[BPF] Support to emit debugInfo for extern variables

extern variable usage in BPF is different from traditional
pure user space application. Recent discussion in linux bpf
mailing list has two use cases where debug info types are
required to use extern variables:
  - extern types are required to have a suitable interface
    in libbpf (bpf loader) to provide kernel config parameters
    to bpf programs.
    https://lore.kernel.org/bpf/CAEf4BzYCNo5GeVGMhp3fhysQ=_axAf=23PtwaZs-yAyafmXC9g@mail.gmail.com/T/#t
  - extern types are required so kernel bpf verifier can
    verify program which uses external functions more precisely.
    This will make later link with actual external function no
    need to reverify.
    https://lore.kernel.org/bpf/87eez4odqp.fsf@toke.dk/T/#m8d5c3e87ffe7f2764e02d722cb0d8cbc136880ed

This patch added bpf support to consume such info into BTF,
which can then be used by bpf loader. Function processFuncPrototypes()
only adds extern function definitions into BTF. The functions
with actual definition have been added to BTF in some other places.

Differential Revision: https://reviews.llvm.org/D70697

7 files changed, 729 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak-section.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak-section.ll
new file mode 100644
index 00000000000..94256c6d46a
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak-section.ll
@@ -0,0 +1,99 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+;
+; Source code:
+;   extern int global_func(char c) __attribute__((weak, section("abc")));
+;   int test() {
+;      return global_func(0);
+;   }
+; Compilation flag:
+;   clang -target bpf -O2 -g -S -emit-llvm test.c
+
+; Function Attrs: nounwind
+define dso_local i32 @test() local_unnamed_addr #0 !dbg !13 {
+entry:
+  %call = tail call i32 @global_func(i8 signext 0) #2, !dbg !16
+  ret i32 %call, !dbg !17
+}
+declare !dbg !4 extern_weak dso_local i32 @global_func(i8 signext) local_unnamed_addr #1 section "abc"
+
+; CHECK:             .section        .BTF,"",@progbits
+; CHECK-NEXT:        .short  60319                   # 0xeb9f
+; CHECK-NEXT:        .byte   1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .long   24
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   76
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
+; CHECK-NEXT:        .long   218103808               # 0xd000000
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   1                       # BTF_KIND_INT(id = 2)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   16777248                # 0x1000020
+; CHECK-NEXT:        .long   5                       # BTF_KIND_FUNC(id = 3)
+; CHECK-NEXT:        .long   201326592               # 0xc000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 4)
+; CHECK-NEXT:        .long   218103809               # 0xd000001
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   5
+; CHECK-NEXT:        .long   55                      # BTF_KIND_INT(id = 5)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   16777224                # 0x1000008
+; CHECK-NEXT:        .long   60                      # BTF_KIND_VAR(id = 6)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   72                      # BTF_KIND_DATASEC(id = 7)
+; CHECK-NEXT:        .long   251658241               # 0xf000001
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   6
+; CHECK-NEXT:        .long   global_func
+; CHECK-NEXT:        .long   8
+; CHECK-NEXT:        .byte   0                       # string offset=0
+; CHECK-NEXT:        .ascii  "int"                   # string offset=1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "test"                  # string offset=5
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".text"                 # string offset=10
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "/tmp/home/yhs/work/tests/extern/test.c" # string offset=16
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "char"                  # string offset=55
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "global_func"           # string offset=60
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "abc"                   # string offset=72
+; CHECK-NEXT:        .byte   0
+
+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 }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!9, !10, !11}
+!llvm.ident = !{!12}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (https://github.com/llvm/llvm-project.git 71a9518c93fe1dce9611c24bc707e5baf1f39f0d)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/extern")
+!2 = !{}
+!3 = !{!4}
+!4 = !DISubprogram(name: "global_func", scope: !1, file: !1, line: 1, type: !5, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7, !8}
