Make more fields of InlineParams optional.

[eraman]

Summary

InlineHintThreshold and HotCallsiteThreshold are now optional. Also fixes a superfluous comparison while applying hot callsite threshold. NFC.

[chandlerc]

LGTM

include/llvm/Analysis/InlineCost.h

 /// (such as the pre-inliner) might have custom logic to compute \c InlineParams
 /// object.
 
 struct InlineParams {
   /// The default threshold to start with for a callee.
   int DefaultThreshold;
 
   /// Threshold to use for callees with inline hint.
-  int HintThreshold;
+  Optional<int> HintThreshold;
 
   /// Threshold to use for cold callees.
   Optional<int> ColdThreshold;
 
   /// Threshold to use when the caller is optimized for size.
   Optional<int> OptSizeThreshold;
 
   /// Threshold to use when the caller is optimized for minsize.
   Optional<int> OptMinSizeThreshold;
 
   /// Threshold to use when the callsite is considered hot.
-  int HotCallSiteThreshold;
+  Optional<int> HotCallSiteThreshold;
 };
 
 /// Generate the parameters to tune the inline cost analysis based only on the
 /// commandline options.
 InlineParams getInlineParams();
 
 /// Generate the parameters to tune the inline cost analysis based on command
 /// line options. If -inline-threshold option is not explicitly passed,

lib/Analysis/InlineCost.cpp

void CallAnalyzer::updateThreshold(CallSite CS, Function &Callee) {
 
   Function *Caller = CS.getCaller();
 
   // return min(A, B) if B is valid.
   auto MinIfValid = [](int A, Optional<int> B) {
     return B ? std::min(A, B.getValue()) : A;
   };
 
+  // return max(A, B) if B is valid.
+  auto MaxIfValid = [](int A, Optional<int> B) {
+    return B ? std::max(A, B.getValue()) : A;
+  };
+
   // Use the OptMinSizeThreshold or OptSizeThreshold knob if they are available
   // and reduce the threshold if the caller has the necessary attribute.
   if (Caller->optForMinSize())
     Threshold = MinIfValid(Threshold, Params.OptMinSizeThreshold);
   else if (Caller->optForSize())
     Threshold = MinIfValid(Threshold, Params.OptSizeThreshold);
 
   bool HotCallsite = false;
   uint64_t TotalWeight;
   if (CS.getInstruction()->extractProfTotalWeight(TotalWeight) &&
       PSI->isHotCount(TotalWeight)) {
     HotCallsite = true;
   }
 
   // Listen to the inlinehint attribute or profile based hotness information
   // when it would increase the threshold and the caller does not need to
   // minimize its size.
   bool InlineHint = Callee.hasFnAttribute(Attribute::InlineHint) ||
                     PSI->isHotFunction(&Callee);
   if (InlineHint && !Caller->optForMinSize())
-    Threshold = std::max(Threshold, Params.HintThreshold);
+    Threshold = MaxIfValid(Threshold, Params.HintThreshold);
 
-  if (HotCallsite && HotCallSiteThreshold > Threshold &&
-      !Caller->optForMinSize())
-    Threshold = std::max(Threshold, Params.HotCallSiteThreshold);
+  if (HotCallsite && !Caller->optForMinSize())
+    Threshold = MaxIfValid(Threshold, Params.HotCallSiteThreshold);
 
   bool ColdCallee = PSI->isColdFunction(&Callee);
   // For cold callees, use the ColdThreshold knob if it is available and reduces
   // the threshold.
   if (ColdCallee)
     Threshold = MinIfValid(Threshold, Params.ColdThreshold);
 
   // Finally, take the target-specific inlining threshold multiplier into