From one of the examples from http://embed.cs.utah.edu/embarrassing/dec_09/harvest/gcc-head_llvm-gcc-head/ struct _fat_ptr { unsigned char *curr; unsigned char *base; unsigned char *last_plus_one; }; int Cyc_string_ungetc (int ignore, struct _fat_ptr *sptr); int Cyc_string_ungetc (int ignore, struct _fat_ptr *sptr) { struct _fat_ptr *_T0; struct _fat_ptr *_T1; struct _fat_ptr _T2; int _T3; struct _fat_ptr _ans; int _change; { _T0 = sptr; _T1 = sptr; _T2 = *sptr; _T3 = -1; _ans = _T2; _change = -1; _ans.curr += 4294967295U; *sptr = _ans; return (0); } } Testing on GCC: (GNU) 4.5.0 20091219 With -O2 this generates only midly inefficient code (although still a bit larger than llvm's very neat 8b 44 24 08 mov 0x8(%esp),%eax 4: ff 08 decl (%eax) 6: 31 c0 xor %eax,%eax 8: c3 ret ) -O2 code: subl $32, %esp movl 40(%esp), %eax movl (%eax), %edx subl $1, %edx movl %edx, (%eax) xorl %eax, %eax addl $32, %esp ret That's a bit dumb because it allocates stack without using it and also does not use a subl $1,(eax), but explicit load-modify-store, but not overly bad (I'll open a separate bug for the load/modify/store) But with -Os the code is really bad: pushl %edi movl $3, %ecx pushl %esi subl $32, %esp movl 48(%esp), %eax leal 20(%esp), %edi movl %eax, %esi rep movsl leal 8(%esp), %edi leal 20(%esp), %esi movl (%eax), %edx movb $3, %cl rep movsl leal 8(%esp), %esi movl %eax, %edi decl %edx movb $3, %cl rep movsl movl %edx, (%eax) addl $32, %esp xorl %eax, %eax popl %esi popl %edi ret It doesn't modify the object in place, but instead copies it around. Unsurprisingly that generates that much larger (and slower code)
I think fixing this will also fix the PR 42586 on the trunk. Confirmed, a regression from 4.4. SRA is worse off on the trunk for this case than with 4.4.
Patch restoring the 4.4 behavior posted to the mailing list: http://gcc.gnu.org/ml/gcc-patches/2010-01/msg00976.html
Subject: Bug 42585 Author: jamborm Date: Thu Jan 21 16:18:06 2010 New Revision: 156156 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=156156 Log: 2010-01-21 Martin Jambor <mjambor@suse.cz> PR tree-optimization/42585 * tree-sra.c (struct access): New field grp_total_scalarization. (dump_access): Dump the new field. (should_scalarize_away_bitmap): New variable. (cannot_scalarize_away_bitmap): Likewise. (sra_initialize): Allocate new bitmaps. (sra_deinitialize): Free new bitmaps. (create_access_1): New function. (create_access): Parts moved to create_access_1. (type_consists_of_records_p): New function. (completely_scalarize_record): Likewise. (build_access_from_expr): Set bit in cannot_scalarize_away_bitmap. (build_accesses_from_assign): Set bits in should_scalarize_away_bitmap. (sort_and_splice_var_accesses): Hint groups with a total_scalarization access. (analyze_all_variable_accesses): Completely scalarize small eligible records. * testsuite/gcc.dg/tree-ssa/pr42585.c: New test. Added: trunk/gcc/testsuite/gcc.dg/tree-ssa/pr42585.c Modified: trunk/gcc/ChangeLog trunk/gcc/testsuite/ChangeLog trunk/gcc/tree-sra.c
Rev 156156 breaks the build for targets that do not explicitly define MOVE_RATIO in their backend (e.g. rs6000).
Problem here, is that the default MOVE_RATIO is in expr.h. It is really a default definition of a target macro so it should be defined in defaults.h.
*** Bug 42842 has been marked as a duplicate of this bug. ***
I understand that the bootstrap problem is PR 42836 and is now fixed (thanks for that). SRA now removes the structures in the testcase from bug description and so I consider this to be fixed.
