Move the stripping of invalid debug info from the Verifier to AutoUpgrade.

This came out of a recent discussion on llvm-dev
(https://reviews.llvm.org/D38042). Currently the Verifier will strip
the debug info metadata from a module if it finds the dbeug info to be
malformed. This feature is very valuable since it allows us to improve
the Verifier by making it stricter without breaking bcompatibility,
but arguable the Verifier pass should not be modifying the IR. This
patch moves the stripping of broken debug info into AutoUpgrade
(UpgradeDebugInfo to be precise), which is a much better location for
this since the stripping of malformed (i.e., produced by older, buggy
versions of Clang) is a (harsh) form of AutoUpgrade.

This change is mostly NFC in nature, the one big difference is the
behavior when LLVM module passes are introducing malformed debug
info. Prior to this patch, a NoAsserts build would have printed a
warning and stripped the debug info, after this patch the Verifier
will report a fatal error. I believe this behavior is actually more
desirable anyway.

Differential Revision: https://reviews.llvm.org/D38184

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314699 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 22 insertions, 14 deletions

diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 9ae5ff1f6ef..4dc5d81cd08 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -237,7 +237,8 @@ bool LLParser::ValidateEndOfModule() {
     }
   }
 
-  UpgradeDebugInfo(*M);
+  if (UpgradeDebugInfo)
+    llvm::UpgradeDebugInfo(*M);
 
   UpgradeModuleFlags(*M);
 
diff --git a/lib/AsmParser/LLParser.h b/lib/AsmParser/LLParser.h
index d5b059355c4..5dadf521538 100644
--- a/lib/AsmParser/LLParser.h
+++ b/lib/AsmParser/LLParser.h
@@ -139,11 +139,16 @@ namespace llvm {
     std::map<Value*, std::vector<unsigned> > ForwardRefAttrGroups;
     std::map<unsigned, AttrBuilder> NumberedAttrBuilders;
 
+    /// Only the llvm-as tool may set this to false to bypass
+    /// UpgradeDebuginfo so it can generate broken bitcode.
+    bool UpgradeDebugInfo;
+
   public:
     LLParser(StringRef F, SourceMgr &SM, SMDiagnostic &Err, Module *M,
-             SlotMapping *Slots = nullptr)
+             SlotMapping *Slots = nullptr, bool UpgradeDebugInfo = true)
         : Context(M->getContext()), Lex(F, SM, Err, M->getContext()), M(M),
-          Slots(Slots), BlockAddressPFS(nullptr) {}
+          Slots(Slots), BlockAddressPFS(nullptr),
+          UpgradeDebugInfo(UpgradeDebugInfo) {}
     bool Run();
 
     bool parseStandaloneConstantValue(Constant *&C, const SlotMapping *Slots);
diff --git a/lib/AsmParser/Parser.cpp b/lib/AsmParser/Parser.cpp
index bee07ad9e0a..a43ae2b5577 100644
--- a/lib/AsmParser/Parser.cpp
+++ b/lib/AsmParser/Parser.cpp
@@ -23,22 +23,21 @@
 using namespace llvm;
 
 bool llvm::parseAssemblyInto(MemoryBufferRef F, Module &M, SMDiagnostic &Err,
-                             SlotMapping *Slots) {
+                             SlotMapping *Slots, bool UpgradeDebugInfo) {
   SourceMgr SM;
   std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(F);
   SM.AddNewSourceBuffer(std::move(Buf), SMLoc());
 
-  return LLParser(F.getBuffer(), SM, Err, &M, Slots).Run();
+  return LLParser(F.getBuffer(), SM, Err, &M, Slots, UpgradeDebugInfo).Run();
 }
 
-std::unique_ptr<Module> llvm::parseAssembly(MemoryBufferRef F,
-                                            SMDiagnostic &Err,
-                                            LLVMContext &Context,
-                                            SlotMapping *Slots) {
+std::unique_ptr<Module>
+llvm::parseAssembly(MemoryBufferRef F, SMDiagnostic &Err, LLVMContext &Context,
+                    SlotMapping *Slots, bool UpgradeDebugInfo) {
   std::unique_ptr<Module> M =
       make_unique<Module>(F.getBufferIdentifier(), Context);
 
-  if (parseAssemblyInto(F, *M, Err, Slots))
+  if (parseAssemblyInto(F, *M, Err, Slots, UpgradeDebugInfo))
     return nullptr;
 
   return M;
@@ -47,7 +46,8 @@ std::unique_ptr<Module> llvm::parseAssembly(MemoryBufferRef F,
 std::unique_ptr<Module> llvm::parseAssemblyFile(StringRef Filename,
                                                 SMDiagnostic &Err,
                                                 LLVMContext &Context,
-                                                SlotMapping *Slots) {
+                                                SlotMapping *Slots,
+                                                bool UpgradeDebugInfo) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
       MemoryBuffer::getFileOrSTDIN(Filename);
   if (std::error_code EC = FileOrErr.getError()) {
@@ -56,15 +56,17 @@ std::unique_ptr<Module> llvm::parseAssemblyFile(StringRef Filename,
     return nullptr;
   }
 
-  return parseAssembly(FileOrErr.get()->getMemBufferRef(), Err, Context, Slots);
+  return parseAssembly(FileOrErr.get()->getMemBufferRef(), Err, Context, Slots,
+                       UpgradeDebugInfo);
 }
 
 std::unique_ptr<Module> llvm::parseAssemblyString(StringRef AsmString,
                                                   SMDiagnostic &Err,
                                                   LLVMContext &Context,
-                                                  SlotMapping *Slots) {
+                                                  SlotMapping *Slots,
+                                                  bool UpgradeDebugInfo) {
   MemoryBufferRef F(AsmString, "<string>");
-  return parseAssembly(F, Err, Context, Slots);
+  return parseAssembly(F, Err, Context, Slots, UpgradeDebugInfo);
 }
 
 Constant *llvm::parseConstantValue(StringRef Asm, SMDiagnostic &Err,