[llvm-commits] [llvm] r123684 - /llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp

[Owen Anderson]

Author: resistor
Date: Mon Jan 17 16:39:54 2011
New Revision: 123684

URL: http://llvm.org/viewvc/llvm-project?rev=123684&view=rev
Log:
Remove dead code, that I apparently wrote a while back.  We seem to be doing well enough
without whatever this was trying to do.  When/if someone has the time to do some empirical
evaluations, it might be worth it to figure out what this code was trying to do and see if
it's worth resurrecting/fixing.

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

Modified: llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp?rev=123684&r1=123683&r2=123684&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp Mon Jan 17 16:39:54 2011
@@ -99,21 +99,6 @@
   
   unsigned LoopSize = Metrics.NumInsts;
   
-  // If we can identify the induction variable, we know that it will become
-  // constant when we unroll the loop, so factor that into our loop size 
-  // estimate.
-  // FIXME: We have to divide by InlineConstants::InstrCost because the
-  // measure returned by CountCodeReductionForConstant is not an instruction
-  // count, but rather a weight as defined by InlineConstants.  It would 
-  // probably be a good idea to standardize on a single weighting scheme by
-  // pushing more of the logic for weighting into CodeMetrics.
-  if (PHINode *IndVar = L->getCanonicalInductionVariable()) {
-    unsigned SizeDecrease = Metrics.CountCodeReductionForConstant(IndVar);
-    // NOTE: Because SizeDecrease is a fuzzy estimate, we don't want to allow
-    // it to totally negate the cost of unrolling a loop.
-    SizeDecrease = SizeDecrease > LoopSize / 2 ? LoopSize / 2 : SizeDecrease;
-  }
-  
   // Don't allow an estimate of size zero.  This would allows unrolling of loops
   // with huge iteration counts, which is a compile time problem even if it's
   // not a problem for code quality.