Revert "Preserve SIL when merging modules"

lib/AST/Module.cpp

@@ -663,11 +663,13 @@ ModuleDecl::lookupConformance(Type type, ProtocolDecl *protocol) {
   if (auto inherited = dyn_cast<InheritedProtocolConformance>(conformance)) {
     // Dig out the conforming nominal type.
     auto rootConformance = inherited->getRootNormalConformance();
-    auto conformingClass
+    auto conformingNominal
       = rootConformance->getType()->getClassOrBoundGenericClass();
 
     // Map up to our superclass's type.
-    auto superclassTy = type->getSuperclassForDecl(conformingClass);
+    Type superclassTy = type->getSuperclass();
+    while (superclassTy->getAnyNominal() != conformingNominal)
+      superclassTy = superclassTy->getSuperclass();
 
     // Compute the conformance for the inherited type.
     auto inheritedConformance = lookupConformance(superclassTy, protocol);

lib/Driver/ToolChains.cpp

@@ -687,14 +687,6 @@ ToolChain::constructInvocation(const MergeModuleJobAction &job,
   // serialized ASTs.
   Arguments.push_back("-parse-as-library");
 
-  // Merge serialized SIL from partial modules.
-  Arguments.push_back("-sil-merge-partial-modules");
-
-  // Disable SIL optimization passes; we've already optimized the code in each
-  // partial mode.
-  Arguments.push_back("-disable-diagnostic-passes");
-  Arguments.push_back("-disable-sil-perf-optzns");
-
   addCommonFrontendArgs(*this, context.OI, context.Output, context.Args,
                         Arguments);
   context.Args.AddLastArg(Arguments, options::OPT_import_objc_header);

validation-test/Evolution/test_function_change_transparent_body.swift

@@ -1,6 +1,9 @@
-// RUN: %target-resilience-test
+// RUN: %target-resilience-test-wmo
 // REQUIRES: executable_test
 
+// FIXME: shouldn't need -whole-module-optimization here; we need to fix the
+// frontend to merge serialized SIL functions from different translation units
+
 import StdlibUnittest
 import function_change_transparent_body