6a7f57668a
When the RISC-V disassembler encounters an unknown instruction, it
currently just prints the value of the bytes, like this:
Dump of assembler code for function custom_insn:
0x00010132 <+0>: addi sp,sp,-16
0x00010134 <+2>: sw s0,12(sp)
0x00010136 <+4>: addi s0,sp,16
0x00010138 <+6>: 0x52018b
0x0001013c <+10>: 0x9c45
My proposal, in this patch, is to change the behaviour to this:
Dump of assembler code for function custom_insn:
0x00010132 <+0>: addi sp,sp,-16
0x00010134 <+2>: sw s0,12(sp)
0x00010136 <+4>: addi s0,sp,16
0x00010138 <+6>: .4byte 0x52018b
0x0001013c <+10>: .2byte 0x9c45
Adding the .4byte and .2byte opcodes. The benefit that I see here is
that in the patched version of the tools, the disassembler output can
be fed back into the assembler and it should assemble to the same
binary format. Before the patch, the disassembler output is invalid
assembly.
I've started a RISC-V specific test file under binutils so that I can
add a test for this change.
binutils/ChangeLog:
* testsuite/binutils-all/riscv/riscv.exp: New file.
* testsuite/binutils-all/riscv/unknown.d: New file.
* testsuite/binutils-all/riscv/unknown.s: New file.
opcodes/ChangeLog:
* riscv-dis.c (riscv_disassemble_insn): Print a .%dbyte opcode
before an unknown instruction, '%d' is replaced with the
instruction length.
27 lines
1.3 KiB
ArmAsm
27 lines
1.3 KiB
ArmAsm
/* Copyright (C) 2021 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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.text
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/* The following instruction is in the area set aside for
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custom instruction extensions. As such it is unlikely that
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an upstream extension should ever clash with this. */
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.insn r 0x0b, 0x0, 0x0, x3, x4, x5
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/* Unlike the above, the following is just a reserved
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instruction encoding. This means that in the future an
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extension to the compressed instruction set might use this
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encoding. If/when that happens we'll need to find a
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different unused encoding within the compressed instruction
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space. */
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.insn ca 0x1, 0x27, 0x2, x8, x9
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