[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216 --- Comment #12 from Bernd Schmidt --- It looks like a patch was committed - can this be closed?
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216 Jakub Jelinek changed: What|Removed |Added Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #13 from Jakub Jelinek --- .
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216 --- Comment #14 from Marc Glisse --- (In reply to Bernd Schmidt from comment #12) > It looks like a patch was committed - can this be closed? There is still PR62263, so not all cases are handled, but if all those mentioned in this PR are fixed, then it is enough to keep the other one open.
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216 --- Comment #11 from Jakub Jelinek jakub at gcc dot gnu.org --- Author: jakub Date: Mon May 13 11:04:26 2013 New Revision: 198823 URL: http://gcc.gnu.org/viewcvs?rev=198823root=gccview=rev Log: PR tree-optimization/45216 PR tree-optimization/57157 * tree-ssa-forwprop.c (simplify_rotate): Only recognize the (-Y) (B - 1) variant if OP is |. * expmed.c (expand_shift_1): For rotations by const0_rtx just return shifted. Use (-op1) (prec - 1) as other_amount instead of prec - op1. * c-c++-common/rotate-1.c: Add 32 tests with +. * c-c++-common/rotate-1a.c: Adjust. * c-c++-common/rotate-2.c: Add 32 tests with +, expect only 48 rotates. * c-c++-common/rotate-2b.c: New test. * c-c++-common/rotate-3.c: Add 32 tests with +. * c-c++-common/rotate-4.c: Add 32 tests with +, expect only 48 rotates. * c-c++-common/rotate-4b.c: New test. * c-c++-common/rotate-5.c: New test. Added: trunk/gcc/testsuite/c-c++-common/rotate-5.c Modified: trunk/gcc/ChangeLog trunk/gcc/expmed.c trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/c-c++-common/rotate-1.c trunk/gcc/testsuite/c-c++-common/rotate-1a.c trunk/gcc/testsuite/c-c++-common/rotate-2.c trunk/gcc/testsuite/c-c++-common/rotate-3.c trunk/gcc/testsuite/c-c++-common/rotate-4.c trunk/gcc/tree-ssa-forwprop.c
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216 Bug 45216 depends on bug 57157, which changed state. Bug 57157 Summary: Poor optimization of portable rotate idiom http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57157 What|Removed |Added Status|NEW |RESOLVED Resolution|--- |FIXED
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216 Steven Bosscher steven at gcc dot gnu.org changed: What|Removed |Added Depends on||57157 --- Comment #9 from Steven Bosscher steven at gcc dot gnu.org --- The patches for bug 57157 may fix this bug also.
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216 Jakub Jelinek jakub at gcc dot gnu.org changed: What|Removed |Added CC||jakub at gcc dot gnu.org --- Comment #10 from Jakub Jelinek jakub at gcc dot gnu.org --- They certainly mean to.
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216
--- Comment #8 from Marc Glisse glisse at gcc dot gnu.org 2012-12-01 08:51:12
UTC ---
(In reply to comment #7)
unsigned long rotate_left(unsigned long a, unsigned int shift)
{
return a shift | a (sizeof(a) * 8 - shift);
}
We have a regression in C++ in 4.8 there. Comparing -O3 -fdump-tree-optimized
in gcc-4.7, g++-4.7 and gcc-4.8:
D.1708_3 = a_1(D) r shift_2(D);
and in g++-4.8:
shift.0_2 = (int) shift_1(D);
_4 = a_3(D) shift.0_2;
_5 = 64 - shift_1(D);
_6 = (int) _5;
_7 = a_3(D) _6;
_8 = _7 | _4;
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216
Nick Kossifidis mickflemm at gmail dot com changed:
What|Removed |Added
CC||mickflemm at gmail dot com
--- Comment #7 from Nick Kossifidis mickflemm at gmail dot com 2012-12-01
01:37:35 UTC ---
In my case it does detect an even more complex scenario but it doesn't detect
it when using integer typedefs from sys/types.h, more specifically:
unsigned long rotate_left(unsigned long a, unsigned int shift)
{
return a shift | a (sizeof(a) * 8 - shift);
}
results
080483d4 rotate_left:
80483d4:55 push %ebp
80483d5:89 e5mov%esp,%ebp
80483d7:53 push %ebx
80483d8:8b 45 0c mov0xc(%ebp),%eax
