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cmd/vendor/golang.org/x/arch/arm: several issues in ARM disassembler's plan9 syntax #23159

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benshi001 opened this issue Dec 17, 2017 · 7 comments
Open

cmd/vendor/golang.org/x/arch/arm: several issues in ARM disassembler's plan9 syntax #23159

benshi001 opened this issue Dec 17, 2017 · 7 comments
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NeedsFix The path to resolution is known, but the work has not been done.
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@benshi001
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Though the ARM disassembler can decode most instruction binaries into gnu syntax correctly, there are several issues in plan9 syntax decoding.

  1. op name
    15f715e7| 1 plan9 SDIV R7, R5, R5
    It should be "DIV R7, R5, R5", and many others are also incorrect.
    MLA should be MULA
    UDIV should be DIVU
    ......

  2. LDM/STM
    ed003be9| 1 plan9 LDMDB [R0,R2-R3,R5-R7], R11!
    2.1 their op name should be MOVM
    2.2 () should be used instead of []
    2.3 The DB/IA/DA/IB suffixes should be decoded to .W/.P suffixes

  3. SWP/SWPB
    939007e1| 1 plan9 SWP [R7], R3, R9
    3.1. () should be used instead of []
    3.2 The parameter order is incorrect

  4. VMRS/VMSR
    109ae1ee| 1 plan9 VMSR R9, FPSCR
    The op name is incorrect

  5. FP instructions
    5.1 op name: VADD.F32->ADDF, VSUB.F64->SUBD, ......
    5.2 register name: S2->F1, S4->F2, ...
    5.3 vcvt has incorrect form
    5.4 vmov has incorrect form

  6. XTB/XTH/XTBU/XTHU should be MOVB/MOVH

  7. STREX/LDREX has incorrect parameter order

  8. XTAB/XTAH/XTABU/XTAHU has incorrect form
@ALTree ALTree added the NeedsFix The path to resolution is known, but the work has not been done. label Dec 18, 2017
@ALTree ALTree added this to the Go1.11 milestone Dec 18, 2017
@benshi001
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  1. VFMA/VNFMA like instructions are not support

    decode_test.go:66: Decode(002aa1ee|) [gnu] = error: unknown instruction, 0, want FMULF F0, F1, F2, 4
    decode_test.go:66: Decode(202aa1ee|) [gnu] = error: unknown instruction, 0, want FMULF S1, F1, F2, 4
    decode_test.go:66: Decode(802aa1ee|) [gnu] = error: unknown instruction, 0, want FMULF F0, S3, F2, 4
    decode_test.go:66: Decode(002ae1ee|) [gnu] = error: unknown instruction, 0, want FMULF F0, F1, S5, 4
    decode_test.go:66: Decode(035ba40e|) [gnu] = error: unknown instruction, 0, want FMULD.EQ F3, F4, F5, 4
    decode_test.go:66: Decode(002aa21e|) [gnu] = error: unknown instruction, 0, want FMULF.NE F0, F2, F2, 4
    decode_test.go:66: Decode(035ba5ee|) [gnu] = error: unknown instruction, 0, want FMULD F3, F5, F5, 4

The GNU tool chain support them.
8: eea12a00 vfma.f32 s4, s2, s0
c: eea12a20 vfma.f32 s4, s2, s1
10: eea12a80 vfma.f32 s4, s3, s0
14: eee12a00 vfma.f32 s5, s2, s0
18: eea45b03 vfma.f64 d5, d4, d3
1c: eea22a00 vfma.f32 s4, s4, s0
20: eea55b03 vfma.f64 d5, d5, d3

@benshi001
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Most issues are fixed in https://go-review.googlesource.com/c/arch/+/85455, except

  1. LDM/STM -> MOVM
  2. plan9 name: MLA->MULA, UDIV->DIVU, ...
  3. VFMA/VNFMA support

@benshi001
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Remaining issue after https://go-review.googlesource.com/c/arch/+/85455 is merged.

  1. LDM/STM -> MOVM
  2. plan9 name: MLA->MULA, UDIV->DIVU, ...
  3. VFMA/VNFMA support
  4. 0xe6a98877 is decoded to "SXTAB R7@>$16, R9, R8", with an unnecessary '$'

@benshi001 benshi001 modified the milestones: Go1.11, Unplanned May 21, 2018
@benshi001 benshi001 self-assigned this May 21, 2018
@benshi001
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This issue is not quite critical, since normal arm developers still can understand with those minor inconsistency.

@smasher164
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Do you mind if I take a look at adding VFMA/VNFMA support for Go 1.12?

@heisen-li
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Do you accept the repair of these problems now?

@benshi001
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benshi001 commented Jun 28, 2020 •
edited

Do you accept the repair of these problems now?

Any fix is appreciated.

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@ALTree @smasher164 @benshi001 @heisen-li