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arm: clang: Update support slightly

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- Move most of the flags required into LLVM_RELFLAGS to test at build
  time instead of requiring them to be passed in.
- Update doc/README.clang to reflect this
- Switch to rpi_2 as the example as it's closer to working out of the
  box than rpi is.

Cc: Jeroen Hofstee <jeroen@myspectrum.nl>
Signed-off-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Tom Rini 2016-03-16 19:55:55 -04:00
parent 40345e9ea7
commit b745e82837
3 changed files with 15 additions and 9 deletions
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3
arch/arm/Makefile
View File

@ -16,7 +16,8 @@ arch-$(CONFIG_CPU_SA1100) =-march=armv4
arch-$(CONFIG_CPU_PXA) =
arch-$(CONFIG_CPU_ARM1136) =-march=armv5
arch-$(CONFIG_CPU_ARM1176) =-march=armv5t
arch-$(CONFIG_CPU_V7) =$(call cc-option, -march=armv7-a, -march=armv5)
arch-$(CONFIG_CPU_V7) =$(call cc-option, -march=armv7-a, \
$(call cc-option, -march=armv7, -march=armv5))
arch-$(CONFIG_ARM64) =-march=armv8-a
# Evaluate arch cc-option calls now

6
arch/arm/config.mk
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@ -19,6 +19,12 @@ PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections \
PLATFORM_RELFLAGS += $(call cc-option, -msoft-float) \
$(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,))
# LLVM support
LLVMS_RELFLAGS := $(call cc-option,-mllvm,) \
$(call cc-option,-target arm-none-eabi,) \
$(call cc-option,-arm-use-movt=0,)
PLATFORM_RELFLAGS += $(LLVM_RELFLAGS)
PLATFORM_CPPFLAGS += -D__ARM__
# Choose between ARM/Thumb instruction sets

15
doc/README.clang
View File

@ -26,10 +26,10 @@ Debian (based)
Binary packages can be installed as usual, e.g.:
sudo apt-get install clang
To compile U-Boot with clang on linux without IAS use e.g.:
export TRIPLET=arm-linux-gnueabi && export CROSS_COMPILE="$TRIPLET-"
make HOSTCC=clang CC="clang -target $TRIPLET -mllvm -arm-use-movt=0 -no-integrated-as" rpi_defconfig
make HOSTCC=clang CC="clang -target $TRIPLET -mllvm -arm-use-movt=0 -no-integrated-as" all V=1 -j8
Note that we still use binutils for some tools so we must continue to set
CROSS_COMPILE. To compile U-Boot with clang on linux without IAS use e.g.:
make HOSTCC=clang rpi_2_defconfig
make HOSTCC=clang CROSS_COMPILE=arm-linux-gnueabi- CC=clang -j8
It can also be used to compile sandbox:
make HOSTCC=clang sandbox_defconfig
@ -46,8 +46,8 @@ ln -s /usr/local/bin/arm-gnueabi-freebsd-as /usr/bin/arm-freebsd-eabi-as
# The following commands compile U-Boot using the clang xdev toolchain.
# NOTE: CROSS_COMPILE and target differ on purpose!
export CROSS_COMPILE=arm-gnueabi-freebsd-
gmake CC="clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd -no-integrated-as -mllvm -arm-use-movt=0" rpi_defconfig
gmake CC="clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd -no-integrated-as -mllvm -arm-use-movt=0" -j8
gmake rpi_2_defconfig
gmake CC="clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd" -j8
Given that U-Boot will default to gcc, above commands can be
simplified with a simple wrapper script, listed below.
@ -56,5 +56,4 @@ simplified with a simple wrapper script, listed below.
---
#!/bin/sh
exec clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd -no-integrated-as -mllvm -arm-use-movt=0 "$@"
exec clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd "$@"