[llvm] 6d07802 - [BPF] handle typedef of struct/union for CO-RE relocations
Yonghong Song via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 4 08:53:25 PST 2020
Author: Yonghong Song
Date: 2020-02-04T08:53:03-08:00
New Revision: 6d07802d63a8589447de0a697696447a583de9d8
URL: https://github.com/llvm/llvm-project/commit/6d07802d63a8589447de0a697696447a583de9d8
DIFF: https://github.com/llvm/llvm-project/commit/6d07802d63a8589447de0a697696447a583de9d8.diff
LOG: [BPF] handle typedef of struct/union for CO-RE relocations
Linux commit
https://github.com/torvalds/linux/commit/1cf5b23988ea0086a252a5c8b005b075f1e9b030#diff-289313b9fec99c6f0acfea19d9cfd949
uses "#pragma clang attribute push (__attribute__((preserve_access_index)),
apply_to = record)"
to apply CO-RE relocations to all records including the following pattern:
#pragma clang attribute push (__attribute__((preserve_access_index)), apply_to = record)
typedef struct {
int a;
} __t;
#pragma clang attribute pop
int test(__t *arg) { return arg->a; }
The current approach to use struct/union type in the relocation record will
result in an anonymous struct, which make later type matching difficult
in bpf loader. In fact, current BPF backend will fail the above program
with assertion:
clang: ../lib/Target/BPF/BPFAbstractMemberAccess.cpp:796: ...
Assertion `TypeName.size()' failed.
clang will change to use the type of the base of the member access
which will preserve the typedef modifier for the
preserve_{struct,union}_access_index intrinsics in the above example.
Here we adjust BPF backend to accept that the debuginfo
type metadata may be 'typedef' and handle them properly.
Differential Revision: https://reviews.llvm.org/D73902
Added:
llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-struct-2.ll
llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-union-2.ll
Modified:
llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp b/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
index 4379d49008a1..7a6bbaf2e16d 100644
--- a/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
+++ b/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
@@ -189,18 +189,20 @@ bool BPFAbstractMemberAccess::runOnModule(Module &M) {
return doTransformation(M);
}
-static bool SkipDIDerivedTag(unsigned Tag) {
+static bool SkipDIDerivedTag(unsigned Tag, bool skipTypedef) {
if (Tag != dwarf::DW_TAG_typedef && Tag != dwarf::DW_TAG_const_type &&
Tag != dwarf::DW_TAG_volatile_type &&
Tag != dwarf::DW_TAG_restrict_type &&
Tag != dwarf::DW_TAG_member)
- return false;
+ return false;
+ if (Tag == dwarf::DW_TAG_typedef && !skipTypedef)
+ return false;
return true;
}
-static DIType * stripQualifiers(DIType *Ty) {
+static DIType * stripQualifiers(DIType *Ty, bool skipTypedef = true) {
while (auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
- if (!SkipDIDerivedTag(DTy->getTag()))
+ if (!SkipDIDerivedTag(DTy->getTag(), skipTypedef))
break;
Ty = DTy->getBaseType();
}
@@ -209,7 +211,7 @@ static DIType * stripQualifiers(DIType *Ty) {
static const DIType * stripQualifiers(const DIType *Ty) {
while (auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
- if (!SkipDIDerivedTag(DTy->getTag()))
+ if (!SkipDIDerivedTag(DTy->getTag(), true))
break;
Ty = DTy->getBaseType();
}
@@ -710,7 +712,7 @@ Value *BPFAbstractMemberAccess::computeBaseAndAccessKey(CallInst *Call,
// calculated here as all debuginfo types are available.
// Get type name and calculate the first index.
- // We only want to get type name from structure or union.
+ // We only want to get type name from typedef, structure or union.
// If user wants a relocation like
// int *p; ... __builtin_preserve_access_index(&p[4]) ...
// or
@@ -727,12 +729,15 @@ Value *BPFAbstractMemberAccess::computeBaseAndAccessKey(CallInst *Call,
if (!Base)
Base = CInfo.Base;
- DIType *Ty = stripQualifiers(cast<DIType>(CInfo.Metadata));
+ DIType *PossibleTypeDef = stripQualifiers(cast<DIType>(CInfo.Metadata),
+ false);
+ DIType *Ty = stripQualifiers(PossibleTypeDef);
if (CInfo.Kind == BPFPreserveUnionAI ||
CInfo.Kind == BPFPreserveStructAI) {
- // struct or union type
- TypeName = std::string(Ty->getName());
- TypeMeta = Ty;
+ // struct or union type. If the typedef is in the metadata, always
+ // use the typedef.
