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>

llvm-svn: 183045

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
index 64f8e96884c..35ce794c7f1 100644
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -108,6 +108,14 @@ bool TargetTransformInfo::isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV,
                                         Scale);
 }
 
+int TargetTransformInfo::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
+                                              int64_t BaseOffset,
+                                              bool HasBaseReg,
+                                              int64_t Scale) const {
+  return PrevTTI->getScalingFactorCost(Ty, BaseGV, BaseOffset, HasBaseReg,
+                                       Scale);
+}
+
 bool TargetTransformInfo::isTruncateFree(Type *Ty1, Type *Ty2) const {
   return PrevTTI->isTruncateFree(Ty1, Ty2);
 }
@@ -457,6 +465,15 @@ struct NoTTI : ImmutablePass, TargetTransformInfo {
     return !BaseGV && BaseOffset == 0 && Scale <= 1;
   }
 
+  int getScalingFactorCost(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
+                           bool HasBaseReg, int64_t Scale) const {
+    // Guess that all legal addressing mode are free.
+    if(isLegalAddressingMode(Ty, BaseGV, BaseOffset, HasBaseReg, Scale))
+      return 0;
+    return -1;
+  }
+
+
   bool isTruncateFree(Type *Ty1, Type *Ty2) const {
     return false;
   }