[LLDB][MIPS] Fix ReadRegisterValue for registers with constant 32 bit size regardless of ABI

[mohit.bhakkad]

Summary

sr, cause and config5 have 32 bit size irrespective of ABI

[tberghammer]

Please see inline comments

P.S.: Next time please upload the diff with full context (git diff -U999999999) as it is easier to review that way

source/Plugins/Process/Linux/NativeRegisterContextLinux_mips64.cpp

1392 ↗

(On Diff #44467)

You can't compare a string literal and a const char* like this (it will compare the pointers only). You have to use ::strcmp or use the ConstString class in some form.

1393–1395 ↗

(On Diff #44467)

Reading these lines are very difficult. I think something like this would be much cleaner (I haven't fixed the string comparisons and haven't tested it):

void* target_address = ((uint8_t*)&regs) + offset + 4 * (arch.GetMachine() == llvm::Triple::mips);
uint32_t target_size;
if (reg_name == "sr" || reg_name == "cause" || reg_name == "config5")
    target_size = 4;
else
    target_size = arch.GetFlags() & lldb_private::ArchSpec::eMIPSABI_O32 ? 4 : 8;
value.SetBytes(target_address, target_size, arch.GetByteOrder());

[mohit.bhakkad]

Sorry for the mess in last revision.
Updated as per suggestion.

[tberghammer]

Looks good. Thanks for cleaning it up

lldb/trunk/source/Plugins/Process/Linux/NativeRegisterContextLinux_mips64.cpp

NativeRegisterContextLinux_mips64::DoReadRegisterValue(uint32_t offset,
 
     // Clear all bits in RegisterValue before writing actual value read from ptrace to avoid garbage value in 32-bit MSB 
     value.SetBytes((void *)(((unsigned char *)&regs) + offset), 8, GetByteOrder());
     Error error = NativeProcessLinux::PtraceWrapper(PTRACE_GETREGS, m_thread.GetID(), NULL, &regs, sizeof regs);
     if (error.Success())
     {
         lldb_private::ArchSpec arch;
         if (m_thread.GetProcess()->GetArchitecture(arch))
-            value.SetBytes((void *)(((unsigned char *)&regs) + offset + 4 * (arch.GetMachine() == llvm::Triple::mips)), arch.GetFlags() & lldb_private::ArchSpec::eMIPSABI_O32 ? 4 : 8, arch.GetByteOrder());
+        {
+            void* target_address = ((uint8_t*)&regs) + offset + 4 * (arch.GetMachine() == llvm::Triple::mips;
+            uint32_t target_size;
+            if ((::strcmp(reg_name, "sr") == 0) || (::strcmp(reg_name, "cause") == 0) || (::strcmp(reg_name, "config5") == 0))
+                target_size = 4;
+            else
+                target_size = arch.GetFlags() & lldb_private::ArchSpec::eMIPSABI_O32 ? 4 : 8;
+            value.SetBytes(target_address, target_size, arch.GetByteOrder());
+        }
         else
             error.SetErrorString("failed to get architecture");
     }
     return error;
 }
 
 Error
 NativeRegisterContextLinux_mips64::DoWriteRegisterValue(uint32_t offset,