+ TypeName = std::string(PossibleTypeDef->getName());
+ TypeMeta = PossibleTypeDef;
PatchImm += FirstIndex * (Ty->getSizeInBits() >> 3);
break;
}
diff --git a/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-struct-2.ll b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-struct-2.ll
new file mode 100644
index 000000000000..25c59a049b16
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-struct-2.ll
@@ -0,0 +1,89 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck %s
+; RUN: llc -march=bpfel -mattr=+alu32 -filetype=asm -o - %s | FileCheck %s
+;
+; Source code:
+; #pragma clang attribute push (__attribute__((preserve_access_index)), apply_to = record)
+; typedef struct {
+; int a;
+; } __t;
+; #pragma clang attribute pop
+;
+; int test(__t *arg) { return arg->a; }
+; Compiler flag to generate IR:
+; clang -target bpf -S -O2 -g -emit-llvm test.c
+
+%struct.__t = type { i32 }
+
+; Function Attrs: nounwind readonly
+define dso_local i32 @test(%struct.__t* readonly %arg) local_unnamed_addr #0 !dbg !13 {
+entry:
+ call void @llvm.dbg.value(metadata %struct.__t* %arg, metadata !18, metadata !DIExpression()), !dbg !19
+ %0 = tail call i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.__ts(%struct.__t* %arg, i32 0, i32 0), !dbg !20, !llvm.preserve.access.index !4
+ %1 = load i32, i32* %0, align 4, !dbg !20, !tbaa !21
+ ret i32 %1, !dbg !26
+}
+
+; CHECK: .long 1 # BTF_KIND_TYPEDEF(id = 2)
+; CHECK-NEXT: .long 134217728 # 0x8000000
+; CHECK-NEXT: .long 3
+; CHECK-NEXT: .long 0 # BTF_KIND_STRUCT(id = 3)
+; CHECK-NEXT: .long 67108865 # 0x4000001
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 5
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 0 # 0x0
+;
+; CHECK: .ascii "__t" # string offset=1
+; CHECK: .byte 97 # string offset=5
+; CHECK: .ascii ".text" # string offset=20
+; CHECK: .ascii "0:0" # string offset=26
+;
+; CHECK: .long 16 # FieldReloc
+; CHECK-NEXT: .long 20 # Field reloc section string offset=20
+; CHECK-NEXT: .long 1
+; CHECK-NEXT: .long .Ltmp{{[0-9]+}}
+; CHECK-NEXT: .long 2
+; CHECK-NEXT: .long 26
+; CHECK-NEXT: .long 0
+
+; Function Attrs: nounwind readnone
+declare i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.__ts(%struct.__t*, i32, i32) #1
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+
+attributes #0 = { 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" }
+attributes #1 = { nounwind readnone }
+attributes #2 = { nounwind readnone speculatable}
+
+!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 11.0.0 (https://github.com/llvm/llvm-project.git 5125d1c934efa69ffc1902ce3b8f2f288653a92f)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/core_bug")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIDerivedType(tag: DW_TAG_typedef, name: "__t", file: !1, line: 4, baseType: !5)
+!5 = distinct !DICompositeType(tag: DW_TAG_structure_type, file: !1, line: 2, size: 32, elements: !6)
+!6 = !{!7}
+!7 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !5, file: !1, line: 3, baseType: !8, size: 32)
+!8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!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 11.0.0 (https://github.com/llvm/llvm-project.git 5125d1c934efa69ffc1902ce3b8f2f288653a92f)"}
+!13 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 7, type: !14, scopeLine: 7, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, isDefinition: true, isOptimized: true, unit: !0, retainedNodes: !17)
+!14 = !DISubroutineType(types: !15)
+!15 = !{!8, !16}
+!16 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !4, size: 64)
+!17 = !{!18}
+!18 = !DILocalVariable(name: "arg", arg: 1, scope: !13, file: !1, line: 7, type: !16)
+!19 = !DILocation(line: 0, scope: !13)
+!20 = !DILocation(line: 7, column: 34, scope: !13)
+!21 = !{!22, !23, i64 0}
+!22 = !{!"", !23, i64 0}
+!23 = !{!"int", !24, i64 0}
+!24 = !{!"omnipotent char", !25, i64 0}
+!25 = !{!"Simple C/C++ TBAA"}
+!26 = !DILocation(line: 7, column: 22, scope: !13)
