[BPF] fix typedef issue for offset relocation

Currently, the CO-RE offset relocation does not work
if any struct/union member or array element is a typedef.
For example,
  typedef const int arr_t[7];
  struct input {
      arr_t a;
  };
  func(...) {
       struct input *in = ...;
       ... __builtin_preserve_access_index(&in->a[1]) ...
  }
The BPF backend calculated default offset is 0 while
4 is the correct answer. Similar issues exist for struct/union
typedef's.

When getting struct/union member or array element type,
we should trace down to the type by skipping typedef
and qualifiers const/volatile as this is what clang did
to generate getelementptr instructions.
(const/volatile member type qualifiers are already
ignored by clang.)

This patch fixed this issue, for each access index,
skipping typedef and const/volatile/restrict BTF types.

Signed-off-by: Yonghong Song <yhs@fb.com>

Differential Revision: https://reviews.llvm.org/D65259

llvm-svn: 367062

4 files changed, 388 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-array.ll b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-array.ll
new file mode 100644
index 00000000000..7843c52c5ad
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-array.ll
@@ -0,0 +1,97 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck %s
+;
+; Source code:
+;   typedef const int arr_t[7];
+;   typedef arr_t __arr;
+;   typedef __arr _arr;
+;   struct __s { _arr a; };
+;   typedef struct __s s;
+;   #define _(x) (__builtin_preserve_access_index(x))
+;   int get_value(const void *addr);
+;   int test(s *arg) {
+;     return get_value(_(&arg->a[1]));
+;   }
+; clang -target bpf -S -O2 -g -emit-llvm test.c
+
+%struct.__s = type { [7 x i32] }
+
+; Function Attrs: nounwind
+define dso_local i32 @test(%struct.__s* %arg) local_unnamed_addr #0 !dbg !7 {
+entry:
+  call void @llvm.dbg.value(metadata %struct.__s* %arg, metadata !24, metadata !DIExpression()), !dbg !25
+  %0 = tail call [7 x i32]* @llvm.preserve.struct.access.index.p0a7i32.p0s_struct.__ss(%struct.__s* %arg, i32 0, i32 0), !dbg !26, !llvm.preserve.access.index !13
+  %1 = tail call i32* @llvm.preserve.array.access.index.p0i32.p0a7i32([7 x i32]* %0, i32 1, i32 1), !dbg !26
+  %2 = bitcast i32* %1 to i8*, !dbg !26
+  %call = tail call i32 @get_value(i8* %2) #4, !dbg !27
+  ret i32 %call, !dbg !28
+}
+
+; CHECK:        .cfi_startproc
+; CHECK: [[RELOC:.Ltmp[0-9]+]]:
+; CHECK:         r2 = 4
+; CHECK:         r1 += r2
+; CHECK:         call get_value
+
+; CHECK:         .long   {{[0-9]+}}              # BTF_KIND_STRUCT(id = [[TYPE_ID:[0-9]+]])
+; CHECK:         .ascii  ".text"                 # string offset=[[SEC_INDEX:[0-9]+]]
+; CHECK-NEXT:    .byte   0
+; CHECK:         .ascii  "0:0:1"                 # string offset=[[ACCESS_STR:[0-9]+]]
+; CHECK-NEXT:    .byte   0
+; CHECK:         .long   12                      # OffsetReloc
+; CHECK-NEXT:    .long   [[SEC_INDEX]]           # Offset reloc section string offset=[[SEC_INDEX]]
+; CHECK-NEXT:    .long   1
+; CHECK-NEXT:    .long   [[RELOC]]
+; CHECK-NEXT:    .long   [[TYPE_ID]]
+; CHECK-NEXT:    .long   [[ACCESS_STR]]
+
+declare dso_local i32 @get_value(i8*) local_unnamed_addr #1
+
+; Function Attrs: nounwind readnone
+declare [7 x i32]* @llvm.preserve.struct.access.index.p0a7i32.p0s_struct.__ss(%struct.__s*, i32 immarg, i32 immarg) #2
+
+; Function Attrs: nounwind readnone
+declare i32* @llvm.preserve.array.access.index.p0i32.p0a7i32([7 x i32]*, i32 immarg, i32 immarg) #2
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #3
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
