[lldb-dev] lldb test failures on 32bit

[Michael Sartain]

I realized Andrew's reloc-fix-32.patch & stack-fix-32.patch weren't checked
in and I didn't have them. Applying both of those with my patch below
allows me to step over the 32-bit printf() calls now.

Are those patches what you hope to check in at some point Andrew?

And please let me know if it's ok to check this in:

http://llvm-reviews.chandlerc.com/D1189

Thanks!
 -Mike

On Thu, Aug 15, 2013 at 10:39 AM, Michael Sartain <mikesart at gmail.com>wrote:

> On Tue, Aug 13, 2013 at 6:22 PM, Michael Sartain <mikesart at gmail.com>wrote:
>
>> Unwind info does exist for addresses in main(), and all of this works as
>> expected in x64.
>>
>> I'll start debugging where this is failing...
>>
>
>  For x86 elf files, the plt_entsize wasn't being rounded to the proper
> alignment - this was causing the .plt symbols to be incorrect, along with
> unwind info, etc. This patch fixes that:
>
> http://llvm-reviews.chandlerc.com/D1189
>
> The next problem is we're using the x64 register set, but then calling
> into the i386 ABI. Ie, this call:
>
>  246|     addr_t pc;
>  247+>    if (!ReadGPRValue (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC,
> pc))
>  248|     {
>
> Winds up here:
>
> 1092|     ExecutionContext exe_ctx(m_thread.shared_from_this());
> 1093|     Process *process = exe_ctx.GetProcessPtr();
> 1094|     if (have_unwindplan_regloc == false)
> 1095|     {
> 1096|         // If a volatile register is being requested, we don't want
> to forward the next frame's register contents
> 1097|         // up the stack -- the register is not retrievable at this
> frame.
> 1098|         ABI *abi = process ? process->GetABI().get() : NULL;
> 1099|         if (abi)
> 1100|         {
> 1101+>            const RegisterInfo *reg_info =
> GetRegisterInfoAtIndex(lldb_regnum);
> 1102|             if (reg_info && abi->RegisterIsVolatile (reg_info))
> 1103|             {
>  1104|                 UnwindLogMsg ("did not supply reg location for %d
> (%s) because it is volatile",
> 1105|                     lldb_regnum, reg_info->name ? reg_info->name :
> "??");
> 1106|                 return
> UnwindLLDB::RegisterSearchResult::eRegisterIsVolatile;
> 1107|             }
> 1108|         }
>
> Which calls into this function:
>
> 902| bool
> 903| ABIMacOSX_i386::RegisterIsCalleeSaved (const RegisterInfo *reg_info)
> 904| {
> 905|     if (reg_info)
> 906|     {
> 907|         // Saved registers are ebx, ebp, esi, edi, esp, eip
> 908|         const char *name = reg_info->name;
> 909|         if (name[0] == 'e')
> 910|         {
>
> reg_info->name is "rip", and so ABIMacOSX_i386::RegisterIsCalleeSaved() is
> returning false.
>
> ABIMacOSX_i386.cpp looks like it does several things using register names.
>
> > Actually, RegisterContext_i386 doesn't get used in the case of a 32-bit
> inferior on a 64-bit host.  In that scenario we use RegisterContext_x86_64
> and do some mapping under the covers for 32-bit targets.
>
> Does this mean this is an issue with RegisterContext_x86_64 returning
> "rip" and not "eip"?
>
> Thanks.
>  -Mike
>
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