[gem5-dev] Change in gem5/gem5[develop]: scons: Enable LTO and partial linking with gcc >= 8.1.
Gabe Black has submitted this change. ( https://gem5-review.googlesource.com/c/public/gem5/+/27131 ) Change subject: scons: Enable LTO and partial linking with gcc >= 8.1. .. scons: Enable LTO and partial linking with gcc >= 8.1. The bug(s) which prevented LTO and partial linking from working with gcc have been fixed in my local version (9.3), and according to one of the original bug reports: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69866 A fix was committed in gcc version 8.1. The original code left in the SConstruct describing the problem with versions greated than 6.0 also enabled an -flinker-output option and set it to "rel". That option doesn't show up in the gcc 8.4 documentation even though it was added in 6.0, but in the 9.3 documentation it describes it and says that it defaults to "rel" when the -r (partial linking) option is used. This *should* mean that LTO and partial linking can be used together with no issues after version 8.1, and at most by version 9.3. If someone finds that that isn't true, then the range of bad versions can be expanded. Change-Id: Ie0529d077a0042ef55e2af995d01430d1695c031 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27131 Tested-by: Gem5 Cloud Project GCB service account <345032938...@cloudbuild.gserviceaccount.com> Tested-by: kokoro Reviewed-by: Gabe Black Maintainer: Gabe Black --- M SConstruct 1 file changed, 6 insertions(+), 11 deletions(-) Approvals: Gabe Black: Looks good to me, approved; Looks good to me, approved kokoro: Regressions pass Gem5 Cloud Project GCB service account: Regressions pass diff --git a/SConstruct b/SConstruct index 8be1ced..215c0b6 100755 --- a/SConstruct +++ b/SConstruct @@ -401,27 +401,22 @@ main['GCC_VERSION'] = gcc_version -if compareVersions(gcc_version, '4.9') >= 0: +if compareVersions(gcc_version, '4.9') >= 0 and \ + compareVersions(gcc_version, '8.1') < 0: # Incremental linking with LTO is currently broken in gcc versions -# 4.9 and above. A version where everything works completely hasn't -# yet been identified. +# 4.9 to 8.1. # # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67548 -main['BROKEN_INCREMENTAL_LTO'] = True -if compareVersions(gcc_version, '6.0') >= 0: +# # gcc versions 6.0 and greater accept an -flinker-output flag which # selects what type of output the linker should generate. This is # necessary for incremental lto to work, but is also broken in -# current versions of gcc. It may not be necessary in future -# versions. We add it here since it might be, and as a reminder that -# it exists. It's excluded if lto is being forced. +# versions of gcc up to 8.1. # # https://gcc.gnu.org/gcc-6/changes.html # https://gcc.gnu.org/ml/gcc-patches/2015-11/msg03161.html # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69866 -if not GetOption('force_lto'): -main.Append(PSHLINKFLAGS='-flinker-output=rel') -main.Append(PLINKFLAGS='-flinker-output=rel') +main['BROKEN_INCREMENTAL_LTO'] = True disable_lto = GetOption('no_lto') if not disable_lto and main.get('BROKEN_INCREMENTAL_LTO', False) and \ -- To view, visit https://gem5-review.googlesource.com/c/public/gem5/+/27131 To unsubscribe, or for help writing mail filters, visit https://gem5-review.googlesource.com/settings Gerrit-Project: public/gem5 Gerrit-Branch: develop Gerrit-Change-Id: Ie0529d077a0042ef55e2af995d01430d1695c031 Gerrit-Change-Number: 27131 Gerrit-PatchSet: 5 Gerrit-Owner: Gabe Black Gerrit-Reviewer: Bobby R. Bruce Gerrit-Reviewer: Gabe Black Gerrit-Reviewer: Gabe Black Gerrit-Reviewer: Gem5 Cloud Project GCB service account <345032938...@cloudbuild.gserviceaccount.com> Gerrit-Reviewer: Jason Lowe-Power Gerrit-Reviewer: kokoro Gerrit-CC: Earl Ou Gerrit-CC: Jui-min Lee Gerrit-CC: Yu-hsin Wang Gerrit-MessageType: merged ___ gem5-dev mailing list gem5-dev@gem5.org http://m5sim.org/mailman/listinfo/gem5-dev
[gem5-dev] Change in gem5/gem5[develop]: scons: Enable LTO and partial linking with gcc >= 8.1.
