[PATCH] D79112: [SelectionDAG] Add the option of disabling generic combines.

[Marcello Maggioni via Phabricator via llvm-commits]

kariddi updated this revision to Diff 261014.
kariddi added a comment.

Adding an attribute in DAGCombiner that caches disableGenericCombines() calls.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D79112/new/

https://reviews.llvm.org/D79112

Files:
  llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp


Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -130,12 +130,14 @@
   class DAGCombiner {
     SelectionDAG &DAG;
     const TargetLowering &TLI;
+    const SelectionDAGTargetInfo *STI;
     CombineLevel Level;
     CodeGenOpt::Level OptLevel;
     bool LegalDAG = false;
     bool LegalOperations = false;
     bool LegalTypes = false;
     bool ForCodeSize;
+    bool DisableGenericCombines;
 
     /// Worklist of all of the nodes that need to be simplified.
     ///
@@ -223,9 +225,11 @@
 
   public:
     DAGCombiner(SelectionDAG &D, AliasAnalysis *AA, CodeGenOpt::Level OL)
-        : DAG(D), TLI(D.getTargetLoweringInfo()), Level(BeforeLegalizeTypes),
-          OptLevel(OL), AA(AA) {
+        : DAG(D), TLI(D.getTargetLoweringInfo()),
+          STI(D.getSubtarget().getSelectionDAGInfo()),
+          Level(BeforeLegalizeTypes), OptLevel(OL), AA(AA) {
       ForCodeSize = DAG.shouldOptForSize();
+      DisableGenericCombines = STI && STI->disableGenericCombines(OptLevel);
 
       MaximumLegalStoreInBits = 0;
       // We use the minimum store size here, since that's all we can guarantee
@@ -1649,7 +1653,9 @@
 }
 
 SDValue DAGCombiner::combine(SDNode *N) {
-  SDValue RV = visit(N);
+  SDValue RV;
+  if (DisableGenericCombines)
+    RV = visit(N);
 
   // If nothing happened, try a target-specific DAG combine.
   if (!RV.getNode()) {
@@ -11747,7 +11753,6 @@
   if (!AllowFusionGlobally && !isContractable(N))
     return SDValue();
 
-  const SelectionDAGTargetInfo *STI = DAG.getSubtarget().getSelectionDAGInfo();
   if (STI && STI->generateFMAsInMachineCombiner(OptLevel))
     return SDValue();
 
@@ -11965,7 +11970,6 @@
   if (!AllowFusionGlobally && !isContractable(N))
     return SDValue();
 
-  const SelectionDAGTargetInfo *STI = DAG.getSubtarget().getSelectionDAGInfo();
   if (STI && STI->generateFMAsInMachineCombiner(OptLevel))
     return SDValue();
 
Index: llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h
===================================================================
--- llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h
+++ llvm/include/llvm/CodeGen/SelectionDAGTargetInfo.h
@@ -160,6 +160,11 @@
   virtual bool generateFMAsInMachineCombiner(CodeGenOpt::Level OptLevel) const {
     return false;
   }
+
+  // Return true if the Machine Combiner should disable generic combines.
+  virtual bool disableGenericCombines(CodeGenOpt::Level OptLevel) const {
+    return false;
+  }
 };
 
 } // end namespace llvm


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