yonghong-song created this revision. yonghong-song added reviewers: ast, anakryiko. Herald added subscribers: cfe-commits, arphaman. Herald added a project: clang.
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 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. The patch use the base lvalue type for the "base" value to annotate preservee_{struct,union}_access_index intrinsics. In the above example, the type will be "__t" which preserved the type name. Repository: rG LLVM Github Monorepo https://reviews.llvm.org/D73900 Files: clang/lib/CodeGen/CGExpr.cpp clang/test/CodeGen/builtin-preserve-access-index-typedef.c Index: clang/test/CodeGen/builtin-preserve-access-index-typedef.c =================================================================== --- /dev/null +++ clang/test/CodeGen/builtin-preserve-access-index-typedef.c @@ -0,0 +1,24 @@ +// REQUIRES: bpf-registered-target +// RUN: %clang -target bpf -emit-llvm -S -g %s -o - | FileCheck %s + +#pragma clang attribute push (__attribute__((preserve_access_index)), apply_to = record) +typedef struct { + int a; +} __t; +typedef union { + int b; +} __u; +#pragma clang attribute pop + +int test1(__t *arg) { return arg->a; } +int test2(const __u *arg) { return arg->b; } + + +// CHECK: define dso_local i32 @test1 +// CHECK: call i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.__ts(%struct.__t* %{{[0-9a-z]+}}, i32 0, i32 0), !dbg !{{[0-9]+}}, !llvm.preserve.access.index ![[TYPEDEF_STRUCT:[0-9]+]] +// CHECK: define dso_local i32 @test2 +// CHECK: call %union.__u* @llvm.preserve.union.access.index.p0s_union.__us.p0s_union.__us(%union.__u* %{{[0-9a-z]+}}, i32 0), !dbg !{{[0-9]+}}, !llvm.preserve.access.index ![[CONST_TYPEDEF:[0-9]+]] +// +// CHECK: ![[TYPEDEF_STRUCT]] = !DIDerivedType(tag: DW_TAG_typedef, name: "__t" +// CHECK: ![[CONST_TYPEDEF]] = !DIDerivedType(tag: DW_TAG_const_type, baseType: ![[TYPEDEF_UNION:[0-9]+]] +// CHECK: ![[TYPEDEF_UNION]] = !DIDerivedType(tag: DW_TAG_typedef, name: "__u" Index: clang/lib/CodeGen/CGExpr.cpp =================================================================== --- clang/lib/CodeGen/CGExpr.cpp +++ clang/lib/CodeGen/CGExpr.cpp @@ -4024,17 +4024,17 @@ return CGF.Builder.CreateStructGEP(base, idx, field->getName()); } -static Address emitPreserveStructAccess(CodeGenFunction &CGF, Address base, - const FieldDecl *field) { +static Address emitPreserveStructAccess(CodeGenFunction &CGF, LValue base, + Address addr, const FieldDecl *field) { const RecordDecl *rec = field->getParent(); - llvm::DIType *DbgInfo = CGF.getDebugInfo()->getOrCreateRecordType( - CGF.getContext().getRecordType(rec), rec->getLocation()); + llvm::DIType *DbgInfo = CGF.getDebugInfo()->getOrCreateStandaloneType( + base.getType(), rec->getLocation()); unsigned idx = CGF.CGM.getTypes().getCGRecordLayout(rec).getLLVMFieldNo(field); return CGF.Builder.CreatePreserveStructAccessIndex( - base, idx, CGF.getDebugInfoFIndex(rec, field->getFieldIndex()), DbgInfo); + addr, idx, CGF.getDebugInfoFIndex(rec, field->getFieldIndex()), DbgInfo); } static bool hasAnyVptr(const QualType Type, const ASTContext &Context) { @@ -4158,8 +4158,8 @@ if (IsInPreservedAIRegion || (getDebugInfo() && rec->hasAttr<BPFPreserveAccessIndexAttr>())) { // Remember the original union field index - llvm::DIType *DbgInfo = getDebugInfo()->getOrCreateRecordType( - getContext().getRecordType(rec), rec->getLocation()); + llvm::DIType *DbgInfo = getDebugInfo()->getOrCreateStandaloneType(base.getType(), + rec->getLocation()); addr = Address( Builder.CreatePreserveUnionAccessIndex( addr.getPointer(), getDebugInfoFIndex(rec, field->getFieldIndex()), DbgInfo), @@ -4176,7 +4176,7 @@ addr = emitAddrOfFieldStorage(*this, addr, field); else // Remember the original struct field index - addr = emitPreserveStructAccess(*this, addr, field); + addr = emitPreserveStructAccess(*this, base, addr, field); } // If this is a reference field, load the reference right now.