diff --git a/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-union-2.ll b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-union-2.ll
new file mode 100644
index 000000000000..b9c324b7b30c
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/CORE/offset-reloc-typedef-union-2.ll
@@ -0,0 +1,88 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck %s
+; RUN: llc -march=bpfel -mattr=+alu32 -filetype=asm -o - %s | FileCheck %s
+;
+; Source code:
+; #pragma clang attribute push (__attribute__((preserve_access_index)), apply_to = record)
+; typedef union {
+; int a;
+; } __t;
+; #pragma clang attribute pop
+;
+; int test(__t *arg) { return arg->a; }
+; Compiler flag to generate IR:
+; clang -target bpf -S -O2 -g -emit-llvm test.c
+
+%union.__t = type { i32 }
+
+; Function Attrs: nounwind readonly
+define dso_local i32 @test(%union.__t* readonly %arg) local_unnamed_addr #0 !dbg !13 {
+entry:
+ call void @llvm.dbg.value(metadata %union.__t* %arg, metadata !18, metadata !DIExpression()), !dbg !19
+ %0 = tail call %union.__t* @llvm.preserve.union.access.index.p0s_union.__ts.p0s_union.__ts(%union.__t* %arg, i32 0), !dbg !20, !llvm.preserve.access.index !4
+ %a = getelementptr %union.__t, %union.__t* %0, i64 0, i32 0, !dbg !20
+ %1 = load i32, i32* %a, align 4, !dbg !20, !tbaa !21
+ ret i32 %1, !dbg !24
+}
+
+; CHECK: .long 1 # BTF_KIND_TYPEDEF(id = 2)
+; CHECK-NEXT: .long 134217728 # 0x8000000
+; CHECK-NEXT: .long 3
+; CHECK-NEXT: .long 0 # BTF_KIND_UNION(id = 3)
+; CHECK-NEXT: .long 83886081 # 0x5000001
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 5
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 0 # 0x0
+;
+; CHECK: .ascii "__t" # string offset=1
+; CHECK: .byte 97 # string offset=5
+; CHECK: .ascii ".text" # string offset=20
+; CHECK: .ascii "0:0" # string offset=26
+;
+; CHECK: .long 16 # FieldReloc
+; CHECK-NEXT: .long 20 # Field reloc section string offset=20
+; CHECK-NEXT: .long 1
+; CHECK-NEXT: .long .Ltmp{{[0-9]+}}
+; CHECK-NEXT: .long 2
+; CHECK-NEXT: .long 26
+; CHECK-NEXT: .long 0
+
+; Function Attrs: nounwind readnone
+declare %union.__t* @llvm.preserve.union.access.index.p0s_union.__ts.p0s_union.__ts(%union.__t*, i32) #1
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+
+attributes #0 = { 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" }
+attributes #1 = { nounwind readnone }
+attributes #2 = { nounwind readnone speculatable}
+
+!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 11.0.0 (https://github.com/llvm/llvm-project.git 5125d1c934efa69ffc1902ce3b8f2f288653a92f)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp/home/yhs/work/tests/core_bug")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIDerivedType(tag: DW_TAG_typedef, name: "__t", file: !1, line: 4, baseType: !5)
+!5 = distinct !DICompositeType(tag: DW_TAG_union_type, file: !1, line: 2, size: 32, elements: !6)
+!6 = !{!7}
+!7 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !5, file: !1, line: 3, baseType: !8, size: 32)
+!8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!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 11.0.0 (https://github.com/llvm/llvm-project.git 5125d1c934efa69ffc1902ce3b8f2f288653a92f)"}
+!13 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 7, type: !14, scopeLine: 7, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, isDefinition: true, isOptimized: true, unit: !0, retainedNodes: !17)
+!14 = !DISubroutineType(types: !15)
+!15 = !{!8, !16}
+!16 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !4, size: 64)
+!17 = !{!18}
+!18 = !DILocalVariable(name: "arg", arg: 1, scope: !13, file: !1, line: 7, type: !16)
+!19 = !DILocation(line: 0, scope: !13)
+!20 = !DILocation(line: 7, column: 34, scope: !13)
+!21 = !{!22, !22, i64 0}
+!22 = !{!"omnipotent char", !23, i64 0}
+!23 = !{!"Simple C/C++ TBAA"}
+!24 = !DILocation(line: 7, column: 22, scope: !13)
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