Switch a worklist in CodeGenPrepare to SmallVector and increase the inline

capacity on the Visited SmallPtrSet. On 403.gcc, this is about a 4.5% speedup of
CodeGenPrepare time (which itself is 10% of time spent in the backend).

This is progress towards PR8889.

llvm-svn: 122741

llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp

@@ -623,8 +623,8 @@ bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
   
   // Try to collapse single-value PHI nodes.  This is necessary to undo 
   // unprofitable PRE transformations.
-  std::vector<Value*> worklist;
-  SmallPtrSet<Value*, 4> Visited;
+  SmallVector<Value*, 8> worklist;
+  SmallPtrSet<Value*, 16> Visited;
   worklist.push_back(Addr);
   
   // Use a worklist to iteratively look through PHI nodes, and ensure that