[CSOptimizer] Use conformsToKnownProtocol to check whether parameter conforms to ExpressibleBy{Array, Dictionary}Literal

The existing check is no-op because it would never produce a null for
`paramType` under the conditions in `else` branch. A better
API it use here is `conformsToKnownProtocol` just like in other cases.

Author: xedin

lib/Sema/CSOptimizer.cpp

@@ -1316,27 +1316,20 @@ static void determineBestChoicesInContext(
               return 0.3;
           }
 
-          auto &ctx = cs.getASTContext();
-
           // Check if the other side conforms to `ExpressibleByArrayLiteral`
           // protocol (in some way). We want an overly optimistic result
           // here to avoid under-favoring.
           if (candidateType->isArray() &&
-              checkConformanceWithoutContext(
-                  paramType,
-                  ctx.getProtocol(KnownProtocolKind::ExpressibleByArrayLiteral),
-                  /*allowMissing=*/true))
+              TypeChecker::conformsToKnownProtocol(
+                  paramType, KnownProtocolKind::ExpressibleByArrayLiteral))
             return 0.3;
 
           // Check if the other side conforms to
           // `ExpressibleByDictionaryLiteral` protocol (in some way).
           // We want an overly optimistic result here to avoid under-favoring.
           if (candidateType->isDictionary() &&
-              checkConformanceWithoutContext(
-                  paramType,
-                  ctx.getProtocol(
-                      KnownProtocolKind::ExpressibleByDictionaryLiteral),
-                  /*allowMissing=*/true))
+              TypeChecker::conformsToKnownProtocol(
+                  paramType, KnownProtocolKind::ExpressibleByDictionaryLiteral))
             return 0.3;
         }
 

validation-test/Sema/type_checker_perf/fast/array_literals_with_custom_types.swift.gyb

@@ -0,0 +1,16 @@
+// RUN: %scale-test --begin 1 --end 15 --step 1 --select NumLeafScopes %s
+// REQUIRES: asserts,no_asan
+
+struct MyIntValue: ExpressibleByArrayLiteral {
+    init(arrayLiteral: Int...) {}
+}
+
+func +(x: MyIntValue, y: MyIntValue) -> MyIntValue { [] }
+func +(x: MyIntValue, y: Int) -> MyIntValue { [] }
+
+func test(y: Int) {
+%for i in range(0, N):
+  [1] + y +
+%end
+  [1] + y
+}