Now using a variant of the existing inlining heuristics to decide whether to create a given specialization of a function in PartialSpecialization. If the total performance bonus across all callsites passing the same constant exceeds the specialization cost, we create the specialization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116158 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 70 insertions, 0 deletions

diff --git a/lib/Analysis/InlineCost.cpp b/lib/Analysis/InlineCost.cpp
index a0e2ec7..b103897 100644
--- a/lib/Analysis/InlineCost.cpp
+++ b/lib/Analysis/InlineCost.cpp
@@ -312,6 +312,42 @@ bool InlineCostAnalyzer::FunctionInfo::NeverInline()
           Metrics.containsIndirectBr);
 
 }
+// getSpecializationBonus - The heuristic used to determine the per-call
+// performance boost for using a specialization of Callee with argument
+// specializedArgNo replaced by a constant.
+int InlineCostAnalyzer::getSpecializationBonus(Function *Callee,
+         SmallVectorImpl<unsigned> &SpecializedArgNos)
+{
+  if (Callee->mayBeOverridden())
+    return 0;
+  
+  int Bonus = 0;
+  // If this function uses the coldcc calling convention, prefer not to
+  // specialize it.
+  if (Callee->getCallingConv() == CallingConv::Cold)
+    Bonus -= InlineConstants::ColdccPenalty;
+  
+  // Get information about the callee.
+  FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee];
+  
+  // If we haven't calculated this information yet, do so now.
+  if (CalleeFI->Metrics.NumBlocks == 0)
+    CalleeFI->analyzeFunction(Callee);
+
+
+  for (unsigned i = 0, s = SpecializedArgNos.size();
+       i < s; ++i )
+  {
+    Bonus += CalleeFI->ArgumentWeights[SpecializedArgNos[i]].ConstantBonus;
+  }
+  // Calls usually take a long time, so they make the specialization gain 
+  // smaller.
+  Bonus -= CalleeFI->Metrics.NumCalls * InlineConstants::CallPenalty;
+
+  return Bonus;
+}
+
+
 // getInlineCost - The heuristic used to determine if we should inline the
 // function call or not.
 //
@@ -442,6 +478,40 @@ InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
   return llvm::InlineCost::get(InlineCost);
 }
 
+// getSpecializationCost - The heuristic used to determine the code-size
+// impact of creating a specialized version of Callee with argument
+// SpecializedArgNo replaced by a constant.
+InlineCost InlineCostAnalyzer::getSpecializationCost(Function *Callee,
+                               SmallVectorImpl<unsigned> &SpecializedArgNos)
+{
+  // Don't specialize functions which can be redefined at link-time to mean
+  // something else.
+  if (Callee->mayBeOverridden())
+    return llvm::InlineCost::getNever();
+  
+  // Get information about the callee.
+  FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee];
+  
+  // If we haven't calculated this information yet, do so now.
+  if (CalleeFI->Metrics.NumBlocks == 0)
+    CalleeFI->analyzeFunction(Callee);
+
+  int Cost = 0;
+  
+  // Look at the orginal size of the callee.  Each instruction counts as 5.
+  Cost += CalleeFI->Metrics.NumInsts * InlineConstants::InstrCost;
+
+  // Offset that with the amount of code that can be constant-folded
+  // away with the given arguments replaced by constants.
+  for (SmallVectorImpl<unsigned>::iterator an = SpecializedArgNos.begin(),
+       ae = SpecializedArgNos.end(); an != ae; ++an)
+  {
+    Cost -= CalleeFI->ArgumentWeights[*an].ConstantWeight;
+  }
+
+  return llvm::InlineCost::get(Cost);
+}
+
 // getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a
 // higher threshold to determine if the function call should be inlined.
 float InlineCostAnalyzer::getInlineFudgeFactor(CallSite CS) {