[PDB] Restore the calling convention from PDB

Summary:
This patch implements restoring of the calling convention from PDB.
It is necessary for expressions evaluation, if we want to call a function
of the debuggee process with a calling convention other than ccall.

Reviewers: clayborg, zturner, labath, asmith

Reviewed By: clayborg

Subscribers: teemperor, lldb-commits, stella.stamenova

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D52501

2 files changed, 25 insertions, 2 deletions

diff --git a/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp b/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
index a4c4459bf56..50076307001 100644
--- a/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
+++ b/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
@@ -331,6 +331,26 @@ static bool IsAnonymousNamespaceName(const std::string &name) {
   return name == "`anonymous namespace'" || name == "`anonymous-namespace'";
 }
 
+static clang::CallingConv TranslateCallingConvention(PDB_CallingConv pdb_cc) {
+  switch (pdb_cc) {
+  case llvm::codeview::CallingConvention::NearC:
+    return clang::CC_C;
+  case llvm::codeview::CallingConvention::NearStdCall:
+    return clang::CC_X86StdCall;
+  case llvm::codeview::CallingConvention::NearFast:
+    return clang::CC_X86FastCall;
+  case llvm::codeview::CallingConvention::ThisCall:
+    return clang::CC_X86ThisCall;
+  case llvm::codeview::CallingConvention::NearVector:
+    return clang::CC_X86VectorCall;
+  case llvm::codeview::CallingConvention::NearPascal:
+    return clang::CC_X86Pascal;
+  default:
+    assert(false && "Unknown calling convention");
+    return clang::CC_C;
+  }
+}
+
 PDBASTParser::PDBASTParser(lldb_private::ClangASTContext &ast) : m_ast(ast) {}
 
 PDBASTParser::~PDBASTParser() {}
@@ -603,9 +623,10 @@ lldb::TypeSP PDBASTParser::CreateLLDBTypeFromPDBType(const PDBSymbol &type) {
       type_quals |= clang::Qualifiers::Const;
     if (func_sig->isVolatileType())
       type_quals |= clang::Qualifiers::Volatile;
+    auto cc = TranslateCallingConvention(func_sig->getCallingConvention());
     CompilerType func_sig_ast_type =
         m_ast.CreateFunctionType(return_ast_type, arg_list.data(),
-                                 arg_list.size(), is_variadic, type_quals);
+                                 arg_list.size(), is_variadic, type_quals, cc);
 
     GetDeclarationForSymbol(type, decl);
     return std::make_shared<lldb_private::Type>(
diff --git a/lldb/source/Symbol/ClangASTContext.cpp b/lldb/source/Symbol/ClangASTContext.cpp
index 23e94884e37..fe47f29f18b 100644
--- a/lldb/source/Symbol/ClangASTContext.cpp
+++ b/lldb/source/Symbol/ClangASTContext.cpp
@@ -2058,7 +2058,8 @@ FunctionDecl *ClangASTContext::CreateFunctionDeclaration(
 
 CompilerType ClangASTContext::CreateFunctionType(
     ASTContext *ast, const CompilerType &result_type, const CompilerType *args,
-    unsigned num_args, bool is_variadic, unsigned type_quals) {
+    unsigned num_args, bool is_variadic, unsigned type_quals,
+    clang::CallingConv cc) {
   if (ast == nullptr)
     return CompilerType(); // invalid AST
 
@@ -2086,6 +2087,7 @@ CompilerType ClangASTContext::CreateFunctionType(
 
   // TODO: Detect calling convention in DWARF?
   FunctionProtoType::ExtProtoInfo proto_info;
+  proto_info.ExtInfo = cc;
   proto_info.Variadic = is_variadic;
   proto_info.ExceptionSpec = EST_None;
   proto_info.TypeQuals = type_quals;