[Lldb-commits] [lldb] [lldb][AArch64][Linux] Add field information for the CPSR register (PR #70300)

[Alex Langford via lldb-commits]

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@@ -0,0 +1,102 @@
+//===-- RegisterFlagsLinux_arm64.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 "RegisterFlagsLinux_arm64.h"
+#include "lldb/lldb-private-types.h"
+
+// This file is built on all systems because it is used by native processes and
+// core files, so we manually define the needed HWCAP values here.
+
+#define HWCAP_DIT (1 << 24)
+#define HWCAP_SSBS (1 << 28)
+
+#define HWCAP2_BTI (1 << 17)
+#define HWCAP2_MTE (1 << 18)
+
+using namespace lldb_private;
+
+LinuxArm64RegisterFlags::Fields
+LinuxArm64RegisterFlags::DetectCPSRFields(uint64_t hwcap, uint64_t hwcap2) {
+  // The fields here are a combination of the Arm manual's SPSR_EL1,
+  // plus a few changes where Linux has decided not to make use of them at all,
+  // or at least not from userspace.
+
+  // Status bits that are always present.
+  std::vector<RegisterFlags::Field> cpsr_fields{
+      {"N", 31}, {"Z", 30}, {"C", 29}, {"V", 28},
+      // Bits 27-26 reserved.
+  };
+
+  if (hwcap2 & HWCAP2_MTE)
+    cpsr_fields.push_back({"TCO", 25});
+  if (hwcap & HWCAP_DIT)
+    cpsr_fields.push_back({"DIT", 24});
+
+  // UAO and PAN are bits 23 and 22 and have no meaning for userspace so
+  // are treated as reserved by the kernel.
+
+  cpsr_fields.push_back({"SS", 21});
+  cpsr_fields.push_back({"IL", 20});
+  // Bits 19-14 reserved.
+
+  // Bit 13, ALLINT, requires FEAT_NMI that isn't relevant to userspace, and we
+  // can't detect either, don't show this field.
+  if (hwcap & HWCAP_SSBS)
+    cpsr_fields.push_back({"SSBS", 12});
+  if (hwcap2 & HWCAP2_BTI)
+    cpsr_fields.push_back({"BTYPE", 10, 11});
+
+  cpsr_fields.push_back({"D", 9});
+  cpsr_fields.push_back({"A", 8});
+  cpsr_fields.push_back({"I", 7});
+  cpsr_fields.push_back({"F", 6});
+  // Bit 5 reserved
+  // Called "M" in the ARMARM.
+  cpsr_fields.push_back({"nRW", 4});
+  // This is a 4 bit field M[3:0] in the ARMARM, we split it into parts.
+  cpsr_fields.push_back({"EL", 2, 3});
+  // Bit 1 is unused and expected to be 0.
+  cpsr_fields.push_back({"SP", 0});
+
+  return cpsr_fields;
+}
+
+void LinuxArm64RegisterFlags::DetectFields(uint64_t hwcap, uint64_t hwcap2) {
+  for (auto &reg : m_registers)
+    reg.m_flags.SetFields(reg.m_detector(hwcap, hwcap2));
+  m_has_detected = true;
+}
+
+void LinuxArm64RegisterFlags::UpdateRegisterInfo(const RegisterInfo *reg_info,
+                                                 uint32_t num_regs) {
+  assert(m_has_detected &&
+         "Must call DetectFields before updating register info.");
+
+  // Register names will not be duplicated, so we do not want to compare against
+  // one if it has already been found. Each time we find one, we erase it from
+  // this list.
+  std::vector<std::pair<const char *, const RegisterFlags *>> search_registers;
+  for (const auto &reg : m_registers) {
+    // It is possible that a register is all extension dependent fields, and
+    // none of them are present.
+    if (reg.m_flags.GetFields().size())
+      search_registers.push_back({reg.m_name, &reg.m_flags});
+  }
+
+  uint32_t idx = 0;
+  for (; idx < num_regs && search_registers.size(); ++idx, ++reg_info) {
+    auto end = search_registers.cend();
+    for (auto it = search_registers.cbegin(); it != end; ++it) {
+      if (std::strcmp(reg_info->name, it->first) == 0) {
+        reg_info->flags_type = it->second;
+        search_registers.erase(it);
+        break;
+      }
+    }
+  }
+}
----------------
bulbazord wrote:

This just removes register information when iterating over `search_registers` right? There are a few things I might be missing, but I would recommend that you write this more succinctly with a use of `remove_if` (either from `std` or `llvm`, I kind of prefer the `llvm` version myself).

https://github.com/llvm/llvm-project/pull/70300