+!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!8 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!9 = !{i32 7, !"Dwarf Version", i32 4}
+!10 = !{i32 2, !"Debug Info Version", i32 3}
+!11 = !{i32 1, !"wchar_size", i32 4}
+!12 = !{!"clang version 10.0.0 (https://github.com/llvm/llvm-project.git 71a9518c93fe1dce9611c24bc707e5baf1f39f0d)"}
+!13 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 2, type: !14, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!14 = !DISubroutineType(types: !15)
+!15 = !{!7}
+!16 = !DILocation(line: 3, column: 11, scope: !13)
+!17 = !DILocation(line: 3, column: 4, scope: !13)
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak.ll
new file mode 100644
index 00000000000..e841fafc4da
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak.ll
@@ -0,0 +1,91 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+;
+; Source code:
+;   extern int global_func(char c) __attribute__((weak));
+;   int test() {
+;     return global_func(0);
+;   }
+; Compilation flag:
+;   clang -target bpf -O2 -g -S -emit-llvm test.c
+
+; Function Attrs: nounwind
+define dso_local i32 @test() local_unnamed_addr #0 !dbg !13 {
+entry:
+  %call = tail call i32 @global_func(i8 signext 0) #2, !dbg !16
+  ret i32 %call, !dbg !17
+}
+declare !dbg !4 extern_weak dso_local i32 @global_func(i8 signext) local_unnamed_addr #1
+
+; CHECK:             .section        .BTF,"",@progbits
+; CHECK-NEXT:        .short  60319                   # 0xeb9f
+; CHECK-NEXT:        .byte   1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .long   24
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   92
+; CHECK-NEXT:        .long   92
+; CHECK-NEXT:        .long   72
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
+; CHECK-NEXT:        .long   218103808               # 0xd000000
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   1                       # BTF_KIND_INT(id = 2)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   16777248                # 0x1000020
+; CHECK-NEXT:        .long   5                       # BTF_KIND_FUNC(id = 3)
+; CHECK-NEXT:        .long   201326592               # 0xc000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 4)
+; CHECK-NEXT:        .long   218103809               # 0xd000001
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   5
+; CHECK-NEXT:        .long   55                      # BTF_KIND_INT(id = 5)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   16777224                # 0x1000008
+; CHECK-NEXT:        .long   60                      # BTF_KIND_VAR(id = 6)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .byte   0                       # string offset=0
+; CHECK-NEXT:        .ascii  "int"                   # string offset=1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "test"                  # string offset=5
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".text"                 # string offset=10
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "/tmp/home/yhs/work/tests/extern/test.c" # string offset=16
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "char"                  # string offset=55
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "global_func"           # string offset=60
+; CHECK-NEXT:        .byte   0
+
+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 }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!9, !10, !11}
+!llvm.ident = !{!12}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (https://github.com/llvm/llvm-project.git 71a9518c93fe1dce9611c24bc707e5baf1f39f0d)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/extern")
+!2 = !{}
+!3 = !{!4}
+!4 = !DISubprogram(name: "global_func", scope: !1, file: !1, line: 1, type: !5, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7, !8}
+!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!8 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!9 = !{i32 7, !"Dwarf Version", i32 4}
+!10 = !{i32 2, !"Debug Info Version", i32 3}
+!11 = !{i32 1, !"wchar_size", i32 4}
+!12 = !{!"clang version 10.0.0 (https://github.com/llvm/llvm-project.git 71a9518c93fe1dce9611c24bc707e5baf1f39f0d)"}
+!13 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 2, type: !14, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!14 = !DISubroutineType(types: !15)
+!15 = !{!7}
+!16 = !DILocation(line: 3, column: 11, scope: !13)
+!17 = !DILocation(line: 3, column: 4, scope: !13)
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-func.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-func.ll
new file mode 100644
index 00000000000..a91e1c53c12
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-func.ll
@@ -0,0 +1,92 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+;
+; Source code:
+;   extern int global_func(char c);
+;   int test() {
+;     return global_func(0);
+;   }
+; Compilation flag:
