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From: "tromey at sourceware dot org" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug compile/25575] Compile command crashes or fails with AVX
 registers and -O2
Date: Sat, 09 Jan 2021 19:43:47 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D25575

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
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                 CC|                            |tromey at sourceware dot o=
rg

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
The problem here seems to me that the DWARF expression for 'x' references
register 207, but up in generate_c_for_variable_locations:

  gdb::unique_xmalloc_ptr<unsigned char> registers_used
    (XCNEWVEC (unsigned char, gdbarch_num_regs (gdbarch)));

and

(top-gdb) p gdbarch_num_regs(gdbarch)
$6 =3D 155

So this is also an invalid memory access as well I think.


Digging a bit deeper I see that ymm0 is apparently a pseudo-register.
So, I think there are a couple of problems here.

One is that the DWARF-lowering code should probably translate
to gdb register numbers.

But, to do this, we'd also have to handle pseudos.  But, I don't think
there's a way to translate pseudo-registers to their underlying GDB
registers.  I guess this can be done in an ad hoc way by the tdep code.

Not sure how to approach this.  Maybe the whole thing could be
rephrased in terms of regsets?

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