[sanitizers] Use covering ObjectFormatType switches

Summary:
This patch removes the `default` case from some switches on
`llvm::Triple::ObjectFormatType`, and cases for the missing enumerators
(`UnknownObjectFormat`, `Wasm`, and `XCOFF`) are then added.

For `UnknownObjectFormat`, the effect of the action for the `default`
case is maintained; otherwise, where `llvm_unreachable` is called,
`report_fatal_error` is used instead.

Where the `default` case returns a default value, `report_fatal_error`
is used for XCOFF as a placeholder. For `Wasm`, the effect of the action
for the `default` case in maintained.

The code is structured to avoid strongly implying that the `Wasm` case
is present for any reason other than to make the switch cover all
`ObjectFormatType` enumerator values.

Reviewers: sfertile, jasonliu, daltenty

Reviewed By: sfertile

Subscribers: hiraditya, aheejin, sunfish, llvm-commits, cfe-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D64222

llvm-svn: 366544

Author: hubert-reinterpretcast

clang/lib/CodeGen/BackendUtil.cpp

@@ -231,9 +231,13 @@ static bool asanUseGlobalsGC(const Triple &T, const CodeGenOptions &CGOpts) {
     return true;
   case Triple::ELF:
     return CGOpts.DataSections && !CGOpts.DisableIntegratedAS;
-  default:
-    return false;
+  case Triple::XCOFF:
+    llvm::report_fatal_error("ASan not implemented for XCOFF.");
+  case Triple::Wasm:
+  case Triple::UnknownObjectFormat:
+    break;
   }
+  return false;
 }
 
 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -1919,7 +1919,12 @@ StringRef ModuleAddressSanitizer::getGlobalMetadataSection() const {
   case Triple::COFF:  return ".ASAN$GL";
   case Triple::ELF:   return "asan_globals";
   case Triple::MachO: return "__DATA,__asan_globals,regular";
-  default: break;
+  case Triple::Wasm:
+  case Triple::XCOFF:
+    report_fatal_error(
+        "ModuleAddressSanitizer not implemented for object file format.");
+  case Triple::UnknownObjectFormat:
+    break;
   }
   llvm_unreachable("unsupported object format");
 }