llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-codegen
Author: Can H. Tartanoglu (caniko)
<details>
<summary>Changes</summary>
## Summary
This makes LLVM's BTF debug info emission work for any ELF target, not just
BPF. The Clang driver gains a new `-gbtf` flag (matching GCC) that causes the
compiler to emit `.BTF` and `.BTF.ext` sections directly from IR debug metadata
— no `pahole` step required.
Companion to #<!-- -->183915 which adds BTF merging/dedup in lld. Together they
enable native BTF for Linux kernel builds with Clang, including LTO + Rust
configurations where pahole's DWARF→BTF conversion currently breaks.
## What's here
**BTFDebug split** — the existing monolithic `BTFDebug` (1800 lines in
`lib/Target/BPF/`) is split into:
- **Target-independent base** (`llvm/include/llvm/CodeGen/BTFDebug.h`,
`llvm/lib/CodeGen/AsmPrinter/BTFDebug.cpp`) — all type visiting from IR debug
metadata, string table, `.BTF` section emission, `.BTF.ext` FuncInfo + LineInfo
subsections, global variable processing. No target dependencies.
- **BPF subclass** (`BPFBTFDebug` in `lib/Target/BPF/`) — CO-RE field
relocations, `.maps` section handling, BPF instruction lowering
(`InstLower()`). These are BPF-only concepts.
**Clang driver** — `-gbtf` flag that:
- Implies debug info (LimitedDebugInfo if none specified)
- Implies DWARF generation (BTF reads the same IR metadata)
- Sets a `"BTF"` module flag, read by the backend
**AsmPrinter integration** — the base `AsmPrinter::doInitialization()`
instantiates `BTFDebug` when it sees `getBTFFlag() &&
isOSBinFormatELF() && !isBPF() && hasDebugInfo()`. BPF keeps
using its own `BPFBTFDebug` through `BPFAsmPrinter`. BTF and DWARF coexist —
both consume IR metadata independently, same as CodeView + DWARF on Windows.
**Tests**:
- 7 X86 BTF lit tests (`llvm/test/CodeGen/X86/BTF/`): int, struct, enum, func,
global-var, no-flag gating, BTF+DWARF coexistence
- Clang driver test (`clang/test/Driver/gbtf.c`): flag forwarding, debug info
implication, negative case
- Clang codegen test (`clang/test/CodeGen/btf-module-flag.c`): module flag
emission
- 104/104 existing BPF BTF lit tests pass unchanged
## Motivation
The kernel's Kconfig has:
```
config RUST
depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
```
`DEBUG_INFO_BTF=y` depends on pahole for DWARF→BTF conversion, which is slow,
fragile with LTO, and doesn't handle Rust well. With compiler-emitted BTF + lld
merging (#<!-- -->183915), the pahole dependency goes away and this Kconfig
restriction can be lifted.
## Design notes
The trickiest part of the split was preserving string table ordering. BPF's
`beginInstruction()` processes CO-RE relocations (adding type name strings)
*before* constructing line info (adding filename/line strings). The refactored
base class calls a `processBeginInstruction()` virtual hook before line info,
so BPF's string ordering is preserved and all 104 existing tests pass without
modification.
For non-BPF targets, `.BTF.ext` only contains FuncInfo and LineInfo — no
FieldReloc subsection, since CO-RE is a BPF-only concept.
I'd appreciate review from @<!-- -->yonghong-song and @<!-- -->eddyz87 on the
BTFDebug split — the BPF subclass should be functionally identical to the
original code.
