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Re: [PATCH 1/4] Mark all member functions with memory models always inline
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Andi Kleen <andi at firstfloor dot org>, Andi Kleen <ak at linux dot intel dot com>, Jonathan Wakely <jwakely dot gcc at gmail dot com>, gcc-patches at gcc dot gnu dot org, libstdc++ at gcc dot gnu dot org, rth at redhat dot com
- Date: Wed, 20 Mar 2013 12:20:27 +0100
- Subject: Re: [PATCH 1/4] Mark all member functions with memory models always inline
- References: <1363440569-17331-1-git-send-email-andi at firstfloor dot org> <CAH6eHdR=VhEfAes6S97CfBf0Newe1h3EeoxreRKKHpi4mpJh=w at mail dot gmail dot com> <20130319064639 dot GA12913 at tucnak dot redhat dot com> <20130319155121 dot GM19692 at tassilo dot jf dot intel dot com> <20130319161022 dot GE12913 at tucnak dot redhat dot com> <20130319173016 dot GF20853 at two dot firstfloor dot org> <CAFiYyc3Gfc_KMupTFdA9V3DEz8bXovKb_E7inG7CNwwgEw3MCg at mail dot gmail dot com> <20130320104613 dot GK12913 at tucnak dot redhat dot com>
On Wed, Mar 20, 2013 at 11:46 AM, Jakub Jelinek <firstname.lastname@example.org> wrote:
> On Wed, Mar 20, 2013 at 11:38:03AM +0100, Richard Biener wrote:
>> Not without using information created by TER which is disabled for this
>> case because of different line information. If TER would not be disabled
>> for this reason it would already work automagically.
> Would relaxing that in TER for constants help in the case of:
> static inline __attribute__((always_inline)) ...
> foo (..., int m = __ATOMIC_SEQ_CST)
> if (something)
> bar ();
> baz ();
> __atomic_test_and_set (&x, m);
> test ()
> foo (..., __ATOMIC_HLE_ACQUIRE | __ATOMIC_SEQ_CST);
> though? I'd think as the temp = 0x10005; would be in a different bb, TER
> wouldn't do anything here, for -O1 of course CCP or similar would propagate
> that, but for -O0 we'd still have to walk the chain of SSA_NAMEs.
True. I was for a long time thinking of running a CCP pass at -O0 ...
and only restrict what we sustitute into (builtin arguments and asm operands).
Walking the SSA def chain would also be possible - preferably from
cfgexpand.c when we process the stmt. But you'll eventually lose
debug info like for
int i = 1;
when we then never expand the SSA name def i_2 = 1 because we are
never visiting its use ...