Under VFE/WME, disable mangled accessors and disable LLVM MergeFunctions (#39969)

Author: kubamracek

lib/Frontend/CompilerInvocation.cpp

@@ -1972,14 +1972,32 @@ static bool ParseIRGenArgs(IRGenOptions &Opts, ArgList &Args,
 
   if (Args.hasArg(OPT_enable_llvm_vfe)) {
     Opts.VirtualFunctionElimination = true;
+
+    // FIXME(mracek): There are still some situations where we use mangled name
+    // without symbolic references, which means the dependency is not statically
+    // visible to the compiler/linker. Temporarily disable mangled accessors
+    // until we fix that.
+    Opts.DisableConcreteTypeMetadataMangledNameAccessors = true;
   }
 
   if (Args.hasArg(OPT_enable_llvm_wme)) {
     Opts.WitnessMethodElimination = true;
+
+    // FIXME(mracek): There are still some situations where we use mangled name
+    // without symbolic references, which means the dependency is not statically
+    // visible to the compiler/linker. Temporarily disable mangled accessors
+    // until we fix that.
+    Opts.DisableConcreteTypeMetadataMangledNameAccessors = true;
   }
 
   if (Args.hasArg(OPT_conditional_runtime_records)) {
     Opts.ConditionalRuntimeRecords = true;
+
+    // FIXME(mracek): There are still some situations where we use mangled name
+    // without symbolic references, which means the dependency is not statically
+    // visible to the compiler/linker. Temporarily disable mangled accessors
+    // until we fix that.
+    Opts.DisableConcreteTypeMetadataMangledNameAccessors = true;
   }
 
   if (Args.hasArg(OPT_internalize_at_link)) {

lib/IRGen/IRGen.cpp

@@ -231,6 +231,12 @@ void swift::performLLVMOptimizations(const IRGenOptions &Opts,
         llvm::createAlwaysInlinerLegacyPass(/*insertlifetime*/false);
   }
 
+  // LLVM MergeFunctions doesn't understand the string in the metadata on calls
+  // in @llvm.type.checked.load intrinsics is important, and mis-compiles
+  // (mis-merge) unrelated functions.
+  if (Opts.VirtualFunctionElimination || Opts.WitnessMethodElimination)
+    PMBuilder.MergeFunctions = false;
+
   bool RunSwiftSpecificLLVMOptzns =
       !Opts.DisableSwiftSpecificLLVMOptzns && !Opts.DisableLLVMOptzns;