[PATCH] x86-64: Fix TLSDESC relaxation for x32

[H.J. Lu]

On Sat, Jan 18, 2020 at 3:07 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> For X32, TLSDESC sequences can be
>
> 8d 05 00 00 00 00       lea     x@TLSDESC(%rip), %eax
> 67 ff 10                call    *x@TLSCALL(%eax)
>

For x32, we must encode "lea x@TLSDESC(%rip), %reg" with a REX prefix
even if it isn't required.  Otherwise linker can’t safely perform GDesc -> LE
optimization.  If the lea encoding has a variable length, linker can't
tell where
it starts.  Here is the updated patch to always generate a REX prefix.


-- 
H.J.
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