From 968292cb93198442138128d850fd54dc7edc0035 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Mon, 12 Apr 2021 22:45:51 -0700 Subject: [PATCH] BPF: generate proper BTF for globals with WeakODRLinkage For a global weak symbol defined as below: char g __attribute__((weak)) = 2; LLVM generates an allocated global with WeakAnyLinkage, for which BPF backend generates proper BTF info. For the above example, if a modifier "const" is added like const char g __attribute__((weak)) = 2; LLVM generates an allocated global with WeakODRLinkage, for which BPF backend didn't generate any BTF as it didn't handle WeakODRLinkage. This patch addes support for WeakODRLinkage and proper BTF info can be generated for weak symbol defined with "const" modifier. Differential Revision: https://reviews.llvm.org/D100362 --- llvm/lib/Target/BPF/BTFDebug.cpp | 1 + llvm/test/CodeGen/BPF/BTF/weak-global-3.ll | 86 ++++++++++++++++++++++ 2 files changed, 87 insertions(+) create mode 100644 llvm/test/CodeGen/BPF/BTF/weak-global-3.ll diff --git a/llvm/lib/Target/BPF/BTFDebug.cpp b/llvm/lib/Target/BPF/BTFDebug.cpp index bedf159430dc..9249d679c7bd 100644 --- a/llvm/lib/Target/BPF/BTFDebug.cpp +++ b/llvm/lib/Target/BPF/BTFDebug.cpp @@ -1196,6 +1196,7 @@ void BTFDebug::processGlobals(bool ProcessingMapDef) { if (Linkage != GlobalValue::InternalLinkage && Linkage != GlobalValue::ExternalLinkage && Linkage != GlobalValue::WeakAnyLinkage && + Linkage != GlobalValue::WeakODRLinkage && Linkage != GlobalValue::ExternalWeakLinkage) continue; diff --git a/llvm/test/CodeGen/BPF/BTF/weak-global-3.ll b/llvm/test/CodeGen/BPF/BTF/weak-global-3.ll new file mode 100644 index 000000000000..dbd6380a9f1a --- /dev/null +++ b/llvm/test/CodeGen/BPF/BTF/weak-global-3.ll @@ -0,0 +1,86 @@ +; 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: +; const volatile char g __attribute__((weak)) = 2; +; int test() { +; return g; +; } +; Compilation flag: +; clang -target bpf -O2 -g -S -emit-llvm test.c + +@g = weak_odr dso_local constant i8 2, align 1, !dbg !0 + +; Function Attrs: nofree norecurse nounwind willreturn +define dso_local i32 @test() local_unnamed_addr #0 !dbg !13 { +entry: + %0 = load volatile i8, i8* @g, align 1, !dbg !17, !tbaa !18 + %conv = sext i8 %0 to i32, !dbg !17 + ret i32 %conv, !dbg !21 +} + +; CHECK: .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 201326593 # 0xc000001 +; CHECK-NEXT: .long 1 +; CHECK-NEXT: .long 0 # BTF_KIND_CONST(id = 4) +; CHECK-NEXT: .long 167772160 # 0xa000000 +; CHECK-NEXT: .long 5 +; CHECK-NEXT: .long 0 # BTF_KIND_VOLATILE(id = 5) +; CHECK-NEXT: .long 150994944 # 0x9000000 +; CHECK-NEXT: .long 6 +; CHECK-NEXT: .long 47 # BTF_KIND_INT(id = 6) +; CHECK-NEXT: .long 16777216 # 0x1000000 +; CHECK-NEXT: .long 1 +; CHECK-NEXT: .long 16777224 # 0x1000008 +; CHECK-NEXT: .long 52 # BTF_KIND_VAR(id = 7) +; CHECK-NEXT: .long 234881024 # 0xe000000 +; CHECK-NEXT: .long 4 +; CHECK-NEXT: .long 1 +; CHECK-NEXT: .long 54 # BTF_KIND_DATASEC(id = 8) +; CHECK-NEXT: .long 251658241 # 0xf000001 +; CHECK-NEXT: .long 0 +; CHECK-NEXT: .long 7 +; CHECK-NEXT: .long g +; CHECK-NEXT: .long 1 + +; CHECK: .ascii "int" # string offset=1 +; CHECK: .ascii "test" # string offset=5 +; CHECK: .ascii "char" # string offset=47 +; CHECK: .byte 103 # string offset=52 +; CHECK: .ascii ".rodata" # string offset=54 + +attributes #0 = { nofree norecurse nounwind willreturn "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" } + +!llvm.dbg.cu = !{!2} +!llvm.module.flags = !{!9, !10, !11} +!llvm.ident = !{!12} + +!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression()) +!1 = distinct !DIGlobalVariable(name: "g", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true) +!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 13.0.0 (https://github.com/llvm/llvm-project.git 9cc417cbca1cece0d55fa3d1e15682943a06139e)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, splitDebugInlining: false, nameTableKind: None) +!3 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/btf/tests") +!4 = !{} +!5 = !{!0} +!6 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !7) +!7 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !8) +!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 13.0.0 (https://github.com/llvm/llvm-project.git 9cc417cbca1cece0d55fa3d1e15682943a06139e)"} +!13 = distinct !DISubprogram(name: "test", scope: !3, file: !3, line: 2, type: !14, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4) +!14 = !DISubroutineType(types: !15) +!15 = !{!16} +!16 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!17 = !DILocation(line: 3, column: 10, scope: !13) +!18 = !{!19, !19, i64 0} +!19 = !{!"omnipotent char", !20, i64 0} +!20 = !{!"Simple C/C++ TBAA"} +!21 = !DILocation(line: 3, column: 3, scope: !13)