[CSSPGO][Preinliner] Set default value of sample-profile-inline-limit-max to 3000

[hoy]

Summary

The default value of sample-profile-inline-limit-max is defined as 10000 in sampleprofile.cpp. This is too big for cspreinliner which works with assembly size instead of IR size. The value 3000 turns out to be a good tradeoff. Compared to the value 10000, 3000 gives as good performance and code size, but lower build time.

[wlei]

LGTM.

llvm/tools/llvm-profgen/CSPreInliner.cpp

: UseContextCost(UseContextCostForPreInliner),
       ContextTracker(Profiles, nullptr), ProfileMap(Profiles), Binary(Binary),
       Summary(Summary) {
   // Set default preinliner hot/cold call site threshold tuned with CSSPGO.
   // for good performance with reasonable profile size.
   if (!SampleHotCallSiteThreshold.getNumOccurrences())
     SampleHotCallSiteThreshold = 1500;
   if (!SampleColdCallSiteThreshold.getNumOccurrences())
     SampleColdCallSiteThreshold = 0;
+  if (!ProfileInlineLimitMax.getNumOccurrences())
+    ProfileInlineLimitMax = 3000;
 }
 
 std::vector<StringRef> CSPreInliner::buildTopDownOrder() {
   std::vector<StringRef> Order;
   ProfiledCallGraph ProfiledCG(ContextTracker);
 
   // Now that we have a profiled call graph, construct top-down order
   // by building up SCC and reversing SCC order.