From 41a1550ef59b0eaab87e55393d6441ec06b6f2a7 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Tue, 4 Jan 2011 18:54:18 +0000
Subject: [PATCH] Branch instructions don't produce values, so there's no need
 to generate a value number for them.  This avoids adding them to the various
 value numbering tables, resulting in a minor (~3%) speedup for GVN on 40.gcc.

llvm-svn: 122819
---
 llvm/lib/Transforms/Scalar/GVN.cpp | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 43e850c65e88..cf82ebc027f8 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1670,14 +1670,9 @@ bool GVN::processInstruction(Instruction *I,
     return Changed;
   }
 
-  uint32_t NextNum = VN.getNextUnusedValueNumber();
-  unsigned Num = VN.lookup_or_add(I);
-
   // For conditions branches, we can perform simple conditional propagation on
   // the condition value itself.
   if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
-    insert_table(Num, I, I->getParent());
-  
     if (!BI->isConditional() || isa<Constant>(BI->getCondition()))
       return false;
     
@@ -1699,6 +1694,9 @@ bool GVN::processInstruction(Instruction *I,
     return false;
   }
 
+  uint32_t NextNum = VN.getNextUnusedValueNumber();
+  unsigned Num = VN.lookup_or_add(I);
+
   // Allocations are always uniquely numbered, so we can save time and memory
   // by fast failing them.
   if (isa<AllocaInst>(I) || isa<TerminatorInst>(I) || isa<PHINode>(I)) {