I can't add custom instructions to RISC-V GNU GCC

Asked Jan 03 '23 at 06:44

Active Jan 03 '23 at 06:47

Viewed 162 times

I want to add custom instructions to riscv64-gnu-gcc. I added the following code to riscv-opc.c and riscv-opc.h while referring to the following sites. I am getting an error for some reason. Why? Ubuntu20.04, riscv64-gnu-tool 12.2.0. I plan to run a C program on a RISC-V 32bit IM compatible CPU.

I added these codes.

///home/ubuntu2/riscv-gnu-toolchain/binutils/gdb/opcodes/riscv-opc.c
{"custom",     32, INSN_CLASS_I,     "d,s,t", MATCH_CUSTOM, MASK_CUSTOM, match_opcode, 0}

~/riscv-opc.h
#define MATCH_CUSTOM 0x700b
#define MASK_CUSTOM  0xfe00707f

DECLARE_INSN(custom, MATCH_CUSTOM, MASK_CUSTOM)

I did command and got errors.

//terminal
$cd riscv-gnu-toolchain
$make clean 
$make build-binutils
$cd /home/sample_code
$riscv64-unknown-linux-gnu-gcc -march=rv32im -mabi=ilp32 custom_.c

custom.c: Assembler messages:
custom.c:2: Error: unrecognized opcode `custom a1,a2,a3'

//custom.c code
int main(void){
    asm("custom a1, a2, a3");
}

edited Jan 03 '23 at 06:47

asked Jan 03 '23 at 06:44

riddles vann

1

I see that you added it inside a folder called gdb. gdb is a debugger and you're not using the debugger. Maybe you need to add it somewhere else, to add it to the assembler? – user253751 Jan 03 '23 at 07:09
OK. where should I add it? – riddles vann Jan 03 '23 at 07:43
I don't know. Just saying there's probably another place than gdb – user253751 Jan 03 '23 at 07:44
are you trying to use a create a pseudo instruction? please call the `riscv64-unknown-linux-gnu-as` directly and ensure it is the right one. – Jesse Taube Jan 04 '23 at 00:14
the corect files are ``` opcodes/riscv-opc.c include/opcode/riscv-opc.h include/opcode/riscv.h gas/config/tc-riscv.c ``` – Jesse Taube Jan 04 '23 at 00:17

I can't add custom instructions to RISC-V GNU GCC

0 Answers0