fwprop: fix REG_DEAD notes rendered incorrect

Alexandre Oliva aoliva@redhat.com
Thu Oct 27 13:32:00 GMT 2011


fwprop may propagate a SET_SRC that contains the last use of a REG to a
later point, but it will leave the REG_DEAD note in place, even though
it is no longer correct.  I noticed this while investigating PR50826:
the initialization of the internal_arg_pointer has a REG_DEAD note for
%r29, but even after it is fwpropped, the note remains there.  This
patch fixes this bug.

It also reduces the risk of code divergence in VTA-enabled compilations,
by enabling the simpler test in all_uses_available_at when there are
debug insns between the def and the use.

Regstrapped on x86_64-linux-gnu and i686-linux-gnu.  Ok to install?

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-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer


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