[PATCH] D30680: new method TargetTransformInfo::supportsVectorElementLoadStore() for LoopVectorizer

[Jonas Paulsson via Phabricator via llvm-commits]

jonpa created this revision.
Herald added a subscriber: mzolotukhin.

Since SystemZ supports vector element load / store instructions, there is no need for extracts / inserts if a vector load / store gets scalarized. This patch lets Target specify that it supports such instructions by means of a new TTI virtual method that defaults to false.

The use for this is in the LoopVectorizer getScalarizationOverhead() method. As a side note, I am thinking perhaps this function should go into BasicTTIImpl.h, but since there are a at least two changes in review in this area, I am waiting with that.


https://reviews.llvm.org/D30680

Files:
  include/llvm/Analysis/TargetTransformInfo.h
  include/llvm/Analysis/TargetTransformInfoImpl.h
  lib/Analysis/TargetTransformInfo.cpp
  lib/Target/SystemZ/SystemZTargetTransformInfo.h
  lib/Transforms/Vectorize/LoopVectorize.cpp


Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3723,13 +3723,15 @@
 
   unsigned Cost = 0;
   Type *RetTy = ToVectorTy(I->getType(), VF);
-  if (!RetTy->isVoidTy())
+  if (!RetTy->isVoidTy() &&
+      (!isa<LoadInst>(I) || !TTI.supportsVectorElementLoadStore()))
     Cost += TTI.getScalarizationOverhead(RetTy, true, false);
 
   if (CallInst *CI = dyn_cast<CallInst>(I)) {
     SmallVector<const Value *, 4> Operands(CI->arg_operands());
     Cost += TTI.getOperandsScalarizationOverhead(Operands, VF);
-  } else {
+  }
+  else if (!isa<StoreInst>(I) || !TTI.supportsVectorElementLoadStore()) {
     SmallVector<const Value *, 4> Operands(I->operand_values());
     Cost += TTI.getOperandsScalarizationOverhead(Operands, VF);
   }
Index: lib/Target/SystemZ/SystemZTargetTransformInfo.h
===================================================================
--- lib/Target/SystemZ/SystemZTargetTransformInfo.h
+++ lib/Target/SystemZ/SystemZTargetTransformInfo.h
@@ -55,6 +55,8 @@
   unsigned getNumberOfRegisters(bool Vector);
   unsigned getRegisterBitWidth(bool Vector);
 
+  bool supportsVectorElementLoadStore() { return true; }
+
   bool isFPVectorizationPotentiallyUnsafe() { return false; }
 
   int getArithmeticInstrCost(
Index: lib/Analysis/TargetTransformInfo.cpp
===================================================================
--- lib/Analysis/TargetTransformInfo.cpp
+++ lib/Analysis/TargetTransformInfo.cpp
@@ -197,6 +197,10 @@
   return TTIImpl->getOperandsScalarizationOverhead(Args, VF, VecTy);
 }
 
+bool TargetTransformInfo::supportsVectorElementLoadStore() const {
+  return TTIImpl->supportsVectorElementLoadStore();
+}
+
 bool TargetTransformInfo::enableAggressiveInterleaving(bool LoopHasReductions) const {
   return TTIImpl->enableAggressiveInterleaving(LoopHasReductions);
 }
Index: include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfoImpl.h
+++ include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -262,6 +262,8 @@
   unsigned getOperandsScalarizationOverhead(ArrayRef<const Value *> Args,
                                   unsigned VF, Type *VecTy) { return 0; }
 
+  bool supportsVectorElementLoadStore() { return false; }
+
   bool enableAggressiveInterleaving(bool LoopHasReductions) { return false; }
 
   bool enableInterleavedAccessVectorization() { return false; }
Index: include/llvm/Analysis/TargetTransformInfo.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfo.h
+++ include/llvm/Analysis/TargetTransformInfo.h
@@ -434,6 +434,8 @@
   unsigned getOperandsScalarizationOverhead(ArrayRef<const Value *> Args,
                                      unsigned VF, Type *VecTy = nullptr) const;
 
+  bool supportsVectorElementLoadStore() const;
+
   /// \brief Don't restrict interleaved unrolling to small loops.
   bool enableAggressiveInterleaving(bool LoopHasReductions) const;
 
@@ -775,6 +777,7 @@
   getScalarizationOverhead(Type *Ty, bool Insert, bool Extract) = 0;
   virtual unsigned getOperandsScalarizationOverhead(ArrayRef<const Value *> Args,
                                                    unsigned VF, Type *VecTy) = 0;
+  virtual bool supportsVectorElementLoadStore() = 0;
   virtual bool enableAggressiveInterleaving(bool LoopHasReductions) = 0;
   virtual bool enableInterleavedAccessVectorization() = 0;
   virtual bool isFPVectorizationPotentiallyUnsafe() = 0;
@@ -980,6 +983,10 @@
     return Impl.getOperandsScalarizationOverhead(Args, VF, VecTy);
   }
 
+  bool supportsVectorElementLoadStore() override {
+    return Impl.supportsVectorElementLoadStore();
+  }
+
   bool enableAggressiveInterleaving(bool LoopHasReductions) override {
     return Impl.enableAggressiveInterleaving(LoopHasReductions);
   }


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