verify-di: Implement DebugInfoVerifier

Implement DebugInfoVerifier, which steals verification relying on
DebugInfoFinder from Verifier.

  - Adds LegacyDebugInfoVerifierPassPass, a ModulePass which wraps
    DebugInfoVerifier.  Uses -verify-di command-line flag.

  - Change verifyModule() to invoke DebugInfoVerifier as well as
    Verifier.

  - Add a call to createDebugInfoVerifierPass() wherever there was a
    call to createVerifierPass().

This implementation as a module pass should sidestep efficiency issues,
allowing us to turn debug info verification back on.

<rdar://problem/15500563>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206300 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/Verifier.h

@@ -28,6 +28,7 @@ namespace llvm {
 
 class Function;
 class FunctionPass;
+class ModulePass;
 class Module;
 class PreservedAnalyses;
 class raw_ostream;
@@ -58,6 +59,18 @@ bool verifyModule(const Module &M, raw_ostream *OS = nullptr);
 /// Note that this creates a pass suitable for the legacy pass manager. It has nothing to do with \c VerifierPass.
 FunctionPass *createVerifierPass(bool FatalErrors = true);
 
+/// \brief Create a debug-info verifier pass.
+///
+/// Check a module for validity of debug info. This is essentially a pass
+/// wrapped around the debug-info parts of \a verifyModule().  When the pass
+/// detects a verification error it is always printed to stderr, and by default
+/// they are fatal. You can override that by passing \c false to \p
+/// FatalErrors.
+///
+/// Note that this creates a pass suitable for the legacy pass manager. It has
+/// nothing to do with \c VerifierPass.
+ModulePass *createDebugInfoVerifierPass(bool FatalErrors = true);
+
 class VerifierPass {
   bool FatalErrors;
 

include/llvm/InitializePasses.h

@@ -103,6 +103,7 @@ void initializeDAHPass(PassRegistry&);
 void initializeDCEPass(PassRegistry&);
 void initializeDSEPass(PassRegistry&);
 void initializeDebugIRPass(PassRegistry&);
+void initializeDebugInfoVerifierLegacyPassPass(PassRegistry &);
 void initializeDeadInstEliminationPass(PassRegistry&);
 void initializeDeadMachineInstructionElimPass(PassRegistry&);
 void initializeDelinearizationPass(PassRegistry &);