[PATCH] D54175: [PGO] context sensitive PGO

[Rong Xu via Phabricator via llvm-commits]

xur added inline comments.


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Comment at: lib/Transforms/Instrumentation/PGOInstrumentation.cpp:618
+  // Reserve bit 60-63 for other information purpose.
+  FunctionHash &= 0x0FFFFFFFFFFFFFFF;
+  if (IsCS)
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davidxl wrote:
> This won't work well -- the non-CS FunctionHash may collide with CS hash. How do you differentiate?  
> 
> Also doing this for nonCS profiling also breaks the backward compatibility -- old profile with high bits set in hash won't be found anymore. It may also create more hash conflicts.
That is the reason I bump the version number.  I use the version number to tell if this is old Hash format or new Hash format.


https://reviews.llvm.org/D54175