+attributes #3 = { nounwind readnone speculatable }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (trunk 366831) (llvm/trunk 366867)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/llvm/core-bugs")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0 (trunk 366831) (llvm/trunk 366867)"}
+!7 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 8, type: !8, scopeLine: 8, flags: DIFlagPrototyped, isDefinition: true, isOptimized: true, unit: !0, retainedNodes: !23)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
+!12 = !DIDerivedType(tag: DW_TAG_typedef, name: "s", file: !1, line: 5, baseType: !13)
+!13 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "__s", file: !1, line: 4, size: 224, elements: !14)
+!14 = !{!15}
+!15 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !13, file: !1, line: 4, baseType: !16, size: 224)
+!16 = !DIDerivedType(tag: DW_TAG_typedef, name: "_arr", file: !1, line: 3, baseType: !17)
+!17 = !DIDerivedType(tag: DW_TAG_typedef, name: "__arr", file: !1, line: 2, baseType: !18)
+!18 = !DIDerivedType(tag: DW_TAG_typedef, name: "arr_t", file: !1, line: 1, baseType: !19)
+!19 = !DICompositeType(tag: DW_TAG_array_type, baseType: !20, size: 224, elements: !21)
+!20 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !10)
+!21 = !{!22}
+!22 = !DISubrange(count: 7)
+!23 = !{!24}
+!24 = !DILocalVariable(name: "arg", arg: 1, scope: !7, file: !1, line: 8, type: !11)
+!25 = !DILocation(line: 0, scope: !7)
+!26 = !DILocation(line: 9, column: 20, scope: !7)
+!27 = !DILocation(line: 9, column: 10, scope: !7)
+!28 = !DILocation(line: 9, column: 3, scope: !7)
diff --git a/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-struct.ll b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-struct.ll
new file mode 100644
index 00000000000..a0d7532bf48
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-struct.ll
@@ -0,0 +1,90 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck %s
+;
+; Source code:
+;   typedef int _int;
+;   typedef _int __int;
+;   struct __s { __int a; __int b; };
+;   typedef struct __s _s;
+;   typedef _s s;
+;   #define _(x) (__builtin_preserve_access_index(x))
+;   int get_value(const void *addr);
+;   int test(s *arg) {
+;     return get_value(_(&arg->b));
+;   }
+; clang -target bpf -S -O2 -g -emit-llvm test.c
+
+%struct.__s = type { i32, i32 }
+
+; Function Attrs: nounwind
+define dso_local i32 @test(%struct.__s* %arg) local_unnamed_addr #0 !dbg !7 {
+entry:
+  call void @llvm.dbg.value(metadata %struct.__s* %arg, metadata !21, metadata !DIExpression()), !dbg !22
+  %0 = tail call i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.__ss(%struct.__s* %arg, i32 1, i32 1), !dbg !23, !llvm.preserve.access.index !14
+  %1 = bitcast i32* %0 to i8*, !dbg !23
+  %call = tail call i32 @get_value(i8* %1) #4, !dbg !24
+  ret i32 %call, !dbg !25
+}
+
+; CHECK:        .cfi_startproc
+; CHECK:        [[RELOC:.Ltmp[0-9]+]]:
+; CHECK:        r2 = 4
+; CHECK:        r1 += r2
+; CHECK:        call get_value
+
+; CHECK:        .long   {{[0-9]+}}              # BTF_KIND_STRUCT(id = [[TYPE_ID:[0-9]+]])
+; CHECK:        .ascii  ".text"                 # string offset=[[SEC_STR:[0-9]+]]
+; CHECK-NEXT:   .byte   0
+; CHECK:        .ascii  "0:1"                   # string offset=[[ACCESS_STR:[0-9]+]]
+; CHECK-NEXT:   .byte   0
+; CHECK:        .long   12                      # OffsetReloc
+; CHECK-NEXT:   .long   [[SEC_STR]]             # Offset reloc section string offset={{[0-9]+}}
+; CHECK-NEXT:   .long   1
+; CHECK-NEXT:   .long   [[RELOC]]
+; CHECK-NEXT:   .long   [[TYPE_ID]]
+; CHECK-NEXT:   .long   [[ACCESS_STR]]
+
+declare dso_local i32 @get_value(i8*) local_unnamed_addr #1
+
+; Function Attrs: nounwind readnone
