Always link SIL for partial modules in SILGen

Previously we would only link `.sib` partial
modules in SILGen, with other kinds of serialized
ASTs being linked just before the SILOptimizer if
`-sil-merge-partial-modules` was specified.
However linking them always seems to be the desired
behaviour, so adjust SILGen to link SIL for all
serialized AST inputs.

Author: hamishknight

include/swift/SIL/SILModule.h

@@ -561,10 +561,6 @@ class SILModule {
   /// i.e. it can be linked by linkFunction.
   bool hasFunction(StringRef Name);
 
-  /// Link all definitions in all segments that are logically part of
-  /// the same AST module.
-  void linkAllFromCurrentModule();
-
   /// Look up the SILWitnessTable representing the lowering of a protocol
   /// conformance, and collect the substitutions to apply to the referenced
   /// witnesses, if any.

lib/Frontend/Frontend.cpp

@@ -982,22 +982,17 @@ void CompilerInstance::freeASTContext() {
 /// Perform "stable" optimizations that are invariant across compiler versions.
 static bool performMandatorySILPasses(CompilerInvocation &Invocation,
                                       SILModule *SM) {
+  // Don't run diagnostic passes at all when merging modules.
   if (Invocation.getFrontendOptions().RequestedAction ==
       FrontendOptions::ActionType::MergeModules) {
-    // Don't run diagnostic passes at all.
-  } else if (!Invocation.getDiagnosticOptions().SkipDiagnosticPasses) {
-    if (runSILDiagnosticPasses(*SM))
-      return true;
-  } else {
+    return false;
+  }
+  if (Invocation.getDiagnosticOptions().SkipDiagnosticPasses) {
     // Even if we are not supposed to run the diagnostic passes, we still need
     // to run the ownership evaluator.
-    if (runSILOwnershipEliminatorPass(*SM))
-      return true;
+    return runSILOwnershipEliminatorPass(*SM);
   }
-
-  if (Invocation.getSILOptions().MergePartialModules)
-    SM->linkAllFromCurrentModule();
-  return false;
+  return runSILDiagnosticPasses(*SM);
 }
 
 /// Perform SIL optimization passes if optimizations haven't been disabled.

lib/SIL/IR/SILModule.cpp

@@ -427,11 +427,6 @@ bool SILModule::hasFunction(StringRef Name) {
   return getSILLoader()->hasSILFunction(Name);
 }
 
-void SILModule::linkAllFromCurrentModule() {
-  getSILLoader()->getAllForModule(getSwiftModule()->getName(),
-                                  /*PrimaryFile=*/nullptr);
-}
-
 void SILModule::invalidateSILLoaderCaches() {
   getSILLoader()->invalidateCaches();
 }

lib/SILGen/SILGen.cpp

@@ -1928,12 +1928,12 @@ ASTLoweringRequest::evaluate(Evaluator &evaluator,
   }
 
   // Also make sure to process any intermediate files that may contain SIL.
-  bool hasSIB = llvm::any_of(desc.getFiles(), [](const FileUnit *File) -> bool {
-    auto *SASTF = dyn_cast<SerializedASTFile>(File);
-    return SASTF && SASTF->isSIB();
-  });
-  if (hasSIB) {
-    auto primary = desc.context.dyn_cast<FileUnit *>();
+  bool shouldDeserialize =
+      llvm::any_of(desc.getFiles(), [](const FileUnit *File) -> bool {
+        return isa<SerializedASTFile>(File);
+      });
+  if (shouldDeserialize) {
+    auto *primary = desc.context.dyn_cast<FileUnit *>();
     silMod->getSILLoader()->getAllForModule(silMod->getSwiftModule()->getName(),
                                             primary);
   }

tools/sil-func-extractor/SILFunctionExtractor.cpp

@@ -275,16 +275,10 @@ int main(int argc, char **argv) {
   auto SILMod = performASTLowering(CI.getMainModule(), CI.getSILTypes(),
                                    CI.getSILOptions());
 
-  // Load the SIL if we have a non-SIB serialized module. SILGen handles SIB for
-  // us.
+  // Load in all the SIL if we're allowed to.
   if (Invocation.hasSerializedAST() && !extendedInfo.isSIB()) {
-    auto SL = SerializedSILLoader::create(
-        CI.getASTContext(), SILMod.get(), nullptr);
-
-    if (DisableSILLinking)
-      SL->getAllForModule(CI.getMainModule()->getName(), nullptr);
-    else
-      SL->getAll();
+    if (!DisableSILLinking)
+      SILMod->getSILLoader()->getAll();
   }
 
   if (CommandLineFunctionNames.empty() && FunctionNameFile.empty())

tools/sil-opt/SILOpt.cpp

@@ -464,15 +464,10 @@ int main(int argc, char **argv) {
   }
   SILMod->setSerializeSILAction([]{});
 
-  // Load the SIL if we have a non-SIB serialized module. SILGen handles SIB for
-  // us.
+  // Load in all the SIL if we're allowed to.
   if (Invocation.hasSerializedAST() && !extendedInfo.isSIB()) {
-    auto SL = SerializedSILLoader::create(
-        CI.getASTContext(), SILMod.get(), nullptr);
-    if (DisableSILLinking)
-      SL->getAllForModule(CI.getMainModule()->getName(), nullptr);
-    else
-      SL->getAll();
+    if (!DisableSILLinking)
+      SILMod->getSILLoader()->getAll();
   }
 
   if (!RemarksFilename.empty()) {