[OPENMP]Initial support for the delayed diagnostics.

It is important to delay the emission of the diagnostic messages for the
functions unless it is proved that the function is going to be used on
the device side. It is required to support compilation with some of the
target-specific system headers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@353540 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/LangOptions.def

@@ -203,7 +203,6 @@ LANGOPT(OpenMPUseTLS      , 1, 0, "Use TLS for threadprivates or runtime calls")
 LANGOPT(OpenMPIsDevice    , 1, 0, "Generate code only for OpenMP target device")
 LANGOPT(OpenMPCUDAMode    , 1, 0, "Generate code for OpenMP pragmas in SIMT/SPMD mode")
 LANGOPT(OpenMPCUDAForceFullRuntime , 1, 0, "Force to use full runtime in all constructs when offloading to CUDA devices")
-LANGOPT(OpenMPHostCXXExceptions    , 1, 0, "C++ exceptions handling in the host code.")
 LANGOPT(OpenMPCUDANumSMs  , 32, 0, "Number of SMs for CUDA devices.")
 LANGOPT(OpenMPCUDABlocksPerSM  , 32, 0, "Number of blocks per SM for CUDA devices.")
 LANGOPT(OpenMPOptimisticCollapse  , 1, 0, "Use at most 32 bits to represent the collapsed loop nest counter.")

include/clang/Sema/Sema.h

@@ -8763,6 +8763,9 @@ private:
   /// Pop OpenMP function region for non-capturing function.
   void popOpenMPFunctionRegion(const sema::FunctionScopeInfo *OldFSI);
 
+  /// Check whether we're allowed to call Callee from the current function.
+  void checkOpenMPDeviceFunction(SourceLocation Loc, FunctionDecl *Callee);
+
   /// Checks if a type or a declaration is disabled due to the owning extension
   /// being disabled, and emits diagnostic messages if it is disabled.
   /// \param D type or declaration to be checked.
@@ -10249,6 +10252,23 @@ public:
   /// Same as CUDADiagIfDeviceCode, with "host" and "device" switched.
   DeviceDiagBuilder CUDADiagIfHostCode(SourceLocation Loc, unsigned DiagID);
 
+  /// Creates a DeviceDiagBuilder that emits the diagnostic if the current
+  /// context is "used as device code".
+  ///
+  /// - If CurContext is a `declare target` function or it is known that the
+  /// function is emitted for the device, emits the diagnostics immediately.
+  /// - If CurContext is a non-`declare target` function and we are compiling
+  ///   for the device, creates a diagnostic which is emitted if and when we
+  ///   realize that the function will be codegen'ed.
+  ///
+  /// Example usage:
+  ///
+  ///  // Variable-length arrays are not allowed in NVPTX device code.
+  ///  if (diagIfOpenMPDeviceCode(Loc, diag::err_vla_unsupported))
+  ///    return ExprError();
+  ///  // Otherwise, continue parsing as normal.
+  DeviceDiagBuilder diagIfOpenMPDeviceCode(SourceLocation Loc, unsigned DiagID);
+
   enum CUDAFunctionTarget {
     CFT_Device,
     CFT_Global,

lib/Frontend/CompilerInvocation.cpp

@@ -2827,7 +2827,6 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
 
   // Set the flag to prevent the implementation from emitting device exception
   // handling code for those requiring so.
-  Opts.OpenMPHostCXXExceptions = Opts.Exceptions && Opts.CXXExceptions;
   if ((Opts.OpenMPIsDevice && T.isNVPTX()) || Opts.OpenCLCPlusPlus) {
     Opts.Exceptions = 0;
     Opts.CXXExceptions = 0;

lib/Sema/SemaExpr.cpp

@@ -14896,6 +14896,9 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
   }
 
   Func->markUsed(Context);
+
+  if (LangOpts.OpenMP && LangOpts.OpenMPIsDevice)
+    checkOpenMPDeviceFunction(Loc, Func);
 }
 
 static void

lib/Sema/SemaExprCXX.cpp

@@ -750,12 +750,13 @@ ExprResult Sema::BuildCXXThrow(SourceLocation OpLoc, Expr *Ex,
                                bool IsThrownVarInScope) {
   // Don't report an error if 'throw' is used in system headers.
   if (!getLangOpts().CXXExceptions &&
-      !getSourceManager().isInSystemHeader(OpLoc) &&
-      (!getLangOpts().OpenMPIsDevice ||
-       !getLangOpts().OpenMPHostCXXExceptions ||
-       isInOpenMPTargetExecutionDirective() ||
-       isInOpenMPDeclareTargetContext()))
-    Diag(OpLoc, diag::err_exceptions_disabled) << "throw";
+      !getSourceManager().isInSystemHeader(OpLoc)) {
+    // Delay error emission for the OpenMP device code.
+    if (LangOpts.OpenMP && LangOpts.OpenMPIsDevice)
+      diagIfOpenMPDeviceCode(OpLoc, diag::err_exceptions_disabled) << "throw";
+    else
+      Diag(OpLoc, diag::err_exceptions_disabled) << "throw";
+  }
 
