Loop Strength Reduce: Scaling factor cost.

Account for the cost of scaling factor in Loop Strength Reduce when rating the
formulae. This uses a target hook.

The default implementation of the hook is: if the addressing mode is legal, the
scaling factor is free.

<rdar://problem/13806271>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183045 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 0 deletions

diff --git a/include/llvm/Analysis/TargetTransformInfo.h b/include/llvm/Analysis/TargetTransformInfo.h
index a9d6725d86..eb29e3483d 100644
--- a/include/llvm/Analysis/TargetTransformInfo.h
+++ b/include/llvm/Analysis/TargetTransformInfo.h
@@ -225,6 +225,16 @@ public:
                                      int64_t BaseOffset, bool HasBaseReg,
                                      int64_t Scale) const;
 
+  /// \brief Return the cost of the scaling factor used in the addressing
+  /// mode represented by AM for this target, for a load/store
+  /// of the specified type.
+  /// If the AM is supported, the return value must be >= 0.
+  /// If the AM is not supported, it returns a negative value.
+  /// TODO: Handle pre/postinc as well.
+  virtual int getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
+                                   int64_t BaseOffset, bool HasBaseReg,
+                                   int64_t Scale) const;
+
   /// isTruncateFree - Return true if it's free to truncate a value of
   /// type Ty1 to type Ty2. e.g. On x86 it's free to truncate a i32 value in
   /// register EAX to i16 by referencing its sub-register AX.