GCC 7.5 Release Candidate available from gcc.gnu.org

[Bill Schmidt]

On 11/11/19 7:26 AM, Richard Biener wrote:
> On Fri, 8 Nov 2019, Bill Schmidt wrote:
>
>> On 11/7/19 5:48 AM, Matthias Klose wrote:
>>> On 05.11.19 13:45, Richard Biener wrote:
>>>> The first release candidate for GCC 7.5 is available from
>>>>
>>>>  Â  https://gcc.gnu.org/pub/gcc/snapshots/7.5.0-RC-20191105/
>>>>
>>>> and shortly its mirrors.  It has been generated from SVN revision 277823.
>>>>
>>>> I have so far bootstrapped and tested the release candidate on
>>>> {x86_64,i586,ppc64le,s390x,aarch64}-linux.  Please test it
>>>> and report any issues to bugzilla.
>>>>
>>>> If all goes well, I'd like to release 7.5 on Thursday, November 14th.
>>> With a distribution build (Ubuntu) on amd64, i386, armhf, arm64, ppc64el and
>>> s390x, I don't see any regressions in the GCC testsuite (compared to 7.4.0),
>>> except for two issues on ppc64el:
>>>
>>> FAIL: gcc.target/powerpc/pr87532.c (test for excess errors)
>>> Excess errors:
>>> /build/gcc-7-8odB_r/gcc-7-7.4.0/src/gcc/testsuite/gcc.target/powerpc/pr87532.c:45:27:
>>> warning: format '%d' expects argument of type 'int', but argument 2 has type
>>> 'size_t {aka long unsigned int}' [-Wformat=]
>>>
>>> is a new test, and only caused by default hardening settings.
>>>
>>> PASS: gcc.dg/vect/slp-perm-4.c execution test
>>> FAIL: gcc.dg/vect/slp-perm-4.c scan-tree-dump-times vect "vectorized 1
>>> loops" 1
>>> PASS: gcc.dg/vect/slp-perm-4.c scan-tree-dump-times vect "gaps requires
>>> scalar epilogue loop" 0
>>> FAIL: gcc.dg/vect/slp-perm-4.c scan-tree-dump-times vect "vectorizing
>>> stmts using SLP" 1
>>
>> I finally bisected this to r275208:
>>
>>
>> 2019-08-30  Richard Biener  <rguenther@suse.de  <mailto:rguenther%40suse.de>>
>>
>> 	Backport from mainline
>> 	2019-05-27  Richard Biener  <rguenther@suse.de
>> 	<mailto:rguenther%40suse.de>>
>>
>> 	PR tree-optimization/90637
>> 	* tree-ssa-sink.c (statement_sink_location): Honor the
>> 	computed sink location for single-uses.
>>
>> 	* gcc.dg/gomp/pr90637.c: New testcase.
>>
>> 	2019-06-21  Richard Biener  <rguenther@suse.de
>> <mailto:rguenther%40suse.de>>
>>
>> 	PR tree-optimization/90930
>> 	* tree-ssa-reassoc.c (rewrite_expr_tree_parallel): Set visited
>> 	flag on new stmts to avoid re-processing them.
>>
>> 	2019-05-15  Richard Biener  <rguenther@suse.de
>> <mailto:rguenther%40suse.de>>
>>
>> 	PR c/90474
>> 	* c-common.c (c_common_mark_addressable_vec): Also mark
>> 	a COMPOUND_LITERAL_EXPR_DECL addressable similar to
>> 	c_mark_addressable.
>>
>> 	2019-04-25  Richard Biener  <rguenther@suse.de
>> <mailto:rguenther%40suse.de>>
>>
>> 	PR middle-end/90194
>> 	* match.pd: Add pattern to simplify view-conversion of an
>> 	empty constructor.
>>
>> 	* g++.dg/torture/pr90194.C: New testcase.
>>
>> 	2019-04-24  Richard Biener  <rguenther@suse.de
>> <mailto:rguenther%40suse.de>>
>>
>> 	PR middle-end/90213
>> 	* gimple-fold.c (fold_const_aggregate_ref_1): Do multiplication
>> 	by size and BITS_PER_UNIT on poly-wide-ints.
>>
>> 	2019-04-15  Richard Biener  <rguenther@suse.de
>> <mailto:rguenther%40suse.de>>
>>
>> 	PR tree-optimization/90071
>> 	* tree-ssa-reassoc.c (init_range_entry): Do not pick up
>> 	abnormal operands from def stmts.
>>
>> 	* gcc.dg/torture/pr90071.c: New testcase.
>>
>> 	2019-03-13  Richard Biener  <rguenther@suse.de
>> <mailto:rguenther%40suse.de>>
>>
>> 	PR middle-end/89677
>> 	* tree-scalar-evolution.c (simplify_peeled_chrec): Do not
>> 	throw FP expressions at tree-affine.
>>
>> 	* gcc.dg/torture/pr89677.c: New testcase.
>>
>>
>> This looks rather familiar, actually.  I seem to recall an SLP degradation
>> from a change to tree-ssa-sink.c on trunk this release.  Richi, could there be
>> a missing backport here?
> Not sure - it's reassoc that messes up things here and a
> --param tree-reassoc-width=1 "fixes" the failure.  For PR90930 I
> restricted this to the last pass instance (but only on trunk).
> Does it also fail on the GCC 8 and 9 branches?  Ah, on GCC 8 at least
> the default target setting for this seems to be 1 (it's non-FP,
> maybe you changed that), with explicit --param tree-reassoc-width={2,3,4}
> it also fails the same way.


OK; yes, I think one of our team did some refining of the reassoc 
parameters in that timeframe, so this makes sense.

>
> It's a bit late to try thinking about backporting this change
> but I'll now consider it for GCC 9 at least.
>
> So IMHO a latent issue, somehow the rev. triggered "inconsistent"
> reassoc for the testcase.  I'm going to leave it as-is for GCC 7.5
> (with the testsuite regression).
>
> Are you fine with that?  An explicit --param tree-reassoc-width=1
> on the testcase also would work for me if you prefer that.


I am fine with leaving the testcase regressed; we have a good 
explanation and this isn't a serious issue for users.  Thanks for 
investigating!

Bill

>
> Thanks,
> Richard.