[llvm] r252775 - Add target preference for GatherAllAliases max depth

[Matt Arsenault via llvm-commits]

Author: arsenm
Date: Wed Nov 11 12:44:33 2015
New Revision: 252775

URL: http://llvm.org/viewvc/llvm-project?rev=252775&view=rev
Log:
Add target preference for GatherAllAliases max depth

Modified:
    llvm/trunk/include/llvm/Target/TargetLowering.h
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp

Modified: llvm/trunk/include/llvm/Target/TargetLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetLowering.h?rev=252775&r1=252774&r2=252775&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetLowering.h (original)
+++ llvm/trunk/include/llvm/Target/TargetLowering.h Wed Nov 11 12:44:33 2015
@@ -833,6 +833,10 @@ public:
     return TargetDAGCombineArray[NT >> 3] & (1 << (NT&7));
   }
 
+  unsigned getGatherAllAliasesMaxDepth() const {
+    return GatherAllAliasesMaxDepth;
+  }
+
   /// \brief Get maximum # of store operations permitted for llvm.memset
   ///
   /// This function returns the maximum number of store operations permitted
@@ -1946,6 +1950,12 @@ protected:
   ///      is[Z|FP]ExtFree of the related types is not true.
   virtual bool isExtFreeImpl(const Instruction *I) const { return false; }
 
+  /// Depth that GatherAllAliases should should continue looking for chain
+  /// dependencies when trying to find a more preferrable chain. As an
+  /// approximation, this should be more than the number of consecutive stores
+  /// expected to be merged.
+  unsigned GatherAllAliasesMaxDepth;
+
   /// \brief Specify maximum number of store instructions per memset call.
   ///
   /// When lowering \@llvm.memset this field specifies the maximum number of

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=252775&r1=252774&r2=252775&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Nov 11 12:44:33 2015
@@ -14455,7 +14455,7 @@ void DAGCombiner::GatherAllAliases(SDNod
     // FIXME: The depth check could be made to return the last non-aliasing
     // chain we found before we hit a tokenfactor rather than the original
     // chain.
-    if (Depth > 6) {
+    if (Depth > TLI.getGatherAllAliasesMaxDepth()) {
       Aliases.clear();
       Aliases.push_back(OriginalChain);
       return;

Modified: llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp?rev=252775&r1=252774&r2=252775&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp (original)
+++ llvm/trunk/lib/CodeGen/TargetLoweringBase.cpp Wed Nov 11 12:44:33 2015
@@ -774,6 +774,7 @@ TargetLoweringBase::TargetLoweringBase(c
   MinFunctionAlignment = 0;
   PrefFunctionAlignment = 0;
   PrefLoopAlignment = 0;
+  GatherAllAliasesMaxDepth = 6;
   MinStackArgumentAlignment = 1;
   InsertFencesForAtomic = false;
   MinimumJumpTableEntries = 4;