[Lldb-commits] [lldb] [lldb][MachO] Fix inspection of global variables that start with 'O' (PR #161521)
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Wed Oct 1 06:37:49 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lldb
Author: Michael Buch (Michael137)
<details>
<summary>Changes</summary>
On Darwin C-symbols are prefixed with a '_'. The LLDB Macho-O parses handles Objective-C metadata symbols starting with '_OBJC' specially. Previously global symbols starting with a '_O' prefix were lost because of incorrectly scoped if-guards. This patch removes those checks.
There is more cleanup that can be done in this file because there's a bunch of duplicated checks for these ObjC symbols. I decided to leave that for an NFC follow-up.
Depends on https://github.com/llvm/llvm-project/pull/161520
rdar://158159242
---
Full diff: https://github.com/llvm/llvm-project/pull/161521.diff
3 Files Affected:
- (modified) lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp (+42-48)
- (added) lldb/test/Shell/Expr/TestGlobalSymbolObjCConflict.c (+33)
- (modified) lldb/test/Shell/lit.cfg.py (+1-1)
``````````diff
diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index fada1fda2b4bc..91c93be1b8cfd 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -2805,32 +2805,29 @@ void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
is_gsym = true;
sym[sym_idx].SetExternal(true);
- if (symbol_name && symbol_name[0] == '_' &&
- symbol_name[1] == 'O') {
- llvm::StringRef symbol_name_ref(symbol_name);
- if (symbol_name_ref.starts_with(
- g_objc_v2_prefix_class)) {
- symbol_name_non_abi_mangled = symbol_name + 1;
- symbol_name =
- symbol_name + g_objc_v2_prefix_class.size();
- type = eSymbolTypeObjCClass;
- demangled_is_synthesized = true;
-
- } else if (symbol_name_ref.starts_with(
- g_objc_v2_prefix_metaclass)) {
- symbol_name_non_abi_mangled = symbol_name + 1;
- symbol_name =
- symbol_name + g_objc_v2_prefix_metaclass.size();
- type = eSymbolTypeObjCMetaClass;
- demangled_is_synthesized = true;
- } else if (symbol_name_ref.starts_with(
- g_objc_v2_prefix_ivar)) {
- symbol_name_non_abi_mangled = symbol_name + 1;
- symbol_name =
- symbol_name + g_objc_v2_prefix_ivar.size();
- type = eSymbolTypeObjCIVar;
- demangled_is_synthesized = true;
- }
+ llvm::StringRef symbol_name_ref(symbol_name);
+ if (symbol_name_ref.starts_with(
+ g_objc_v2_prefix_class)) {
+ symbol_name_non_abi_mangled = symbol_name + 1;
+ symbol_name =
+ symbol_name + g_objc_v2_prefix_class.size();
+ type = eSymbolTypeObjCClass;
+ demangled_is_synthesized = true;
+
+ } else if (symbol_name_ref.starts_with(
+ g_objc_v2_prefix_metaclass)) {
+ symbol_name_non_abi_mangled = symbol_name + 1;
+ symbol_name =
+ symbol_name + g_objc_v2_prefix_metaclass.size();
+ type = eSymbolTypeObjCMetaClass;
+ demangled_is_synthesized = true;
+ } else if (symbol_name_ref.starts_with(
+ g_objc_v2_prefix_ivar)) {
+ symbol_name_non_abi_mangled = symbol_name + 1;
+ symbol_name =
+ symbol_name + g_objc_v2_prefix_ivar.size();
+ type = eSymbolTypeObjCIVar;
+ demangled_is_synthesized = true;
} else {
if (nlist.n_value != 0)
symbol_section = section_info.GetSection(
@@ -3652,7 +3649,7 @@ void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
if (is_debug) {
switch (nlist.n_type) {
- case N_GSYM:
+ case N_GSYM: {
// global symbol: name,,NO_SECT,type,0
// Sometimes the N_GSYM value contains the address.
