[gcc r10-9816] RISC-V: For '-march' and '-mabi' options, add 'Negative' property mentions itself.

[gcc r10-9816] RISC-V: For '-march' and '-mabi' options, add 'Negative' property mentions itself.

[Kito Cheng]

https://gcc.gnu.org/g:ee359d860d750e7c6d0acf397b31b35dfa4513fe

commit r10-9816-gee359d860d750e7c6d0acf397b31b35dfa4513fe
Author: Geng Qi <gengqi@linux.alibaba.com>
Date:   Wed Apr 28 16:29:33 2021 +0800

    RISC-V: For '-march' and '-mabi' options, add 'Negative' property mentions itself.
    
    When use multi-lib riscv-tool-chain. A bug is triggered when there are two
    '-march' at command line.
    riscv64-unknown-elf-gcc -march=rv32gcp -mabi=ilp32f -march=rv32gcpzp64 HelloWorld.c
    /lhome/gengq/riscv64-linux-ptest/lib/gcc/riscv64-unknown-elf/10.2.0/../../../../riscv64-unknown-elf/bin/ld: /lhome/gengq/riscv64-linux-ptest/lib/gcc/riscv64-unknown-elf/10.2.0/../../../../riscv64-unknown-elf/lib/crt0.o: ABI is incompatible with that of the selected emulation:
      target emulation `elf64-littleriscv' does not match `elf32-littleriscv'
    /lhome/gengq/riscv64-linux-ptest/lib/gcc/riscv64-unknown-elf/10.2.0/../../../../riscv64-unknown-elf/bin/ld: failed to merge target specific data of file /lhome/gengq/riscv64-linux-ptest/lib/gcc/riscv64-unknown-elf/10.2.0/../../../../riscv64-unknown-elf/lib/crt0.o
    /lhome/gengq/riscv64-linux-ptest/lib/gcc/riscv64-unknown-elf/10.2.0/../../../../riscv64-unknown-elf/bin/ld: /lhome/gengq/riscv64-linux-ptest/lib/gcc/riscv64-unknown-elf/10.2.0/crtbegin.o: ABI is incompatible with that of the selected emulation:
      target emulation `elf64-littleriscv' does not match `elf32-littleriscv'
    /lhome/gengq/riscv64-linux-ptest/lib/gcc/riscv64-unknown-elf/10.2.0/../../../../riscv64-unknown-elf/bin/ld: failed to merge target specific data of file /lhome/gengq/riscv64-linux-ptest/lib/gcc/riscv64-unknown-elf/10.2.0/crtbegin.o
    ......
    
    This patch fix it. And the DRIVER would prune the extra '-march' and '-mabi'
    options and keep only the last one valid.
    
    gcc/ChangeLog:
            * config/riscv/riscv.opt (march=,mabi=): Negative itself.
    
    (cherry picked from commit 17f2908fcf058e145cff275966e34f8c7f57c2c5)

Diff:
---
 gcc/config/riscv/riscv.opt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/config/riscv/riscv.opt b/gcc/config/riscv/riscv.opt
index 29de246759e..e726a12fd45 100644
--- a/gcc/config/riscv/riscv.opt
+++ b/gcc/config/riscv/riscv.opt
@@ -30,7 +30,7 @@ Target Report Var(TARGET_PLT) Init(1)
 When generating -fpic code, allow the use of PLTs. Ignored for fno-pic.
 
 mabi=
-Target Report RejectNegative Joined Enum(abi_type) Var(riscv_abi) Init(ABI_ILP32)
+Target Report RejectNegative Joined Enum(abi_type) Var(riscv_abi) Init(ABI_ILP32) Negative(mabi=)
 Specify integer and floating-point calling convention.
 
 mpreferred-stack-boundary=
@@ -71,7 +71,7 @@ Target Report Mask(DIV)
 Use hardware instructions for integer division.
 
 march=
-Target Report RejectNegative Joined
+Target Report RejectNegative Joined Negative(march=)
 -march=	Generate code for given RISC-V ISA (e.g. RV64IM).  ISA strings must be
 lower-case.