Debug Info: Support DW_AT_calling_convention on composite types.

This implements the DWARF 5 feature described at
http://www.dwarfstd.org/ShowIssue.php?issue=141215.1

This allows a consumer to understand whether a composite data type is
trivially copyable and thus should be passed by value instead of by
reference. The canonical example is being able to distinguish the
following two types:

  // S is not trivially copyable because of the explicit destructor.
  struct S {
     ~S() {}
  };

  // T is a POD type.
  struct T {
     ~T() = default;
  };

This patch adds two new (DI)flags to LLVM metadata: TypePassByValue
and TypePassByReference.

<rdar://problem/36034922>
Differential Revision: https://reviews.llvm.org/D41743

llvm-svn: 321844

3 files changed, 9 insertions, 1 deletions

diff --git a/llvm/include/llvm-c/DebugInfo.h b/llvm/include/llvm-c/DebugInfo.h
index d17c690be4d..a5e5653630c 100644
--- a/llvm/include/llvm-c/DebugInfo.h
+++ b/llvm/include/llvm-c/DebugInfo.h
@@ -52,6 +52,8 @@ typedef enum {
   LLVMDIFlagBitField = 1 << 19,
   LLVMDIFlagNoReturn = 1 << 20,
   LLVMDIFlagMainSubprogram = 1 << 21,
+  LLVMDIFlagTypePassByValue = 1 << 22,
+  LLVMDIFlagTypePassByReference = 1 << 23,
   LLVMDIFlagIndirectVirtualBase = (1 << 2) | (1 << 5),
   LLVMDIFlagAccessibility = LLVMDIFlagPrivate | LLVMDIFlagProtected |
                             LLVMDIFlagPublic,
diff --git a/llvm/include/llvm/IR/DebugInfoFlags.def b/llvm/include/llvm/IR/DebugInfoFlags.def
index 7ea6346998f..96cc3e56285 100644
--- a/llvm/include/llvm/IR/DebugInfoFlags.def
+++ b/llvm/include/llvm/IR/DebugInfoFlags.def
@@ -43,6 +43,8 @@ HANDLE_DI_FLAG((1 << 18), IntroducedVirtual)
 HANDLE_DI_FLAG((1 << 19), BitField)
 HANDLE_DI_FLAG((1 << 20), NoReturn)
 HANDLE_DI_FLAG((1 << 21), MainSubprogram)
+HANDLE_DI_FLAG((1 << 22), TypePassByValue)
+HANDLE_DI_FLAG((1 << 23), TypePassByReference)
 
 // To avoid needing a dedicated value for IndirectVirtualBase, we use
 // the bitwise or of Virtual and FwdDecl, which does not otherwise
@@ -52,7 +54,7 @@ HANDLE_DI_FLAG((1 << 2) | (1 << 5), IndirectVirtualBase)
 #ifdef DI_FLAG_LARGEST_NEEDED
 // intended to be used with ADT/BitmaskEnum.h
 // NOTE: always must be equal to largest flag, check this when adding new flag
-HANDLE_DI_FLAG((1 << 21), Largest)
+HANDLE_DI_FLAG((1 << 23), Largest)
 #undef DI_FLAG_LARGEST_NEEDED
 #endif
 
diff --git a/llvm/include/llvm/IR/DebugInfoMetadata.h b/llvm/include/llvm/IR/DebugInfoMetadata.h
index 75b0c43b651..f58f3df7b74 100644
--- a/llvm/include/llvm/IR/DebugInfoMetadata.h
+++ b/llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -633,6 +633,10 @@ public:
   bool isStaticMember() const { return getFlags() & FlagStaticMember; }
   bool isLValueReference() const { return getFlags() & FlagLValueReference; }
   bool isRValueReference() const { return getFlags() & FlagRValueReference; }
+  bool isTypePassByValue() const { return getFlags() & FlagTypePassByValue; }
+  bool isTypePassByReference() const {
+    return getFlags() & FlagTypePassByReference;
+  }
 
   static bool classof(const Metadata *MD) {
     switch (MD->getMetadataID()) {