cc @<!-- -->4ast @<!-- -->anakryiko
---
Patch is 75.17 KiB, truncated to 20.00 KiB below, full version:
https://github.com/llvm/llvm-project/pull/183929.diff
24 Files Affected:
- (modified) clang/include/clang/Basic/DebugOptions.def (+3)
- (modified) clang/include/clang/Options/Options.td (+4)
- (modified) clang/lib/CodeGen/CodeGenModule.cpp (+4)
- (modified) clang/lib/Driver/ToolChains/Clang.cpp (+15)
- (added) clang/test/CodeGen/btf-module-flag.c (+11)
- (added) clang/test/Driver/gbtf.c (+27)
- (renamed) llvm/include/llvm/CodeGen/BTFDebug.h (+29-29)
- (modified) llvm/include/llvm/IR/Module.h (+3)
- (modified) llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (+8)
- (renamed) llvm/lib/CodeGen/AsmPrinter/BTFDebug.cpp (+27-355)
- (modified) llvm/lib/CodeGen/AsmPrinter/CMakeLists.txt (+2)
- (modified) llvm/lib/IR/Module.cpp (+7)
- (modified) llvm/lib/Target/BPF/BPFAsmPrinter.cpp (+3-3)
- (modified) llvm/lib/Target/BPF/BPFAsmPrinter.h (+2-2)
- (added) llvm/lib/Target/BPF/BPFBTFDebug.cpp (+313)
- (added) llvm/lib/Target/BPF/BPFBTFDebug.h (+66)
- (modified) llvm/lib/Target/BPF/CMakeLists.txt (+1-1)
- (added) llvm/test/CodeGen/X86/BTF/btf-with-dwarf.ll (+33)
- (added) llvm/test/CodeGen/X86/BTF/enum.ll (+59)
- (added) llvm/test/CodeGen/X86/BTF/func.ll (+73)
- (added) llvm/test/CodeGen/X86/BTF/global-var.ll (+68)
- (added) llvm/test/CodeGen/X86/BTF/int.ll (+42)
- (added) llvm/test/CodeGen/X86/BTF/no-btf-flag.ll (+28)
- (added) llvm/test/CodeGen/X86/BTF/struct.ll (+70)
``````````diff
diff --git a/clang/include/clang/Basic/DebugOptions.def
b/clang/include/clang/Basic/DebugOptions.def
index 604e87e615a69..73e1dfb4e4c23 100644
--- a/clang/include/clang/Basic/DebugOptions.def
+++ b/clang/include/clang/Basic/DebugOptions.def
@@ -116,6 +116,9 @@ VALUE_DEBUGOPT(DwarfVersion, 3, 0, Compatible)
/// CodeView and DWARF into the same object.
DEBUGOPT(EmitCodeView, 1, 0, Compatible)
+/// Whether we should emit BTF debug information. BTF can coexist with DWARF.
+DEBUGOPT(EmitBTF, 1, 0, Compatible)
+
/// Whether to emit the .debug$H section containing hashes of CodeView types.
DEBUGOPT(CodeViewGHash, 1, 0, Compatible)
diff --git a/clang/include/clang/Options/Options.td
b/clang/include/clang/Options/Options.td
index 1021d95e4005b..9a2e61d30a870 100644
--- a/clang/include/clang/Options/Options.td
+++ b/clang/include/clang/Options/Options.td
@@ -4978,6 +4978,10 @@ def gcodeview : Flag<["-"], "gcodeview">, Group<g_Group>,
HelpText<"Generate CodeView debug information">,
Visibility<[ClangOption, CC1Option, CC1AsOption, CLOption, DXCOption]>,
MarshallingInfoFlag<CodeGenOpts<"EmitCodeView">>;
+def gbtf : Flag<["-"], "gbtf">, Group<g_Group>,
+ HelpText<"Generate BTF debug information">,
+ Visibility<[ClangOption, CC1Option, CC1AsOption]>,
+ MarshallingInfoFlag<CodeGenOpts<"EmitBTF">>;
defm codeview_ghash : BoolOption<"g", "codeview-ghash",
CodeGenOpts<"CodeViewGHash">, DefaultFalse,
PosFlag<SetTrue, [], [ClangOption, CC1Option],
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp
b/clang/lib/CodeGen/CodeGenModule.cpp
index c31bcabe49016..614c2c31534c1 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1138,6 +1138,10 @@ void CodeGenModule::Release() {
// Indicate that we want CodeView in the metadata.
getModule().addModuleFlag(llvm::Module::Warning, "CodeView", 1);
}
+ if (CodeGenOpts.EmitBTF) {
+ // Indicate that we want BTF debug info in the metadata.
