Bobby R. Bruce has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/29272 )
Change subject: scons: Revert LTO and partial linking for gcc >=8.1
..
scons: Revert LTO and partial linking for gcc >=8.1
This reverts commit f41abbdb5cf5c67233f3d730885d43517969afda,
"scons: Enable LTO and partial linking with gcc >= 8.1."
LTO and partial linking does not work on GCC 9.3 on Ubuntu 20.04 when
compiling gem5.fast. This error was exposed via the following command:
```
docker run -u $UID:$GID --volume $(pwd):/gem5 -w /gem5 --rm \
gcr.io/gem5-test/ubuntu-20.04_all-dependencies:latest scons \
build/MIPS/gem5.fast
```
The following error was received:
```
usr/bin/ld: cannot find lib.fo.partial.lto.o: No such file or directory
/usr/bin/ld: error: could not unlink output file
collect2: error: ld returned 1 exit status
scons: *** [build/MIPS/mem/ruby/system/lib.fo.partial] Error 1
```
Issue-on: https://gem5.atlassian.net/browse/GEM5-555
https://gem5.atlassian.net/browse/GEM5-557
Change-Id: Id9e7fc81aec9f94524acc92c05aabdf96bd284cd
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/29272
Reviewed-by: Jason Lowe-Power
Maintainer: Jason Lowe-Power
Tested-by: kokoro
---
M SConstruct
1 file changed, 11 insertions(+), 6 deletions(-)
Approvals:
Jason Lowe-Power: Looks good to me, approved; Looks good to me, approved
kokoro: Regressions pass
diff --git a/SConstruct b/SConstruct
index 0a18c3d..82fad3b 100755
--- a/SConstruct
+++ b/SConstruct
@@ -404,22 +404,27 @@
main['GCC_VERSION'] = gcc_version
-if compareVersions(gcc_version, '4.9') >= 0 and \
- compareVersions(gcc_version, '8.1') < 0:
+if compareVersions(gcc_version, '4.9') >= 0:
# Incremental linking with LTO is currently broken in gcc versions
-# 4.9 to 8.1.
+# 4.9 and above. A version where everything works completely hasn't
+# yet been identified.
#
# 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
-# versions of gcc up to 8.1.
+# 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.
#
# 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
-main['BROKEN_INCREMENTAL_LTO'] = True
+if not GetOption('force_lto'):
+main.Append(PSHLINKFLAGS='-flinker-output=rel')
+main.Append(PLINKFLAGS='-flinker-output=rel')
disable_lto = GetOption('no_lto')
if not disable_lto and main.get('BROKEN_INCREMENTAL_LTO', False) and \
--
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Gerrit-Project: public/gem5
Gerrit-Branch: release-staging-v20.0.0.0
Gerrit-Change-Id: Id9e7fc81aec9f94524acc92c05aabdf96bd284cd
Gerrit-Change-Number: 29272
Gerrit-PatchSet: 4
Gerrit-Owner: Bobby R. Bruce
Gerrit-Reviewer: Bobby R. Bruce
Gerrit-Reviewer: Earl Ou
Gerrit-Reviewer: Gabe Black
Gerrit-Reviewer: Hoa Nguyen
Gerrit-Reviewer: Jason Lowe-Power
Gerrit-Reviewer: Jason Lowe-Power
Gerrit-Reviewer: kokoro
Gerrit-MessageType: merged
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