+declare i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.__ss(%struct.__s*, i32 immarg, i32 immarg) #2
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #3
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
+attributes #3 = { nounwind readnone speculatable }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (trunk 366831) (llvm/trunk 366867)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/llvm/core-bugs")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0 (trunk 366831) (llvm/trunk 366867)"}
+!7 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 8, type: !8, scopeLine: 8, flags: DIFlagPrototyped, isDefinition: true, isOptimized: true, unit: !0, retainedNodes: !20)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
+!12 = !DIDerivedType(tag: DW_TAG_typedef, name: "s", file: !1, line: 5, baseType: !13)
+!13 = !DIDerivedType(tag: DW_TAG_typedef, name: "_s", file: !1, line: 4, baseType: !14)
+!14 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "__s", file: !1, line: 3, size: 64, elements: !15)
+!15 = !{!16, !19}
+!16 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !14, file: !1, line: 3, baseType: !17, size: 32)
+!17 = !DIDerivedType(tag: DW_TAG_typedef, name: "__int", file: !1, line: 2, baseType: !18)
+!18 = !DIDerivedType(tag: DW_TAG_typedef, name: "_int", file: !1, line: 1, baseType: !10)
+!19 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !14, file: !1, line: 3, baseType: !17, size: 32, offset: 32)
+!20 = !{!21}
+!21 = !DILocalVariable(name: "arg", arg: 1, scope: !7, file: !1, line: 8, type: !11)
+!22 = !DILocation(line: 0, scope: !7)
+!23 = !DILocation(line: 9, column: 20, scope: !7)
+!24 = !DILocation(line: 9, column: 10, scope: !7)
+!25 = !DILocation(line: 9, column: 3, scope: !7)
diff --git a/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-union.ll b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-union.ll
new file mode 100644
index 00000000000..caefc2b4bc6
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-union.ll
@@ -0,0 +1,90 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck %s
+;
+; Source code:
+;   typedef int _int;
+;   typedef _int __int;
+;   union __s { __int a; __int b; };
+;   typedef union __s _s;
+;   typedef _s s;
+;   #define _(x) (__builtin_preserve_access_index(x))
+;   int get_value(const void *addr);
+;   int test(s *arg) {
+;     return get_value(_(&arg->b));
+;   }
+; clang -target bpf -S -O2 -g -emit-llvm test.c
+
+%union.__s = type { i32 }
+
+; Function Attrs: nounwind
+define dso_local i32 @test(%union.__s* %arg) local_unnamed_addr #0 !dbg !7 {
+entry:
+  call void @llvm.dbg.value(metadata %union.__s* %arg, metadata !21, metadata !DIExpression()), !dbg !22
+  %0 = tail call %union.__s* @llvm.preserve.union.access.index.p0s_union.__ss.p0s_union.__ss(%union.__s* %arg, i32 1), !dbg !23, !llvm.preserve.access.index !14
+  %1 = bitcast %union.__s* %0 to i8*, !dbg !23
+  %call = tail call i32 @get_value(i8* %1) #4, !dbg !24
+  ret i32 %call, !dbg !25
+}
+
+; CHECK:        .cfi_startproc
+; CHECK: [[RELOC:.Ltmp[0-9]+]]:
+; CHECK:         r2 = 0
+; CHECK:         r1 += r2
+; CHECK:         call get_value
+
+; CHECK:         .long   {{[0-9]+}}              # BTF_KIND_UNION(id = [[TYPE_ID:[0-9]+]])
+; CHECK:         .ascii  ".text"                 # string offset=[[SEC_INDEX:[0-9]+]]
+; CHECK-NEXT:    .byte   0
+; CHECK:         .ascii  "0:1"                   # string offset=[[ACCESS_STR:[0-9]+]]
+; CHECK-NEXT:    .byte   0
+; CHECK:         .long   12                      # OffsetReloc
+; CHECK-NEXT:    .long   [[SEC_INDEX]]           # Offset reloc section string offset=[[SEC_INDEX]]
+; CHECK-NEXT:    .long   1
