MantisBT - CMake
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IDProjectCategoryView StatusDate SubmittedLast Update
0015570CMake(No Category)public2015-05-14 14:222016-06-10 14:31
ReporterStephen Kelly 
Assigned ToKitware Robot 
PrioritynormalSeverityminorReproducibilityhave not tried
StatusclosedResolutionmoved 
PlatformOSOS Version
Product Version 
Target VersionFixed in Version 
Summary0015570: Review POSITION_INDEPENDENT_CODE use of -fPIE
Description
cmLocalGenerator::AddPositionIndependentFlags uses -fPIE for executables and -fPIC for libraries. This caused issues in Qt:

 https://bugreports.qt.io/browse/QTBUG-45755 [^]
 
 https://codereview.qt-project.org/#/c/112060/ [^]
 
 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65886 [^]

Someone who understands the terms-of-art used in the discussion should review what cmake is doing here.
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Issue History
Date ModifiedUsernameFieldChange
2015-05-14 14:22Stephen KellyNew Issue
2015-05-25 10:38Stephen KellyNote Added: 0038797
2015-05-25 12:49Stephen KellyNote Edited: 0038797bug_revision_view_page.php?bugnote_id=38797#r1788
2016-06-10 14:29Kitware RobotNote Added: 0042778
2016-06-10 14:29Kitware RobotStatusnew => resolved
2016-06-10 14:29Kitware RobotResolutionopen => moved
2016-06-10 14:29Kitware RobotAssigned To => Kitware Robot
2016-06-10 14:31Kitware RobotStatusresolved => closed

Notes
(0038797)
Stephen Kelly   
2015-05-25 10:38   
(edited on: 2015-05-25 12:49)
There is an option for building GCC in the works in the hjl/pie/master branch which makes GCC use -fPIE by default for executables:
 
 https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=64364101d6c888e20eb1146ee2baac4b08e684cf [^]


  Add --enable-default-pie option to GCC configure

  Add --enable-default-pie option to configure GCC to generate PIE by
  default.

  gcc/

  2015-05-19 Magnus Granberg <zorry@gentoo.org>
      H.J. Lu <hongjiu.lu@intel.com>

