[PATCH 1/2] RISC-V: Support -mlittle-endian and -mbig-endian

[Marcus Comstedt]

gcc/
        * config/riscv/elf.h (LINK_SPEC): Pass linker endianness flag.
        * config/riscv/freebsd.h (LINK_SPEC): Likewise.
        * config/riscv/linux.h (LINK_SPEC): Likewise.
        * config/riscv/riscv.h (ASM_SPEC): Pass -mbig-endian and
        -mlittle-endian.
        (BYTES_BIG_ENDIAN): Handle big endian.
        (WORDS_BIG_ENDIAN): Define to BYTES_BIG_ENDIAN.
        * config/riscv/riscv.opt (-mbig-endian, -mlittle-endian): New
        options.
---
 gcc/config/riscv/elf.h     | 2 ++
 gcc/config/riscv/freebsd.h | 2 ++
 gcc/config/riscv/linux.h   | 2 ++
 gcc/config/riscv/riscv.h   | 6 ++++--
 gcc/config/riscv/riscv.opt | 8 ++++++++
 5 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/gcc/config/riscv/elf.h b/gcc/config/riscv/elf.h
index d136d46e4fa..973efdaed7b 100644
--- a/gcc/config/riscv/elf.h
+++ b/gcc/config/riscv/elf.h
@@ -20,6 +20,8 @@ along with GCC; see the file COPYING3.  If not see
 #define LINK_SPEC "\
 -melf" XLEN_SPEC "lriscv \
 %{mno-relax:--no-relax} \
+%{mbig-endian:-EB} \
+%{mlittle-endian:-EL} \
 %{shared}"
 
 /* Link against Newlib libraries, because the ELF backend assumes Newlib.
diff --git a/gcc/config/riscv/freebsd.h b/gcc/config/riscv/freebsd.h
index a48bf9bffe4..f3aca9f7673 100644
--- a/gcc/config/riscv/freebsd.h
+++ b/gcc/config/riscv/freebsd.h
@@ -44,6 +44,8 @@ along with GCC; see the file COPYING3.  If not see
   %{p:%nconsider using `-pg' instead of `-p' with gprof (1)}   \
   %{v:-V}                                                      \
   %{assert*} %{R*} %{rpath*} %{defsym*}                                \
+  %{mbig-endian:-EB}                                           \
+  %{mlittle-endian:-EL}                                                \
   %{shared:-Bshareable %{h*} %{soname*}}                       \
   %{symbolic:-Bsymbolic}                                       \
   %{static:-Bstatic}                                           \
diff --git a/gcc/config/riscv/linux.h b/gcc/config/riscv/linux.h
index 9238de5bc92..e74f5d3f914 100644
--- a/gcc/config/riscv/linux.h
+++ b/gcc/config/riscv/linux.h
@@ -60,6 +60,8 @@ along with GCC; see the file COPYING3.  If not see
 #define LINK_SPEC "\
 -melf" XLEN_SPEC "lriscv" LD_EMUL_SUFFIX " \
 %{mno-relax:--no-relax} \
+%{mbig-endian:-EB} \
+%{mlittle-endian:-EL} \
 %{shared} \
   %{!shared: \
     %{!static: \
diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
index c6f8bee07ef..0b667d2e8b9 100644
--- a/gcc/config/riscv/riscv.h
+++ b/gcc/config/riscv/riscv.h
@@ -91,6 +91,8 @@ extern const char *riscv_default_mtune (int argc, const char 
**argv);
 %{" FPIE_OR_FPIC_SPEC ":-fpic} \
 %{march=*} \
 %{mabi=*} \
+%{mbig-endian} \
+%{mlittle-endian} \
 %(subtarget_asm_spec)" \
 ASM_MISA_SPEC
 
@@ -126,8 +128,8 @@ ASM_MISA_SPEC
 /* Target machine storage layout */
 
 #define BITS_BIG_ENDIAN 0
-#define BYTES_BIG_ENDIAN 0
-#define WORDS_BIG_ENDIAN 0
+#define BYTES_BIG_ENDIAN (TARGET_BIG_ENDIAN != 0)
+#define WORDS_BIG_ENDIAN (BYTES_BIG_ENDIAN)
 
 #define MAX_BITS_PER_WORD 64
 
diff --git a/gcc/config/riscv/riscv.opt b/gcc/config/riscv/riscv.opt
index 761a09d18c3..e294e223151 100644
--- a/gcc/config/riscv/riscv.opt
+++ b/gcc/config/riscv/riscv.opt
@@ -21,6 +21,14 @@
 HeaderInclude
 config/riscv/riscv-opts.h
 
+mbig-endian
+Target RejectNegative Mask(BIG_ENDIAN)
+Assume target CPU is configured as big endian.
+
+mlittle-endian
+Target RejectNegative InverseMask(BIG_ENDIAN)
+Assume target CPU is configured as little endian.
+
 mbranch-cost=
 Target RejectNegative Joined UInteger Var(riscv_branch_cost)
 -mbranch-cost=N        Set the cost of branches to roughly N instructions.
-- 
2.26.2