[PATCH] [msan] Run more optimization after MemorySanitizer pass

[Evgeniy Stepanov]

On Tue, Jan 29, 2013 at 10:19 PM, John McCall <rjmccall at apple.com> wrote:
> On Jan 29, 2013, at 3:29 AM, Evgeniy Stepanov <eugenis at google.com> wrote:
>> ================
>> Comment at: lib/CodeGen/BackendUtil.cpp:190
>> @@ +189,3 @@
>> +  // MemorySanitizer.
>> +  if (Builder.OptLevel > 0) {
>> +    PM.add(createEarlyCSEPass());
>> ----------------
>> Alexey Samsonov wrote:
>>> I think that some comment mentioning the "difference" made by each optimization would
>>> be nice.
>> I don't think explaining the difference made by each pass is possible (and would not be helpful). I can add some aggregate performance numbers tomorrow (need to remeasure).
>
> Are you re-running these passes to regain general optimization opportunities
> after your pass removes or adjusts the msan instrumentation, or are you
> re-running them to exploit opportunities *with* the msan instrumentation?

The latter. They are here to optimize the new code that is generated
in MemorySanitizerPass.