[llvm-commits] [llvm] r122819 - /llvm/trunk/lib/Transforms/Scalar/GVN.cpp

[Owen Anderson]

Author: resistor
Date: Tue Jan  4 12:54:18 2011
New Revision: 122819

URL: http://llvm.org/viewvc/llvm-project?rev=122819&view=rev
Log:
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.

Modified:
    llvm/trunk/lib/Transforms/Scalar/GVN.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=122819&r1=122818&r2=122819&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Tue Jan  4 12:54:18 2011
@@ -1670,14 +1670,9 @@
     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 @@
     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)) {