionId: recursionToken,
+                unionTypes: (type.flags & TypeFlags.Union) ? (type as UnionType).types?.map(t => t.id) : undefined,
+                intersectionTypes: (type.flags & TypeFlags.Intersection) ? (type as IntersectionType).types.map(t => t.id) : undefined,
+                aliasTypeArguments: type.aliasTypeArguments?.map(t => t.id),
+                keyofType: (type.flags & TypeFlags.Index) ? (type as IndexType).type?.id : undefined,
+                ...indexedAccessProperties,
+                ...referenceProperties,
+                ...conditionalProperties,
+                firstDeclaration: firstDeclaration && {
+                    path: firstFile.path,
+                    start: indexFromOne(getLineAndCharacterOfPosition(firstFile, firstDeclaration.pos)),
+                    end: indexFromOne(getLineAndCharacterOfPosition(getSourceFileOfNode(firstDeclaration), firstDeclaration.end)),
+                },
+                flags: Debug.formatTypeFlags(type.flags).split("|"),
+                display,
+            };
+
+            fs.writeSync(typesFd, JSON.stringify(descriptor));
+            if (i < numTypes - 1) {
+                fs.writeSync(typesFd, ",\n");
+            }
+        }
+
+        fs.writeSync(typesFd, "]\n");
+
+        fs.closeSync(typesFd);
+
+        performance.mark("endDumpTypes");
+        performance.measure("Dump types", "beginDumpTypes", "endDumpTypes");
+    }
+
+    export function dumpLegend() {
+        if (!legendPath) {
+            return;
+        }
+        Debug.assert(fs);
+
+        fs.writeFileSync(legendPath, JSON.stringify(legend));
+    }
+
+    interface TraceRecord {
+        configFilePath?: string;
+        tracePath: string;
+        typesPath?: string;
+    }
+}

src/compiler/transformer.ts

@@ -222,7 +222,12 @@ namespace ts {
         state = TransformationState.Initialized;
 
         // Transform each node.
-        const transformed = map(nodes, allowDtsFiles ? transformation : transformRoot);
+        const transformed: T[] = [];
+        for (const node of nodes) {
+            tracing.begin(tracing.Phase.Emit, "transformNodes", node.kind === SyntaxKind.SourceFile ? { path: (node as any as SourceFile).path } : { kind: node.kind, pos: node.pos, end: node.end });
+            transformed.push((allowDtsFiles ? transformation : transformRoot)(node));
+            tracing.end();
+        }
 
         // prevent modification of the lexical environment.
         state = TransformationState.Completed;

src/compiler/tsbuildPublic.ts

@@ -23,6 +23,7 @@ namespace ts {
         /* @internal */ extendedDiagnostics?: boolean;
         /* @internal */ locale?: string;
         /* @internal */ generateCpuProfile?: string;
+        /* @internal */ generateTrace?: string;
 
         [option: string]: CompilerOptionsValue | undefined;
     }

src/compiler/tsconfig.json

@@ -17,6 +17,7 @@
         "performance.ts",
         "perfLogger.ts",
         "semver.ts",
+        "tracing.ts",
 
         "types.ts",
         "sys.ts",

src/compiler/types.ts

@@ -3776,6 +3776,8 @@ namespace ts {
 
         /* @internal */ getClassifiableNames(): Set<__String>;
 
+        getTypeCatalog(): readonly Type[];
+
         getNodeCount(): number;
         getIdentifierCount(): number;
         getSymbolCount(): number;
@@ -4110,12 +4112,15 @@ namespace ts {
         /* @internal */ getGlobalDiagnostics(): Diagnostic[];
         /* @internal */ getEmitResolver(sourceFile?: SourceFile, cancellationToken?: CancellationToken): EmitResolver;
 
+        /* @internal */ getTypeCatalog(): readonly Type[];
+
         /* @internal */ getNodeCount(): number;
         /* @internal */ getIdentifierCount(): number;
         /* @internal */ getSymbolCount(): number;
         /* @internal */ getTypeCount(): number;
         /* @internal */ getInstantiationCount(): number;
         /* @internal */ getRelationCacheSizes(): { assignable: number, identity: number, subtype: number, strictSubtype: number };
+        /* @internal */ getRecursionIdentity(type: Type): object | undefined;
 