+; CHECK-NEXT:    .long   [[RELOC]]
+; CHECK-NEXT:    .long   [[TYPE_ID]]
+; CHECK-NEXT:    .long   [[ACCESS_STR]]
+
+declare dso_local i32 @get_value(i8*) local_unnamed_addr #1
+
+; Function Attrs: nounwind readnone
+declare %union.__s* @llvm.preserve.union.access.index.p0s_union.__ss.p0s_union.__ss(%union.__s*, i32 immarg) #2
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #3
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
+attributes #3 = { nounwind readnone speculatable }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (trunk 366831) (llvm/trunk 366867)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/llvm/core-bugs")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0 (trunk 366831) (llvm/trunk 366867)"}
+!7 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 8, type: !8, scopeLine: 8, flags: DIFlagPrototyped, isDefinition: true, isOptimized: true, unit: !0, retainedNodes: !20)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
+!12 = !DIDerivedType(tag: DW_TAG_typedef, name: "s", file: !1, line: 5, baseType: !13)
+!13 = !DIDerivedType(tag: DW_TAG_typedef, name: "_s", file: !1, line: 4, baseType: !14)
+!14 = distinct !DICompositeType(tag: DW_TAG_union_type, name: "__s", file: !1, line: 3, size: 32, elements: !15)
+!15 = !{!16, !19}
+!16 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !14, file: !1, line: 3, baseType: !17, size: 32)
+!17 = !DIDerivedType(tag: DW_TAG_typedef, name: "__int", file: !1, line: 2, baseType: !18)
+!18 = !DIDerivedType(tag: DW_TAG_typedef, name: "_int", file: !1, line: 1, baseType: !10)
+!19 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !14, file: !1, line: 3, baseType: !17, size: 32)
+!20 = !{!21}
+!21 = !DILocalVariable(name: "arg", arg: 1, scope: !7, file: !1, line: 8, type: !11)
+!22 = !DILocation(line: 0, scope: !7)
+!23 = !DILocation(line: 9, column: 20, scope: !7)
+!24 = !DILocation(line: 9, column: 10, scope: !7)
+!25 = !DILocation(line: 9, column: 3, scope: !7)
diff --git a/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef.ll b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef.ll
new file mode 100644
index 00000000000..c09d97991d9
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef.ll
@@ -0,0 +1,111 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck %s
+;
+; Source code:
+;   struct s { int a; int b; };
+;   typedef struct s __s;
+;   union u { __s c; __s d; };
+;   typedef union u __u;
+;   typedef __u arr_t[7];
+;   typedef arr_t __arr;
+;
+;   #define _(x) (__builtin_preserve_access_index(x))
+;   int get_value(const void *addr);
+;   int test(__arr *arg) {
+;     return get_value(_(&arg[1]->d.b));
+;   }
+; clang -target bpf -S -O2 -g -emit-llvm test.c
+; The offset reloc offset should be 12 from the base "arg".
+
+%union.u = type { %struct.s }
+%struct.s = type { i32, i32 }
+
+; Function Attrs: nounwind
+define dso_local i32 @test([7 x %union.u]* %arg) local_unnamed_addr #0 !dbg !7 {
+entry:
+  call void @llvm.dbg.value(metadata [7 x %union.u]* %arg, metadata !28, metadata !DIExpression()), !dbg !29
+  %0 = tail call [7 x %union.u]* @llvm.preserve.array.access.index.p0a7s_union.us.p0a7s_union.us([7 x %union.u]* %arg, i32 0, i32 1), !dbg !30
+  %arraydecay = getelementptr inbounds [7 x %union.u], [7 x %union.u]* %0, i64 0, i64 0, !dbg !30
+  %1 = tail call %union.u* @llvm.preserve.union.access.index.p0s_union.us.p0s_union.us(%union.u* %arraydecay, i32 1), !dbg !30, !llvm.preserve.access.index !16
+  %d = getelementptr inbounds %union.u, %union.u* %1, i64 0, i32 0, !dbg !30
+  %2 = tail call i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.ss(%struct.s* %d, i32 1, i32 1), !dbg !30, !llvm.preserve.access.index !20