Index: clang/test/CodeGen/builtin-preserve-access-index-typedef.c =================================================================== --- /dev/null +++ clang/test/CodeGen/builtin-preserve-access-index-typedef.c @@ -0,0 +1,24 @@ +// REQUIRES: bpf-registered-target +// RUN: %clang -target bpf -emit-llvm -S -g %s -o - | FileCheck %s + +#pragma clang attribute push (__attribute__((preserve_access_index)), apply_to = record) +typedef struct { + int a; +} __t; +typedef union { + int b; +} __u; +#pragma clang attribute pop + +int test1(__t *arg) { return arg->a; } +int test2(const __u *arg) { return arg->b; } + + +// CHECK: define dso_local i32 @test1 +// CHECK: call i32* @llvm.preserve.struct.access.index.p0i32.p0s_struct.__ts(%struct.__t* %{{[0-9a-z]+}}, i32 0, i32 0), !dbg !{{[0-9]+}}, !llvm.preserve.access.index ![[TYPEDEF_STRUCT:[0-9]+]] +// CHECK: define dso_local i32 @test2 +// CHECK: call %union.__u* @llvm.preserve.union.access.index.p0s_union.__us.p0s_union.__us(%union.__u* %{{[0-9a-z]+}}, i32 0), !dbg !{{[0-9]+}}, !llvm.preserve.access.index ![[CONST_TYPEDEF:[0-9]+]] +// +// CHECK: ![[TYPEDEF_STRUCT]] = !DIDerivedType(tag: DW_TAG_typedef, name: "__t" +// CHECK: ![[CONST_TYPEDEF]] = !DIDerivedType(tag: DW_TAG_const_type, baseType: ![[TYPEDEF_UNION:[0-9]+]] +// CHECK: ![[TYPEDEF_UNION]] = !DIDerivedType(tag: DW_TAG_typedef, name: "__u" Index: clang/lib/CodeGen/CGExpr.cpp =================================================================== --- clang/lib/CodeGen/CGExpr.cpp +++ clang/lib/CodeGen/CGExpr.cpp @@ -4024,17 +4024,17 @@ return CGF.Builder.CreateStructGEP(base, idx, field->getName()); } -static Address emitPreserveStructAccess(CodeGenFunction &CGF, Address base, - const FieldDecl *field) { +static Address emitPreserveStructAccess(CodeGenFunction &CGF, LValue base, + Address addr, const FieldDecl *field) { const RecordDecl *rec = field->getParent(); - llvm::DIType *DbgInfo = CGF.getDebugInfo()->getOrCreateRecordType( - CGF.getContext().getRecordType(rec), rec->getLocation()); + llvm::DIType *DbgInfo = CGF.getDebugInfo()->getOrCreateStandaloneType( + base.getType(), rec->getLocation()); unsigned idx = CGF.CGM.getTypes().getCGRecordLayout(rec).getLLVMFieldNo(field); return CGF.Builder.CreatePreserveStructAccessIndex( - base, idx, CGF.getDebugInfoFIndex(rec, field->getFieldIndex()), DbgInfo); + addr, idx, CGF.getDebugInfoFIndex(rec, field->getFieldIndex()), DbgInfo); } static bool hasAnyVptr(const QualType Type, const ASTContext &Context) { @@ -4158,8 +4158,8 @@ if (IsInPreservedAIRegion || (getDebugInfo() && rec->hasAttr<BPFPreserveAccessIndexAttr>())) { // Remember the original union field index - llvm::DIType *DbgInfo = getDebugInfo()->getOrCreateRecordType( - getContext().getRecordType(rec), rec->getLocation()); + llvm::DIType *DbgInfo = getDebugInfo()->getOrCreateStandaloneType(base.getType(), + rec->getLocation()); addr = Address( Builder.CreatePreserveUnionAccessIndex( addr.getPointer(), getDebugInfoFIndex(rec, field->getFieldIndex()), DbgInfo), @@ -4176,7 +4176,7 @@ addr = emitAddrOfFieldStorage(*this, addr, field); else // Remember the original struct field index - addr = emitPreserveStructAccess(*this, addr, field); + addr = emitPreserveStructAccess(*this, base, addr, field); } // If this is a reference field, load the reference right now.
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