+;   clang -target bpf -O2 -g -S -emit-llvm test.c
+
+; Function Attrs: nounwind
+define dso_local i32 @test() local_unnamed_addr #0 !dbg !13 {
+entry:
+  %call = tail call i32 @global_func(i8 signext 0) #2, !dbg !16
+  ret i32 %call, !dbg !17
+}
+
+; CHECK:             .section        .BTF,"",@progbits
+; CHECK-NEXT:        .short  60319                   # 0xeb9f
+; CHECK-NEXT:        .byte   1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .long   24
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   92
+; CHECK-NEXT:        .long   92
+; CHECK-NEXT:        .long   72
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
+; CHECK-NEXT:        .long   218103808               # 0xd000000
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   1                       # BTF_KIND_INT(id = 2)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   16777248                # 0x1000020
+; CHECK-NEXT:        .long   5                       # BTF_KIND_FUNC(id = 3)
+; CHECK-NEXT:        .long   201326592               # 0xc000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 4)
+; CHECK-NEXT:        .long   218103809               # 0xd000001
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   5
+; CHECK-NEXT:        .long   55                      # BTF_KIND_INT(id = 5)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   16777224                # 0x1000008
+; CHECK-NEXT:        .long   60                      # BTF_KIND_VAR(id = 6)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .byte   0                       # string offset=0
+; CHECK-NEXT:        .ascii  "int"                   # string offset=1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "test"                  # string offset=5
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".text"                 # string offset=10
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "/tmp/home/yhs/work/tests/extern/test.c" # string offset=16
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "char"                  # string offset=55
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "global_func"           # string offset=60
+; CHECK-NEXT:        .byte   0
+
+declare !dbg !4 dso_local i32 @global_func(i8 signext) local_unnamed_addr #1
+
+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 }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!9, !10, !11}
+!llvm.ident = !{!12}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 (https://github.com/llvm/llvm-project.git 77e5c60f04c4597ba5704d3cee61c6d359404ccd)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/extern")
+!2 = !{}
+!3 = !{!4}
+!4 = !DISubprogram(name: "global_func", scope: !1, file: !1, line: 1, type: !5, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7, !8}
+!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!8 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!9 = !{i32 2, !"Dwarf Version", i32 4}
+!10 = !{i32 2, !"Debug Info Version", i32 3}
+!11 = !{i32 1, !"wchar_size", i32 4}
+!12 = !{!"clang version 10.0.0 (https://github.com/llvm/llvm-project.git 77e5c60f04c4597ba5704d3cee61c6d359404ccd)"}
+!13 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 2, type: !14, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!14 = !DISubroutineType(types: !15)
+!15 = !{!7}
+!16 = !DILocation(line: 3, column: 10, scope: !13)
+!17 = !DILocation(line: 3, column: 3, scope: !13)
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-section.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-section.ll
new file mode 100644
index 00000000000..1a9c576be8a
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-section.ll
@@ -0,0 +1,123 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+;
+; Source code:
+;   extern int global_func(char c) __attribute__((section("abc")));
+;   extern char ch __attribute__((section("abc")));
+;   int test() {
+;     return global_func(0) + ch;
+;   }
+; Compilation flag:
+;   clang -target bpf -O2 -g -S -emit-llvm test.c
+
+@ch = external dso_local local_unnamed_addr global i8, section "abc", align 1, !dbg !0
+
+; Function Attrs: nounwind
+define dso_local i32 @test() local_unnamed_addr #0 !dbg !16 {
+entry:
+  %call = tail call i32 @global_func(i8 signext 0) #2, !dbg !19
+  %0 = load i8, i8* @ch, align 1, !dbg !20, !tbaa !21
+  %conv = sext i8 %0 to i32, !dbg !20
+  %add = add nsw i32 %call, %conv, !dbg !24
+  ret i32 %add, !dbg !25
+}
+
+; CHECK:             .section        .BTF,"",@progbits
+; CHECK-NEXT:        .short  60319                   # 0xeb9f
+; CHECK-NEXT:        .byte   1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .long   24
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   144
+; CHECK-NEXT:        .long   144
+; CHECK-NEXT:        .long   79
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
