Skip to content

Latest commit

 

History

History
118 lines (93 loc) · 4.06 KB

Riscduino.Readme.md

File metadata and controls

118 lines (93 loc) · 4.06 KB
Raw

This file Documents the sequence step to add custom instruction into the riscv toolchain.

File contributor: Mukund Vijayvergiya/S SAHANA

Instruction to be added:

mod r1, r2, r3
R[r1] = R[r2] % R[r3]

#1. Clone the RISC-V opcodes repository:

   git clone --depth 1 https://github.com/riscduino/riscv-opcodes.git
   cd riscv-opcodes

#2. Adding the instruction to the RISC-V opcodes repository: Since mod operation is an integer related function it should be added to rv_i file in the opcode repository.

gvim rv_i and append text “mod  rd rs1 rs2 31..25=1  14..12=0 6..2=2    1..0=3”

#3. Run make command to obtain MATCH and MASK values. These values are present in the encoding.out.h file generated by parse.py.

make
gvim encoding.out.h and check “MATCH_MOD” and “MASK_MOD” text

#4. Modifying riscv-opc.h file in : Clone the riscv gnu tool chain

git clone --depth 1 https://github.com/riscv-collab/riscv-gnu-toolchain

modify the file: /binutils/include/opcode/riscv-opc.h Additions to be done:

+ #define MATCH_MOD 0x200000b
+ #define MASK_MOD 0xfe00707f

+ DECLARE_INSN(mod, MATCH_MOD, MASK_MOD)

#5.Append below text in :/binutils/opcodes/riscv-opc.c

	 --name, xlen, isa, operands, match, mask, match_func, pinfo. 
	+ {"mod",         0, INSN_CLASS_I, "d,s,t",     MATCH_MOD, MASK_MOD,match_opcode,0},

#6.Building the new compiler inside the folder

mkdir build
cd build
../configure  --prefix=/opt/riscv64_expt
sudo make linux

The result will be a 64-bit gnu compiler built at /opt/ricv64_expt. This compile will support the custom mod instruction.

ls /opt/riscv64_expt/bin/
riscv64-unknown-linux-gnu-addr2line  riscv64-unknown-linux-gnu-gcc         riscv64-unknown-linux-gnu-gdb            riscv64-unknown-linux-gnu-objcopy
riscv64-unknown-linux-gnu-ar         riscv64-unknown-linux-gnu-gcc-13.2.1  riscv64-unknown-linux-gnu-gdb-add-index  riscv64-unknown-linux-gnu-objdump
riscv64-unknown-linux-gnu-as         riscv64-unknown-linux-gnu-gcc-ar      riscv64-unknown-linux-gnu-gfortran       riscv64-unknown-linux-gnu-ranlib
riscv64-unknown-linux-gnu-c++        riscv64-unknown-linux-gnu-gcc-nm      riscv64-unknown-linux-gnu-gprof          riscv64-unknown-linux-gnu-readelf
riscv64-unknown-linux-gnu-c++filt    riscv64-unknown-linux-gnu-gcc-ranlib  riscv64-unknown-linux-gnu-ld             riscv64-unknown-linux-gnu-run
riscv64-unknown-linux-gnu-cpp        riscv64-unknown-linux-gnu-gcov        riscv64-unknown-linux-gnu-ld.bfd         riscv64-unknown-linux-gnu-size
riscv64-unknown-linux-gnu-elfedit    riscv64-unknown-linux-gnu-gcov-dump   riscv64-unknown-linux-gnu-lto-dump       riscv64-unknown-linux-gnu-strings
riscv64-unknown-linux-gnu-g++        riscv64-unknown-linux-gnu-gcov-tool   riscv64-unknown-linux-gnu-nm             riscv64-unknown-linux-gnu-strip

#7. Create following mod example at File: /test/mod/mod_test.c

#include <stdio.h>
int main() {
   int a,b,c;
   a = 5;
   b = 2;
   asm volatile (
     "mod %[z], %[x], %[y]\n\t"
      :[z] "=r" (c)
      :[x] "r" (a),[y] "r" (b)
      );
   if (c != 1) {
       printf("\n[[FAILED]]\n");
       return -1;
   }
   printf("\n[[PASSED]]\n");
   return 0;
}

#8. compile

cd <riscv-gnu-toolchain>/test/mod/
/opt/riscv64_expt/bin/riscv64-unknown-linux-gnu-gcc mod_test.c -o mod_test

Checking the object dump for instruction using grep:

/opt/riscv64_expt/bin/riscv64-unknown-linux-gnu-objdump -D  mod_test >dump.txt
paste dump.txt | grep -n -A 20 "<main>" > result.txt

Reference