+ getModule().addModuleFlag(llvm::Module::Warning, "BTF", 1);
+ }
if (CodeGenOpts.CodeViewGHash) {
getModule().addModuleFlag(llvm::Module::Warning, "CodeViewGHash", 1);
}
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp
b/clang/lib/Driver/ToolChains/Clang.cpp
index 7e544bd1042ea..02dd263e59d7b 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4480,6 +4480,18 @@ renderDebugOptions(const ToolChain &TC, const Driver &D,
const llvm::Triple &T,
if (const Arg *A = Args.getLastArg(options::OPT_gcodeview))
EmitCodeView = checkDebugInfoOption(A, Args, D, TC);
+ bool EmitBTF = false;
+ if (const Arg *A = Args.getLastArg(options::OPT_gbtf))
+ EmitBTF = checkDebugInfoOption(A, Args, D, TC);
+
+ // BTF reads IR debug metadata, which requires DWARF generation.
+ if (EmitBTF) {
+ if (DebugInfoKind == llvm::codegenoptions::NoDebugInfo)
+ DebugInfoKind = llvm::codegenoptions::LimitedDebugInfo;
+ if (!EmitDwarf)
+ EmitDwarf = true;
+ }
+
// If the user asked for debug info but did not explicitly specify -gcodeview
// or -gdwarf, ask the toolchain for the default format.
if (!EmitCodeView && !EmitDwarf &&
@@ -4624,6 +4636,9 @@ renderDebugOptions(const ToolChain &TC, const Driver &D,
const llvm::Triple &T,
options::OPT_gno_codeview_command_line);
}
+ if (EmitBTF)
+ CmdArgs.push_back("-gbtf");
+
Args.addOptOutFlag(CmdArgs, options::OPT_ginline_line_tables,
options::OPT_gno_inline_line_tables);
diff --git a/clang/test/CodeGen/btf-module-flag.c
b/clang/test/CodeGen/btf-module-flag.c
new file mode 100644
index 0000000000000..cf9fdb2c76704
--- /dev/null
+++ b/clang/test/CodeGen/btf-module-flag.c
@@ -0,0 +1,11 @@
+// Verify that -gbtf sets the "BTF" module flag in LLVM IR.
+//
+// RUN: %clang -target x86_64-linux-gnu -gbtf -g -S -emit-llvm -o - %s \
+// RUN: | FileCheck %s --check-prefix=BTF
+// RUN: %clang -target x86_64-linux-gnu -g -S -emit-llvm -o - %s \
+// RUN: | FileCheck %s --check-prefix=NO-BTF
+
+// BTF: !{i32 2, !"BTF", i32 1}
+// NO-BTF-NOT: !"BTF"
+
+int main(void) { return 0; }
diff --git a/clang/test/Driver/gbtf.c b/clang/test/Driver/gbtf.c
new file mode 100644
index 0000000000000..6fd25ceb95d95
--- /dev/null
+++ b/clang/test/Driver/gbtf.c
@@ -0,0 +1,27 @@
+// Test the -gbtf flag behavior in the Clang driver.
+//
+// -gbtf forwards to cc1.
+// RUN: %clang -target x86_64-linux-gnu -gbtf -### %s 2>&1 \
+// RUN: | FileCheck -check-prefix=BTF %s
+//
+// -gbtf alone implies debug info (LimitedDebugInfo).
+// RUN: %clang -target x86_64-linux-gnu -gbtf -### %s 2>&1 \
+// RUN: | FileCheck -check-prefix=BTF-DEBUGINFO %s
+//
+// -gbtf with explicit -g also works.
+// RUN: %clang -target x86_64-linux-gnu -g -gbtf -### %s 2>&1 \
+// RUN: | FileCheck -check-prefix=BTF %s
+//
+// Without -gbtf, no -gbtf in cc1 args.
+// RUN: %clang -target x86_64-linux-gnu -g -### %s 2>&1 \
+// RUN: | FileCheck -check-prefix=NO-BTF %s
+//
+// -gbtf works on aarch64 too (any ELF target).
