[llvm-commits] [llvm] r113439 - in /llvm/trunk: lib/Transforms/Scalar/LoopUnrollPass.cpp test/Transforms/LoopUnroll/call.ll

[Chris Lattner]

On Sep 8, 2010, at 4:10 PM, Owen Anderson wrote:

> Author: resistor
> Date: Wed Sep  8 18:10:07 2010
> New Revision: 113439
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=113439&view=rev
> Log:
> Relax the "don't unroll loops containing calls" rule.  Instead, when a loop contains a call, lower the
> unrolling threshold to the optimize-for-size threshold.  Basically, for loops containing calls, unrolling
> can still be profitable as long as the loop is REALLY small.

This doesn't seem like the right approach: loop unroll should use the same code size estimator as the inliner.  It just treats calls as having a large code size.  As long as the estimator says that the loop body (minus any expected shrinkage) is under the threshold, whether it has a call or not shouldn't matter.

-Chris