[clang] Rework dontcall attributes

To avoid using the AST when emitting diagnostics, split the "dontcall"
attribute into "dontcall-warn" and "dontcall-error", and also add the
frontend attribute value as the LLVM attribute value. This gives us all
the information to report diagnostics we need from within the IR (aside
from access to the original source).

One downside is we directly use LLVM's demangler rather than using the
existing Clang diagnostic pretty printing of symbols.

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D110364

1 files changed, 13 insertions, 24 deletions

diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 789c06a..6e1d7f3 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -27,6 +27,7 @@
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
+#include "llvm/Demangle/Demangle.h"
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
@@ -760,30 +761,18 @@ void BackendConsumer::OptimizationFailureHandler(
 }
 
 void BackendConsumer::DontCallDiagHandler(const DiagnosticInfoDontCall &D) {
-  if (const Decl *DE = Gen->GetDeclForMangledName(D.getFunctionName()))
-    if (const auto *FD = dyn_cast<FunctionDecl>(DE)) {
-      assert(FD->hasAttr<ErrorAttr>() &&
-             "expected error or warning function attribute");
-
-      if (const auto *EA = FD->getAttr<ErrorAttr>()) {
-        assert((EA->isError() || EA->isWarning()) &&
-               "ErrorAttr neither error or warning");
-
-        SourceLocation LocCookie =
-            SourceLocation::getFromRawEncoding(D.getLocCookie());
-
-        // FIXME: we can't yet diagnose indirect calls. When/if we can, we
-        // should instead assert that LocCookie.isValid().
-        if (!LocCookie.isValid())
-          return;
-
-        Diags.Report(LocCookie, EA->isError()
-                                    ? diag::err_fe_backend_error_attr
-                                    : diag::warn_fe_backend_warning_attr)
-            << FD << EA->getUserDiagnostic();
-      }
-    }
-  // TODO: assert if DE or FD were nullptr?
+  SourceLocation LocCookie =
+      SourceLocation::getFromRawEncoding(D.getLocCookie());
+
+  // FIXME: we can't yet diagnose indirect calls. When/if we can, we
+  // should instead assert that LocCookie.isValid().
+  if (!LocCookie.isValid())
+    return;
+
+  Diags.Report(LocCookie, D.getSeverity() == DiagnosticSeverity::DS_Error
+                              ? diag::err_fe_backend_error_attr
+                              : diag::warn_fe_backend_warning_attr)
+      << llvm::demangle(D.getFunctionName().str()) << D.getNote();
 }
 
 /// This function is invoked when the backend needs