[LLVMdev] RFC: GLIBCXX_DEBUG ScheduleDAG Patch
evan.cheng at apple.com
Fri Jan 4 10:59:20 PST 2008
On Jan 2, 2008, at 12:44 PM, David Greene wrote:
> On Saturday 22 December 2007 02:33, Evan Cheng wrote:
>>> After some very simple testing, I see slowdowns of around 1.7%. I
>>> this is ok, but want to check.
>> Can you clarify? Is this 1.7% slowdown of scheduling time or overall
>> codegen time? If it's the later, then it seems a bit too much. Also,
>> please test it with all the MultiSource/Applications.
> It's 1.7% overall.
That seems somewhat steep. Can you see how much of the scheduling
slow down there is?
> Does the nightly test build provide compile-time information? I
> see from
> the Makefile that it uses -time-passes. I assume the "Today's LLC
> header on the nightly page comes from that and reflects the compile
> for the test.
The better way is to add a custom report for this. See
TEST.llc.Makefile and TEST.llc.report under llvm-test as an example.
You can do make TEST=llc to generate custom reports. If this change
can somehow be optionally controlled, then you can set it as llcbeta
option and write a custom report that compare the time spend in some
particular passes (TEST.beta-compare is an example, but it comparesf
The biggest problem is right now time spent in scheduling is lumped
into "DAG->DAG Instruction Selection" time because it's part of the
pass. It would be nice if we can somehow bring it out.
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