toolchain-wrapper: use -ffp-contract=off on MIPS Xburst for gcc >= 4.6
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@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@bootlin.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk
index 0b26037..b8074ef 100644
--- a/toolchain/toolchain-wrapper.mk
+++ b/toolchain/toolchain-wrapper.mk
@@ -32,8 +32,14 @@
# 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)"'