[PATCH] D44735: [LV] Add TTI::shouldMaximizeVectorBandwidth to allow enabling it per target

[Krzysztof Parzyszek via Phabricator via llvm-commits]

kparzysz created this revision.
kparzysz added reviewers: hsaito, dcaballe.

The default implementation returns false and keeps the current behavior.

This change is related to https://reviews.llvm.org/D44523 and https://reviews.llvm.org/D44574.


Repository:
  rL LLVM

https://reviews.llvm.org/D44735

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


Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -6139,7 +6139,8 @@
   }
 
   unsigned MaxVF = MaxVectorSize;
-  if (MaximizeBandwidth && !OptForSize) {
+  if (TTI.shouldMaximizeVectorBandwidth(OptForSize) ||
+      (MaximizeBandwidth && !OptForSize)) {
     // Collect all viable vectorization factors larger than the default MaxVF
     // (i.e. MaxVectorSize).
     SmallVector<unsigned, 8> VFs;
Index: lib/Analysis/TargetTransformInfo.cpp
===================================================================
--- lib/Analysis/TargetTransformInfo.cpp
+++ lib/Analysis/TargetTransformInfo.cpp
@@ -333,6 +333,10 @@
 unsigned TargetTransformInfo::getMinVectorRegisterBitWidth() const {
   return TTIImpl->getMinVectorRegisterBitWidth();
 }
+ 
+bool TargetTransformInfo::shouldMaximizeVectorBandwidth(bool OptSize) const {
+  return TTIImpl->shouldMaximizeVectorBandwidth(OptSize);
+}
 
 bool TargetTransformInfo::shouldConsiderAddressTypePromotion(
     const Instruction &I, bool &AllowPromotionWithoutCommonHeader) const {
Index: include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfoImpl.h
+++ include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -346,6 +346,8 @@
   unsigned getRegisterBitWidth(bool Vector) const { return 32; }
 
   unsigned getMinVectorRegisterBitWidth() { return 128; }
+ 
+  bool shouldMaximizeVectorBandwidth(bool OptSize) const { return false; }
 
   bool
   shouldConsiderAddressTypePromotion(const Instruction &I,
Index: include/llvm/Analysis/TargetTransformInfo.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfo.h
+++ include/llvm/Analysis/TargetTransformInfo.h
@@ -666,6 +666,14 @@
   /// \return The width of the smallest vector register type.
   unsigned getMinVectorRegisterBitWidth() const;
 
+  /// \return True if the vectorization factor should be chosen to
+  /// make the vector of the smallest element type match the size of a
+  /// vector register. For wider element types, this could result in
+  /// creating vectors that span multiple vector registers.
+  /// If false, the vectorization factor will be chosen based on the
+  /// size of the widest element type.
+  bool shouldMaximizeVectorBandwidth(bool OptSize) const;
+
   /// \return True if it should be considered for address type promotion.
   /// \p AllowPromotionWithoutCommonHeader Set true if promoting \p I is
   /// profitable without finding other extensions fed by the same input.
@@ -1042,6 +1050,7 @@
   virtual unsigned getNumberOfRegisters(bool Vector) = 0;
   virtual unsigned getRegisterBitWidth(bool Vector) const = 0;
   virtual unsigned getMinVectorRegisterBitWidth() = 0;
+  virtual bool shouldMaximizeVectorBandwidth(bool OptSize) const = 0;
   virtual bool shouldConsiderAddressTypePromotion(
       const Instruction &I, bool &AllowPromotionWithoutCommonHeader) = 0;
   virtual unsigned getCacheLineSize() = 0;
@@ -1332,6 +1341,9 @@
   unsigned getMinVectorRegisterBitWidth() override {
     return Impl.getMinVectorRegisterBitWidth();
   }
+  bool shouldMaximizeVectorBandwidth(bool OptSize) const override {
+    return Impl.shouldMaximizeVectorBandwidth(OptSize);
+  }
   bool shouldConsiderAddressTypePromotion(
       const Instruction &I, bool &AllowPromotionWithoutCommonHeader) override {
     return Impl.shouldConsiderAddressTypePromotion(


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