ARM Cost model: Use the size of vector registers and widest vectorizable instruction to determine the max vectorization factor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172010 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/TargetTransformInfo.h

@@ -148,6 +148,9 @@ public:
   /// set to false, it returns the number of scalar registers.
   virtual unsigned getNumberOfRegisters(bool Vector) const;
 
+  /// \return The width of the largest scalar or vector register type.
+  virtual unsigned getRegisterBitWidth(bool Vector) const;
+
   /// \return The maximum unroll factor that the vectorizer should try to
   /// perform for this target. This number depends on the level of parallelism
   /// and the number of execution units in the CPU.

lib/Analysis/TargetTransformInfo.cpp

@@ -92,6 +92,10 @@ unsigned TargetTransformInfo::getNumberOfRegisters(bool Vector) const {
   return PrevTTI->getNumberOfRegisters(Vector);
 }
 
+unsigned TargetTransformInfo::getRegisterBitWidth(bool Vector) const {
+  return PrevTTI->getRegisterBitWidth(Vector);
+}
+
 unsigned TargetTransformInfo::getMaximumUnrollFactor() const {
   return PrevTTI->getMaximumUnrollFactor();
 }
@@ -220,6 +224,10 @@ struct NoTTI : ImmutablePass, TargetTransformInfo {
     return 8;
   }
 
+  unsigned  getRegisterBitWidth(bool Vector) const {
+    return 32;
+  }
+
   unsigned getMaximumUnrollFactor() const {
     return 1;
   }

lib/CodeGen/BasicTargetTransformInfo.cpp

@@ -84,6 +84,7 @@ public:
 
   virtual unsigned getNumberOfRegisters(bool Vector) const;
   virtual unsigned getMaximumUnrollFactor() const;
+  virtual unsigned getRegisterBitWidth(bool Vector) const;
   virtual unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty) const;
   virtual unsigned getShuffleCost(ShuffleKind Kind, Type *Tp,
                                   int Index, Type *SubTp) const;
@@ -183,6 +184,10 @@ unsigned BasicTTI::getNumberOfRegisters(bool Vector) const {
   return 1;
 }
 
+unsigned BasicTTI::getRegisterBitWidth(bool Vector) const {
+  return 32;
+}
+
 unsigned BasicTTI::getMaximumUnrollFactor() const {
   return 1;
 }

lib/Target/ARM/ARMTargetTransformInfo.cpp

@@ -94,6 +94,16 @@ public:
     return 16;
   }
 
+  unsigned getRegisterBitWidth(bool Vector) const {
+    if (Vector) {
+      if (ST->hasNEON())
+        return 128;
+      return 0;
+    }
+
+    return 32;
+  }
+
   unsigned getMaximumUnrollFactor() const {
     // These are out of order CPUs:
     if (ST->isCortexA15() || ST->isSwift())

lib/Target/X86/X86TargetTransformInfo.cpp

@@ -83,6 +83,7 @@ public:
   /// @{
 
   virtual unsigned getNumberOfRegisters(bool Vector) const;
+  virtual unsigned getRegisterBitWidth(bool Vector) const;
   virtual unsigned getMaximumUnrollFactor() const;
   virtual unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty) const;
   virtual unsigned getShuffleCost(ShuffleKind Kind, Type *Tp,
@@ -165,11 +166,27 @@ X86TTI::PopcntSupportKind X86TTI::getPopcntSupport(unsigned TyWidth) const {
 }
 
 unsigned X86TTI::getNumberOfRegisters(bool Vector) const {
+  if (Vector && !ST->hasSSE1())
+    return 0;
+
   if (ST->is64Bit())
     return 16;
   return 8;
 }
 
+unsigned X86TTI::getRegisterBitWidth(bool Vector) const {
+  if (Vector) {
+    if (ST->hasAVX()) return 256;
+    if (ST->hasSSE1()) return 128;
+    return 0;
+  }
+
+  if (ST->is64Bit())
+    return 64;
+  return 32;
+
+}
+
 unsigned X86TTI::getMaximumUnrollFactor() const {
   if (ST->isAtom())
     return 1;

lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -113,9 +113,6 @@ static const unsigned MaxLoopSizeThreshold = 32;
 /// number of pointers. Notice that the check is quadratic!
 static const unsigned RuntimeMemoryCheckThreshold = 4;
 
-/// This is the highest vector width that we try to generate.
-static const unsigned MaxVectorSize = 8;
-
 namespace {
 
 // Forward declarations.
@@ -523,6 +520,10 @@ public:
   /// possible.
   unsigned selectVectorizationFactor(bool OptForSize, unsigned UserVF);
 
+  /// \returns The size (in bits) of the widest type in the code that
+  /// needs to be vectorized. We ignore values that remain scalar such as
+  /// 64 bit loop indices.
+  unsigned getWidestType();
 
   /// \return The most profitable unroll factor.
   /// If UserUF is non-zero then this method finds the best unroll-factor
@@ -2621,6 +2622,20 @@ LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize,
   unsigned TC = SE->getSmallConstantTripCount(TheLoop, TheLoop->getLoopLatch());
   DEBUG(dbgs() << "LV: Found trip count:"<<TC<<"\n");
 
