arm/armasm: fix bug of plan9 register list argument

If the register list contains multiple sub-lists, e.g., [R0,R2-R3,R5-R7],
current implementation just flushes the last sub-list, i.e., [R5-R7].
The fix flushes previous sub-lists if any.

Fixes golang/go#19142

Change-Id: Ic4eaec76e4f654bf0b92b398b71b2050cede3cbb
Reviewed-on: https://go-review.googlesource.com/37172
Reviewed-by: Cherry Zhang <[email protected]>
Run-TryBot: Cherry Zhang <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>

Author: wei xiao

arm/armasm/plan9x.go

@@ -185,6 +185,8 @@ func plan9Arg(inst *Inst, pc uint64, symname func(uint64) (string, uint64), arg
 				} else {
 					fmt.Fprintf(&buf, "R%d-R%d", start, end)
 				}
+				start = -2
+				end = -2
 			}
 		}
 		for i := 0; i < 16; i++ {
@@ -195,6 +197,8 @@ func plan9Arg(inst *Inst, pc uint64, symname func(uint64) (string, uint64), arg
 				}
 				start = i
 				end = i
+			} else {
+				flush()
 			}
 		}
 		flush()

arm/armasm/testdata/decode.txt

@@ -304,3 +304,4 @@ ff818c71|	1	gnu	strdvc r8, [ip, pc]
 |6b5721d3	1	gnu	error: unknown instruction
 |76452001	1	gnu	error: unknown instruction
 |97acd647	1	gnu	error: unknown instruction
+ed003be9|	1	plan9	LDMDB [R0,R2-R3,R5-R7], R11!