[Buildroot] [git commit branch/2020.08.x] toolchain/toolchain-wrapper: disable -ftree-loop-distribute-patterns when building for microblaze with gcc >= 10

Peter Korsgaard peter at korsgaard.com
Thu Oct 29 22:25:15 UTC 2020


commit: https://git.buildroot.net/buildroot/commit/?id=969bc43c672d33af74495a32ca4b5d36a8f5d0d0
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2020.08.x

GCC 10 now enable by default -ftree-loop-distribute-patterns at -O2 or -Os
optimization level instead of -O3, see commit [1].

Due to this change, the microblaze kernel doesn't boot (as reported by
toolchain-builder project).

The gcc docs between version 9 and 10 has been updated accordingly [2] [3]
but there no word about this change in the gcc 10 changelog [4].

Fixes microblazebe:
https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359536 (glibc)
https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359538 (musl)
https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359540 (uClubc-ng)

Fixes microblazeel:
https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359542 (glibc)
https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359544 (musl)
https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359546 (uClibc-ng)

This has been reported upsteam [5].

[1] https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=5879ab5fafedc8f6f9bfe95a4cf8501b0df90edd
[2] https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Optimize-Options.html#Optimize-Options
[3] https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gcc/Optimize-Options.html#Optimize-Options
[4] https://gcc.gnu.org/gcc-10/changes.html
[5] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97208

Signed-off-by: Romain Naour <romain.naour at gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
(cherry picked from commit 7cbc19471bedae4f83de75e6e6a6c77660e83c59)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 toolchain/toolchain-wrapper.mk | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk
index f1312c5c7f..8b551e3a18 100644
--- a/toolchain/toolchain-wrapper.mk
+++ b/toolchain/toolchain-wrapper.mk
@@ -33,6 +33,14 @@ TOOLCHAIN_WRAPPER_OPTS += -DBR_NEED_SOURCE_DATE_EPOCH
 endif
 endif
 
+# Disable -ftree-loop-distribute-patterns on microblaze to
+# workaround a compiler bug with gcc 10 and -O2, -Os or -O3.
+# https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=5879ab5fafedc8f6f9bfe95a4cf8501b0df90edd
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97208
+ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_10)$(BR2_microblaze),yy)
+TOOLCHAIN_WRAPPER_OPTS += -fno-tree-loop-distribute-patterns
+endif
+
 # We create a list like '"-mfoo", "-mbar", "-mbarfoo"' so that each flag is a
 # separate argument when used in execv() by the toolchain wrapper.
 TOOLCHAIN_WRAPPER_ARGS += \


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