Re: [PATCH GCC]Allow cfgcleanup to remove forwarder loop preheaders and latches

["Bin.Cheng" <amker dot cheng at gmail dot com>]

Sorry, I didn't test it against logical_op_short_circuit target.  I
will look into this PR.

Thanks,
bin

On Fri, Feb 28, 2014 at 9:34 AM, Hans-Peter Nilsson <hp@bitrange.com> wrote:
> On Tue, 25 Feb 2014, bin.cheng wrote:
>
>> Hi,
>> This patch is to fix regression reported in PR60280 by removing forward loop
>> headers/latches in cfg cleanup if possible.  Several tests are broken by
>> this change since cfg cleanup is shared by all optimizers.  Some tests has
>> already been fixed by recent patches, I went through and fixed the others.
>> One case needs to be clarified is "gcc.dg/tree-prof/update-loopch.c".  When
>> GCC removing a basic block, it checks profile information by calling
>> check_bb_profile after redirecting incoming edges of the bb.  This certainly
>> results in warnings about invalid profile information and causes the case to
>> fail.  I will send a patch to skip checking profile information for a
>> removing basic block in stage 1 if it sounds reasonable.  For now I just
>> twisted the case itself.
>>
>> Bootstrap and tested on x86_64 and arm_a15.
>>
>> Is it OK?
>>
>>
>> 2014-02-25  Bin Cheng  <bin.cheng@arm.com>
>>
>>       PR target/60280
>>       * tree-cfgcleanup.c (tree_forwarder_block_p): Protect loop
>>       preheaders and latches only if requested.  Fix latch if it
>>       is removed.
>>       * tree-ssa-dom.c (tree_ssa_dominator_optimize): Set
>>       LOOPS_HAVE_PREHEADERS.
>>
>> gcc/testsuite/ChangeLog
>> 2014-02-25  Bin Cheng  <bin.cheng@arm.com>
>>
>>       PR target/60280
>>       * gnat.dg/renaming5.adb: Change to two expected gotos.
>>       * gcc.dg/tree-ssa/pr21559.c: Change back to three expected
>>       jump threads.
>>       * gcc.dg/tree-prof/update-loopch.c: Check two "Invalid sum"
>>       messages for removed basic block.
>>       * gcc.dg/tree-ssa/ivopt_1.c: Fix unreliable scanning string.
>>       * gcc.dg/tree-ssa/ivopt_2.c: Ditto.
>>       * gcc.dg/tree-ssa/ivopt_3.c: Ditto.
>>       * gcc.dg/tree-ssa/ivopt_4.c: Ditto.
>
> Do you need to also update gcc.dg/tree-ssa/ssa-dom-thread-4.c,
> at least for logical_op_short_circuit targets?
> (There's a nice analysis comment there by Richard S which may
> also have to be updated.)
>
> This caused a regression for logical_op_short_circuit targets, I
> entered PR60363 for convenience.
>
> brgds, H-P



-- 
Best Regards.