+; CHECK-NEXT:        .long   218103808               # 0xd000000
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   1                       # BTF_KIND_INT(id = 2)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   16777248                # 0x1000020
+; CHECK-NEXT:        .long   5                       # BTF_KIND_FUNC(id = 3)
+; CHECK-NEXT:        .long   201326592               # 0xc000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   55                      # BTF_KIND_INT(id = 4)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   16777224                # 0x1000008
+; CHECK-NEXT:        .long   60                      # BTF_KIND_VAR(id = 5)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 6)
+; CHECK-NEXT:        .long   218103809               # 0xd000001
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   63                      # BTF_KIND_VAR(id = 7)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   6
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   75                      # BTF_KIND_DATASEC(id = 8)
+; CHECK-NEXT:        .long   251658242               # 0xf000002
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   5
+; CHECK-NEXT:        .long   ch
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   7
+; CHECK-NEXT:        .long   global_func
+; CHECK-NEXT:        .long   8
+; CHECK-NEXT:        .byte   0                       # string offset=0
+; CHECK-NEXT:        .ascii  "int"                   # string offset=1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "test"                  # string offset=5
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".text"                 # string offset=10
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "/tmp/home/yhs/work/tests/extern/test.c" # string offset=16
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "char"                  # string offset=55
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "ch"                    # string offset=60
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "global_func"           # string offset=63
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "abc"                   # string offset=75
+; CHECK-NEXT:        .byte   0
+
+declare !dbg !6 dso_local i32 @global_func(i8 signext) local_unnamed_addr #1 section "abc"
+
+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 }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!12, !13, !14}
+!llvm.ident = !{!15}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "ch", scope: !2, file: !3, line: 2, type: !10, isLocal: false, isDefinition: false)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0 (https://github.com/llvm/llvm-project.git 0ad024346185b3f0b5167438e126568982b1168d)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, retainedTypes: !5, globals: !11, nameTableKind: None)
+!3 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/extern")
+!4 = !{}
+!5 = !{!6}
+!6 = !DISubprogram(name: "global_func", scope: !3, file: !3, line: 1, type: !7, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !4)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9, !10}
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!11 = !{!0}
+!12 = !{i32 2, !"Dwarf Version", i32 4}
+!13 = !{i32 2, !"Debug Info Version", i32 3}
+!14 = !{i32 1, !"wchar_size", i32 4}
+!15 = !{!"clang version 10.0.0 (https://github.com/llvm/llvm-project.git 0ad024346185b3f0b5167438e126568982b1168d)"}
+!16 = distinct !DISubprogram(name: "test", scope: !3, file: !3, line: 3, type: !17, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4)
+!17 = !DISubroutineType(types: !18)
+!18 = !{!9}
+!19 = !DILocation(line: 4, column: 10, scope: !16)
+!20 = !DILocation(line: 4, column: 27, scope: !16)
+!21 = !{!22, !22, i64 0}
+!22 = !{!"omnipotent char", !23, i64 0}
+!23 = !{!"Simple C/C++ TBAA"}
+!24 = !DILocation(line: 4, column: 25, scope: !16)
+!25 = !DILocation(line: 4, column: 3, scope: !16)
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-struct-weak.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-struct-weak.ll
new file mode 100644
index 00000000000..1400d4b2f39
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-struct-weak.ll
@@ -0,0 +1,101 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+;
+; Source code:
+;   typedef struct t1 { int f1; } __t1;
+;   extern __t1 global __attribute__((weak));
+;   int test() { return global.f1; }
+; Compilation flag:
+;   clang -target bpf -O2 -g -S -emit-llvm test.c
+
+%struct.t1 = type { i32 }
+
+@global = extern_weak dso_local local_unnamed_addr global %struct.t1, align 4, !dbg !0
+; Function Attrs: norecurse nounwind readonly
+define dso_local i32 @test() local_unnamed_addr #0 !dbg !15 {
+entry:
+  %0 = load i32, i32* getelementptr (%struct.t1, %struct.t1* @global, i64 0, i32 0), align 4, !dbg !18, !tbaa !19
