[Clang][CGDebugInfo][ObjC] Mark objc bitfields with the DIFlagBitfield flag

[jmmartinez]

clang-format

[aprantl]

How does this affect the generated DWARF? Have you tested that this does the right thing in LLDB?

[jmmartinez]

In D140195#4001989, @aprantl wrote:

How does this affect the generated DWARF? Have you tested that this does the right thing in LLDB?

It shouldn't affect the generated DWARF on LLVM's main branch.
Currently, LLVM relies on the field size to know if a member is a bitfield or not.

However, if we apply the patch https://reviews.llvm.org/D96334 , if the DIFlagBitField attribute is not added, the members won't be treated as bitfields.

Unluckly, I wasn't able to test the combination of https://reviews.llvm.org/D96334 and this patch together. If you have some pointers about how to trigger a test job on "Green Dragon", or how to test lldb's objective-c tests on Linux I'd be happy to test.

[aprantl]

Unluckly, I wasn't able to test the combination of https://reviews.llvm.org/D96334 and this patch together. If you have some pointers about how to trigger a test job on "Green Dragon", or how to test lldb's objective-c tests on Linux I'd be happy to test.

There's no way to request a test from green dragon. There is also no way to test LLDB's Objective-C support on Linux, or at least I'm not aware of anyone maintaining a port of LLDB to the GNUstep Objective-C runtime.
So I tried out the patch on a Mac locally and the entire LLDB testsuite still passes.

[jmmartinez]

In D140195#4008724, @aprantl wrote:

Unluckly, I wasn't able to test the combination of https://reviews.llvm.org/D96334 and this patch together. If you have some pointers about how to trigger a test job on "Green Dragon", or how to test lldb's objective-c tests on Linux I'd be happy to test.

There's no way to request a test from green dragon. There is also no way to test LLDB's Objective-C support on Linux, or at least I'm not aware of anyone maintaining a port of LLDB to the GNUstep Objective-C runtime.
So I tried out the patch on a Mac locally and the entire LLDB testsuite still passes.

Thanks for the help in testing! Did you happen to test with https://reviews.llvm.org/D96334 ? If you confirm I'll "revert the revert" (commit 920de9c94caff0b3ac21bf637487b07cb9aea98a).

clang/lib/CodeGen/CGDebugInfo.cpp

for (ObjCIvarDecl *Field = ID->all_declared_ivar_begin(); Field;
     llvm::DINode::DIFlags Flags = llvm::DINode::FlagZero;
     if (Field->getAccessControl() == ObjCIvarDecl::Protected)
       Flags = llvm::DINode::FlagProtected;
     else if (Field->getAccessControl() == ObjCIvarDecl::Private)
       Flags = llvm::DINode::FlagPrivate;
     else if (Field->getAccessControl() == ObjCIvarDecl::Public)
       Flags = llvm::DINode::FlagPublic;
 
+    if (Field->isBitField())
+      Flags |= llvm::DINode::FlagBitField;
+
     llvm::MDNode *PropertyNode = nullptr;
     if (ObjCImplementationDecl *ImpD = ID->getImplementation()) {
       if (ObjCPropertyImplDecl *PImpD =
               ImpD->FindPropertyImplIvarDecl(Field->getIdentifier())) {
         if (ObjCPropertyDecl *PD = PImpD->getPropertyDecl()) {
           SourceLocation Loc = PD->getLocation();
           llvm::DIFile *PUnit = getOrCreateFile(Loc);
           unsigned PLine = getLineNumber(Loc);

clang/test/CodeGenObjC/debug-info-ivars.m

 // CHECK-NOT:            offset:
 // CHECK-SAME:           flags: DIFlagProtected
 // CHECK: ![[INT]] = !DIBasicType(name: "int"
 // CHECK: !DIDerivedType(tag: DW_TAG_member, name: "flag_1"
 // CHECK-SAME:           line: 11
 // CHECK-SAME:           baseType: ![[UNSIGNED:[0-9]+]]
 // CHECK-SAME:           size: 9,
 // CHECK-NOT:            offset:
-// CHECK-SAME:           flags: DIFlagProtected
+// CHECK-SAME:           flags: DIFlagProtected | DIFlagBitField
 // CHECK: ![[UNSIGNED]] = !DIBasicType(name: "unsigned int"
 // CHECK: !DIDerivedType(tag: DW_TAG_member, name: "flag_2"
 // CHECK-SAME:           line: 12
 // CHECK-SAME:           baseType: ![[UNSIGNED]]
 // CHECK-SAME:           size: 9, offset: 1,
-// CHECK-SAME:           flags: DIFlagProtected
+// CHECK-SAME:           flags: DIFlagProtected | DIFlagBitField
 // CHECK: !DIDerivedType(tag: DW_TAG_member, name: "flag_3"
 // CHECK-SAME:           line: 14
 // CHECK-SAME:           baseType: ![[UNSIGNED]]
 // CHECK-SAME:           size: 9, offset: 3,
-// CHECK-SAME:           flags: DIFlagProtected
+// CHECK-SAME:           flags: DIFlagProtected | DIFlagBitField