   // Exceptions aren't allowed in CUDA device code.
   if (getLangOpts().CUDA)

lib/Sema/SemaOpenMP.cpp

@@ -1393,6 +1393,56 @@ void Sema::popOpenMPFunctionRegion(const FunctionScopeInfo *OldFSI) {
   DSAStack->popFunction(OldFSI);
 }
 
+static bool isOpenMPDeviceDelayedContext(Sema &S) {
+  assert(S.LangOpts.OpenMP && S.LangOpts.OpenMPIsDevice &&
+         "Expected OpenMP device compilation.");
+  return !S.isInOpenMPTargetExecutionDirective() &&
+         !S.isInOpenMPDeclareTargetContext();
+}
+
+/// Do we know that we will eventually codegen the given function?
+static bool isKnownEmitted(Sema &S, FunctionDecl *FD) {
+  assert(S.LangOpts.OpenMP && S.LangOpts.OpenMPIsDevice &&
+         "Expected OpenMP device compilation.");
+  // Templates are emitted when they're instantiated.
+  if (FD->isDependentContext())
+    return false;
+
+  if (OMPDeclareTargetDeclAttr::isDeclareTargetDeclaration(
+          FD->getCanonicalDecl()))
+    return true;
+
+  // Otherwise, the function is known-emitted if it's in our set of
+  // known-emitted functions.
+  return S.DeviceKnownEmittedFns.count(FD) > 0;
+}
+
+Sema::DeviceDiagBuilder Sema::diagIfOpenMPDeviceCode(SourceLocation Loc,
+                                                     unsigned DiagID) {
+  assert(LangOpts.OpenMP && LangOpts.OpenMPIsDevice &&
+         "Expected OpenMP device compilation.");
+  return DeviceDiagBuilder((isOpenMPDeviceDelayedContext(*this) &&
+                            !isKnownEmitted(*this, getCurFunctionDecl()))
+                               ? DeviceDiagBuilder::K_Deferred
+                               : DeviceDiagBuilder::K_Immediate,
+                           Loc, DiagID, getCurFunctionDecl(), *this);
+}
+
+void Sema::checkOpenMPDeviceFunction(SourceLocation Loc, FunctionDecl *Callee) {
+  assert(LangOpts.OpenMP && LangOpts.OpenMPIsDevice &&
+         "Expected OpenMP device compilation.");
+  assert(Callee && "Callee may not be null.");
+  FunctionDecl *Caller = getCurFunctionDecl();
+
+  // If the caller is known-emitted, mark the callee as known-emitted.
+  // Otherwise, mark the call in our call graph so we can traverse it later.
+  if (!isOpenMPDeviceDelayedContext(*this) ||
+      (Caller && isKnownEmitted(*this, Caller)))
+    markKnownEmitted(*this, Caller, Callee, Loc, isKnownEmitted);
+  else if (Caller)
+    DeviceCallGraph[Caller].insert({Callee, Loc});
+}
+
 bool Sema::isOpenMPCapturedByRef(const ValueDecl *D, unsigned Level) const {
   assert(LangOpts.OpenMP && "OpenMP is not allowed");
 

lib/Sema/SemaStmt.cpp

@@ -3997,12 +3997,13 @@ StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
                                   ArrayRef<Stmt *> Handlers) {
   // Don't report an error if 'try' is used in system headers.
   if (!getLangOpts().CXXExceptions &&
-      !getSourceManager().isInSystemHeader(TryLoc) &&
-      (!getLangOpts().OpenMPIsDevice ||
-       !getLangOpts().OpenMPHostCXXExceptions ||
-       isInOpenMPTargetExecutionDirective() ||
-       isInOpenMPDeclareTargetContext()))
-    Diag(TryLoc, diag::err_exceptions_disabled) << "try";
+      !getSourceManager().isInSystemHeader(TryLoc)) {
+    // Delay error emission for the OpenMP device code.
+    if (LangOpts.OpenMP && LangOpts.OpenMPIsDevice)
+      diagIfOpenMPDeviceCode(TryLoc, diag::err_exceptions_disabled) << "try";
+    else
+      Diag(TryLoc, diag::err_exceptions_disabled) << "try";
+  }
 
   // Exceptions aren't allowed in CUDA device code.
   if (getLangOpts().CUDA)

test/OpenMP/nvptx_target_exceptions_messages.cpp

@@ -68,4 +68,17 @@ int baz2() {
   return 2 + baz3();
 }
 
+int baz1() { throw 1; } // expected-error {{cannot use 'throw' with exceptions disabled}}
+
+int foobar1();
+int foobar2();
+
+int (*A)() = &foobar1;
+#pragma omp declare target
+int (*B)() = &foobar2;
+#pragma omp end declare target
+
+int foobar1() { throw 1; }
+int foobar2() { throw 1; } // expected-error {{cannot use 'throw' with exceptions disabled}}
+
 #endif // HEADER