[Lldb-commits] [lldb] [lldb][AArch64] Correct type of 32 bit GPR RegisterValues when using core files (PR #70054)

[David Spickett via lldb-commits]

https://github.com/DavidSpickett created https://github.com/llvm/llvm-project/pull/70054

As ReadRegister always read into a uint64_t, when it called operator= with uint64_t it was setting the RegisterValue's type to eTypeUInt64 regardless of its size.

This mostly works because most registers are 64 bit, and very few bits of code rely on the type being correct. However, cpsr, fpsr and fpcr are in fact 32 bit, and my upcoming register fields code relies on this type being correct.

Which is how I found this bug and unfortunately is the only way to test it. As RegisterValue::Type never makes it out via the API anywhere. So this change will be tested once I start adding register field information.

>From fe4fba18d7fbe6d7e0111ca592d4c517262d8122 Mon Sep 17 00:00:00 2001
From: David Spickett <david.spickett at linaro.org>
Date: Tue, 24 Oct 2023 14:56:58 +0000
Subject: [PATCH] [lldb][AArch64] Correct type of 32 bit GPR RegisterValues
 when using core files

As ReadRegister always read into a uint64_t, when it called operator= with uint64_t
it was setting the RegisterValue's type to eTypeUInt64 regardless of its size.

This mostly works because most registers are 64 bit, and very few bits of code
rely on the type being correct. However, cpsr, fpsr and fpcr are in fact 32 bit,
and my upcoming register fields code relies on this type being correct.

Which is how I found this bug and unfortunately is the only way to test it.
As RegisterValue::Type never makes it out via the API anywhere. So this
change will be tested once I start adding register field information.
---
 .../Process/elf-core/RegisterContextPOSIXCore_arm64.cpp   | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/lldb/source/Plugins/Process/elf-core/RegisterContextPOSIXCore_arm64.cpp b/lldb/source/Plugins/Process/elf-core/RegisterContextPOSIXCore_arm64.cpp
index 6f6c6d073939a61..f3e763b0475ceb1 100644
--- a/lldb/source/Plugins/Process/elf-core/RegisterContextPOSIXCore_arm64.cpp
+++ b/lldb/source/Plugins/Process/elf-core/RegisterContextPOSIXCore_arm64.cpp
@@ -184,11 +184,9 @@ bool RegisterContextCorePOSIX_arm64::ReadRegister(const RegisterInfo *reg_info,
 
   offset = reg_info->byte_offset;
   if (offset + reg_info->byte_size <= GetGPRSize()) {
-    uint64_t v = m_gpr_data.GetMaxU64(&offset, reg_info->byte_size);
-    if (offset == reg_info->byte_offset + reg_info->byte_size) {
-      value = v;
-      return true;
-    }
+    value.SetFromMemoryData(*reg_info, m_gpr_data.GetDataStart() + offset,
+                            reg_info->byte_size, lldb::eByteOrderLittle, error);
+    return error.Success();
   }
 
   const uint32_t reg = reg_info->kinds[lldb::eRegisterKindLLDB];