Subject: Bug 42585 Author: hjl Date: Sun Feb 7 04:41:22 2010 New Revision: 156562 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=156562 Log: Backport testcases from mainline to 4.4. 2010-02-06 H.J. Lu <hongjiu.lu@intel.com> Backport from mainline: 2010-02-05 Dodji Seketeli <dodji@redhat.com> PR c++/42915 * g++.dg/other/crash-9.C: New test. 2010-02-03 Jason Merrill <jason@redhat.com> PR c++/40138 * g++.dg/ext/builtin11.C: New. 2010-02-03 Richard Guenther <rguenther@suse.de> PR tree-optimization/42944 * gcc.dg/errno-1.c: New testcase. 2010-02-03 Richard Guenther <rguenther@suse.de> PR middle-end/42927 * gcc.c-torture/compile/pr42927.c: New testcase. 2010-01-29 Dodji Seketeli <dodji@redhat.com> PR c++/42758 PR c++/42634 PR c++/42336 PR c++/42797 PR c++/42880 * g++.dg/other/crash-5.C: New test. * g++.dg/other/crash-7.C: New test. * g++.dg/other/crash-8.C: New test. 2010-01-28 Uros Bizjak <ubizjak@gmail.com> PR target/42891 * gcc.target/i386/pr42891.c: New test. 2010-01-28 Richard Guenther <rguenther@suse.de> PR middle-end/42883 * g++.dg/torture/pr42883.C: New testcase. 2010-01-28 Michael Matz <matz@suse.de> * gcc.target/i386/pr42881.c: New test. 2010-01-28 Dodji Seketeli <dodji@redhat.com> PR c++/42713 PR c++/42820 * g++.dg/template/typedef27.C: New test case. * g++.dg/template/typedef28.C: New test case. 2010-01-27 Jakub Jelinek <jakub@redhat.com> PR middle-end/42874 * gcc.dg/vla-22.c: New test. 2010-01-26 Richard Guenther <rguenther@suse.de> PR tree-optimization/42250 * gcc.dg/pr42250.c: New testcase. 2010-01-25 Tobias Burnus <burnus@net-b.de> PR fortran/42858 * gfortran.dg/generic_21.f90: New test. 2010-01-21 Martin Jambor <mjambor@suse.cz> PR tree-optimization/42585 * gcc.dg/tree-ssa/pr42585.c: New test. 2010-01-20 Alexandre Oliva <aoliva@redhat.com> PR debug/42715 * gcc.dg/pr42715.c: New. 2010-01-20 Richard Guenther <rguenther@suse.de> PR tree-optimization/42717 * gcc.c-torture/compile/pr42717.c: New testcase. 2010-01-19 Paul Thomas <pault@gcc.gnu.org> PR fortran/42783 * gfortran.dg/bounds_check_15.f90 : New test. 2010-01-18 Dodji Seketeli <dodji@redhat.com> PR c++/42766 * g++.dg/conversion/op6.C: New test. 2010-01-18 Richard Guenther <rguenther@suse.de> PR tree-optimization/42781 * gfortran.fortran-torture/compile/pr42781.f90: New testcase. 2010-01-17 Richard Guenther <rguenther@suse.de> PR middle-end/42248 * gcc.c-torture/execute/pr42248.c: New testcase. 2010-01-17 Janus Weil <janus@gcc.gnu.org> PR fortran/42677 * gfortran.dg/interface_assignment_5.f90: New test. 2010-01-15 Richard Guenther <rguenther@suse.de> PR middle-end/42739 * g++.dg/torture/pr42739.C: New testcase. 2010-01-14 Jerry DeLisle <jvdelisle@gcc.gnu.org> PR fortran/42684 * gfortran.dg/interface_31.f90: New test. 2010-01-14 Martin Jambor <mjambor@suse.cz> PR tree-optimization/42706 * gcc.dg/ipa/pr42706.c: New testcase. 2010-01-14 Martin Jambor <mjambor@suse.cz> PR tree-optimization/42714 * g++.dg/torture/pr42714.C: New test. 2010-01-14 Alexander Monakov <amonakov@ispras.ru> PR rtl-optimization/42388 * gcc.dg/pr42388.c: New. 2010-01-14 Alexander Monakov <amonakov@ispras.ru> PR rtl-optimization/42294 * gfortran.dg/pr42294.f: New. 2010-01-14 Ira Rosen <irar@il.ibm.com> PR tree-optimization/42709 * gcc.dg/vect/pr42709.c: New test. 2010-01-13 Richard Guenther <rguenther@suse.de> PR tree-optimization/42730 * gcc.c-torture/compile/pr42730.c: New testcase. 2010-01-13 Martin Jambor <mjambor@suse.cz> PR tree-optimization/42704 * g++.dg/torture/pr42704.C: New test. 2010-01-13 Martin Jambor <mjambor@suse.cz> PR tree-optimization/42703 * gcc.c-torture/compile/pr42703.c: New test. 2010-01-13 Richard Guenther <rguenther@suse.de> PR tree-optimization/42705 * gcc.c-torture/compile/pr42705.c: New testcase. 2010-01-13 Richard Guenther <rguenther@suse.de> PR middle-end/42716 * gcc.c-torture/compile/pr42716.c: New testcase. 2010-01-12 Joseph Myers <joseph@codesourcery.com> PR c/42708 * gcc.c-torture/compile/pr42708-1.c: New test. 2010-01-09 Alexandre Oliva <aoliva@redhat.com> PR middle-end/42363 * gcc.dg/torture/pr42363.c: New. 2010-01-09 Alexandre Oliva <aoliva@redhat.com> PR debug/42604 PR debug/42395 * gcc.dg/vect/pr42604.c: New. * gcc.dg/vect/pr42395.c: New. 2010-01-09 Richard Guenther <rguenther@suse.de> PR middle-end/42512 * gcc.c-torture/execute/pr42512.c: New testcase. Added: branches/gcc-4_4-branch/gcc/testsuite/g++.dg/conversion/op6.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/conversion/op6.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/ext/builtin11.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/ext/builtin11.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/other/crash-5.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/other/crash-5.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/other/crash-7.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/other/crash-7.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/other/crash-8.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/other/crash-8.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/other/crash-9.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/other/crash-9.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/typedef27.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/template/typedef27.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/typedef28.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/template/typedef28.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/torture/pr42704.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/torture/pr42704.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/torture/pr42714.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/torture/pr42714.