Hello Gabe Black, I'd like you to do a code review. Please visit https://gem5-review.googlesource.com/c/public/gem5/+/27131 to review the following change. Change subject: scons: Enable LTO and partial linking with gcc >= 8.1. .. scons: Enable LTO and partial linking with gcc >= 8.1. The bug(s) which prevented LTO and partial linking from working with gcc have been fixed in my local version (9.3), and according to one of the original bug reports: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69866 A fix was committed in gcc version 8.1. The original code left in the SConstruct describing the problem with versions greated than 6.0 also enabled an -flinker-output option and set it to "rel". That option doesn't show up in the gcc 8.4 documentation even though it was added in 6.0, but in the 9.3 documentation it describes it and says that it defaults to "rel" when the -r (partial linking) option is used. This *should* mean that LTO and partial linking can be used together with no issues after version 8.1, and at most by version 9.3. If someone finds that that isn't true, then the range of bad versions can be expanded. Change-Id: Ie0529d077a0042ef55e2af995d01430d1695c031 --- M SConstruct 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/SConstruct b/SConstruct index 0f36eac..c8d1428 100755 --- a/SConstruct +++ b/SConstruct @@ -169,7 +169,7 @@ AddLocalOption('--with-systemc-tests', dest='with_systemc_tests', action='store_true', help='Build systemc tests') -from gem5_scons import Transform, error, warning +from gem5_scons import Transform, error, warning, summarize_warnings if GetOption('no_lto') and GetOption('force_lto'): error('--no-lto and --force-lto are mutually exclusive') @@ -401,27 +401,22 @@ main['GCC_VERSION'] = gcc_version -if compareVersions(gcc_version, '4.9') >= 0: +if compareVersions(gcc_version, '4.9') >= 0 and \ + compareVersions(gcc_version, '8.1') < 0: # Incremental linking with LTO is currently broken in gcc versions -# 4.9 and above. A version where everything works completely hasn't -# yet been identified. +# 4.9 to 8.1. # # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67548 -main['BROKEN_INCREMENTAL_LTO'] = True -if compareVersions(gcc_version, '6.0') >= 0: +# # gcc versions 6.0 and greater accept an -flinker-output flag which # selects what type of output the linker should generate. This is # necessary for incremental lto to work, but is also broken in -# current versions of gcc. It may not be necessary in future -# versions. We add it here since it might be, and as a reminder that -# it exists. It's excluded if lto is being forced. +# versions of gcc up to 8.1. # # https://gcc.gnu.org/gcc-6/changes.html # https://gcc.gnu.org/ml/gcc-patches/2015-11/msg03161.html # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69866 -if not GetOption('force_lto'): -main.Append(PSHLINKFLAGS='-flinker-output=rel') -main.Append(PLINKFLAGS='-flinker-output=rel') +main['BROKEN_INCREMENTAL_LTO'] = True disable_lto = GetOption('no_lto') if not disable_lto and main.get('BROKEN_INCREMENTAL_LTO', False) and \ @@ -430,7 +425,7 @@ 'at the same time, so lto is being disabled. To force lto on ' 'anyway, use the --force-lto option. That will disable ' 'partial linking.') -disable_lto = True +#disable_lto = True # Add the appropriate Link-Time Optimization (LTO) flags # unless LTO is explicitly turned off. Note that these flags -- To view, visit https://gem5-review.googlesource.com/c/public/gem5/+/27131 To unsubscribe, or for help writing mail filters, visit https://gem5-review.googlesource.com/settings Gerrit-Project: public/gem5 Gerrit-Branch: develop Gerrit-Change-Id: Ie0529d077a0042ef55e2af995d01430d1695c031 Gerrit-Change-Number: 27131 Gerrit-PatchSet: 1 Gerrit-Owner: Gabe Black Gerrit-Reviewer: Gabe Black Gerrit-MessageType: newchange ___ gem5-dev mailing list gem5-dev@gem5.org http://m5sim.org/mailman/listinfo/gem5-dev