Richard Biener writes:
> Given there is now PR67167 I am going forward with the earlier posted
> patch to switch SCCVN to PHI elimination in favor of another PHI
> (to remove IVs) rather than in favor of its only executable edge value.
>
> I still see no way to capture both cases without detecting the choice
> and re-numbering the SCC twice, eventually choosing the "better" outcome.
> And then the situation where both cases happen in the same SCC is not
> handled either.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
>
> Richard.
>
> 2015-08-13 Richard Biener <[email protected]>
>
> PR tree-optimization/66502
> PR tree-optimization/67167
> * tree-ssa-sccvn.c (vn_phi_compute_hash): Do not include
> backedge arguments.
> (vn_phi_lookup): Adjust.
> (vn_phi_insert): Likewise.
> (visit_phi): Prefer to value-number to another PHI node
> over value-numbering to a PHI argument.
> (init_scc_vn): Mark DFS back edges.
Richard,
I suspect this patch r226850 caused internal compiler error on
./gcc/testsuite/gcc.c-torture/compile/20121027-1.c on arm-non-eabi.
The ICE gone away if I revert this patch.
it can be easily reproduced by the following command. -mfpu and
-mfloat are necessary.
./cc1 -O3 -nostdinc 20121027-1.c -march=armv8-a -mthumb
-mfpu=crypto-neon-fp-armv8 -mfloat-abi=hard
cc1 is generated from
../gcc/configure --target=arm-none-eabi --enable-languages=c,c++
do you mind to have a look?
Thanks.
--
Regards,
Jiong