+  ret i32 %0, !dbg !24
+}
+
+; CHECK:             .section        .BTF,"",@progbits
+; CHECK-NEXT:        .short  60319                   # 0xeb9f
+; CHECK-NEXT:        .byte   1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .long   24
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   92
+; CHECK-NEXT:        .long   92
+; CHECK-NEXT:        .long   73
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
+; CHECK-NEXT:        .long   218103808               # 0xd000000
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   1                       # BTF_KIND_INT(id = 2)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   16777248                # 0x1000020
+; CHECK-NEXT:        .long   5                       # BTF_KIND_FUNC(id = 3)
+; CHECK-NEXT:        .long   201326592               # 0xc000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   55                      # BTF_KIND_TYPEDEF(id = 4)
+; CHECK-NEXT:        .long   134217728               # 0x8000000
+; CHECK-NEXT:        .long   5
+; CHECK-NEXT:        .long   60                      # BTF_KIND_STRUCT(id = 5)
+; CHECK-NEXT:        .long   67108865                # 0x4000001
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   63
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0                       # 0x0
+; CHECK-NEXT:        .long   66                      # BTF_KIND_VAR(id = 6)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .byte   0                       # string offset=0
+; CHECK-NEXT:        .ascii  "int"                   # string offset=1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "test"                  # string offset=5
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".text"                 # string offset=10
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "/tmp/home/yhs/work/tests/extern/test.c" # string offset=16
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "__t1"                  # string offset=55
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "t1"                    # string offset=60
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "f1"                    # string offset=63
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "global"                # string offset=66
+; CHECK-NEXT:        .byte   0
+
+attributes #0 = { norecurse nounwind readonly "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" }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!11, !12, !13}
+!llvm.ident = !{!14}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "global", scope: !2, file: !3, line: 2, type: !6, isLocal: false, isDefinition: false)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0 (https://github.com/llvm/llvm-project.git 71a9518c93fe1dce9611c24bc707e5baf1f39f0d)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
+!3 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/extern")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIDerivedType(tag: DW_TAG_typedef, name: "__t1", file: !3, line: 1, baseType: !7)
+!7 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t1", file: !3, line: 1, size: 32, elements: !8)
+!8 = !{!9}
+!9 = !DIDerivedType(tag: DW_TAG_member, name: "f1", scope: !7, file: !3, line: 1, baseType: !10, size: 32)
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !{i32 7, !"Dwarf Version", i32 4}
+!12 = !{i32 2, !"Debug Info Version", i32 3}
+!13 = !{i32 1, !"wchar_size", i32 4}
+!14 = !{!"clang version 10.0.0 (https://github.com/llvm/llvm-project.git 71a9518c93fe1dce9611c24bc707e5baf1f39f0d)"}
+!15 = distinct !DISubprogram(name: "test", scope: !3, file: !3, line: 3, type: !16, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4)
+!16 = !DISubroutineType(types: !17)
+!17 = !{!10}
+!18 = !DILocation(line: 3, column: 28, scope: !15)
+!19 = !{!20, !21, i64 0}
+!20 = !{!"t1", !21, i64 0}
+!21 = !{!"int", !22, i64 0}
+!22 = !{!"omnipotent char", !23, i64 0}
+!23 = !{!"Simple C/C++ TBAA"}
+!24 = !DILocation(line: 3, column: 14, scope: !15)
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-struct.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-struct.ll
new file mode 100644
index 00000000000..7a354e68662
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-struct.ll
@@ -0,0 +1,102 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+;
+; Source code:
+;   typedef struct t1 { int f1; } __t1;
+;   extern __t1 global;
+;   int test() { return global.f1; }
+; Compilation flag:
+;   clang -target bpf -O2 -g -S -emit-llvm test.c
+
+%struct.t1 = type { i32 }
+
+@global = external dso_local local_unnamed_addr global %struct.t1, align 4, !dbg !0
+
+; Function Attrs: norecurse nounwind readonly
+define dso_local i32 @test() local_unnamed_addr #0 !dbg !15 {
+entry:
