Revert r111375, "move gep decomposition out of ValueTracking into BasicAA. The

form of", it doesn't pass tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111385 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 0 deletions

diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h
index 7b6026fea0..b9634f04ec 100644
--- a/include/llvm/Analysis/ValueTracking.h
+++ b/include/llvm/Analysis/ValueTracking.h
@@ -77,6 +77,25 @@ namespace llvm {
   ///
   bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0);
 
+  /// DecomposeGEPExpression - If V is a symbolic pointer expression, decompose
+  /// it into a base pointer with a constant offset and a number of scaled
+  /// symbolic offsets.
+  ///
+  /// The scaled symbolic offsets (represented by pairs of a Value* and a scale
+  /// in the VarIndices vector) are Value*'s that are known to be scaled by the
+  /// specified amount, but which may have other unrepresented high bits. As
+  /// such, the gep cannot necessarily be reconstructed from its decomposed
+  /// form.
+  ///
+  /// When TargetData is around, this function is capable of analyzing
+  /// everything that Value::getUnderlyingObject() can look through.  When not,
+  /// it just looks through pointer casts.
+  ///
+  const Value *DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
+                 SmallVectorImpl<std::pair<const Value*, int64_t> > &VarIndices,
+                                      const TargetData *TD);
+    
+  
   
   /// FindInsertedValue - Given an aggregrate and an sequence of indices, see if
   /// the scalar value indexed is already around as a register, for example if