[lldb][AArch64][Linux] Add field information for the fpsr register

[DavidSpickett]

This one is easy because none of the fields depend on extensions. Only thing to note is that I've ignored some AArch32 only fields.

(lldb) register read fpsr
    fpsr = 0x00000000
         = (QC = 0, IDC = 0, IXC = 0, UFC = 0, OFC = 0, DZC = 0, IOC = 0)

[llvmbot]

@llvm/pr-subscribers-lldb

Author: David Spickett (DavidSpickett)

Changes

This one is easy because none of the fields depend on extensions. Only thing to note is that I've ignored some AArch32 only fields.

(lldb) register read fpsr
    fpsr = 0x00000000
         = (QC = 0, IDC = 0, IXC = 0, UFC = 0, OFC = 0, DZC = 0, IOC = 0)

---

Full diff: https://github.com/llvm/llvm-project/pull/71651.diff

4 Files Affected:

• (modified) lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp (+20)
• (modified) lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h (+3-1)
• (modified) lldb/test/API/commands/register/register/register_command/TestRegisters.py (+3-2)
• (modified) lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py (+1)

diff --git a/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp b/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp
index 043789bd6d21e47..f2f8b3b3211663d 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.cpp
@@ -20,6 +20,26 @@
 
 using namespace lldb_private;
 
+LinuxArm64RegisterFlags::Fields
+LinuxArm64RegisterFlags::DetectFPSRFields(uint64_t hwcap, uint64_t hwcap2) {
+  // fpsr's contents are constant.
+  (void)hwcap;
+  (void)hwcap2;
+
+  return {
+      // Bits 31-28 are N/Z/C/V, only used by AArch32.
+      {"QC", 27},
+      // Bits 26-8 reserved.
+      {"IDC", 7},
+      // Bits 6-5 reserved.
+      {"IXC", 4},
+      {"UFC", 3},
+      {"OFC", 2},
+      {"DZC", 1},
+      {"IOC", 0},
+  };
+}
+
 LinuxArm64RegisterFlags::Fields
 LinuxArm64RegisterFlags::DetectCPSRFields(uint64_t hwcap, uint64_t hwcap2) {
   // The fields here are a combination of the Arm manual's SPSR_EL1,
diff --git a/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h b/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h
index 6c7a3b61a1425ee..1058ac2c70bdc5d 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterFlagsLinux_arm64.h
@@ -56,6 +56,7 @@ class LinuxArm64RegisterFlags {
   using DetectorFn = std::function<Fields(uint64_t, uint64_t)>;
 
   static Fields DetectCPSRFields(uint64_t hwcap, uint64_t hwcap2);
+  static Fields DetectFPSRFields(uint64_t hwcap, uint64_t hwcap2);
 
   struct RegisterEntry {
     RegisterEntry(llvm::StringRef name, unsigned size, DetectorFn detector)
@@ -65,8 +66,9 @@ class LinuxArm64RegisterFlags {
     llvm::StringRef m_name;
     RegisterFlags m_flags;
     DetectorFn m_detector;
-  } m_registers[1] = {
+  } m_registers[2] = {
       RegisterEntry("cpsr", 4, DetectCPSRFields),
+      RegisterEntry("fpsr", 4, DetectFPSRFields),
   };
 
   // Becomes true once field detection has been run for all registers.
diff --git a/lldb/test/API/commands/register/register/register_command/TestRegisters.py b/lldb/test/API/commands/register/register/register_command/TestRegisters.py
index f29b2ab5d8f259d..2bd1d6f08f08478 100644
--- a/lldb/test/API/commands/register/register/register_command/TestRegisters.py
+++ b/lldb/test/API/commands/register/register/register_command/TestRegisters.py
@@ -622,13 +622,14 @@ def test_info_register(self):
     @skipUnlessPlatform(["linux"])
     @skipIf(archs=no_match(["aarch64"]))
     def test_register_read_fields(self):
-        """Test that when debugging a live process, we see the fields of the
-        CPSR register."""
+        """Test that when debugging a live process, we see the fields of certain
+        registers."""
         self.build()
         self.common_setup()
 
         # N/Z/C/V bits will always be present, so check only for those.
         self.expect("register read cpsr", substrs=["= (N = 0, Z = 1, C = 1, V = 0"])
+        self.expect("register read fpsr", substrs=["= (QC = 0, IDC = 0, IXC = 0"])
 
     @skipUnlessPlatform(["linux"])
     @skipIf(archs=no_match(["x86_64"]))
diff --git a/lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py b/lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py
index a083fab18eabcbc..1a913c2c0843cbc 100644
--- a/lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py
+++ b/lldb/test/API/functionalities/postmortem/elf-core/TestLinuxCore.py
@@ -577,6 +577,7 @@ def test_aarch64_sve_regs_full(self):
         # Register field information should work with core files as it does a live process.
         # The N/Z/C/V bits are always present so just check for those.
         self.expect("register read cpsr", substrs=["= (N = 0, Z = 0, C = 0, V = 0"])
+        self.expect("register read fpsr", substrs=["= (QC = 0, IDC = 0, IXC = 0"])
 
     @skipIfLLVMTargetMissing("AArch64")
     def test_aarch64_pac_regs(self):

[DavidSpickett]

It may be worth adding a fast path for "constant" information, but I would like to look into that after the initial set of 5 registers is in.

[bulbazord]

Looks straightforward to me.

[jasonmolenda]

Looks good.