Pass EphValues by const-ref as it is not modified in the callee

[sebpop]

LGTM.

llvm/trunk/include/llvm/Analysis/CodeMetrics.h

struct CodeMetrics {
   /// The inliner is more aggressive with inlining vector kernels.
   unsigned NumVectorInsts = 0;
 
   /// \brief How many 'ret' instructions the blocks contain.
   unsigned NumRets = 0;
 
   /// \brief Add information about a block to the current state.
   void analyzeBasicBlock(const BasicBlock *BB, const TargetTransformInfo &TTI,
-                         SmallPtrSetImpl<const Value*> &EphValues);
+                         const SmallPtrSetImpl<const Value*> &EphValues);
 
   /// \brief Collect a loop's ephemeral values (those used only by an assume
   /// or similar intrinsics in the loop).
   static void collectEphemeralValues(const Loop *L, AssumptionCache *AC,
                                      SmallPtrSetImpl<const Value *> &EphValues);
 
   /// \brief Collect a functions's ephemeral values (those used only by an
   /// assume or similar intrinsics in the function).
   static void collectEphemeralValues(const Function *L, AssumptionCache *AC,
                                      SmallPtrSetImpl<const Value *> &EphValues);
 };
 
 }
 
 #endif

llvm/trunk/lib/Analysis/CodeMetrics.cpp

void CodeMetrics::collectEphemeralValues(
 
   completeEphemeralValues(WorkSet, EphValues);
 }
 
 /// Fill in the current structure with information gleaned from the specified
 /// block.
 void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB,
                                     const TargetTransformInfo &TTI,
-                                    SmallPtrSetImpl<const Value*> &EphValues) {
+                                    const SmallPtrSetImpl<const Value*> &EphValues) {
   ++NumBlocks;
   unsigned NumInstsBeforeThisBB = NumInsts;
   for (const Instruction &I : *BB) {
     // Skip ephemeral values.
     if (EphValues.count(&I))
       continue;
 
     // Special handling for calls.