The RISC-V assembler generates fake labels with the name '.L0 ' as
part of the debug information (see
gas/config/tc-riscv.h:FAKE_LABEL_NAME).
The problem is that currently, when disassembling an object file, the
output looks like this (this is an example from the GDB testsuite, but
is pretty representative of anything with debug information):
000000000000001e <main>:
1e: 7179 addi sp,sp,-48
20: f406 sd ra,40(sp)
22: f022 sd s0,32(sp)
24: 1800 addi s0,sp,48
0000000000000026 <.L0 >:
26: 87aa mv a5,a0
28: feb43023 sd a1,-32(s0)
2c: fcc43c23 sd a2,-40(s0)
30: fef42623 sw a5,-20(s0)
0000000000000034 <.L0 >:
34: fec42783 lw a5,-20(s0)
38: 0007871b sext.w a4,a5
3c: 678d lui a5,0x3
3e: 03978793 addi a5,a5,57 # 3039 <.LASF30+0x2a9d>
42: 02f71463 bne a4,a5,6a <.L0 >
0000000000000046 <.L0 >:
46: 000007b7 lui a5,0x0
4a: 0007b783 ld a5,0(a5) # 0 <need_malloc>
4e: 6f9c ld a5,24(a5)
0000000000000050 <.L0 >:
50: 86be mv a3,a5
52: 466d li a2,27
54: 4585 li a1,1
56: 000007b7 lui a5,0x0
5a: 00078513 mv a0,a5
5e: 00000097 auipc ra,0x0
62: 000080e7 jalr ra # 5e <.L0 +0xe>
0000000000000066 <.L0 >:
66: 4785 li a5,1
68: a869 j 102 <.L0 >
000000000000006a <.L0 >:
6a: 000007b7 lui a5,0x0
6e: 00078513 mv a0,a5
72: 00000097 auipc ra,0x0
76: 000080e7 jalr ra # 72 <.L0 +0x8>
The frequent repeated '.L0 ' labels are pointless, as they are
non-unique there's no way to match a use of '.L0 ' to its appearence
in the output, so we'd be better off just not printing it at all.
That's what this patch does by defining a 'symbol_is_valid' method for
RISC-V. With this commit, the same disassembly now looks like this:
000000000000001e <main>:
1e: 7179 addi sp,sp,-48
20: f406 sd ra,40(sp)
22: f022 sd s0,32(sp)
24: 1800 addi s0,sp,48
26: 87aa mv a5,a0
28: feb43023 sd a1,-32(s0)
2c: fcc43c23 sd a2,-40(s0)
30: fef42623 sw a5,-20(s0)
34: fec42783 lw a5,-20(s0)
38: 0007871b sext.w a4,a5
3c: 678d lui a5,0x3
3e: 03978793 addi a5,a5,57 # 3039 <.LASF30+0x2a9d>
42: 02f71463 bne a4,a5,6a <.L4>
46: 000007b7 lui a5,0x0
4a: 0007b783 ld a5,0(a5) # 0 <need_malloc>
4e: 6f9c ld a5,24(a5)
50: 86be mv a3,a5
52: 466d li a2,27
54: 4585 li a1,1
56: 000007b7 lui a5,0x0
5a: 00078513 mv a0,a5
5e: 00000097 auipc ra,0x0
62: 000080e7 jalr ra # 5e <main+0x40>
66: 4785 li a5,1
68: a869 j 102 <.L5>
000000000000006a <.L4>:
6a: 000007b7 lui a5,0x0
6e: 00078513 mv a0,a5
72: 00000097 auipc ra,0x0
76: 000080e7 jalr ra # 72 <.L4+0x8>
In order to share the fake label between the assembler and the
libopcodes library, I've added some new defines RISCV_FAKE_LABEL_NAME
and RISCV_FAKE_LABEL_CHAR in include/opcode/riscv.h. I could have
just moved FAKE_LABEL_NAME to the include file, however, I thnk this
would be confusing, someone working on the assembler would likely not
expect to find FAKE_LABEL_NAME defined outside of the assembler source
tree. By introducing the RISCV_FAKE_LABEL_* defines I can leave the
assembler standard FAKE_LABEL_ defines in the assembler source, but
still share the RISCV_FAKE_LABEL_* with libopcodes.
gas/ChangeLog:
* config/tc-riscv.h (FAKE_LABEL_NAME): Define as
RISCV_FAKE_LABEL_NAME.
(FAKE_LABEL_CHAR): Define as RISCV_FAKE_LABEL_CHAR.
include/ChangeLog:
* dis-asm.h (riscv_symbol_is_valid): Declare.
* opcode/riscv.h (RISCV_FAKE_LABEL_NAME): Define.
(RISCV_FAKE_LABEL_CHAR): Define.
opcodes/ChangeLog:
* disassembler.c (disassemble_init_for_target): Add RISC-V
initialisation.
* riscv-dis.c (riscv_symbol_is_valid): New function.
884b49e3a9