Add the notion of deferred diagnostics.

Summary:
This patch lets you create diagnostics that are emitted if and only if a
particular FunctionDecl is codegen'ed.

This is necessary for CUDA, where some constructs -- e.g. calls from
host+device functions to host functions when compiling for device -- are
allowed to appear in semantically-correct programs, but only if they're
never codegen'ed.

Reviewers: rnk

Subscribers: cfe-commits, tra

Differential Revision: https://reviews.llvm.org/D23241

llvm-svn: 278735

1 files changed, 37 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index f20baab784b..2dcccf4c6c8 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -497,6 +497,16 @@ void CodeGenModule::Release() {
   EmitVersionIdentMetadata();
 
   EmitTargetMetadata();
+
+  // Emit any deferred diagnostics gathered during codegen.  We didn't emit them
+  // when we first discovered them because that would have halted codegen,
+  // preventing us from gathering other deferred diags.
+  for (const PartialDiagnosticAt &DiagAt : DeferredDiags) {
+    SourceLocation Loc = DiagAt.first;
+    const PartialDiagnostic &PD = DiagAt.second;
+    DiagnosticBuilder Builder(getDiags().Report(Loc, PD.getDiagID()));
+    PD.Emit(Builder);
+  }
 }
 
 void CodeGenModule::UpdateCompletedType(const TagDecl *TD) {
@@ -2872,6 +2882,33 @@ void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD,
                                                  llvm::GlobalValue *GV) {
   const auto *D = cast<FunctionDecl>(GD.getDecl());
 
+  // Emit this function's deferred diagnostics, if none of them are errors.  If
+  // any of them are errors, don't codegen the function, but also don't emit any
+  // of the diagnostics just yet.  Emitting an error during codegen stops
+  // further codegen, and we want to display as many deferred diags as possible.
+  // We'll emit the now twice-deferred diags at the very end of codegen.
+  //
+  // (If a function has both error and non-error diags, we don't emit the
+  // non-error diags here, because order can be significant, e.g. with notes
+  // that follow errors.)
+  auto Diags = D->takeDeferredDiags();
+  bool HasError = llvm::any_of(Diags, [this](const PartialDiagnosticAt &PDAt) {
+    return getDiags().getDiagnosticLevel(PDAt.second.getDiagID(), PDAt.first) >=
+           DiagnosticsEngine::Error;
+  });
+  if (HasError) {
+    DeferredDiags.insert(DeferredDiags.end(),
+                         std::make_move_iterator(Diags.begin()),
+                         std::make_move_iterator(Diags.end()));
+    return;
+  }
+  for (PartialDiagnosticAt &PDAt : Diags) {
+    const SourceLocation &Loc = PDAt.first;
+    const PartialDiagnostic &PD = PDAt.second;
+    DiagnosticBuilder Builder(getDiags().Report(Loc, PD.getDiagID()));
+    PD.Emit(Builder);
+  }
+
   // Compute the function info and LLVM type.
   const CGFunctionInfo &FI = getTypes().arrangeGlobalDeclaration(GD);
   llvm::FunctionType *Ty = getTypes().GetFunctionType(FI);