[PATCH] D124006: [DebugInfo] Use the 'getTypeAlignIfRequired' function to get DW_AT_alignment correct when attribute((__aligned__)) is present.

[Ying Yi via Phabricator via cfe-commits]

MaggieYi updated this revision to Diff 424257.
MaggieYi added a comment.

Thanks David, I have modified the test following your advice.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124006/new/

https://reviews.llvm.org/D124006

Files:
  clang/lib/CodeGen/CGDebugInfo.cpp
  clang/test/CodeGenCXX/debug-info-struct-align.cpp


Index: clang/test/CodeGenCXX/debug-info-struct-align.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/debug-info-struct-align.cpp
@@ -0,0 +1,27 @@
+//  Test for debug info related to DW_AT_alignment attribute in the struct type.
+// RUN: %clang_cc1 -dwarf-version=5 -debug-info-kind=standalone -S -emit-llvm %s -o - | FileCheck %s
+
+// CHECK-DAG: DICompositeType(tag: DW_TAG_structure_type, name: "MyType", {{.*}}, align: 32
+// CHECK-DAG: DICompositeType(tag: DW_TAG_structure_type, name: "MyType1", {{.*}}, align: 8
+// CHECK-DAG: DICompositeType(tag: DW_TAG_structure_type, name: "MyType2", {{.*}}, align: 8
+
+struct MyType {
+  int m;
+} __attribute__((aligned(1)));
+struct MyType mt;
+
+static_assert(alignof(struct MyType) == 4, "alignof MyType is wrong");
+
+struct MyType1 {
+  int m;
+} __attribute__((packed, aligned(1)));
+struct MyType1 mt1;
+
+static_assert(alignof(struct MyType1) == 1, "alignof MyType1 is wrong");
+
+struct MyType2 {
+  __attribute__((packed)) int m;
+} __attribute__((aligned(1)));
+struct MyType2 mt2;
+
+static_assert(alignof(struct MyType2) == 1, "alignof MyType2 is wrong");
Index: clang/lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- clang/lib/CodeGen/CGDebugInfo.cpp
+++ clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3553,7 +3553,11 @@
     return getOrCreateRecordFwdDecl(Ty, RDContext);
 
   uint64_t Size = CGM.getContext().getTypeSize(Ty);
-  auto Align = getDeclAlignIfRequired(D, CGM.getContext());
+  // __attribute__((aligned)) can increase or decrease alignment *except* on a
+  // struct or struct member, where it only increases  alignment unless 'packed'
+  // is also specified. To handle this case, the `getTypeAlignIfRequired` needs
+  // to be used.
+  auto Align = getTypeAlignIfRequired(Ty, CGM.getContext());
 
   SmallString<256> Identifier = getTypeIdentifier(Ty, CGM, TheCU);
 


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