Add getUnrollingPreferences to TTI

Allow targets to customize the default behavior of the generic loop unrolling
transformation. This will be used by the PowerPC backend when targeting the A2
core (which is in-order with a deep pipeline), and using more aggressive
defaults is important.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189565 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 14 insertions, 0 deletions

diff --git a/include/llvm/Analysis/TargetTransformInfo.h b/include/llvm/Analysis/TargetTransformInfo.h
index 06810a7de0..908612c6fa 100644
--- a/include/llvm/Analysis/TargetTransformInfo.h
+++ b/include/llvm/Analysis/TargetTransformInfo.h
@@ -191,6 +191,20 @@ public:
   /// incurs significant execution cost.
   virtual bool isLoweredToCall(const Function *F) const;
 
+  /// Parameters that control the generic loop unrolling transformation.
+  struct UnrollingPreferences {
+    unsigned Threshold; ///< The cost threshold for the unrolled loop.
+    unsigned OptSizeThreshold; ///< The cost threshold for the unrolled loop
+                               ///< when optimizing for size.
+    bool     Partial;   ///< Allow partial loop unrolling.
+    bool     Runtime;   ///< Perform runtime unrolling.
+  };
+
+  /// \brief Get target-customized preferences for the generic loop unrolling
+  /// transformation. Returns true if the UnrollingPreferences struct has been
+  /// initialized.
+  virtual bool getUnrollingPreferences(UnrollingPreferences &UP) const;
+
   /// @}
 
   /// \name Scalar Target Information