[Lldb-commits] [PATCH] D89193: [lldb] [Process/FreeBSDRemote] Support YMM reg via PT_*XSTATE

[Kamil Rytarowski via Phabricator via lldb-commits]

krytarowski added inline comments.


================
Comment at: lldb/source/Plugins/Process/FreeBSDRemote/NativeRegisterContextFreeBSD_x86_64.cpp:448-449
+
+    assert(info.xsave_mask & XFEATURE_ENABLED_X87);
+    assert(info.xsave_mask & XFEATURE_ENABLED_SSE);
+
----------------
emaste wrote:
> mgorny wrote:
> > mgorny wrote:
> > > emaste wrote:
> > > > I wonder if these should be an error rather than assertion?
> > > I suppose the question is if they ever happen in real use. If they do, we should probably handle them gracefully. Otherwise, assertion should be sufficient.
> > I can actually answer the first question myself. According to Intel's manual, it is impossible to disable x87 bit. IIRC attempt to unset it on XCR0 will raise some fault.
> > 
> > The second question is basically whether under any circumstances can FreeBSD kernel disable SSE on XCR0 (this code is only used on systems supporting XSAVE).
> I guess my point is that having these bits unset would indicate a kernel issue or bug, or maybe hardware issue, but never indicate an error or invalid operation in lldb itself.
> 
> Either way I think there is no practical impact, it's not actually going to happen.
If we assert on this code we more trigger software bug in lldb rather than a hardware specifics.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D89193/new/

https://reviews.llvm.org/D89193