  * Makefile.in (COMPILER): Add @NO_PIE_CFLAGS@.
  (BUILD_CFLAGS): Likewise.
  (BUILD_CXXFLAGS): Likewise.
  (LINKER): Add @NO_PIE_FLAG@.
  (BUILD_LDFLAGS): Likewise.
  (libgcc.mvars): Set NO_PIE_CFLAGS to -fno-PIE for
  --enable-default-pie.
  * common.opt (fPIE): Initialize to -1.
  (fpie): Likewise.
  (no-pie): New option.
  (pie): Replace "Negative(shared)" with "Negative(no-pie)".
  * configure.ac: Add --enable-default-pie.
  (NO_PIE_CFLAGS): New. Check if -fno-PIE works. AC_SUBST.
  (NO_PIE_FLAG): New. Check if -no-pie works. AC_SUBST.
  * defaults.h (DEFAULT_FLAG_PIE): New. Default PIE to -fPIE.
  * gcc.c (NO_PIE_SPEC): New.
  (PIE_SPEC): Likewise.
  (NO_FPIE1_SPEC): Likewise.
  (FPIE1_SPEC): Likewise.
  (NO_FPIE2_SPEC): Likewise.
  (FPIE2_SPEC): Likewise.
  (NO_FPIE2_SPEC): Likewise.
  (FPIE_SPEC): Likewise.
  (NO_FPIE_SPEC): Likewise.
  (NO_FPIC1_SPEC): Likewise.
  (FPIC1_SPEC): Likewise.
  (NO_FPIC2_SPEC): Likewise.
  (FPIC2_SPEC): Likewise.
  (NO_FPIC2_SPEC): Likewise.
  (FPIC_SPEC): Likewise.
  (NO_FPIC_SPEC): Likewise.
  (NO_FPIE1_AND_FPIC1_SPEC): Likewise.
  (FPIE1_OR_FPIC1_SPEC): Likewise.
  (NO_FPIE2_AND_FPIC2_SPEC): Likewise.
  (FPIE2_OR_FPIC2_SPEC): Likewise.
  (NO_FPIE_AND_FPIC_SPEC): Likewise.
  (FPIE_OR_FPIC_SPEC): Likewise.
  (LD_PIE_SPEC): Likewise.
  (LINK_PIE_SPEC): Handle -no-pie. Use PIE_SPEC and LD_PIE_SPEC.
  * opts.c (finish_options): Update opts->x_flag_pie if it is -1.
  * config/darwin.h (PIE_SPEC): Renamed to ...
  (DARWIN_PIE_SPEC): This.
  (LINK_SPEC): Replace PIE_SPEC with DARWIN_PIE_SPEC.
  * config/darwin9.h (PIE_SPEC): Renamed to ...
  (DARWIN_PIE_SPEC): This.
  * config/gnu-user.h (GNU_USER_TARGET_STARTFILE_SPEC): Use
  PIE_SPEC and NO_PIE_SPEC if HAVE_LD_PIE is defined.
  * config/openbsd.h (ASM_SPEC): Use FPIE1_OR_FPIC1_SPEC and
  FPIE2_OR_FPIC2_SPEC.
  * config/m68k/netbsd-elf.h (ASM_SPEC): Likewise.
  * config/m68k/openbsd.h (ASM_SPEC): Likewise.
  * gcc/config/sol2.h (ASM_PIC_SPEC): Likewise.
  * config/arm/freebsd.h (SUBTARGET_EXTRA_ASM_SPEC): Likewise.
  * config/arm/netbsd-elf.h (SUBTARGET_EXTRA_ASM_SPEC): Likewise.
  * config/arm/semi.h (SUBTARGET_EXTRA_ASM_SPEC): Likewise.
  * config/cris/linux.h (CRIS_ASM_SUBTARGET_SPEC): Likewise.
  * config/m32r/m32r.h (ASM_SPEC): Likewise.
  * config/m68k/uclinux.h (DRIVER_SELF_SPECS): Likewise.
  * config/rs6000/linux64.h (ASM_SPEC32): Likewise.
  * config/rs6000/sysv4.h (ASM_SPEC): Likewise.
  * config/sparc/freebsd.h (ASM_SPEC): Likewise.
  * config/sparc/linux.h (ASM_SPEC): Likewise.
  * config/sparc/linux64.h (ASM_SPEC): Likewise.
  * config/sparc/netbsd-elf.h (ASM_SPEC): Likewise.
  * config/sparc/openbsd64.h (ASM_SPEC): Likewise.
  * config/sparc/sp-elf.h (ASM_SPEC): Likewise.
  * config/sparc/sp64-elf.h (ASM_SPEC): Likewise.
  * config/sparc/sparc.h (ASM_SPEC): Likewise.
  * config/sparc/sysv4.h (ASM_SPEC): Likewise.
  * config/sparc/vxworks.h (ASM_SPEC): Likewise.
  * config/c6x/elf-common.h (ASM_SPEC): Use NO_FPIC2_SPEC,
  FPIC2_SPEC, FPIC1_SPEC and FPIC2_SPEC.
  * config/c6x/uclinux-elf.h (LINK_SPEC): Use FPIE_SPEC.
  * config/frv/frv.h (DRIVER_SELF_SPECS): Use FPIC_SPEC,
  NO_FPIC_SPEC and NO_FPIE1_AND_FPIC1_SPEC.
  (ASM_SPEC): Use FPIE1_OR_FPIC1_SPEC and FPIE2_OR_FPIC2_SPEC.
  * config/m68k/m68k.h (ASM_PCREL_SPEC): Use FPIC_SPEC and
  NO_FPIC_SPEC.
  * config/mips/gnu-user.h (NO_SHARED_SPECS): Use
  NO_FPIE_AND_FPIC_SPEC.
  * config/mips/vxworks.h (SUBTARGET_ASM_SPEC): Use FPIC_SPEC.
  * config/rs6000/freebsd64.h (ASM_SPEC32): Likewise.
  * config/rs6000/vxworks.h (ASM_SPEC): Likewise.
  * config/vax/linux.h (ASM_SPEC): Likewise.
  * doc/install.texi: Document --enable-default-pie.
  * doc/invoke.texi: Document -no-pie.
  * config.in: Regenerated.
  * configure: Likewise.

  gcc/ada/

  2015-05-19 H.J. Lu <hongjiu.lu@intel.com>

  * gcc-interface/Makefile.in (TOOLS_LIBS): Add @NO_PIE_FLAG@.

  libgcc/

  2015-05-19 H.J. Lu <hongjiu.lu@intel.com>

  * Makefile.in (CRTSTUFF_CFLAGS): Add $(NO_PIE_CFLAGS).



Given that, and given the response in the above linked bug report, there seems to be disagreement between Qt and GCC on whether Qt is doing the right thing.

I don't think CMake should change POSITION_INDEPENDENT_CODE behavior with executables to use -fPIC instead of -fPIE.

The Qt patch at

 https://codereview.qt-project.org/#/c/113025/ [^]

would make Qt not use the CMake POSITION_INDEPENDENT_CODE feature, as it appears to be currently at odds with what Qt wants.
(0042778)
Kitware Robot   
2016-06-10 14:29   
Resolving issue as `moved`.

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