+// RUN: %clang -target aarch64-linux-gnu -gbtf -### %s 2>&1 \
+// RUN: | FileCheck -check-prefix=BTF %s
+
+// BTF: "-gbtf"
+// BTF-DEBUGINFO: "-debug-info-kind=
+// NO-BTF-NOT: "-gbtf"
+
+int main(void) { return 0; }
diff --git a/llvm/lib/Target/BPF/BTFDebug.h
b/llvm/include/llvm/CodeGen/BTFDebug.h
similarity index 90%
rename from llvm/lib/Target/BPF/BTFDebug.h
rename to llvm/include/llvm/CodeGen/BTFDebug.h
index 75858fcc8bfde..925af5d2f8eed 100644
--- a/llvm/lib/Target/BPF/BTFDebug.h
+++ b/llvm/include/llvm/CodeGen/BTFDebug.h
@@ -1,4 +1,4 @@
-//===- BTFDebug.h -----------------------------------------------*- C++
-*-===//
+//===- BTFDebug.h - BTF Debug Info Emission --------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM
Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
@@ -9,10 +9,15 @@
/// \file
/// This file contains support for writing BTF debug info.
///
+/// BTF (BPF Type Format) is a compact debug info format originally designed
+/// for BPF programs but useful for any ELF target. This target-independent
+/// implementation can be used by any backend to emit .BTF and .BTF.ext
+/// sections.
+///
//===----------------------------------------------------------------------===//
-#ifndef LLVM_LIB_TARGET_BPF_BTFDEBUG_H
-#define LLVM_LIB_TARGET_BPF_BTFDEBUG_H
+#ifndef LLVM_CODEGEN_BTFDEBUG_H
+#define LLVM_CODEGEN_BTFDEBUG_H
#include "llvm/ADT/StringMap.h"
#include "llvm/CodeGen/DebugHandlerBase.h"
@@ -53,7 +58,7 @@ class BTFTypeBase {
virtual uint32_t getSize() { return BTF::CommonTypeSize; }
/// Complete BTF type generation after all related DebugInfo types
/// have been visited so their BTF type id's are available
- /// for cross referece.
+ /// for cross reference.
virtual void completeType(BTFDebug &BDebug) {}
/// Emit types for this BTF type entry.
virtual void emitType(MCStreamer &OS);
@@ -286,13 +291,17 @@ struct BTFFieldReloc {
};
/// Collect and emit BTF information.
+///
+/// This is a target-independent base class that handles the core BTF
+/// generation from LLVM IR debug metadata. Target-specific backends
+/// (e.g., BPF) can subclass this to add features like CO-RE relocations.
class BTFDebug : public DebugHandlerBase {
+protected:
MCStreamer &OS;
bool SkipInstruction;
bool LineInfoGenerated;
uint32_t SecNameOff;
uint32_t ArrayIndexTypeId;
- bool MapDefNotCollected;
BTFStringTable StringTable;
std::vector<std::unique_ptr<BTFTypeBase>> TypeEntries;
std::unordered_map<const DIType *, uint32_t> DIToIdMap;
@@ -303,11 +312,10 @@ class BTFDebug : public DebugHandlerBase {
std::map<std::string, std::unique_ptr<BTFKindDataSec>, std::less<>>
DataSecEntries;
std::vector<BTFTypeStruct *> StructTypes;
- std::map<const GlobalVariable *, std::pair<int64_t, uint32_t>> PatchImms;
+ std::set<const Function *> ProtoFunctions;
std::map<const DICompositeType *,
std::vector<std::pair<const DIDerivedType *, BTFTypeDerived *>>>
FixupDerivedTypes;
- std::set<const Function *>ProtoFunctions;
/// Add types to TypeEntries.
/// @{
@@ -336,7 +344,6 @@ class BTFDebug : public DebugHandlerBase {
void visitEnumType(const DICompositeType *ETy, uint32_t &TypeId);
void visitDerivedType(const DIDerivedType *DTy, uint32_t &TypeId,
bool CheckPointer, bool SeenPointer);
- void visitMapDefType(const DIType *Ty, uint32_t &TypeId);
/// @}
/// Check whether the type is a forward declaration candidate or not.
@@ -351,14 +358,13 @@ class BTFDebug : public DebugHandlerBase {
uint32_t Column);
/// Generate types and variables for globals.
