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authorAndrew Burgess <andrew.burgess@embecosm.com>2018-12-03 14:46:18 +0000
committerAndrew Burgess <andrew.burgess@embecosm.com>2018-12-06 09:40:56 +0000
commit884b49e3a91504b9c5528343823d67f4419b73bb (patch)
tree5435b4d2de23ab0ebcfa53bcad6e74e4106042e6 /sim
parenteb7be1abbc59b49e5f60b9ad075496eb619674ae (diff)
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opcodes/riscv: Hide '.L0 ' fake symbols
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.
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