Reduce map lookups (microsoft#24203)

Andy · web-flow · commit 2b5ff29254ad · 2018-05-17T10:02:10.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -15397,10 +15397,11 @@ namespace ts {
                 links.resolvedSignatures = createMap();
             }
             const cacheKey = "" + getTypeId(valueType);
-            if (links.resolvedSignatures.get(cacheKey) && links.resolvedSignatures.get(cacheKey) !== resolvingSignaturesArray) {
-                signatures = links.resolvedSignatures.get(cacheKey);
+            const cachedResolved = links.resolvedSignatures.get(cacheKey);
+            if (cachedResolved && cachedResolved !== resolvingSignaturesArray) {
+                signatures = cachedResolved;
             }
-            else if (!links.resolvedSignatures.get(cacheKey)) {
+            else if (!cachedResolved) {
                 links.resolvedSignatures.set(cacheKey, resolvingSignaturesArray);
                 links.resolvedSignatures.set(cacheKey, signatures = instantiateJsxSignatures(context, signatures));
             }

Original file line number	Diff line number	Diff line change
`@@ -15397,10 +15397,11 @@ namespace ts {`
`15397`	`15397`	`links.resolvedSignatures = createMap();`
`15398`	`15398`	`}`
`15399`	`15399`	`const cacheKey = "" + getTypeId(valueType);`
`15400`		`- if (links.resolvedSignatures.get(cacheKey) && links.resolvedSignatures.get(cacheKey) !== resolvingSignaturesArray) {`
`15401`		`- signatures = links.resolvedSignatures.get(cacheKey);`
	`15400`	`+ const cachedResolved = links.resolvedSignatures.get(cacheKey);`
	`15401`	`+ if (cachedResolved && cachedResolved !== resolvingSignaturesArray) {`
	`15402`	`+ signatures = cachedResolved;`
`15402`	`15403`	`}`
`15403`		`- else if (!links.resolvedSignatures.get(cacheKey)) {`
	`15404`	`+ else if (!cachedResolved) {`
`15404`	`15405`	`links.resolvedSignatures.set(cacheKey, resolvingSignaturesArray);`
`15405`	`15406`	`links.resolvedSignatures.set(cacheKey, signatures = instantiateJsxSignatures(context, signatures));`
`15406`	`15407`	`}`