[hip][cuda] Fix the extended lambda name mangling issue.

Summary:
- HIP/CUDA host side needs to use device kernel symbol name to match the
  device side binaries. Without a consistent naming between host- and
  device-side compilations, it's risky that wrong device binaries are
  executed. Consistent naming is usually not an issue until unnamed
  types are used, especially the lambda. In this patch, the consistent
  name mangling is addressed for the extended lambdas, i.e. the lambdas
  annotated with `__device__`.
- In [Itanium C++ ABI][1], the mangling of the lambda is generally
  unspecified unless, in certain cases, ODR rule is required to ensure
  consisent naming cross TUs. The extended lambda is such a case as its
  name may be part of a device kernel function, e.g., the extended
  lambda is used as a template argument and etc. Thus, we need to force
  ODR for extended lambdas as they are referenced in both device- and
  host-side TUs. Furthermore, if a extended lambda is nested in other
  (extended or not) lambdas, those lambdas are required to follow ODR
  naming as well. This patch revises the current lambda mangle numbering
  to force ODR from an extended lambda to all its parent lambdas.
- On the other side, the aforementioned ODR naming should not change
  those lambdas' original linkages, i.e., we cannot replace the original
  `internal` with `linkonce_odr`; otherwise, we may violate ODR in
  general. This patch introduces a new field `HasKnownInternalLinkage`
  in lambda data to decouple the current linkage calculation based on
  mangling number assigned.

[1]: https://itanium-cxx-abi.github.io/cxx-abi/abi.html

Reviewers: tra, rsmith, yaxunl, martong, shafik

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D68818

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@375309 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 32 insertions, 14 deletions

diff --git a/include/clang/AST/DeclCXX.h b/include/clang/AST/DeclCXX.h
index 0c6c2846c9..66212f72b7 100644
--- a/include/clang/AST/DeclCXX.h
+++ b/include/clang/AST/DeclCXX.h
@@ -389,9 +389,12 @@ class CXXRecordDecl : public RecordDecl {
     /// The number of explicit captures in this lambda.
     unsigned NumExplicitCaptures : 13;
 
+    /// Has known `internal` linkage.
+    unsigned HasKnownInternalLinkage : 1;
+
     /// The number used to indicate this lambda expression for name
     /// mangling in the Itanium C++ ABI.
-    unsigned ManglingNumber = 0;
+    unsigned ManglingNumber : 31;
 
     /// The declaration that provides context for this lambda, if the
     /// actual DeclContext does not suffice. This is used for lambdas that
@@ -406,12 +409,12 @@ class CXXRecordDecl : public RecordDecl {
     /// The type of the call method.
     TypeSourceInfo *MethodTyInfo;
 
-    LambdaDefinitionData(CXXRecordDecl *D, TypeSourceInfo *Info,
-                         bool Dependent, bool IsGeneric,
-                         LambdaCaptureDefault CaptureDefault)
-      : DefinitionData(D), Dependent(Dependent), IsGenericLambda(IsGeneric),
-        CaptureDefault(CaptureDefault), NumCaptures(0), NumExplicitCaptures(0),
-        MethodTyInfo(Info) {
+    LambdaDefinitionData(CXXRecordDecl *D, TypeSourceInfo *Info, bool Dependent,
+                         bool IsGeneric, LambdaCaptureDefault CaptureDefault)
+        : DefinitionData(D), Dependent(Dependent), IsGenericLambda(IsGeneric),
+          CaptureDefault(CaptureDefault), NumCaptures(0),
+          NumExplicitCaptures(0), HasKnownInternalLinkage(0), ManglingNumber(0),
+          MethodTyInfo(Info) {
       IsLambda = true;
 
       // C++1z [expr.prim.lambda]p4:
@@ -1705,6 +1708,13 @@ public:
     return getLambdaData().ManglingNumber;
   }
 
+  /// The lambda is known to has internal linkage no matter whether it has name
+  /// mangling number.
+  bool hasKnownLambdaInternalLinkage() const {
+    assert(isLambda() && "Not a lambda closure type!");
+    return getLambdaData().HasKnownInternalLinkage;
+  }
+
   /// Retrieve the declaration that provides additional context for a
   /// lambda, when the normal declaration context is not specific enough.
   ///
@@ -1718,9 +1728,12 @@ public:
 
   /// Set the mangling number and context declaration for a lambda
   /// class.
-  void setLambdaMangling(unsigned ManglingNumber, Decl *ContextDecl) {
+  void setLambdaMangling(unsigned ManglingNumber, Decl *ContextDecl,
+                         bool HasKnownInternalLinkage = false) {
+    assert(isLambda() && "Not a lambda closure type!");
     getLambdaData().ManglingNumber = ManglingNumber;
     getLambdaData().ContextDecl = ContextDecl;
+    getLambdaData().HasKnownInternalLinkage = HasKnownInternalLinkage;
   }
 
   /// Returns the inheritance model used for this record.
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 1e3d6b93d0..bf8e59d607 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -5926,12 +5926,17 @@ public:
                                          LambdaCaptureDefault CaptureDefault);
 
   /// Start the definition of a lambda expression.
-  CXXMethodDecl *
-  startLambdaDefinition(CXXRecordDecl *Class, SourceRange IntroducerRange,
-                        TypeSourceInfo *MethodType, SourceLocation EndLoc,
-                        ArrayRef<ParmVarDecl *> Params,
-                        ConstexprSpecKind ConstexprKind,
-                        Optional<std::pair<unsigned, Decl *>> Mangling = None);
+  CXXMethodDecl *startLambdaDefinition(CXXRecordDecl *Class,
+                                       SourceRange IntroducerRange,
+                                       TypeSourceInfo *MethodType,
+                                       SourceLocation EndLoc,
+                                       ArrayRef<ParmVarDecl *> Params,
+                                       ConstexprSpecKind ConstexprKind);
+
+  /// Number lambda for linkage purposes if necessary.
+  void handleLambdaNumbering(
+      CXXRecordDecl *Class, CXXMethodDecl *Method,
+      Optional<std::tuple<unsigned, bool, Decl *>> Mangling = None);
 
   /// Endow the lambda scope info with the relevant properties.
   void buildLambdaScope(sema::LambdaScopeInfo *LSI,