[lldb/aarch64] Fix PC register info augmentation (llvm#143499)

This fixes a regression caused by llvm#139817, where we would fail to unwind
(using eh_frame) when using debug stubs (like qemu) which do not provide
eh_frame register numbers.

Unwinding fails because the unwinder tries to convert pc register number
to the "eh_frame" scheme (and fails). Previously that worked because the
code used a slightly different pattern which ended up comparing the
number by converting it to the "generic" scheme (which we do provide).

I don't think that's a bug in the unwinder -- we just need to make sure
we provide the register number all the time.

The associated test is not particularly useful, but I'm hoping it could
be used to test other changes like this as well. Other register
augmentation changes are tested in an end-to-end fashion (by injecting
gdb-remote packets and then trying to read registers). That works well
for testing the addition of subregisters, but it isn't particularly
suitable for testing register numbers, as the only place (that I know
of) where this manifests is during unwinding, and recreating an
unwindable process in a test like this is fairly challenging.

Probably the best way to ensure coverage for this scenario would be to
have lldb-server stop sending eh_frame register numbers (align it with
other gdb-like stubs).

Author: labath

lldb/source/Plugins/ABI/AArch64/ABIAArch64.cpp

@@ -12,6 +12,7 @@
 #include "ABIMacOSX_arm64.h"
 #include "ABISysV_arm64.h"
 #include "Utility/ARM64_DWARF_Registers.h"
+#include "Utility/ARM64_ehframe_Registers.h"
 #include "lldb/Core/PluginManager.h"
 #include "lldb/Target/Process.h"
 
@@ -69,9 +70,9 @@ lldb::addr_t ABIAArch64::FixDataAddress(lldb::addr_t pc) {
 std::pair<uint32_t, uint32_t>
 ABIAArch64::GetEHAndDWARFNums(llvm::StringRef name) {
   if (name == "pc")
-    return {LLDB_INVALID_REGNUM, arm64_dwarf::pc};
+    return {arm64_ehframe::pc, arm64_dwarf::pc};
   if (name == "cpsr")
-    return {LLDB_INVALID_REGNUM, arm64_dwarf::cpsr};
+    return {arm64_ehframe::cpsr, arm64_dwarf::cpsr};
   return MCBasedABI::GetEHAndDWARFNums(name);
 }
 

lldb/unittests/ABI/AArch64/ABIAArch64Test.cpp

@@ -0,0 +1,68 @@
+//===-- ABIAArch64Test.cpp ------------------------------------------------===//
+
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Plugins/ABI/AArch64/ABIMacOSX_arm64.h"
+#include "Plugins/ABI/AArch64/ABISysV_arm64.h"
+#include "Utility/ARM64_DWARF_Registers.h"
+#include "Utility/ARM64_ehframe_Registers.h"
+#include "lldb/Target/DynamicRegisterInfo.h"
+#include "lldb/Utility/ArchSpec.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/TargetSelect.h"
+#include "gtest/gtest.h"
+#include <vector>
+
+using namespace lldb_private;
+using namespace lldb;
+
+class ABIAArch64TestFixture : public testing::TestWithParam<llvm::StringRef> {
+public:
+  static void SetUpTestCase();
+  static void TearDownTestCase();
+
+  //  virtual void SetUp() override { }
+  //  virtual void TearDown() override { }
+
+protected:
+};
+
+void ABIAArch64TestFixture::SetUpTestCase() {
+  LLVMInitializeAArch64TargetInfo();
+  LLVMInitializeAArch64TargetMC();
+  ABISysV_arm64::Initialize();
+  ABIMacOSX_arm64::Initialize();
+}
+
+void ABIAArch64TestFixture::TearDownTestCase() {
+  ABISysV_arm64::Terminate();
+  ABIMacOSX_arm64::Terminate();
+  llvm::llvm_shutdown();
+}
+
+TEST_P(ABIAArch64TestFixture, AugmentRegisterInfo) {
+  ABISP abi_sp = ABI::FindPlugin(ProcessSP(), ArchSpec(GetParam()));
+  ASSERT_TRUE(abi_sp);
+  using Register = DynamicRegisterInfo::Register;
+
+  Register pc{ConstString("pc"), ConstString(), ConstString("GPR")};
+  std::vector<Register> regs{pc};
+
+  abi_sp->AugmentRegisterInfo(regs);
+
+  ASSERT_EQ(regs.size(), 1);
+  Register new_pc = regs[0];
+  EXPECT_EQ(new_pc.name, pc.name);
+  EXPECT_EQ(new_pc.set_name, pc.set_name);
+  EXPECT_EQ(new_pc.regnum_ehframe, arm64_ehframe::pc);
+  EXPECT_EQ(new_pc.regnum_dwarf, arm64_dwarf::pc);
+}
+
+INSTANTIATE_TEST_SUITE_P(ABIAArch64Tests, ABIAArch64TestFixture,
+                         testing::Values("aarch64-pc-linux",
+                                         "arm64-apple-macosx"));

lldb/unittests/ABI/AArch64/CMakeLists.txt

@@ -0,0 +1,9 @@
+add_lldb_unittest(ABIAArch64Tests
+  ABIAArch64Test.cpp
+  LINK_COMPONENTS
+    Support
+    AArch64
+  LINK_LIBS
+    lldbTarget
+    lldbPluginABIAArch64
+  )

lldb/unittests/ABI/CMakeLists.txt

@@ -0,0 +1,3 @@
+if ("AArch64" IN_LIST LLVM_TARGETS_TO_BUILD)
+  add_subdirectory(AArch64)
+endif()

lldb/unittests/CMakeLists.txt

@@ -52,6 +52,7 @@ if (NOT CMAKE_SYSTEM_NAME MATCHES "Windows")
   add_subdirectory(API)
   add_subdirectory(DAP)
 endif()
+add_subdirectory(ABI)
 add_subdirectory(Breakpoint)
 add_subdirectory(Callback)
 add_subdirectory(Core)