[BPF] Generate BTF DebugInfo under BPF target
This patch implements BTF (BPF Type Format).
The BTF is the debug info format for BPF, introduced
in the below linux patch:
https://github.com/torvalds/linux/commit/69b693f0aefa0ed521e8bd02260523b5ae446ad7#diff-06fb1c8825f653d7e539058b72c83332
and further extended several times, e.g.,
https://www.spinics.net/lists/netdev/msg534640.html
https://www.spinics.net/lists/netdev/msg538464.html
https://www.spinics.net/lists/netdev/msg540246.html
The main advantage of implementing in LLVM is:
. better integration/deployment as no extra tools are needed.
. bpf JIT based compilation (like bcc, bpftrace, etc.) can get
BTF without much extra effort.
. BTF line_info needs selective source codes, which can be
easily retrieved when inside the compiler.
This patch implemented BTF generation by registering a BPF
specific DebugHandler in BPFAsmPrinter.
Signed-off-by: Yonghong Song <yhs@fb.com>
Differential Revision: https://reviews.llvm.org/D55752
llvm-svn: 349640
diff --git a/llvm/test/CodeGen/BPF/BTF/func-source.ll b/llvm/test/CodeGen/BPF/BTF/func-source.ll
new file mode 100644
index 0000000..6e1bed3
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/func-source.ll
@@ -0,0 +1,80 @@
+; 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:
+; void f(void) { }
+; Compilation flag:
+; clang -target bpf -O2 -g -gdwarf-5 -gembed-source -S -emit-llvm t.c
+;
+; This test embeds the source code in the IR, so the line info should have
+; correct reference to the lines in the string table.
+
+; Function Attrs: norecurse nounwind readnone
+define dso_local void @f() local_unnamed_addr #0 !dbg !7 {
+entry:
+ ret void, !dbg !10
+}
+
+; 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 24
+; CHECK-NEXT: .long 24
+; CHECK-NEXT: .long 35
+; CHECK-NEXT: .long 0 # BTF_KIND_FUNC_PROTO(id = 1)
+; CHECK-NEXT: .long 218103808 # 0xd000000
+; CHECK-NEXT: .long 0
+; CHECK-NEXT: .long 33 # BTF_KIND_FUNC(id = 2)
+; CHECK-NEXT: .long 201326592 # 0xc000000
+; CHECK-NEXT: .long 1
+; CHECK-NEXT: .byte 0 # string offset=0
+; CHECK-NEXT: .ascii ".text" # string offset=1
+; CHECK-NEXT: .byte 0
+; CHECK-NEXT: .ascii "/tmp/t.c" # string offset=7
+; CHECK-NEXT: .byte 0
+; CHECK-NEXT: .ascii "void f(void) { }" # string offset=16
+; CHECK-NEXT: .byte 0
+; CHECK-NEXT: .byte 102 # string offset=33
+; CHECK-NEXT: .byte 0
+; CHECK-NEXT: .section .BTF.ext,"",@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 20
+; CHECK-NEXT: .long 20
+; CHECK-NEXT: .long 28
+; CHECK-NEXT: .long 8 # FuncInfo
+; CHECK-NEXT: .long 1 # FuncInfo section string offset=1
+; CHECK-NEXT: .long 1
+; CHECK-NEXT: .long .Lfunc_begin0
+; CHECK-NEXT: .long 2
+; CHECK-NEXT: .long 16 # LineInfo
+; CHECK-NEXT: .long 1 # LineInfo section string offset=1
+; CHECK-NEXT: .long 1
+; CHECK-NEXT: .long .Ltmp{{[0-9]+}}
+; CHECK-NEXT: .long 7
+; CHECK-NEXT: .long 16
+; CHECK-NEXT: .long 1040 # Line 1 Col 16
+
+attributes #0 = { norecurse nounwind readnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "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 = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 8.0.0 (trunk 344789) (llvm/trunk 344782)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "t.c", directory: "/tmp", checksumkind: CSK_MD5, checksum: "978599fafe3a080b456e3d95a3710359", source: "void f(void) { }\0A")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 5}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 8.0.0 (trunk 344789) (llvm/trunk 344782)"}
+!7 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, isOptimized: true, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null}
+!10 = !DILocation(line: 1, column: 16, scope: !7)