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.
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
>
>
