[Verifier] Improve error for cross-module references

[loladiro]

Summary

By including the module name in the error message. This makes the error message much more useful and saves a trip to the debugger.

[loladiro]

Redone using VerifierSupport and with a test case to make sure it works.

[loladiro]

@dexonsmith Does this look ok now?

[llvm-commits]

Yup, LGTM.

lib/IR/Verifier.cpp

           "Cannot invoke an intrinsinc other than"
           " donothing or patchpoint",
           &I);
-      Assert(F->getParent() == M, "Referencing function in another module!",
-             &I);
+      Module *ParentM = F->getParent();
+      Assert(ParentM == M,
+             "Referencing function in module `" +
+                 (ParentM ? std::string(ParentM->getName())
+                          : std::string("null")) +
+                 "` from another module (`" +
+                 (M ? std::string(M->getName()) : std::string("null")) + "`)!",
+             &I, F, BB->getParent());
     } else if (BasicBlock *OpBB = dyn_cast<BasicBlock>(I.getOperand(i))) {
       Assert(OpBB->getParent() == BB->getParent(),
              "Referring to a basic block in another function!", &I);