On 05/14/2013 07:05 AM, Claudio Fontana wrote:
>> Conditional branch range is +-1MB. You'll never see a TB that large. You
>> don't need to emit a branch-across-branch.
>
> Is there maybe a way to do it right even in the corner case where we have
> a huge list of hundreds of thousands of instructions without jumps and then a
> conditional jump?
> Are we _guaranteed_ to never see that large a TB with some kind of define,
> similarly to MAX_CODE_GEN_BUFFER_SIZE?
There are three mechanisms that all limit TB size:
(1) OPC_MAX_SIZE, limiting the number of opcodes emitted,
(2) CF_COUNT_MASK, limiting the number of instructions translated,
(3) Instruction pointer crossing a page boundary, where we end a TB
and re-verify the page protection bits of the new page.
Nr 1 is probably the most significant, since it most directly relates to
the number of output instructions, and thus the resulting TB size.
r~