- void processGlobals(bool ProcessingMapDef);
+ virtual void processGlobals();
- /// Process global variable initializer in pursuit for function
- /// pointers.
+ /// Scan a global variable initializer for function references.
void processGlobalInitializer(const Constant *C);
- /// Generate types for function prototypes.
- void processFuncPrototypes(const Function *);
+ /// Generate BTF types for extern function prototypes.
+ void processFuncPrototypes(const Function *F);
/// Generate types for decl annotations.
void processDeclAnnotations(DINodeArray Annotations, uint32_t BaseTypeId,
@@ -368,24 +374,12 @@ class BTFDebug : public DebugHandlerBase {
uint32_t processDISubprogram(const DISubprogram *SP, uint32_t ProtoTypeId,
uint8_t Scope);
- /// Generate BTF type_tag's. If BaseTypeId is nonnegative, the last
- /// BTF type_tag in the chain points to BaseTypeId. Otherwise, it points to
- /// the base type of DTy. Return the type id of the first BTF type_tag
- /// in the chain. If no type_tag's are generated, a negative value
- /// is returned.
+ /// Generate BTF type_tag's.
int genBTFTypeTags(const DIDerivedType *DTy, int BaseTypeId);
- /// Generate one field relocation record.
- void generatePatchImmReloc(const MCSymbol *ORSym, uint32_t RootId,
- const GlobalVariable *, bool IsAma);
-
/// Populating unprocessed type on demand.
unsigned populateType(const DIType *Ty);
- /// Process global variables referenced by relocation instructions
- /// and extern function references.
- void processGlobalValue(const MachineOperand &MO);
-
/// Emit common header of .BTF and .BTF.ext sections.
void emitCommonHeader();
@@ -393,7 +387,7 @@ class BTFDebug : public DebugHandlerBase {
void emitBTFSection();
/// Emit the .BTF.ext section.
- void emitBTFExtSection();
+ virtual void emitBTFExtSection();
protected:
/// Gather pre-function debug information.
@@ -405,8 +399,8 @@ class BTFDebug : public DebugHandlerBase {
public:
BTFDebug(AsmPrinter *AP);
- ///
- bool InstLower(const MachineInstr *MI, MCInst &OutMI);
+ /// Strip DW_TAG_atomic_type wrapper if present.
+ static const DIType *tryRemoveAtomicType(const DIType *Ty);
/// Get the special array index type id.
uint32_t getArrayIndexTypeId() {
@@ -425,6 +419,12 @@ class BTFDebug : public DebugHandlerBase {
return DIToIdMap[Ty];
}
+ /// Called at the beginning of instruction processing, before line info.
+ /// Subclasses can override to handle target-specific instruction processing
+ /// (e.g., CO-RE relocations) that must add strings to the string table
+ /// before line info strings.
+ virtual void processBeginInstruction(const MachineInstr *MI) {}
+
/// Process beginning of an instruction.
void beginInstruction(const MachineInstr *MI) override;
diff --git a/llvm/include/llvm/IR/Module.h b/llvm/include/llvm/IR/Module.h
index 7156a83c9f3cc..dfaf80c9560d4 100644
--- a/llvm/include/llvm/IR/Module.h
+++ b/llvm/include/llvm/IR/Module.h
@@ -908,6 +908,9 @@ class LLVM_ABI Module {
/// Returns zero if not present in module.
unsigned getCodeViewFlag() const;
+ /// Returns true if BTF debug info emission is requested via module flags.
+ bool getBTFFlag() const;
+
/// @}
/// @name Utility functions for querying and setting PIC level
/// @{
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 083b83567e47f..e38d481473c2f 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -11,6 +11,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/BTFDebug.h"
#include "CodeViewDebug.h"
#include "DwarfDebug.h"
#include "DwarfException.h"
@@ -645,6 +646,13 @@ bool AsmPrinter::doInitialization(Module &M) {
Handlers.push_back(std::unique_ptr<DwarfDebug>(DD));
}
}
+ // Emit BTF debug info if requested (via -gbtf). BTF can coexist with
+ // DWARF — both consume the same IR debug metadata independently.
