> On 16 Oct 2021, at 10:27, Andrew Pinski via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>
> On Fri, Oct 15, 2021 at 6:53 AM Andrew MacLeod via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>>
>> I've been looking at the pathological time issue ranger has with the
>> testcase from, uuuuuh.. PR 97623 I think. I've lost the details, but
>> kept the file since it was showing unpleasant behaviour.
>>
>> Most of the time is spent in callbacks from substitute_and_fold to
>> value_on_edge() dealing with PHI results and arguments. Turns out, its
>> virtually all wasted time dealing with SSA_NAMES with the
>> OCCURS_IN_ABNORMAL_PHI flag set..
>>
>> This patch tells ranger not to consider any SSA_NAMEs which occur in
>> abnormal PHIs. This reduces the memory footprint of all the caches, and
>> also has a ripple effect with the new threader code which uses the GORI
>> exports and imports tables, making it faster as well as no ssa-name with
>> the abnormal flag set will be entered into the tables.
>>
>> That alone was not quite enough, as all the sheer volume of call backs
>> still took time, so I added checks in the value_of_* class of routines
>> used by substitute_and_fold to indicate there is no constant value
>> available for any SSA_NAME with that flag set.
>>
>> On my x86_64 box, before this change, that test case looked like:
>>
>> tree VRP : 7.76 ( 4%) 0.23 ( 5%) 8.02
>> ( 4%) 537k ( 0%)
>> tree VRP threader : 7.20 ( 4%) 0.08 ( 2%) 7.28 (
>> 4%) 392k ( 0%)
>> tree Early VRP : 39.22 ( 22%) 0.07 ( 2%) 39.44 (
>> 22%) 1142k ( 0%)
>>
>> And with this patch , the results are:
>>
>> tree VRP : 7.57 ( 6%) 0.26 ( 5%) 7.85
>> ( 6%) 537k ( 0%)
>> tree VRP threader : 0.62 ( 0%) 0.02 ( 0%) 0.65
>> ( 0%) 392k ( 0%)
>> tree Early VRP : 4.00 ( 3%) 0.01 ( 0%) 4.03
>> ( 3%) 1142k ( 0%)
>>
>> Which is a significant improvement, both for EVRP and the threader..
>>
>> The patch adjusts the ranger folder, as well as the hybrid folder.
>>
>> bootstrapped on x86_64-pc-linux-gnu with no regressions and no missed
>> cases that I have been able to find.
>
> Did you test it with go enabled?
> Because others and myself are now running into a bootstrap failure
> most likely due to this patch.
> The number of SSA_NAME_OCCURS_IN_ABNORMAL_PHI in go is increased due
> to -fnon-call-exceptions being true there.
and, presumably for similar reasons, there are around 25 Ada regressions on
several platforms.
the acats output is probably not as helpful as Andrew’s ICE.
Iain
(possibly, there are some D / libphobos regressions too - but I didn’t bisect
those)
>
> Thanks,
> Andrew Pinski
> PS here is the ICE for me:
> libtool: compile:
> /home/apinski/src/upstream-gcc/gcc/objdir/./gcc/gccgo
> -B/home/apinski/src/upstream-gcc/gcc/objdir/./gcc/
> -B/home/apinski/upstream-gcc/x86_64-pc-linux-gnu/bin/
> -B/home/apinski/upstream-gcc/x86_64-pc-linux-gnu/lib/ -isystem
> /home/apinski/upstream-gcc/x86_64-pc-linux-gnu/include -isystem
> /home/apinski/upstream-gcc/x86_64-pc-linux-gnu/sys-include
> -fchecking=1 -minline-all-stringops -O2 -g -m32 -I . -c
> -fgo-pkgpath=cmd/go/internal/modget
> /home/apinski/src/upstream-gcc/gcc/libgo/go/cmd/go/internal/modget/get.go
> /home/apinski/src/upstream-gcc/gcc/libgo/go/cmd/go/internal/modget/query.go
> -o cmd/go/internal/modget.o
> during GIMPLE pass: evrp
> In function ‘cmd/go/internal/modget.resolver.resolveQueries’:
> go1: internal compiler error: tree check: expected class ‘type’, have
> ‘exceptional’ (error_mark) in useless_type_conversion_p, at
> gimple-expr.c:87
> 0x862719 tree_class_check_failed(tree_node const*, tree_code_class,
> char const*, int, char const*)
> /home/apinski/src/upstream-gcc/gcc/gcc/tree.c:8739
> 0x7910ed tree_class_check(tree_node*, tree_code_class, char const*,
> int, char const*)
> /home/apinski/src/upstream-gcc/gcc/gcc/tree.h:3556
> 0x7910ed useless_type_conversion_p(tree_node*, tree_node*)
> /home/apinski/src/upstream-gcc/gcc/gcc/gimple-expr.c:87
> 0xf81a58 verify_gimple_phi
> /home/apinski/src/upstream-gcc/gcc/gcc/tree-cfg.c:5128
> 0xf81a58 verify_gimple_in_cfg(function*, bool)
> /home/apinski/src/upstream-gcc/gcc/gcc/tree-cfg.c:5457
> 0xe54a57 execute_function_todo
> /home/apinski/src/upstream-gcc/gcc/gcc/passes.c:2042
> 0xe5546e execute_todo
> /home/apinski/src/upstream-gcc/gcc/gcc/passes.c:2096
> Please submit a full bug report,
> with preprocessed source if appropriate.
> Please include the complete backtrace with any bug report.
> See <https://gcc.gnu.org/bugs/> for instructions.
>
>
>>
>> I don't want to push it quite yet as I wanted feedback to make sure we
>> don't actually do anything I'm not aware of with SSA_NAMES which have
>> the ABNORMAL_PHI flag set. Most of the code i can find in VRP and
>> vr-values appears to punt, so I presume not even considering those names
>> is fine?
>>
>> This also seems like something that might be worth back-porting,
>> especially the hybrid pass parts...
>>
>> Andrew
