Andrea Di Biagio f033db57e9 [TTI] Improved cost heuristic for cttz/ctlz calls.
This patch is a follow-up of r228826 (see code-review: D7506).

Now that SimplifyCFG uses TargetTransformInfo for cost analysis, we 
have to fix the cost heuristic for intrinsic calls to cttz/ctlz.

This patch defines method 'getIntrinsicCost' in BasicTTIImpl: now, BasicTTIImpl
queries TLI to check if a call to cttz/ctlz is cheap for the target.

Added test cases in Transforms/SimplifyCFG/X86 to verify that on x86,
SimplifyCFG only speculates a call to cttz/ctlz if it is cheap.

Differential Revision: http://reviews.llvm.org/D7554


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228829 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 14:22:18 +00:00
2015-01-30 21:59:28 +00:00
2015-02-04 18:46:00 +00:00

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