         /* @internal */ isArrayType(type: Type): boolean;
         /* @internal */ isTupleType(type: Type): boolean;
@@ -5739,6 +5744,7 @@ namespace ts {
         experimentalDecorators?: boolean;
         forceConsistentCasingInFileNames?: boolean;
         /*@internal*/generateCpuProfile?: string;
+        /*@internal*/generateTrace?: string;
         /*@internal*/help?: boolean;
         importHelpers?: boolean;
         importsNotUsedAsValues?: ImportsNotUsedAsValues;

src/compiler/utilities.ts

@@ -5531,7 +5531,7 @@ namespace ts {
 
     function Type(this: Type, checker: TypeChecker, flags: TypeFlags) {
         this.flags = flags;
-        if (Debug.isDebugging) {
+        if (Debug.isDebugging || tracing.isTracing()) {
             this.checker = checker;
         }
     }

src/executeCommandLine/executeCommandLine.ts

@@ -456,6 +456,7 @@ namespace ts {
         updateSolutionBuilderHost(sys, cb, buildHost);
         const builder = createSolutionBuilder(buildHost, projects, buildOptions);
         const exitStatus = buildOptions.clean ? builder.clean() : builder.build();
+        tracing.dumpLegend();
         return sys.exit(exitStatus);
     }
 
@@ -476,7 +477,7 @@ namespace ts {
         const currentDirectory = host.getCurrentDirectory();
         const getCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames());
         changeCompilerHostLikeToUseCache(host, fileName => toPath(fileName, currentDirectory, getCanonicalFileName));
-        enableStatistics(sys, options);
+        enableStatisticsAndTracing(sys, options, /*isBuildMode*/ false);
 
         const programOptions: CreateProgramOptions = {
             rootNames: fileNames,
@@ -504,7 +505,7 @@ namespace ts {
         config: ParsedCommandLine
     ) {
         const { options, fileNames, projectReferences } = config;
-        enableStatistics(sys, options);
+        enableStatisticsAndTracing(sys, options, /*isBuildMode*/ false);
         const host = createIncrementalCompilerHost(options, sys);
         const exitStatus = ts.performIncrementalCompilation({
             host,
@@ -541,7 +542,7 @@ namespace ts {
         host.createProgram = (rootNames, options, host, oldProgram, configFileParsingDiagnostics, projectReferences) => {
             Debug.assert(rootNames !== undefined || (options === undefined && !!oldProgram));
             if (options !== undefined) {
-                enableStatistics(sys, options);
+                enableStatisticsAndTracing(sys, options, /*isBuildMode*/ true);
             }
             return compileUsingBuilder(rootNames, options, host, oldProgram, configFileParsingDiagnostics, projectReferences);
         };
@@ -610,15 +611,28 @@ namespace ts {
         return system === sys && (compilerOptions.diagnostics || compilerOptions.extendedDiagnostics);
     }
 
-    function enableStatistics(sys: System, compilerOptions: CompilerOptions) {
-        if (canReportDiagnostics(sys, compilerOptions)) {
+    function canTrace(system: System, compilerOptions: CompilerOptions) {
+        return system === sys && compilerOptions.generateTrace;
+    }
+
+    function enableStatisticsAndTracing(system: System, compilerOptions: CompilerOptions, isBuildMode: boolean) {
+        if (canReportDiagnostics(system, compilerOptions)) {
             performance.enable();
         }
+
+        if (canTrace(system, compilerOptions)) {
+            tracing.startTracing(compilerOptions.configFilePath, compilerOptions.generateTrace!, isBuildMode);
+        }
     }
 
     function reportStatistics(sys: System, program: Program) {
-        let statistics: Statistic[];
         const compilerOptions = program.getCompilerOptions();
+
+        if (canTrace(sys, compilerOptions)) {
+            tracing.stopTracing(program.getTypeCatalog());
+        }
+
+        let statistics: Statistic[];
         if (canReportDiagnostics(sys, compilerOptions)) {
             statistics = [];
             const memoryUsed = sys.getMemoryUsage ? sys.getMemoryUsage() : -1;

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -2089,6 +2089,7 @@ declare namespace ts {
          * Gets a type checker that can be used to semantically analyze source files in the program.
          */
         getTypeChecker(): TypeChecker;
+        getTypeCatalog(): readonly Type[];
         getNodeCount(): number;
         getIdentifierCount(): number;
         getSymbolCount(): number;

tests/baselines/reference/api/typescript.d.ts

@@ -2089,6 +2089,7 @@ declare namespace ts {
          * Gets a type checker that can be used to semantically analyze source files in the program.
          */
         getTypeChecker(): TypeChecker;
+        getTypeCatalog(): readonly Type[];
         getNodeCount(): number;
         getIdentifierCount(): number;
         getSymbolCount(): number;

tests/baselines/reference/showConfig/Shows tsconfig for single option/generateTrace/tsconfig.json

@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "generateTrace": "./someString"
+    }
+}