@@ -3668,33 +3665,30 @@ void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
is_gsym = true;
sym[sym_idx].SetExternal(true);
- if (symbol_name && symbol_name[0] == '_' && symbol_name[1] == 'O') {
- llvm::StringRef symbol_name_ref(symbol_name);
- if (symbol_name_ref.starts_with(g_objc_v2_prefix_class)) {
- symbol_name_non_abi_mangled = symbol_name + 1;
- symbol_name = symbol_name + g_objc_v2_prefix_class.size();
- type = eSymbolTypeObjCClass;
- demangled_is_synthesized = true;
-
- } else if (symbol_name_ref.starts_with(
- g_objc_v2_prefix_metaclass)) {
- symbol_name_non_abi_mangled = symbol_name + 1;
- symbol_name = symbol_name + g_objc_v2_prefix_metaclass.size();
- type = eSymbolTypeObjCMetaClass;
- demangled_is_synthesized = true;
- } else if (symbol_name_ref.starts_with(g_objc_v2_prefix_ivar)) {
- symbol_name_non_abi_mangled = symbol_name + 1;
- symbol_name = symbol_name + g_objc_v2_prefix_ivar.size();
- type = eSymbolTypeObjCIVar;
- demangled_is_synthesized = true;
- }
+ llvm::StringRef symbol_name_ref(symbol_name);
+ if (symbol_name_ref.starts_with(g_objc_v2_prefix_class)) {
+ symbol_name_non_abi_mangled = symbol_name + 1;
+ symbol_name = symbol_name + g_objc_v2_prefix_class.size();
+ type = eSymbolTypeObjCClass;
+ demangled_is_synthesized = true;
+
+ } else if (symbol_name_ref.starts_with(g_objc_v2_prefix_metaclass)) {
+ symbol_name_non_abi_mangled = symbol_name + 1;
+ symbol_name = symbol_name + g_objc_v2_prefix_metaclass.size();
+ type = eSymbolTypeObjCMetaClass;
+ demangled_is_synthesized = true;
+ } else if (symbol_name_ref.starts_with(g_objc_v2_prefix_ivar)) {
+ symbol_name_non_abi_mangled = symbol_name + 1;
+ symbol_name = symbol_name + g_objc_v2_prefix_ivar.size();
+ type = eSymbolTypeObjCIVar;
+ demangled_is_synthesized = true;
} else {
if (nlist.n_value != 0)
symbol_section =
section_info.GetSection(nlist.n_sect, nlist.n_value);
type = eSymbolTypeData;
}
- break;
+ } break;
case N_FNAME:
// procedure name (f77 kludge): name,,NO_SECT,0,0
diff --git a/lldb/test/Shell/Expr/TestGlobalSymbolObjCConflict.c b/lldb/test/Shell/Expr/TestGlobalSymbolObjCConflict.c
new file mode 100644
index 0000000000000..da7263648776f
--- /dev/null
+++ b/lldb/test/Shell/Expr/TestGlobalSymbolObjCConflict.c
@@ -0,0 +1,33 @@
+// Tests that LLDB correctly parses global symbols
+// starting with 'O'. On some platforms (e.g., Darwin)
+// C-symbols are prefixed with a '_'. The LLDB Macho-O
+// parses handles Objective-C metadata symbols starting
+// with '_OBJC' specially. This test ensures that we don't
+// lose track of regular global symbols with a '_O' prefix
+// in this.
+
+// RUN: %clang_host -c -g -fno-common %s -o %t.o
+// RUN: %clang_host %t.o -o %t.out
+// RUN: %lldb -b -x %t.out \
+// RUN: -o "b 17" \
+// RUN: -o "run" \
+// RUN: -o "p OglobalVar" \
+// RUN: -o "p Oabc" | FileCheck %s
+
+typedef struct {
+ int a;
+} Oabc_t;
+
+Oabc_t Oabc;
+int OglobalVar;
+
+int main(int argc, const char *argv[]) {
+ Oabc.a = 15;
+ OglobalVar = 10;
+ return OglobalVar + Oabc.a;
+}
+
+// CHECK: (lldb) p OglobalVar
+// CHECK: (int) 10
+// CHECK: (lldb) p Oabc
+// CHECK: (Oabc_t) (a = 15)
diff --git a/lldb/test/Shell/lit.cfg.py b/lldb/test/Shell/lit.cfg.py
index 505847fb763e0..cdc0cfe51f7c6 100644
--- a/lldb/test/Shell/lit.cfg.py
+++ b/lldb/test/Shell/lit.cfg.py
@@ -33,7 +33,7 @@
# suffixes: A list of file extensions to treat as test files. This is overriden
# by individual lit.local.cfg files in the test subdirectories.
-config.suffixes = [".test", ".cpp", ".s", ".m", ".ll"]
+config.suffixes = [".test", ".cpp", ".s", ".m", ".ll", ".c"]
# excludes: A list of directories to exclude from the testsuite. The 'Inputs'
# subdirectories contain auxiliary inputs for various tests in their parent
``````````
</details>
https://github.com/llvm/llvm-project/pull/161521
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