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/torture/pr42739.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/torture/pr42739.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/torture/pr42883.C - copied unchanged from r156561, trunk/gcc/testsuite/g++.dg/torture/pr42883.C branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr42703.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/compile/pr42703.c branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr42705.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/compile/pr42705.c branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr42708-1.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/compile/pr42708-1.c branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr42716.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/compile/pr42716.c branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr42717.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/compile/pr42717.c branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr42730.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/compile/pr42730.c branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr42927.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/compile/pr42927.c branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/execute/pr42248.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/execute/pr42248.c branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/execute/pr42512.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.c-torture/execute/pr42512.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/errno-1.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/errno-1.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/ipa/pr42706.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/ipa/pr42706.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/pr42250.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/pr42250.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/pr42388.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/pr42388.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/pr42715.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/pr42715.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/torture/pr42363.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/torture/pr42363.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/tree-ssa/pr42585.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/tree-ssa/pr42585.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/vect/pr42395.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/vect/pr42395.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/vect/pr42604.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/vect/pr42604.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/vect/pr42709.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/vect/pr42709.c branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/vla-22.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.dg/vla-22.c branches/gcc-4_4-branch/gcc/testsuite/gcc.target/i386/pr42881.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.target/i386/pr42881.c branches/gcc-4_4-branch/gcc/testsuite/gcc.target/i386/pr42891.c - copied unchanged from r156561, trunk/gcc/testsuite/gcc.target/i386/pr42891.c branches/gcc-4_4-branch/gcc/testsuite/gfortran.dg/bounds_check_15.f90 - copied unchanged from r156561, trunk/gcc/testsuite/gfortran.dg/bounds_check_15.f90 branches/gcc-4_4-branch/gcc/testsuite/gfortran.dg/generic_21.f90 - copied unchanged from r156561, trunk/gcc/testsuite/gfortran.dg/generic_21.f90 branches/gcc-4_4-branch/gcc/testsuite/gfortran.dg/interface_31.f90 - copied unchanged from r156561, trunk/gcc/testsuite/gfortran.dg/interface_31.f90 branches/gcc-4_4-branch/gcc/testsuite/gfortran.dg/interface_assignment_5.f90 - copied unchanged from r156561, trunk/gcc/testsuite/gfortran.dg/interface_assignment_5.f90 branches/gcc-4_4-branch/gcc/testsuite/gfortran.dg/pr42294.f - copied unchanged from r156561, trunk/gcc/testsuite/gfortran.dg/pr42294.f branches/gcc-4_4-branch/gcc/testsuite/gfortran.fortran-torture/compile/pr42781.f90 - copied unchanged from r156561, trunk/gcc/testsuite/gfortran.fortran-torture/compile/pr42781.f90 Modified: branches/gcc-4_4-branch/gcc/testsuite/ChangeLog
(In reply to comment #8) > Subject: Bug 42585 > > Author: hjl > Date: Sun Feb 7 04:41:22 2010 > New Revision: 156562 > > URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=156562 > Log: > Backport testcases from mainline to 4.4. > > 2010-02-06 H.J. Lu <hongjiu.lu@intel.com> > > Backport from mainline: ... > PR tree-optimization/42585 > * gcc.dg/tree-ssa/pr42585.c: New test. This caused testsuite regressions for 4.4 on (at least) powerpc64 and arm: http://gcc.gnu.org/ml/gcc-testresults/2010-02/msg02633.html http://gcc.gnu.org/ml/gcc-testresults/2010-02/msg02441.html Note that this test case also fails on trunk for (at least) powerpc64 and arm: http://gcc.gnu.org/ml/gcc-testresults/2010-02/msg02728.html http://gcc.gnu.org/ml/gcc-testresults/2010-02/msg02695.html
(In reply to comment #9) > > This caused testsuite regressions for 4.4 on (at least) powerpc64 and arm: > http://gcc.gnu.org/ml/gcc-testresults/2010-02/msg02633.html > http://gcc.gnu.org/ml/gcc-testresults/2010-02/msg02441.html > > Note that this test case also fails on trunk for (at least) powerpc64 and arm: > http://gcc.gnu.org/ml/gcc-testresults/2010-02/msg02728.html > http://gcc.gnu.org/ml/gcc-testresults/2010-02/msg02695.html > This is a known problem tracked as PR 42855. I am aware of it and intend to do something about it but at the moment there are at least three more important issues I need to take care of.