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toolchain-wrapper: use -ffp-contract=off on MIPS Xburst for gcc >= 4.6

PATCH New Thomas Petazzoni 2 participants 3 messages Mar 31, 2018 – Apr 1, 2018

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Thomas Petazzoni

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#0 lore raw

PATCH 1/1 toolchain-wrapper: use -ffp-contract=off on MIPS Xburst for gcc >= 4.6

From: Waldemar Brodkorb <[email protected]>

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 <[email protected]>

[Thomas: rework to continue supporting pre-gcc-4.6 toolchains, extend the commit log after doing more testing.]

Signed-off-by Thomas Petazzoni <[email protected]>
---
 toolchain/toolchain-wrapper.c  | 3 +++
 toolchain/toolchain-wrapper.mk | 6 ++++++
 2 files changed, 9 insertions(+)
toolchain/toolchain-wrapper.c +3 -0
index 2928ea42d0..c5eb813dd0 100644
@@ -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
toolchain/toolchain-wrapper.mk +6 -0
index 7f72a0cade..6e95545ebf 100644
@@ -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)"'
Signature · 1 line
2.14.3
#1 lore raw

PATCH 1/1 toolchain-wrapper: use -ffp-contract=off on MIPS Xburst for gcc >= 4.6

Quoted 39 lines · Thomas Petazzoni

From: Waldemar Brodkorb <[email protected]>

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'
Quoted 4 lines

Fixes the ci20_defconfig build:

https://gitlab.com/buildroot.org/buildroot/-/jobs/60303132

Fixed that one, but U-Boot fails to build here. I'll submit a patch.

Quoted 4 lines
Signed-off-by Waldemar Brodkorb <[email protected]>

[Thomas: rework to continue supporting pre-gcc-4.6 toolchains, extend the commit log after doing more testing.]

Signed-off-by Thomas Petazzoni <[email protected]>
Reviewed-by Ezequiel Garcia <[email protected]>

Thanks,
Eze

author Applied
#2 lore raw

PATCH 1/1 toolchain-wrapper: use -ffp-contract=off on MIPS Xburst for gcc >= 4.6

In reply to Thomas Petazzoni

Hello,

Quoted 43 lines · Thomas Petazzoni

From: Waldemar Brodkorb <[email protected]>

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

Quoted 8 lines
Signed-off-by Waldemar Brodkorb <[email protected]>

[Thomas: rework to continue supporting pre-gcc-4.6 toolchains, extend the commit log after doing more testing.]

Signed-off-by Thomas Petazzoni <[email protected]>
---
 toolchain/toolchain-wrapper.c  | 3 +++
 toolchain/toolchain-wrapper.mk | 6 ++++++
 2 files changed, 9 insertions(+)

Applied to master, thanks.

Thomas

Signature · 3 lines
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com