[U-Boot] [PATCH v3 06/28] riscv: set -march and -mabi based on the Kconfig configuration

[Lukas Auer]

Use the new Kconfig entries to construct the ISA string for the -march
compiler flag. The -mabi compiler flag is selected based on the base
integer instruction set.

With this change, the C (compressed instructions) ISA extension is now
enabled for all boards with CONFIG_RISCV_ISA_C set. Buildman reports a
decrease in binary size of 71590 bytes.

Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
---

Changes in v3: None
Changes in v2:
- Change ISA string construction, as suggested by Bin Meng

 arch/riscv/Makefile  | 20 ++++++++++++++++++++
 arch/riscv/config.mk |  4 ----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 8fb6a889d8..55d7c6550e 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -3,6 +3,26 @@
 # Copyright (C) 2017 Andes Technology Corporation.
 # Rick Chen, Andes Technology Corporation <rick at andestech.com>
 
+ifeq ($(CONFIG_ARCH_RV64I),y)
+	ARCH_BASE = rv64im
+	ABI = lp64
+endif
+ifeq ($(CONFIG_ARCH_RV32I),y)
+	ARCH_BASE = rv32im
+	ABI = ilp32
+endif
+ifeq ($(CONFIG_RISCV_ISA_A),y)
+	ARCH_A = a
+endif
+ifeq ($(CONFIG_RISCV_ISA_C),y)
+	ARCH_C = c
+endif
+
+ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_C) -mabi=$(ABI)
+
+PLATFORM_CPPFLAGS	+= $(ARCH_FLAGS)
+CFLAGS_EFI		+= $(ARCH_FLAGS)
+
 head-y := arch/riscv/cpu/start.o
 
 libs-y += arch/riscv/cpu/
diff --git a/arch/riscv/config.mk b/arch/riscv/config.mk
index ed9eb0c24c..9088b9ef2c 100644
--- a/arch/riscv/config.mk
+++ b/arch/riscv/config.mk
@@ -14,16 +14,12 @@
 64bit-emul		:= elf64lriscv
 
 ifdef CONFIG_32BIT
-PLATFORM_CPPFLAGS	+= -march=rv32ima -mabi=ilp32
 PLATFORM_LDFLAGS	+= -m $(32bit-emul)
-CFLAGS_EFI		+= -march=rv32ima -mabi=ilp32
 EFI_LDS			:= elf_riscv32_efi.lds
 endif
 
 ifdef CONFIG_64BIT
-PLATFORM_CPPFLAGS	+= -march=rv64ima -mabi=lp64
 PLATFORM_LDFLAGS	+= -m $(64bit-emul)
-CFLAGS_EFI		+= -march=rv64ima -mabi=lp64
 EFI_LDS			:= elf_riscv64_efi.lds
 endif
 
-- 
2.17.2