On 12/10/2015 10:47 AM, Sergey Fedorov wrote:
The "PC advancement" trick was used just after recognizing that a breakpoint exception was going to be generated. This trick has had two points: 1. Guarantee that tb->size isn't zero: there are many places where it's expected to be non-zero. In fact, that is even stated in the comment for this field. 2. Try to satisfy disassembler's check for instruction length. To this end, PC advancement was done for estimated instruction length, but actually, didn't work properly in variable-instruction-length cases.Substitute this trick with checking for TB size at the end of translation. If we get an empty TB then just set tb->size to 1 and skip disassembling. Setting tb->size to 1 is enough to get correct behaviour, whereas an empty TB doesn't obviously need to be disassembled.
This doesn't help when the TB already has instructions, the TB would ordinarily cross a page boundary, and the breakpoint is at the page boundary.
r~
