[PATCH] D89723: [CSSPGO][llvm-profgen]Context-sensitive profile data generation

Wei Mi via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Nov 25 16:32:57 PST 2020

wmi accepted this revision.
wmi added a comment.
This revision is now accepted and ready to land.
Herald added a subscriber: lxfind.


Comment at: llvm/tools/llvm-profgen/PerfReader.h:214-215
+// Class for sample unwinding
+class VirtualUnwinder {
wlei wrote:
> wmi wrote:
> > This virtual unwinder is not doing the classic unwinding thing. It is walking through the LBR stack of a LBR sample, based on the sample's callstack, and infer the callstack for each address range covered by the LBR sample. The comment can be more clear about it.
> Thanks for your suggestion, more comments are added.
That is helpful. Thanks. 

Comment at: llvm/tools/llvm-profgen/ProfileGenerator.cpp:62-70
+  A: (300, 0)
+  B: (0, 100)
+  C: (0, 200)
+  respectively. With these points, follwing logic finds two disjoint
+  region of
wlei wrote:
> wmi wrote:
> > Why there is region [A, B]: 300, but B: (0, 100) only has 100 sample count?
> Sorry for the confusion. See the graph below, here B:(0, 100) is the boundary point, 0 means no samples begin at B, 100 means one sample(sample1) ends at B whose count is 100. I changed the explanation in the comment, see whether it's clear or not.
>   |<--100-->|                  Sample1
>   |<------200------>|          Sample2
>   A         B       C
It is helpful too. Thanks.

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