MaggieYi created this revision.
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aprantl.
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The detailed description of the issue could be found in
https://bugs.llvm.org/show_bug.cgi?id=51277.
In the original code, the 'getDeclAlignIfRequired' function is used.
The 'getDeclAlignIfRequired' function will return the max alignment
of all aligned attributes if the type has aligned attributes. The
function doesn’t consider the type at all.
The 'getTypeAlignIfRequired' function uses the type’s alignment value,
which also used by the 'alignof' function. I think we should use the
function of 'getTypeAlignIfRequired'.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D124006
Files:
clang/lib/CodeGen/CGDebugInfo.cpp
clang/test/CodeGen/debug-info-struct-align.c
Index: clang/test/CodeGen/debug-info-struct-align.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/debug-info-struct-align.c
@@ -0,0 +1,21 @@
+// 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;
+
+struct MyType1 {
+ int m;
+} __attribute__((packed, aligned(1)));
+struct MyType1 mt1;
+
+struct MyType2 {
+ __attribute__((packed))int m;
+} __attribute__((aligned(1)));
+struct MyType2 mt2;
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);
Index: clang/test/CodeGen/debug-info-struct-align.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/debug-info-struct-align.c
@@ -0,0 +1,21 @@
+// 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;
+
+struct MyType1 {
+ int m;
+} __attribute__((packed, aligned(1)));
+struct MyType1 mt1;
+
+struct MyType2 {
+ __attribute__((packed))int m;
+} __attribute__((aligned(1)));
+struct MyType2 mt2;
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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