Re: [PATCH][Middle-end][version 3]2nd patch of PR78809 and PR83026

[Qing Zhao <qing dot zhao at oracle dot com>]

> On Jun 22, 2018, at 11:49 PM, Jeff Law <law@redhat.com> wrote:
> 
> On 05/29/2018 06:08 PM, Qing Zhao wrote:
>> Hi, Jeff,
>> 
>> Thanks a lot for your review and comments.
>> 
>> I have updated my patch based on your suggestion, and retested this whole patch on both X86 and aarch64.
>> 
>> please take a look at the patch again.
>> 
>> thanks.
>> 
>> Qing
>> 
>>> On May 25, 2018, at 3:38 PM, Jeff Law <law@redhat.com> wrote:
>>> So I originally thought you had the core logic wrong in the immediate
>>> uses loop.  But it's actually the case that the return value is the
>>> exact opposite of what I expected.
>>> 
>>> ie, I expected "TRUE" to mean the call was transformed, "FALSE" if it
>>> was not transformed.
>>> 
>>> Can you fix that so it's not so confusing?
>>> 
>>> I think with that change we'll be good to go, but please repost for a
>>> final looksie.
>>> 
>>> THanks,
>>> Jeff
>> 
>> 
>> 0001-2nd-Patch-for-PR78009.patch
>> 
>> 
>> From 750f44ee0777d55b568f07e263babdedd532d315 Mon Sep 17 00:00:00 2001
>> From: qing zhao <qing.zhao@oracle.com <mailto:qing.zhao@oracle.com>>
>> Date: Tue, 29 May 2018 16:15:21 -0400
>> Subject: [PATCH] 2nd Patch for PR78009 Patch for PR83026
>> 
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78809 <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78809>
>> Inline strcmp with small constant strings
>> 
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83026 <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83026>
>> missing strlen optimization for strcmp of unequal strings
>> 
>> The design doc for PR78809 is at:
>> https://www.mail-archive.com/gcc@gcc.gnu.org/msg83822.html <https://www.mail-archive.com/gcc@gcc.gnu.org/msg83822.html>
>> 
>> this patch is for the second part of change of PR78809 and PR83026:
>> 
>> B. for strncmp (s1, s2, n) (!)= 0 or strcmp (s1, s2) (!)= 0
>> 
>>   B.1. (PR83026) When the lengths of both arguments are constant and
>>        it's a strcmp:
>>      * if the lengths are NOT equal, we can safely fold the call
>>        to a non-zero value.
>>      * otherwise, do nothing now.
>> 
>>   B.2. (PR78809) When the length of one argument is constant, try to replace
>>   the call with a __builtin_str(n)cmp_eq call where possible, i.e:
>> 
>>   strncmp (s, STR, C) (!)= 0 in which, s is a pointer to a string, STR is a
>>   string with constant length, C is a constant.
>>     if (C <= strlen(STR) && sizeof_array(s) > C)
>>       {
>>         replace this call with
>>         __builtin_strncmp_eq (s, STR, C) (!)= 0
>>       }
>>     if (C > strlen(STR)
>>       {
>>         it can be safely treated as a call to strcmp (s, STR) (!)= 0
>>         can handled by the following strcmp.
>>       }
>> 
>>   strcmp (s, STR) (!)= 0 in which, s is a pointer to a string, STR is a
>>   string with constant length.
>>     if  (sizeof_array(s) > strlen(STR))
>>       {
>>         replace this call with
>>         __builtin_strcmp_eq (s, STR, strlen(STR)+1) (!)= 0
>>       }
>> 
>>   later when expanding the new __builtin_str(n)cmp_eq calls, first expand them
>>   as __builtin_memcmp_eq, if the expansion does not succeed, change them back
>>   to call to __builtin_str(n)cmp.
>> 
>> adding test case strcmpopt_2.c and strcmpopt_4.c into gcc.dg for part B of
>> PR78809 adding test case strcmpopt_3.c into gcc.dg for PR83026
>> 
>> bootstraped and tested on both X86 and Aarch64. no regression.
>> ---
>> gcc/builtins.c                     |  33 ++++
>> gcc/builtins.def                   |   5 +
>> gcc/gimple-fold.c                  |   5 +
>> gcc/testsuite/gcc.dg/strcmpopt_2.c |  67 ++++++++
>> gcc/testsuite/gcc.dg/strcmpopt_3.c |  31 ++++
>> gcc/testsuite/gcc.dg/strcmpopt_4.c |  16 ++
>> gcc/tree-ssa-strlen.c              | 304 ++++++++++++++++++++++++++++++++++---
>> gcc/tree-ssa-structalias.c         |   2 +
>> gcc/tree.c                         |   8 +
>> 9 files changed, 454 insertions(+), 17 deletions(-)
>> create mode 100644 gcc/testsuite/gcc.dg/strcmpopt_2.c
>> create mode 100644 gcc/testsuite/gcc.dg/strcmpopt_3.c
>> create mode 100644 gcc/testsuite/gcc.dg/strcmpopt_4.c
> Sorry for the long delay.  This needs a ChangeLog.  With the ChangeLog
> it is OK for the trunk.

Hi, Jeff,

the patch had been committed with ChangeLogs as following:

https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=261039 <https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=261039>

thanks.

Qing

> 
> Jeff