https://github.com/Michael137 created
https://github.com/llvm/llvm-project/pull/110481
As this comment around target initialization implies:
```
// This can be NULL if we don't know anything about the architecture or if
// the target for an architecture isn't enabled in the llvm/clang that we
// built
```
There are cases where we might fail to call `InitBuiltinTypes` when creating
the backing `ASTContext` for a `TypeSystemClang`. If that happens, the builtins
`QualType`s, e.g., `VoidPtrTy`/`IntTy`/etc., are not initialized and
dereferencing them as we do in `GetBuiltinTypeForEncodingAndBitSize` (and other
places) will lead to nullptr-dereferences. Example backtrace:
```
(lldb) run
Assertion failed: (!isNull() && "Cannot retrieve a NULL type pointer"),
function getCommonPtr, file Type.h, line 958.
Process 2680 stopped
* thread #15, name = '<lldb.process.internal-state(pid=2712)>', stop reason =
hit program assert
frame #4: 0x000000010cdf3cdc
liblldb.20.0.0git.dylib`DWARFASTParserClang::ExtractIntFromFormValue(lldb_private::CompilerType
const&, lldb_private::plugin::dwarf::DWARFFormValue const&) const (.cold.1) +
liblldb.20.0.0git.dylib`DWARFASTParserClang::ParseObjCMethod(lldb_private::ObjCLanguage::MethodName
const&, lldb_private::plugin::dwarf::DWARFDIE const&,
lldb_private::CompilerType, ParsedDWARFTypeAttributes
, bool) (.cold.1):
-> 0x10cdf3cdc <+0>: stp x29, x30, [sp, #-0x10]!
0x10cdf3ce0 <+4>: mov x29, sp
0x10cdf3ce4 <+8>: adrp x0, 545
0x10cdf3ce8 <+12>: add x0, x0, #0xa25 ; "ParseObjCMethod"
Target 0: (lldb) stopped.
(lldb) bt
* thread #15, name = '<lldb.process.internal-state(pid=2712)>', stop reason =
hit program assert
frame #0: 0x0000000180d08600 libsystem_kernel.dylib`__pthread_kill + 8
frame #1: 0x0000000180d40f50 libsystem_pthread.dylib`pthread_kill + 288
frame #2: 0x0000000180c4d908 libsystem_c.dylib`abort + 128
frame #3: 0x0000000180c4cc1c libsystem_c.dylib`__assert_rtn + 284
* frame #4: 0x000000010cdf3cdc
liblldb.20.0.0git.dylib`DWARFASTParserClang::ExtractIntFromFormValue(lldb_private::CompilerType
const&, lldb_private::plugin::dwarf::DWARFFormValue const&) const (.cold.1) +
frame #5: 0x0000000109d30acc
liblldb.20.0.0git.dylib`lldb_private::TypeSystemClang::GetBuiltinTypeForEncodingAndBitSize(lldb::Encoding,
unsigned long) + 1188
frame #6: 0x0000000109aaaed4
liblldb.20.0.0git.dylib`DynamicLoaderMacOS::NotifyBreakpointHit(void*,
lldb_private::StoppointCallbackContext*, unsigned long long, unsigned long
long) + 384
```
This patch adds a one-time user-visible warning for when we fail to initialize
the AST to indicate that initialization went wrong for the given target.
Additionally, we add checks for whether one of the `ASTContext` `QualType`s is
invalid before dereferencing any builtin types.
The warning would look as follows:
```
(lldb) target create "a.out"
Current executable set to 'a.out' (arm64).
(lldb) b main
warning: Failed to initialize builtin ASTContext types for target
'some-unknown-triple'. Printing variables may behave unexpectedly.
Breakpoint 1: where = a.out`main + 8 at stepping.cpp:5:14, address =
0x0000000100003f90
```
rdar://134869779
>From 0669f9fbeddaf81edfca7e81f4883a1b95a780f6 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuc...@gmail.com>
Date: Mon, 30 Sep 2024 10:53:47 +0100
Subject: [PATCH] [lldb][TypeSystemClang] Add warning and defensive checks when
ASTContext is not fully initialized
---
.../TypeSystem/Clang/TypeSystemClang.cpp | 28 ++++++++++++++++---
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
index b0f49ebf2d2cbb..2f423269fecd2d 100644
--- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
+++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
@@ -54,6 +54,7 @@
#include "Plugins/ExpressionParser/Clang/ClangUserExpression.h"
#include "Plugins/ExpressionParser/Clang/ClangUtil.h"
#include "Plugins/ExpressionParser/Clang/ClangUtilityFunction.h"
+#include "lldb/Core/Debugger.h"
#include "lldb/Core/DumpDataExtractor.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
@@ -697,10 +698,19 @@ void TypeSystemClang::CreateASTContext() {
TargetInfo *target_info = getTargetInfo();
if (target_info)
m_ast_up->InitBuiltinTypes(*target_info);
- else if (auto *log = GetLog(LLDBLog::Expressions))
- LLDB_LOG(log,
- "Failed to initialize builtin ASTContext types for target '{0}'",
- m_target_triple);
+ else {
+ std::string err =
+ llvm::formatv(
+ "Failed to initialize builtin ASTContext types for target '{0}'. "
+ "Printing variables may behave unexpectedly.",
+ m_target_triple)
+ .str();
+
+ LLDB_LOG(GetLog(LLDBLog::Expressions), err.c_str());
+
+ static std::once_flag s_uninitialized_target_warning;
+ Debugger::ReportWarning(std::move(err), /*debugger_id=*/std::nullopt,
&s_uninitialized_target_warning);
+ }
GetASTMap().Insert(m_ast_up.get(), this);
@@ -749,6 +759,11 @@ CompilerType
TypeSystemClang::GetBuiltinTypeForEncodingAndBitSize(Encoding encoding,
size_t bit_size) {
ASTContext &ast = getASTContext();
+ if (!ast.VoidPtrTy) {
+ LLDB_LOG(GetLog(LLDBLog::Expressions), "{0} failed: builtin types on
ASTContext were not initialized properly.", __func__);
+ return {};
+ }
+
switch (encoding) {
case eEncodingInvalid:
if (QualTypeMatchesBitSize(bit_size, ast, ast.VoidPtrTy))
@@ -891,6 +906,11 @@ CompilerType
TypeSystemClang::GetBuiltinTypeForDWARFEncodingAndBitSize(
llvm::StringRef type_name, uint32_t dw_ate, uint32_t bit_size) {
ASTContext &ast = getASTContext();
+ if (!ast.VoidPtrTy) {
+ LLDB_LOG(GetLog(LLDBLog::Expressions), "{0} failed: builtin types on
ASTContext were not initialized properly.", __func__);
+ return {};
+ }
+
switch (dw_ate) {
default:
break;
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