[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #16 from patchapp at dberlin dot org 2006-09-05 01:09 --- Subject: Bug number PR 26069 A patch for this bug has been added to the patch tracker. The mailing list url for the patch is http://gcc.gnu.org/ml/gcc-patches/2006-09/msg00117.html -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #10 from pinskia at gcc dot gnu dot org 2006-08-26 06:41 --- (In reply to comment #8) Richard, Roger's patch for VIEW_CONVERT_EXPR folding hit mainline now. And VCE is documented as being undefined for types of different sizes. maybe we can produce VIEW_CONVERT_EXPRchar[sizeof(type)], expr[0] but I don't know if that solves the issue in the bug report. I am going to look into producing the VCE as above for types which have the same aliasing set or 0 and are either the same size or the outer one is a factor of the larger one. -- pinskia at gcc dot gnu dot org changed: What|Removed |Added AssignedTo|unassigned at gcc dot gnu |pinskia at gcc dot gnu dot |dot org |org Status|NEW |ASSIGNED http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #11 from pinskia at gcc dot gnu dot org 2006-08-26 14:40
---
A related testcase is:
int f(short a)
{
unsigned short b = *(unsigned short*)a;
return b;
}
Which should be optimized into --
int f1(short a)
{
unsigned short b = a;
return b;
}
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #12 from pinskia at gcc dot gnu dot org 2006-08-26 16:41 --- A fix for this runs into another bug which I am about to file. -- pinskia at gcc dot gnu dot org changed: What|Removed |Added AssignedTo|pinskia at gcc dot gnu dot |unassigned at gcc dot gnu |org |dot org Status|ASSIGNED|NEW http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #13 from pinskia at gcc dot gnu dot org 2006-08-26 16:51 --- (In reply to comment #12) A fix for this runs into another bug which I am about to file. I did not file it but did send an email about the problem: http://gcc.gnu.org/ml/gcc/2006-08/msg00510.html -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #14 from pinskia at gcc dot gnu dot org 2006-08-26 23:04 --- And I found a fix for that so trying to work on the orginal testcase again. -- pinskia at gcc dot gnu dot org changed: What|Removed |Added AssignedTo|unassigned at gcc dot gnu |pinskia at gcc dot gnu dot |dot org |org Status|NEW |ASSIGNED http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #15 from pinskia at gcc dot gnu dot org 2006-08-26 23:20 --- (In reply to comment #14) And I found a fix for that so trying to work on the orginal testcase again. Actually I am going to submit a patch for the problem in comment #11 and then I will fix the rest of the bug report. The memcpy issue should be filed seperately as it is harder to fix than the orginal issue. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #9 from mmitchel at gcc dot gnu dot org 2006-05-25 02:33 --- Will not be fixed in 4.1.1; adjust target milestone to 4.1.2. -- mmitchel at gcc dot gnu dot org changed: What|Removed |Added Target Milestone|4.1.1 |4.1.2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #8 from bonzini at gnu dot org 2006-04-18 16:22 --- Richard, Roger's patch for VIEW_CONVERT_EXPR folding hit mainline now. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #7 from mmitchel at gcc dot gnu dot org 2006-02-24 00:26 --- This issue will not be resolved in GCC 4.1.0; retargeted at GCC 4.1.1. -- mmitchel at gcc dot gnu dot org changed: What|Removed |Added Target Milestone|4.0.3 |4.1.1 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
-- mmitchel at gcc dot gnu dot org changed: What|Removed |Added Priority|P3 |P2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #5 from rguenth at gcc dot gnu dot org 2006-02-06 10:34 --- *** Bug 26116 has been marked as a duplicate of this bug. *** -- rguenth at gcc dot gnu dot org changed: What|Removed |Added CC||gianni at mariani dot ws http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #6 from gianni at mariani dot ws 2006-02-06 16:52 --- Just another data point. I tried both the original tell_endian() and the tell_endian_good() functions on the MS Visual Studio 2003 compiler and both generated: ?tell_endian@@YADXZ: 0: b0 01 mov$0x1,%al 2: c3 ret -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #4 from rguenth at gcc dot gnu dot org 2006-02-03 11:55 --- While propagating easily works, we don't fold VIEW_CONVERT_EXPR at all. I remember a patch of Roger which did folding of vector constants or so, but can't find it anymore. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #3 from rguenth at gcc dot gnu dot org 2006-02-02 14:56 --- One may be able to teach forwprop about this optimization, i.e. turn x = 1; x.0_3 = (char *) x; D.1522_4 = *x.0_3; into D.1522_4 = VIEW_CONVERT_EXPR char (x); if that has the right semantics. CCP fold may then be able to optimize it. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
[Bug rtl-optimization/26069] [4.0/4.1/4.2 Regression] Runtime endian-ness check is no longer optimized out.
--- Comment #2 from pinskia at gcc dot gnu dot org 2006-02-02 05:19 ---
If you used GCC's extension of using an union as not violating aliasing rules,
it works there but does not with using the portable ways:
bool tell_endian() {
unsigned x = 1;
return *(char*)x;
}
bool tell_endian1()
{
char a;
int x = 1;
__builtin_memcpy(a, x, 1);
return a;
}
bool tell_endian_good()
{
union{int i;char c;}a;
a.i = 1;
return a.c;
}
-
Only tell_endian_good produces good result.
This looks like the removal of addressof RTL caused this.
--
pinskia at gcc dot gnu dot org changed:
What|Removed |Added
Severity|major |normal
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
GCC host triplet|linux-x86-elf |
GCC target triplet|linux-x86-elf |
Keywords||missed-optimization
Last reconfirmed|-00-00 00:00:00 |2006-02-02 05:19:37
date||
Summary|Runtime endian-ness check is|[4.0/4.1/4.2 Regression]
|no longer optimized out.|Runtime endian-ness check is
||no longer optimized out.
Target Milestone|--- |4.0.3
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069
