From a05a81b10ae6e2fc4f22a59bdb7c7417cca41cfd Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Tue, 10 Jul 2007 00:09:25 +0000
Subject: [PATCH] Use a cheaper test, delaying calling find_leader() until we
 know that it's necessary.  This improves the time to optimize Anton's
 testcase from 21.1s to 17.6s.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@38479 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/GVNPRE.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/Transforms/Scalar/GVNPRE.cpp b/lib/Transforms/Scalar/GVNPRE.cpp
index 4a5dca94098..007c6777195 100644
--- a/lib/Transforms/Scalar/GVNPRE.cpp
+++ b/lib/Transforms/Scalar/GVNPRE.cpp
@@ -565,6 +565,7 @@ class ValueNumberedSet {
     bool insert(Value* v) { return contents.insert(v); }
     void insert(iterator I, iterator E) { contents.insert(I, E); }
     void erase(Value* v) { contents.erase(v); }
+    unsigned count(Value* v) { return contents.count(v); }
     size_t size() { return contents.size(); }
     
     void set(unsigned i)  {
@@ -1173,15 +1174,16 @@ bool GVNPRE::elimination() {
           isa<ShuffleVectorInst>(BI) || isa<InsertElementInst>(BI) ||
           isa<ExtractElementInst>(BI) || isa<SelectInst>(BI) ||
           isa<CastInst>(BI) || isa<GetElementPtrInst>(BI)) {
-         Value *leader = find_leader(availableOut[BB], VN.lookup(BI));
-  
-        if (leader != 0)
+        
+        if (availableOut[BB].test(VN.lookup(BI)) && ! availableOut[BB].count(BI)) {
+          Value *leader = find_leader(availableOut[BB], VN.lookup(BI));
           if (Instruction* Instr = dyn_cast<Instruction>(leader))
             if (Instr->getParent() != 0 && Instr != BI) {
               replace.push_back(std::make_pair(BI, leader));
               erase.push_back(BI);
               ++NumEliminated;
             }
+        }
       }
     }
   }
-- 
2.34.1