From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Wed, 11 Nov 2015 18:44:33 +0000 (+0000)
Subject: Add target preference for GatherAllAliases max depth
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=b8f7aeb21802f773effd28222f24f00942b50c50

Add target preference for GatherAllAliases max depth

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252775 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
index d1770968d43..cb5a5796e98 100644
--- a/include/llvm/Target/TargetLowering.h
+++ b/include/llvm/Target/TargetLowering.h
@@ -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
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 2dd71bd4e7f..a1edb29e486 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -14455,7 +14455,7 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain,
     // 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;
diff --git a/lib/CodeGen/TargetLoweringBase.cpp b/lib/CodeGen/TargetLoweringBase.cpp
index 69eec888745..45c6c9e4b2a 100644
--- a/lib/CodeGen/TargetLoweringBase.cpp
+++ b/lib/CodeGen/TargetLoweringBase.cpp
@@ -774,6 +774,7 @@ TargetLoweringBase::TargetLoweringBase(const TargetMachine &tm) : TM(tm) {
   MinFunctionAlignment = 0;
   PrefFunctionAlignment = 0;
   PrefLoopAlignment = 0;
+  GatherAllAliasesMaxDepth = 6;
   MinStackArgumentAlignment = 1;
   InsertFencesForAtomic = false;
   MinimumJumpTableEntries = 4;