80483db:8b 55 08 mov0x8(%ebp),%edx
80483de:89 d3mov%edx,%ebx
80483e0:89 c1mov%eax,%ecx
80483e2:d3 c3rol%cl,%ebx
80483e4:89 d8mov%ebx,%eax
80483e6:5b pop%ebx
80483e7:5d pop%ebp
80483e8:c3 ret
but
u_int64_t rotate_left(u_int64_t a, u_int32_t shift)
{
return a shift | a (sizeof(a) * 8 - shift);
}
results
080483d4 rotate_left:
80483d4:55 push %ebp
80483d5:89 e5mov%esp,%ebp
80483d7:56 push %esi
80483d8:53 push %ebx
80483d9:83 ec 10 sub$0x10,%esp
80483dc:8b 45 08 mov0x8(%ebp),%eax
80483df:89 45 f0 mov%eax,-0x10(%ebp)
80483e2:8b 45 0c mov0xc(%ebp),%eax
80483e5:89 45 f4 mov%eax,-0xc(%ebp)
80483e8:8b 45 f0 mov-0x10(%ebp),%eax
80483eb:8b 55 f4 mov-0xc(%ebp),%edx
80483ee:8b 4d 10 mov0x10(%ebp),%ecx
80483f1:89 c3mov%eax,%ebx
80483f3:89 d6mov%edx,%esi
80483f5:0f a5 de shld %cl,%ebx,%esi
80483f8:d3 e3shl%cl,%ebx
80483fa:f6 c1 20 test $0x20,%cl
80483fd:74 04je 8048403 ed_rotate_left+0x2f
80483ff:89 demov%ebx,%esi
8048401:31 dbxor%ebx,%ebx
8048403:b9 40 00 00 00 mov$0x40,%ecx
8048408:2b 4d 10 sub0x10(%ebp),%ecx
804840b:0f ad d0 shrd %cl,%edx,%eax
804840e:d3 eashr%cl,%edx
8048410:f6 c1 20 test $0x20,%cl
8048413:74 04je 8048419 ed_rotate_left+0x45
8048415:89 d0mov%edx,%eax
8048417:31 d2xor%edx,%edx
8048419:89 c1mov%eax,%ecx
804841b:09 d9or %ebx,%ecx
804841d:89 4d e8 mov%ecx,-0x18(%ebp)
8048420:89 d1mov%edx,%ecx
8048422:09 f1or %esi,%ecx
8048424:89 4d ec mov%ecx,-0x14(%ebp)
8048427:8b 45 e8 mov-0x18(%ebp),%eax
804842a:8b 55 ec mov-0x14(%ebp),%edx
804842d:83 c4 10 add$0x10,%esp
8048430:5b pop%ebx
8048431:5e pop%esi
8048432:5d pop%ebp
8048433:c3 ret
Here are the typedefs from sys/types.h:
typedef unsigned int u_int32_t __attribute__ ((__mode__ (__SI__)));
typedef unsigned int u_int64_t __attribute__ ((__mode__ (__DI__)));
I also tried with u_int32_t/u_int16_t and other combinations but I get the same
results.
gcc version 4.5.4 (Gentoo 4.5.4 p1.0, pie-0.4.7)
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216 Kai Henningsen kai.extern at gmail dot com changed: What|Removed |Added CC||kai.extern at gmail dot com --- Comment #6 from Kai Henningsen kai.extern at gmail dot com 2010-10-03 08:33:20 UTC --- (In reply to comment #5) Created attachment 21946 [details] Another testcase Here is another test case. Here on this x86_64-unknown-linux-gnu system, gcc recognizes the rotate for 32 and 64 bits, and fails for 16 and 8 bits. Constants or not doesn't seem to make a difference. I should ad that I tested with gcc-4.4.real (Ubuntu 4.4.3-4ubuntu5) 4.4.3.
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
--- Comment #1 from bernds at gcc dot gnu dot org 2010-08-06 22:19 --- Created an attachment (id=21428) -- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21428action=view) A testcase which shows the problem. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
--- Comment #2 from steven at gcc dot gnu dot org 2010-08-06 23:02 --- pathetic... :) -- steven at gcc dot gnu dot org changed: What|Removed |Added Status|UNCONFIRMED |NEW Ever Confirmed|0 |1 Keywords||missed-optimization Last reconfirmed|-00-00 00:00:00 |2010-08-06 23:02:11 date|| http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
--- Comment #3 from steven at gcc dot gnu dot org 2010-08-06 23:17 --- Related to PR17886, where it says that: gcc can detect the (x y)|(x (bitwidth-y)) idiom for rotate and convert it into the machine rotate instruction. But it only works when y is a constant and is not long long. But apparently even this case is not detected anymore. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216
[Bug tree-optimization/45216] Rotate expressions not recognized at tree level
--- Comment #4 from rguenth at gcc dot gnu dot org 2010-08-06 23:41 --- Fold used to detect these. Maybe we're now having different conversions inbetween. -- rguenth at gcc dot gnu dot org changed: What|Removed |Added CC|richard dot guenther at |rguenth at gcc dot gnu dot |gmail dot com |org Severity|normal |enhancement http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45216