+  %0 = load i32, i32* getelementptr inbounds (%struct.t1, %struct.t1* @global, i64 0, i32 0), align 4, !dbg !18, !tbaa !19
+  ret i32 %0, !dbg !24
+}
+
+; CHECK:             .section        .BTF,"",@progbits
+; CHECK-NEXT:        .short  60319                   # 0xeb9f
+; CHECK-NEXT:        .byte   1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .long   24
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   92
+; CHECK-NEXT:        .long   92
+; CHECK-NEXT:        .long   73
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
+; CHECK-NEXT:        .long   218103808               # 0xd000000
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   1                       # BTF_KIND_INT(id = 2)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   16777248                # 0x1000020
+; CHECK-NEXT:        .long   5                       # BTF_KIND_FUNC(id = 3)
+; CHECK-NEXT:        .long   201326592               # 0xc000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   55                      # BTF_KIND_TYPEDEF(id = 4)
+; CHECK-NEXT:        .long   134217728               # 0x8000000
+; CHECK-NEXT:        .long   5
+; CHECK-NEXT:        .long   60                      # BTF_KIND_STRUCT(id = 5)
+; CHECK-NEXT:        .long   67108865                # 0x4000001
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   63
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0                       # 0x0
+; CHECK-NEXT:        .long   66                      # BTF_KIND_VAR(id = 6)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .byte   0                       # string offset=0
+; CHECK-NEXT:        .ascii  "int"                   # string offset=1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "test"                  # string offset=5
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".text"                 # string offset=10
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "/tmp/home/yhs/work/tests/extern/test.c" # string offset=16
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "__t1"                  # string offset=55
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "t1"                    # string offset=60
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "f1"                    # string offset=63
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "global"                # string offset=66
+; CHECK-NEXT:        .byte   0
+
+attributes #0 = { norecurse nounwind readonly "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" }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!11, !12, !13}
+!llvm.ident = !{!14}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "global", scope: !2, file: !3, line: 2, type: !6, isLocal: false, isDefinition: false)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0 (https://github.com/llvm/llvm-project.git 2798d63180f4cc873bdaf689705fd4f9521ae89f)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
+!3 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/extern")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIDerivedType(tag: DW_TAG_typedef, name: "__t1", file: !3, line: 1, baseType: !7)
+!7 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t1", file: !3, line: 1, size: 32, elements: !8)
+!8 = !{!9}
+!9 = !DIDerivedType(tag: DW_TAG_member, name: "f1", scope: !7, file: !3, line: 1, baseType: !10, size: 32)
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !{i32 2, !"Dwarf Version", i32 4}
+!12 = !{i32 2, !"Debug Info Version", i32 3}
+!13 = !{i32 1, !"wchar_size", i32 4}
+!14 = !{!"clang version 10.0.0 (https://github.com/llvm/llvm-project.git 2798d63180f4cc873bdaf689705fd4f9521ae89f)"}
+!15 = distinct !DISubprogram(name: "test", scope: !3, file: !3, line: 4, type: !16, scopeLine: 4, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4)
+!16 = !DISubroutineType(types: !17)
+!17 = !{!10}
+!18 = !DILocation(line: 4, column: 28, scope: !15)
+!19 = !{!20, !21, i64 0}
+!20 = !{!"t1", !21, i64 0}
+!21 = !{!"int", !22, i64 0}
+!22 = !{!"omnipotent char", !23, i64 0}
+!23 = !{!"Simple C/C++ TBAA"}
+!24 = !DILocation(line: 4, column: 14, scope: !15)
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-weak-section.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-weak-section.ll
new file mode 100644
index 00000000000..1848e7f2e28
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-weak-section.ll
@@ -0,0 +1,121 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+;
+; Source code:
+;   extern int global_func(char c) __attribute__((weak, section("abc")));
+;   extern char ch __attribute__((weak, section("abc")));
+;   int test() {
+;     return global_func(0) + ch;
+;   }
+; Compilation flag:
+;   clang -target bpf -O2 -g -S -emit-llvm test.c
+
+@ch = extern_weak dso_local local_unnamed_addr global i8, section "abc", align 1, !dbg !0
+; Function Attrs: nounwind
