[Buildroot] [git commit branch/2018.02.x] toolchain-wrapper: use -ffp-contract=off on MIPS Xburst for gcc >= 4.6
Peter Korsgaard
peter at korsgaard.com
Sun Apr 8 14:54:49 UTC 2018
commit: https://git.buildroot.net/buildroot/commit/?id=66238cb41351c9393fa2c68120bcb8218d90705a
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2018.02.x
Since gcc 4.6, GCC deprecated -mfused-madd, -ffp-contract=off should
be used for the Xburst workaround.
Tested with the MIPS Sourcery 2011.03 toolchain (based on gcc 4.5),
the toolchain wrapper uses -mno-fused-madd, as expected:
$ BR2_DEBUG_WRAPPER=2 ./output/host/bin/mips-linux-gnu-gcc -o toto toto.c
Toolchain wrapper executing:
'/home/thomas/toolchains/mips-2011.03/bin/mips-linux-gnu-gcc'
'--sysroot'
'/home/thomas/projets/buildroot/output/host/mipsel-buildroot-linux-gnu/sysroot'
'-mabi=32'
'-msoft-float'
'-mno-fused-madd'
'-EL'
'-march=mips32r2'
'-o'
'toto'
'toto.c'
And with the MIPS Sourcery 2012.09 toolchain (based on gcc 4.7), the
toolchain wrapper uses -ffp-contract=off, as expected:
$ BR2_DEBUG_WRAPPER=2 ./output/host/bin/mips-linux-gnu-gcc -o toto toto.c
Toolchain wrapper executing:
'/home/thomas/toolchains/mips-2012.09/bin/mips-linux-gnu-gcc'
'--sysroot'
'/home/thomas/projets/buildroot/output/host/mipsel-buildroot-linux-gnu/sysroot'
'-mabi=32'
'-msoft-float'
'-ffp-contract=off'
'-EL'
'-march=mips32r2'
'-o'
'toto'
'toto.c'
Fixes the ci20_defconfig build:
https://gitlab.com/buildroot.org/buildroot/-/jobs/60303132
Signed-off-by: Waldemar Brodkorb <wbx at openadk.org>
[Thomas: rework to continue supporting pre-gcc-4.6 toolchains, extend
the commit log after doing more testing.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
Reviewed-by: Ezequiel Garcia <ezequiel at vanguardiasur.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
(cherry picked from commit 5e58509bfe497c5e85db58f8213b0a44ac79dd3f)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
toolchain/toolchain-wrapper.c | 3 +++
toolchain/toolchain-wrapper.mk | 6 ++++++
2 files changed, 9 insertions(+)
diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
index 2928ea42d0..c5eb813dd0 100644
--- a/toolchain/toolchain-wrapper.c
+++ b/toolchain/toolchain-wrapper.c
@@ -82,6 +82,9 @@ static char *predef_args[] = {
#ifdef BR_NO_FUSED_MADD
"-mno-fused-madd",
#endif
+#ifdef BR_FP_CONTRACT_OFF
+ "-ffp-contract=off",
+#endif
#ifdef BR_BINFMT_FLAT
"-Wl,-elf2flt",
#endif
diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk
index 7f72a0cade..6e95545ebf 100644
--- a/toolchain/toolchain-wrapper.mk
+++ b/toolchain/toolchain-wrapper.mk
@@ -28,8 +28,14 @@ endif
# Avoid FPU bug on XBurst CPUs
ifeq ($(BR2_mips_xburst),y)
+# Before gcc 4.6, -mno-fused-madd was needed, after -ffp-contract is
+# needed
+ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_4_6),y)
+TOOLCHAIN_WRAPPER_ARGS += -DBR_FP_CONTRACT_OFF
+else
TOOLCHAIN_WRAPPER_ARGS += -DBR_NO_FUSED_MADD
endif
+endif
ifeq ($(BR2_CCACHE_USE_BASEDIR),y)
TOOLCHAIN_WRAPPER_ARGS += -DBR_CCACHE_BASEDIR='"$(BASE_DIR)"'
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