+ // Only for ELF targets (BTF uses ELF sections). BPF target handles
+ // BTF emission through its own AsmPrinter with BPFBTFDebug.
+ if (M.getBTFFlag() && Target.isOSBinFormatELF() &&
+ !Target.isBPF() && hasDebugInfo())
+ Handlers.push_back(std::make_unique<BTFDebug>(this));
}
if (M.getNamedMetadata(PseudoProbeDescMetadataName))
diff --git a/llvm/lib/Target/BPF/BTFDebug.cpp
b/llvm/lib/CodeGen/AsmPrinter/BTFDebug.cpp
similarity index 74%
rename from llvm/lib/Target/BPF/BTFDebug.cpp
rename to llvm/lib/CodeGen/AsmPrinter/BTFDebug.cpp
index 46a1df28b8f1d..2a6879384e022 100644
--- a/llvm/lib/Target/BPF/BTFDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/BTFDebug.cpp
@@ -6,19 +6,19 @@
//
//===----------------------------------------------------------------------===//
//
-// This file contains support for writing BTF debug info.
+// This file contains the target-independent implementation of BTF debug info
+// generation. It handles converting LLVM IR debug metadata into BTF type
+// information and emitting .BTF and .BTF.ext ELF sections.
//
//===----------------------------------------------------------------------===//
-#include "BTFDebug.h"
-#include "BPF.h"
-#include "BPFCORE.h"
-#include "MCTargetDesc/BPFMCTargetDesc.h"
+#include "llvm/CodeGen/BTFDebug.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/IR/Constants.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectFileInfo.h"
@@ -29,6 +29,7 @@
#include "llvm/Support/LineIterator.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
#include <optional>
using namespace llvm;
@@ -38,12 +39,12 @@ static const char *BTFKindStr[] = {
#include "llvm/DebugInfo/BTF/BTF.def"
};
-static const DIType *tryRemoveAtomicType(const DIType *Ty) {
+const DIType *BTFDebug::tryRemoveAtomicType(const DIType *Ty) {
if (!Ty)
return Ty;
- auto DerivedTy = dyn_cast<DIDerivedType>(Ty);
- if (DerivedTy && DerivedTy->getTag() == dwarf::DW_TAG_atomic_type)
- return DerivedTy->getBaseType();
+ if (auto *DerivedTy = dyn_cast<DIDerivedType>(Ty))
+ if (DerivedTy->getTag() == dwarf::DW_TAG_atomic_type)
+ return DerivedTy->getBaseType();
return Ty;
}
@@ -101,13 +102,6 @@ void BTFTypeDerived::completeType(BTFDebug &BDebug) {
case BTF::BTF_KIND_CONST:
case BTF::BTF_KIND_VOLATILE:
case BTF::BTF_KIND_RESTRICT:
- // Debug info might contain names for these types, but given that we want
- // to keep BTF minimal and naming reference types doesn't bring any value
- // (what matters is the completeness of the base type), we don't emit them.
- //
- // Furthermore, the Linux kernel refuses to load BPF programs that contain
- // BTF with these types named:
- // https://elixir.bootlin.com/linux/v6.17.1/source/kernel/bpf/btf.c#L2586
BTFType.NameOff = 0;
break;
default:
@@ -119,7 +113,7 @@ void BTFTypeDerived::completeType(BTFDebug &BDebug) {
return;
// The base type for PTR/CONST/VOLATILE could be void.
- const DIType *ResolvedType = tryRemoveAtomicType(DTy->getBaseType());
+ const DIType *ResolvedType =
BTFDebug::tryRemoveAtomicType(DTy->getBaseType());
if (!ResolvedType) {
assert((Kind == BTF::BTF_KIND_PTR || Kind == BTF::BTF_KIND_CONST ||
Kind == BTF::BTF_KIND_VOLATILE) &&
@@ -322,14 +316,6 @@ void BTFTypeStruct::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(STy->getName());
if (STy->getTag() == dwarf::DW_TAG_variant_part) {
- // Variant parts might have a discriminator, which has its own memory
- // location, and variants, which share the memory location afterwards. LLVM
- // DI doesn't consider discriminator as an element and instead keeps
- // it as a separate reference.
