[DebugInfo] Add calling conventions to DISubroutineType

Summary:
This should have been a very simple change, but it was greatly
complicated by the construction of new Decls during IR generation.

In particular, we reconstruct the AST function type in order to get the
implicit 'this' parameter into C++ method types.

We also have to worry about FunctionDecls whose types are not
FunctionTypes because CGBlocks.cpp constructs some dummy FunctionDecls
with 'void' type.

Depends on D21114

Reviewers: aprantl, dblaikie

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D21141

llvm-svn: 272198

2 files changed, 57 insertions, 15 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index a63f5582cd9..e2000ea79aa 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -831,6 +831,39 @@ llvm::DIType *CGDebugInfo::CreateType(const TypedefType *Ty,
       getDeclContextDescriptor(Ty->getDecl()));
 }
 
+static unsigned getDwarfCC(CallingConv CC) {
+  switch (CC) {
+  case CC_C:
+    // Avoid emitting DW_AT_calling_convention if the C convention was used.
+    return 0;
+
+  case CC_X86StdCall:
+    return llvm::dwarf::DW_CC_BORLAND_stdcall;
+  case CC_X86FastCall:
+    return llvm::dwarf::DW_CC_BORLAND_msfastcall;
+  case CC_X86ThisCall:
+    return llvm::dwarf::DW_CC_BORLAND_thiscall;
+  case CC_X86VectorCall:
+    return llvm::dwarf::DW_CC_LLVM_vectorcall;
+  case CC_X86Pascal:
+    return llvm::dwarf::DW_CC_BORLAND_pascal;
+
+  // FIXME: Create new DW_CC_ codes for these calling conventions.
+  case CC_X86_64Win64:
+  case CC_X86_64SysV:
+  case CC_AAPCS:
+  case CC_AAPCS_VFP:
+  case CC_IntelOclBicc:
+  case CC_SpirFunction:
+  case CC_SpirKernel:
+  case CC_Swift:
+  case CC_PreserveMost:
+  case CC_PreserveAll:
+    return 0;
+  }
+  return 0;
+}
+
 llvm::DIType *CGDebugInfo::CreateType(const FunctionType *Ty,
                                       llvm::DIFile *Unit) {
   SmallVector<llvm::Metadata *, 16> EltTys;
@@ -850,7 +883,8 @@ llvm::DIType *CGDebugInfo::CreateType(const FunctionType *Ty,
   }
 
   llvm::DITypeRefArray EltTypeArray = DBuilder.getOrCreateTypeArray(EltTys);
-  return DBuilder.createSubroutineType(EltTypeArray);
+  return DBuilder.createSubroutineType(EltTypeArray, 0,
+                                       getDwarfCC(Ty->getCallConv()));
 }
 
 /// Convert an AccessSpecifier into the corresponding DINode flag.
@@ -1103,7 +1137,8 @@ llvm::DISubroutineType *CGDebugInfo::getOrCreateInstanceMethodType(
   if (Func->getExtProtoInfo().RefQualifier == RQ_RValue)
     Flags |= llvm::DINode::FlagRValueReference;
 
-  return DBuilder.createSubroutineType(EltTypeArray, Flags);
+  return DBuilder.createSubroutineType(EltTypeArray, Flags,
+                                       getDwarfCC(Func->getCallConv()));
 }
 
 /// isFunctionLocalClass - Return true if CXXRecordDecl is defined
@@ -2562,9 +2597,9 @@ CGDebugInfo::getFunctionForwardDeclaration(const FunctionDecl *FD) {
   SmallVector<QualType, 16> ArgTypes;
   for (const ParmVarDecl *Parm: FD->parameters())
     ArgTypes.push_back(Parm->getType());
-  QualType FnType =
-    CGM.getContext().getFunctionType(FD->getReturnType(), ArgTypes,
-                                     FunctionProtoType::ExtProtoInfo());
+  CallingConv CC = FD->getType()->castAs<FunctionType>()->getCallConv();
+  QualType FnType = CGM.getContext().getFunctionType(
+      FD->getReturnType(), ArgTypes, FunctionProtoType::ExtProtoInfo(CC));
   llvm::DISubprogram *SP = DBuilder.createTempFunctionFwdDecl(
       DContext, Name, LinkageName, Unit, Line,
       getOrCreateFunctionType(FD, FnType, Unit), !FD->isExternallyVisible(),
@@ -2668,6 +2703,10 @@ llvm::DISubroutineType *CGDebugInfo::getOrCreateFunctionType(const Decl *D,
 
   if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D))
     return getOrCreateMethodType(Method, F);
+
+  const auto *FTy = FnType->getAs<FunctionType>();
+  CallingConv CC = FTy ? FTy->getCallConv() : CallingConv::CC_C;
+
   if (const ObjCMethodDecl *OMethod = dyn_cast<ObjCMethodDecl>(D)) {
     // Add "self" and "_cmd"
     SmallVector<llvm::Metadata *, 16> Elts;
@@ -2701,7 +2740,7 @@ llvm::DISubroutineType *CGDebugInfo::getOrCreateFunctionType(const Decl *D,
       Elts.push_back(DBuilder.createUnspecifiedParameter());
 
     llvm::DITypeRefArray EltTypeArray = DBuilder.getOrCreateTypeArray(Elts);
-    return DBuilder.createSubroutineType(EltTypeArray);
+    return DBuilder.createSubroutineType(EltTypeArray, 0, getDwarfCC(CC));
   }
 
   // Handle variadic function types; they need an additional
@@ -2715,7 +2754,7 @@ llvm::DISubroutineType *CGDebugInfo::getOrCreateFunctionType(const Decl *D,
           EltTys.push_back(getOrCreateType(FPT->getParamType(i), F));
       EltTys.push_back(DBuilder.createUnspecifiedParameter());
       llvm::DITypeRefArray EltTypeArray = DBuilder.getOrCreateTypeArray(EltTys);
-      return DBuilder.createSubroutineType(EltTypeArray);
+      return DBuilder.createSubroutineType(EltTypeArray, 0, getDwarfCC(CC));
     }
 
   return cast<llvm::DISubroutineType>(getOrCreateType(FnType, F));
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 5c8f57dc005..d32ed7f8b7b 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -762,15 +762,18 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
 
   // Emit subprogram debug descriptor.
   if (CGDebugInfo *DI = getDebugInfo()) {
+    // Reconstruct the type from the argument list so that implicit parameters,
+    // such as 'this' and 'vtt', show up in the debug info. Preserve the calling
+    // convention.
+    CallingConv CC = CallingConv::CC_C;
+    if (auto *FD = dyn_cast_or_null<FunctionDecl>(D))
+      if (const auto *SrcFnTy = FD->getType()->getAs<FunctionType>())
+        CC = SrcFnTy->getCallConv();
     SmallVector<QualType, 16> ArgTypes;
-    for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
-	 i != e; ++i) {
-      ArgTypes.push_back((*i)->getType());
-    }
-
-    QualType FnType =
-      getContext().getFunctionType(RetTy, ArgTypes,
-                                   FunctionProtoType::ExtProtoInfo());
+    for (const VarDecl *VD : Args)
+      ArgTypes.push_back(VD->getType());
+    QualType FnType = getContext().getFunctionType(
+        RetTy, ArgTypes, FunctionProtoType::ExtProtoInfo(CC));
     DI->EmitFunctionStart(GD, Loc, StartLoc, FnType, CurFn, Builder);
   }