From 2942777425516f7b31181fbaecc5485263dfcb01 Mon Sep 17 00:00:00 2001
From: Jessica Clarke <jrtc27@jrtc27.com>
Date: Sun, 11 Jul 2021 03:28:23 +0100
Subject: Makefile: Support building with Clang and LLVM binutils
This is intended to mirror the Linux kernel. Building with CC=clang will
use Clang as the compiler but default to using the existing binutils.
Building with LLVM=1 will default to using Clang and LLVM binutils.
Whilst GCC will accept the -N linker option and forward it on to the
linker, Clang will not, and so in order to support both compilers we
must use -Wl, to forward it to the linker as is required for most other
linker options.
Note that there is currently a bug when using Clang as the compiler and
riscv64-linux-gnu-ld as the linker for FW_PIC=y. At first glance this
appears to be a bug in GNU binutils, but this could also be Clang or
OpenSBI at fault in some subtle way. Thus, for now, advise that this
combination be avoided.
Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Tested-by: Anup Patel <anup.patel@wdc.com>
---
Makefile | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 59 insertions(+), 7 deletions(-)
(limited to 'Makefile')
diff --git a/Makefile b/Makefile
index ba06313..5c188d5 100644
--- a/Makefile
+++ b/Makefile
@@ -76,26 +76,54 @@ OPENSBI_VERSION_MINOR=`grep "define OPENSBI_VERSION_MINOR" $(include_dir)/sbi/sb
OPENSBI_VERSION_GIT=$(shell if [ -d $(src_dir)/.git ]; then git describe 2> /dev/null; fi)
# Setup compilation commands
+ifneq ($(LLVM),)
+CC = clang
+AR = llvm-ar
+LD = ld.lld
+OBJCOPY = llvm-objcopy
+else
ifdef CROSS_COMPILE
CC = $(CROSS_COMPILE)gcc
-CPP = $(CROSS_COMPILE)cpp
AR = $(CROSS_COMPILE)ar
LD = $(CROSS_COMPILE)ld
OBJCOPY = $(CROSS_COMPILE)objcopy
else
CC ?= gcc
-CPP ?= cpp
AR ?= ar
LD ?= ld
OBJCOPY ?= objcopy
endif
+endif
+CPP = $(CC) -E
AS = $(CC)
DTC = dtc
-# Guess the compillers xlen
-OPENSBI_CC_XLEN := $(shell TMP=`$(CC) -dumpmachine | sed 's/riscv\([0-9][0-9]\).*/\1/'`; echo $${TMP})
+ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
+CC_IS_CLANG = y
+else
+CC_IS_CLANG = n
+endif
+
+ifneq ($(shell $(LD) --version 2>&1 | head -n 1 | grep LLD),)
+LD_IS_LLD = y
+else
+LD_IS_LLD = n
+endif
+
+ifeq ($(CC_IS_CLANG),y)
+ifneq ($(CROSS_COMPILE),)
+CLANG_TARGET = --target=$(notdir $(CROSS_COMPILE:%-=%))
+endif
+endif
+
+# Guess the compiler's XLEN
+OPENSBI_CC_XLEN := $(shell TMP=`$(CC) $(CLANG_TARGET) -dumpmachine | sed 's/riscv\([0-9][0-9]\).*/\1/'`; echo $${TMP})
+
+# Guess the compiler's ABI and ISA
+ifneq ($(CC_IS_CLANG),y)
OPENSBI_CC_ABI := $(shell TMP=`$(CC) -v 2>&1 | sed -n 's/.*\(with\-abi=\([a-zA-Z0-9]*\)\).*/\2/p'`; echo $${TMP})
OPENSBI_CC_ISA := $(shell TMP=`$(CC) -v 2>&1 | sed -n 's/.*\(with\-arch=\([a-zA-Z0-9]*\)\).*/\2/p'`; echo $${TMP})
+endif
# Setup platform XLEN
ifndef PLATFORM_RISCV_XLEN
@@ -106,8 +134,21 @@ ifndef PLATFORM_RISCV_XLEN
endif
endif
+ifeq ($(CC_IS_CLANG),y)
+ifeq ($(CROSS_COMPILE),)
+CLANG_TARGET = --target=riscv$(PLATFORM_RISCV_XLEN)-unknown-elf
+endif
+endif
+
+ifeq ($(LD_IS_LLD),y)
+RELAX_FLAG = -mno-relax
+USE_LD_FLAG = -fuse-ld=lld
+else
+USE_LD_FLAG = -fuse-ld=bfd
+endif
+
# Check whether the linker supports creating PIEs
-OPENSBI_LD_PIE := $(shell $(CC) -fPIE -nostdlib -Wl,-pie -x c /dev/null -o /dev/null >/dev/null 2>&1 && echo y || echo n)
+OPENSBI_LD_PIE := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) $(USE_LD_FLAG) -fPIE -nostdlib -Wl,-pie -x c /dev/null -o /dev/null >/dev/null 2>&1 && echo y || echo n)
# Setup list of objects.mk files
ifdef PLATFORM
@@ -197,7 +238,11 @@ else
endif
# Setup compilation commands flags
-GENFLAGS = -I$(platform_src_dir)/include
+ifeq ($(CC_IS_CLANG),y)
+GENFLAGS += $(CLANG_TARGET)
+GENFLAGS += -Wno-unused-command-line-argument
+endif
+GENFLAGS += -I$(platform_src_dir)/include
GENFLAGS += -I$(include_dir)
ifneq ($(OPENSBI_VERSION_GIT),)
GENFLAGS += -DOPENSBI_VERSION_GIT="\"$(OPENSBI_VERSION_GIT)\""
@@ -211,6 +256,7 @@ CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
CFLAGS += -mno-save-restore -mstrict-align
CFLAGS += -mabi=$(PLATFORM_RISCV_ABI) -march=$(PLATFORM_RISCV_ISA)
CFLAGS += -mcmodel=$(PLATFORM_RISCV_CODE_MODEL)
+CFLAGS += $(RELAX_FLAG)
CFLAGS += $(GENFLAGS)
CFLAGS += $(platform-cflags-y)
CFLAGS += -fno-pie -no-pie
@@ -225,18 +271,24 @@ ASFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
ASFLAGS += -mno-save-restore -mstrict-align
ASFLAGS += -mabi=$(PLATFORM_RISCV_ABI) -march=$(PLATFORM_RISCV_ISA)
ASFLAGS += -mcmodel=$(PLATFORM_RISCV_CODE_MODEL)
+ASFLAGS += $(RELAX_FLAG)
ASFLAGS += $(GENFLAGS)
ASFLAGS += $(platform-asflags-y)
ASFLAGS += $(firmware-asflags-y)
ARFLAGS = rcs
-ELFFLAGS += -Wl,--build-id=none -N -static-libgcc -lgcc
+ELFFLAGS += $(USE_LD_FLAG)
+ELFFLAGS += -Wl,--build-id=none -Wl,-N -static-libgcc -lgcc
ELFFLAGS += $(platform-ldflags-y)
ELFFLAGS += $(firmware-ldflags-y)
MERGEFLAGS += -r
+ifeq ($(LD_IS_LLD),y)
+MERGEFLAGS += -b elf
+else
MERGEFLAGS += -b elf$(PLATFORM_RISCV_XLEN)-littleriscv
+endif
MERGEFLAGS += -m elf$(PLATFORM_RISCV_XLEN)lriscv
DTSCPPFLAGS = $(CPPFLAGS) -nostdinc -nostdlib -fno-builtin -D__DTS__ -x assembler-with-cpp
--
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