+  %3 = bitcast i32* %2 to i8*, !dbg !30
+  %call = tail call i32 @get_value(i8* %3) #4, !dbg !31
+  ret i32 %call, !dbg !32
+}
+
+; CHECK:         .cfi_startproc
+; CHECK: [[RELOC:.Ltmp[0-9]+]]:
+; CHECK:         r2 = 12
+; CHECK:         r1 += r2
+; CHECK:         call get_value
+
+; CHECK:         .long   {{[0-9]+}}              # BTF_KIND_UNION(id = [[TYPE_ID:[0-9]+]])
+; CHECK:         .ascii  ".text"                 # string offset=[[SEC_STR:[0-9]+]]
+; CHECK-NEXT:    .byte   0
+; CHECK:         .ascii  "1:1:1"                 # string offset=[[ACCESS_STR:[0-9]+]]
+; CHECK-NEXT:    .byte   0
+; CHECK:         .long   12                      # OffsetReloc
+; CHECK-NEXT:    .long   [[SEC_STR:[0-9]+]]      # Offset reloc section string offset=[[SEC_STR:[0-9]+]]
+; CHECK-NEXT:    .long   1
+; CHECK-NEXT:    .long   [[RELOC:.Ltmp[0-9]+]]
+; CHECK-NEXT:    .long   [[TYPE_ID:[0-9]+]]
+; CHECK-NEXT:    .long   [[ACCESS_STR:[0-9]+]]
+
+declare dso_local i32 @get_value(i8*) local_unnamed_addr #1
+
+; Function Attrs: nounwind readnone
+declare [7 x %union.u]* @llvm.preserve.array.access.index.p0a7s_union.us.p0a7s_union.us([7 x %union.u]*, i32 immarg, i32 immarg) #2
+
+; Function Attrs: nounwind readnone
+declare %union.u* @llvm.preserve.union.access.index.p0s_union.us.p0s_union.us(%union.u*, i32 immarg) #2
+
+; Function Attrs: nounwind readnone
+declare i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.ss(%struct.s*, i32 immarg, i32 immarg) #2
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #3
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
+attributes #3 = { nounwind readnone speculatable }
+attributes #4 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (trunk 366831) (llvm/trunk 366867)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/llvm/core-bugs")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 10.0.0 (trunk 366831) (llvm/trunk 366867)"}
+!7 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 10, type: !8, scopeLine: 10, flags: DIFlagPrototyped, isDefinition: true, isOptimized: true, unit: !0, retainedNodes: !27)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
+!12 = !DIDerivedType(tag: DW_TAG_typedef, name: "__arr", file: !1, line: 6, baseType: !13)
+!13 = !DIDerivedType(tag: DW_TAG_typedef, name: "arr_t", file: !1, line: 5, baseType: !14)
+!14 = !DICompositeType(tag: DW_TAG_array_type, baseType: !15, size: 448, elements: !25)
+!15 = !DIDerivedType(tag: DW_TAG_typedef, name: "__u", file: !1, line: 4, baseType: !16)
+!16 = distinct !DICompositeType(tag: DW_TAG_union_type, name: "u", file: !1, line: 3, size: 64, elements: !17)
+!17 = !{!18, !24}
+!18 = !DIDerivedType(tag: DW_TAG_member, name: "c", scope: !16, file: !1, line: 3, baseType: !19, size: 64)
+!19 = !DIDerivedType(tag: DW_TAG_typedef, name: "__s", file: !1, line: 2, baseType: !20)
+!20 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "s", file: !1, line: 1, size: 64, elements: !21)
+!21 = !{!22, !23}
+!22 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !20, file: !1, line: 1, baseType: !10, size: 32)
+!23 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !20, file: !1, line: 1, baseType: !10, size: 32, offset: 32)
+!24 = !DIDerivedType(tag: DW_TAG_member, name: "d", scope: !16, file: !1, line: 3, baseType: !19, size: 64)
+!25 = !{!26}
+!26 = !DISubrange(count: 7)
+!27 = !{!28}
+!28 = !DILocalVariable(name: "arg", arg: 1, scope: !7, file: !1, line: 10, type: !11)
+!29 = !DILocation(line: 0, scope: !7)
+!30 = !DILocation(line: 11, column: 20, scope: !7)
+!31 = !DILocation(line: 11, column: 10, scope: !7)
+!32 = !DILocation(line: 11, column: 3, scope: !7)