- // To keep BTF simple, let's represent the structure as an union with
- // discriminator as the first element.
- // The offsets inside variant types are already handled correctly in the
- // DI.
const auto *DTy = STy->getDiscriminator();
if (DTy) {
struct BTF::BTFMember Discriminator;
@@ -359,7 +345,7 @@ void BTFTypeStruct::completeType(BTFDebug &BDebug) {
} else {
BTFMember.Offset = DDTy->getOffsetInBits();
}
- const auto *BaseTy = tryRemoveAtomicType(DDTy->getBaseType());
+ const auto *BaseTy = BTFDebug::tryRemoveAtomicType(DDTy->getBaseType());
BTFMember.Type = BDebug.getTypeId(BaseTy);
break;
}
@@ -390,11 +376,6 @@ void BTFTypeStruct::emitType(MCStreamer &OS) {
std::string BTFTypeStruct::getName() { return std::string(STy->getName()); }
-/// The Func kind represents both subprogram and pointee of function
-/// pointers. If the FuncName is empty, it represents a pointee of function
-/// pointer. Otherwise, it represents a subprogram. The func arg names
-/// are empty for pointee of function pointer case, and are valid names
-/// for subprogram.
BTFTypeFuncProto::BTFTypeFuncProto(
const DISubroutineType *STy, uint32_t VLen,
const std::unordered_map<uint32_t, StringRef> &FuncArgNames)
@@ -409,15 +390,13 @@ void BTFTypeFuncProto::completeType(BTFDebug &BDebug) {
IsCompleted = true;
DITypeArray Elements = STy->getTypeArray();
- auto RetType = tryRemoveAtomicType(Elements[0]);
+ auto RetType = BTFDebug::tryRemoveAtomicType(Elements[0]);
BTFType.Type = RetType ? BDebug.getTypeId(RetType) : 0;
BTFType.NameOff = 0;
- // For null parameter which is typically the last one
- // to represent the vararg, encode the NameOff/Type to be 0.
for (unsigned I = 1, N = Elements.size(); I < N; ++I) {
struct BTF::BTFParam Param;
- auto Element = tryRemoveAtomicType(Elements[I]);
+ auto Element = BTFDebug::tryRemoveAtomicType(Elements[I]);
if (Element) {
Param.NameOff = BDebug.addString(FuncArgNames[I]);
Param.Type = BDebug.getTypeId(Element);
@@ -550,7 +529,7 @@ void BTFTypeTypeTag::completeType(BTFDebug &BDebug) {
IsCompleted = true;
BTFType.NameOff = BDebug.addString(Tag);
if (DTy) {
- const DIType *ResolvedType = tryRemoveAtomicType(DTy->getBaseType());
+ const DIType *ResolvedType =
BTFDebug::tryRemoveAtomicType(DTy->getBaseType());
if (!ResolvedType)
BTFType.Type = 0;
else
@@ -574,8 +553,7 @@ uint32_t BTFStringTable::addString(StringRef S) {
BTFDebug::BTFDebug(AsmPrinter *AP)
: DebugHandlerBase(AP), OS(*Asm->OutStreamer), SkipInstruction(false),
- LineInfoGenerated(false), SecNameOff(0), ArrayIndexTypeId(0),
- MapDefNotCollected(true) {
+ LineInfoGenerated(false), SecNameOff(0), ArrayIndexTypeId(0) {
addString("\0");
}
@@ -605,8 +583,6 @@ void BTFDebug::visitBasicType(const DIBasicType *BTy,
uint32_t &TypeId) {
case dwarf::DW_ATE_signed_char:
case dwarf::DW_ATE_unsigned:
case dwarf::DW_ATE_unsigned_char:
- // Create a BTF type instance for this DIBasicType and put it into
- // DIToIdMap for cross-type reference check.
TypeEntry = std::make_unique<BTFTypeInt>(
Encoding, BTy->getSizeInBits(), BTy->getOffsetInBits(),
BTy->getName());
break;
@@ -631,10 +607,6 @@ void BTFDebug::visitSubroutineType(
if (VLen > BTF::MAX_VLEN)
return;
- // Subprogram has a valid non-zero-length name, and t...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/183929
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