[Lldb-commits] [PATCH] D63545: [lldb] [Process/NetBSD] Support reading YMM registers via PT_*XSTATE [DO NOT MERGE]

Thu Jun 20 04:13:51 PDT 2019

labath added a comment.

In D63545#1551675 <https://reviews.llvm.org/D63545#1551675>, @mgorny wrote:

> In D63545#1551627 <https://reviews.llvm.org/D63545#1551627>, @labath wrote:
>
> > We have the same XSTATE<->YMM conversion functions in NativeProcessLinux. It would be nice to extract them to some common place (Plugins/Process/Utility, I guess :P).
>
>
> Hmm, I guess that's doable if we pass the relevant struct fields as pointers.

Maybe have GetYMM(unsigned num, YMM& reg)/SetYMM(unsigned num, const YMM &reg) methods on the XSAVE struct ?

> 
> 
>> The rest seems pretty straight-forward, though you're repeating the patterns that I find really reduntant/annoying. Eg. I don't see the reason to check the null-ness of the XState buffer. It sounds like it should be a hard error for someone to call ReadXState without bothering to arrange for the storage buffer to exist.
> 
> Yeah, I guess that's something I can fix globally first.

Sounds great.

================
Comment at: lldb/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp:239
+
+  if (byte_order == lldb::eByteOrderBig) {
+    ::memcpy(m_xstate_x86_64.xs_fxsave.fx_xmm[reg_index].xmm_bytes,
----------------
mgorny wrote:
> labath wrote:
> > Why would we ever want to do this?
> I was asking myself the exact same thing! But the code is present both on Linux and FreeBSD, so I presumed there is some fancy use case I have no clue about.
Yeah, I don't think that's a safe assumption around here. :)

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