[NFC] [IslNodeBuilder, GPUNodeBuilder] Unify mechanism for looking up replacement Values.

We populate `IslNodeBuilder::ValueMap` which contains replacements for
`llvm::Value`s. There was no simple method to pick up a replacement if
it exists, otherwise fall back to the original.

Create a method `IslNodeBuilder::getLatestValue` which provides this
functionality.

This will be used in a later patch to fix bugs in `PPCGCodeGeneration`
where the latest value is not being used.

Differential Revision: https://reviews.llvm.org/D36000

llvm-svn: 309674

2 files changed, 16 insertions, 5 deletions

diff --git a/polly/include/polly/CodeGen/IslNodeBuilder.h b/polly/include/polly/CodeGen/IslNodeBuilder.h
index f7e07e7e832..1d94d41c496 100644
--- a/polly/include/polly/CodeGen/IslNodeBuilder.h
+++ b/polly/include/polly/CodeGen/IslNodeBuilder.h
@@ -262,6 +262,14 @@ protected:
   /// @param NewValues A map that maps certain llvm::Values to new llvm::Values.
   void updateValues(ValueMapT &NewValues);
 
+  /// Return the most up-to-date version of the llvm::Value for code generation.
+  /// @param Original The Value to check for an up to date version.
+  /// @returns A remapped `Value` from ValueMap, or `Original` if no mapping
+  ///          exists.
+  /// @see IslNodeBuilder::updateValues
+  /// @see IslNodeBuilder::ValueMap
+  Value *getLatestValue(Value *Original) const;
+
   /// Generate code for a marker now.
   ///
   /// For mark nodes with an unknown name, we just forward the code generation
diff --git a/polly/lib/CodeGen/IslNodeBuilder.cpp b/polly/lib/CodeGen/IslNodeBuilder.cpp
index aee7e209714..ecc84f40998 100644
--- a/polly/lib/CodeGen/IslNodeBuilder.cpp
+++ b/polly/lib/CodeGen/IslNodeBuilder.cpp
@@ -324,11 +324,7 @@ void IslNodeBuilder::getReferencesInSubtree(__isl_keep isl_ast_node *For,
   //     2.  test/Isl/CodeGen/OpenMP/loop-body-references-outer-values-3.ll
   SetVector<Value *> ReplacedValues;
   for (Value *V : Values) {
-    auto It = ValueMap.find(V);
-    if (It == ValueMap.end())
-      ReplacedValues.insert(V);
-    else
-      ReplacedValues.insert(It->second);
+    ReplacedValues.insert(getLatestValue(V));
   }
   Values = ReplacedValues;
 }
@@ -349,6 +345,13 @@ void IslNodeBuilder::updateValues(ValueMapT &NewValues) {
   }
 }
 
+Value *IslNodeBuilder::getLatestValue(Value *Original) const {
+  auto It = ValueMap.find(Original);
+  if (It == ValueMap.end())
+    return Original;
+  return It->second;
+}
+
 void IslNodeBuilder::createUserVector(__isl_take isl_ast_node *User,
                                       std::vector<Value *> &IVS,
                                       __isl_take isl_id *IteratorID,