+define dso_local i32 @test() local_unnamed_addr #0 !dbg !16 {
+entry:
+  %call = tail call i32 @global_func(i8 signext 0) #2, !dbg !19
+  %0 = load i8, i8* @ch, align 1, !dbg !20, !tbaa !21
+  %conv = sext i8 %0 to i32, !dbg !20
+  %add = add nsw i32 %call, %conv, !dbg !24
+  ret i32 %add, !dbg !25
+}
+declare !dbg !6 extern_weak dso_local i32 @global_func(i8 signext) local_unnamed_addr #1 section "abc"
+
+; CHECK:             .section        .BTF,"",@progbits
+; CHECK-NEXT:        .short  60319                   # 0xeb9f
+; CHECK-NEXT:        .byte   1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .long   24
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   144
+; CHECK-NEXT:        .long   144
+; CHECK-NEXT:        .long   79
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
+; CHECK-NEXT:        .long   218103808               # 0xd000000
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   1                       # BTF_KIND_INT(id = 2)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   16777248                # 0x1000020
+; CHECK-NEXT:        .long   5                       # BTF_KIND_FUNC(id = 3)
+; CHECK-NEXT:        .long   201326592               # 0xc000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   55                      # BTF_KIND_INT(id = 4)
+; CHECK-NEXT:        .long   16777216                # 0x1000000
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   16777224                # 0x1000008
+; CHECK-NEXT:        .long   60                      # BTF_KIND_VAR(id = 5)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 6)
+; CHECK-NEXT:        .long   218103809               # 0xd000001
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   4
+; CHECK-NEXT:        .long   63                      # BTF_KIND_VAR(id = 7)
+; CHECK-NEXT:        .long   234881024               # 0xe000000
+; CHECK-NEXT:        .long   6
+; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   75                      # BTF_KIND_DATASEC(id = 8)
+; CHECK-NEXT:        .long   251658242               # 0xf000002
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   5
+; CHECK-NEXT:        .long   ch
+; CHECK-NEXT:        .long   1
+; CHECK-NEXT:        .long   7
+; CHECK-NEXT:        .long   global_func
+; CHECK-NEXT:        .long   8
+; CHECK-NEXT:        .byte   0                       # string offset=0
+; CHECK-NEXT:        .ascii  "int"                   # string offset=1
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "test"                  # string offset=5
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".text"                 # string offset=10
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "/tmp/home/yhs/work/tests/extern/test.c" # string offset=16
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "char"                  # string offset=55
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "ch"                    # string offset=60
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "global_func"           # string offset=63
+; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  "abc"                   # string offset=75
+; CHECK-NEXT:        .byte   0
+
+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 }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!12, !13, !14}
+!llvm.ident = !{!15}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "ch", scope: !2, file: !3, line: 2, type: !10, isLocal: false, isDefinition: false)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0 (https://github.com/llvm/llvm-project.git 71a9518c93fe1dce9611c24bc707e5baf1f39f0d)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, retainedTypes: !5, globals: !11, nameTableKind: None)
+!3 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/extern")
+!4 = !{}
+!5 = !{!6}
+!6 = !DISubprogram(name: "global_func", scope: !3, file: !3, line: 1, type: !7, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !4)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9, !10}
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!11 = !{!0}
+!12 = !{i32 7, !"Dwarf Version", i32 4}
+!13 = !{i32 2, !"Debug Info Version", i32 3}
+!14 = !{i32 1, !"wchar_size", i32 4}
+!15 = !{!"clang version 10.0.0 (https://github.com/llvm/llvm-project.git 71a9518c93fe1dce9611c24bc707e5baf1f39f0d)"}
+!16 = distinct !DISubprogram(name: "test", scope: !3, file: !3, line: 3, type: !17, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4)
+!17 = !DISubroutineType(types: !18)
+!18 = !{!9}
+!19 = !DILocation(line: 4, column: 10, scope: !16)
+!20 = !DILocation(line: 4, column: 27, scope: !16)
+!21 = !{!22, !22, i64 0}
+!22 = !{!"omnipotent char", !23, i64 0}
+!23 = !{!"Simple C/C++ TBAA"}
+!24 = !DILocation(line: 4, column: 25, scope: !16)
+!25 = !DILocation(line: 4, column: 3, scope: !16)