+  unsigned WidestType = getWidestType();
+  unsigned WidestRegister = TTI.getRegisterBitWidth(true);
+  unsigned MaxVectorSize = WidestRegister / WidestType;
+  DEBUG(dbgs() << "LV: The Widest type: " << WidestType << " bits.\n");
+  DEBUG(dbgs() << "LV: The Widest register is:" << WidestRegister << "bits.\n");
+
+  if (MaxVectorSize == 0) {
+    DEBUG(dbgs() << "LV: The target has no vector registers.\n");
+    return 1;
+  }
+
+  assert(MaxVectorSize <= 32 && "Did not expect to pack so many elements"
+         " into one vector.");
+  
   unsigned VF = MaxVectorSize;
 
   // If we optimize the program for size, avoid creating the tail loop.
@@ -2672,6 +2687,36 @@ LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize,
   return Width;
 }
 
+unsigned LoopVectorizationCostModel::getWidestType() {
+  unsigned MaxWidth = 8;
+
+  // For each block.
+  for (Loop::block_iterator bb = TheLoop->block_begin(),
+       be = TheLoop->block_end(); bb != be; ++bb) {
+    BasicBlock *BB = *bb;
+
+    // For each instruction in the loop.
+    for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
+      if (Legal->isUniformAfterVectorization(it))
+        continue;
+
+      Type *T = it->getType();
+
+      if (StoreInst *ST = dyn_cast<StoreInst>(it))
+        T = ST->getValueOperand()->getType();
+
+      // PHINodes and pointers are difficult to analyze, but we catch all other
+      // uses of the types in other instructions.
+      if (isa<PHINode>(it) || T->isPointerTy() || T->isVoidTy())
+        continue;
+
+      MaxWidth = std::max(MaxWidth, T->getScalarSizeInBits());
+    }
+  }
+
+  return MaxWidth;
+}
+
 unsigned
 LoopVectorizationCostModel::selectUnrollFactor(bool OptForSize,
                                                unsigned UserUF) {

test/Transforms/LoopVectorize/ARM/gcc-examples.ll

@@ -0,0 +1,60 @@
+; RUN: opt < %s  -loop-vectorize -mtriple=thumbv7-apple-ios3.0.0 -mcpu=swift -S -dce | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:32:64-v128:32:128-a0:0:32-n32-S32"
+target triple = "thumbv7-apple-ios3.0.0"
+
+@b = common global [2048 x i32] zeroinitializer, align 16
+@c = common global [2048 x i32] zeroinitializer, align 16
+@a = common global [2048 x i32] zeroinitializer, align 16
+
+; Select VF = 8;
+;CHECK: @example1
+;CHECK: load <4 x i32>
+;CHECK: add nsw <4 x i32>
+;CHECK: store <4 x i32>
+;CHECK: ret void
+define void @example1() nounwind uwtable ssp {
+  br label %1
+
+; <label>:1                                       ; preds = %1, %0
+  %indvars.iv = phi i64 [ 0, %0 ], [ %indvars.iv.next, %1 ]
+  %2 = getelementptr inbounds [2048 x i32]* @b, i64 0, i64 %indvars.iv
+  %3 = load i32* %2, align 4
+  %4 = getelementptr inbounds [2048 x i32]* @c, i64 0, i64 %indvars.iv
+  %5 = load i32* %4, align 4
+  %6 = add nsw i32 %5, %3
+  %7 = getelementptr inbounds [2048 x i32]* @a, i64 0, i64 %indvars.iv
+  store i32 %6, i32* %7, align 4
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, 256
+  br i1 %exitcond, label %8, label %1
+
+; <label>:8                                       ; preds = %1
+  ret void
+}
+
+;CHECK: @example10b
+;CHECK: load <2 x i16>
+;CHECK: sext <2 x i16>
+;CHECK: store <2 x i32>
+;CHECK: ret void
+define void @example10b(i16* noalias nocapture %sa, i16* noalias nocapture %sb, i16* noalias nocapture %sc, i32* noalias nocapture %ia, i32* noalias nocapture %ib, i32* noalias nocapture %ic) nounwind uwtable ssp {
+  br label %1
+
+; <label>:1                                       ; preds = %1, %0
+  %indvars.iv = phi i64 [ 0, %0 ], [ %indvars.iv.next, %1 ]
+  %2 = getelementptr inbounds i16* %sb, i64 %indvars.iv
+  %3 = load i16* %2, align 2
+  %4 = sext i16 %3 to i32
+  %5 = getelementptr inbounds i32* %ia, i64 %indvars.iv
+  store i32 %4, i32* %5, align 4
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, 1024
+  br i1 %exitcond, label %6, label %1
+
+; <label>:6                                       ; preds = %1
+  ret void
+}
+

test/Transforms/LoopVectorize/X86/avx1.ll

@@ -27,7 +27,7 @@ define i32 @read_mod_write_single_ptr(float* nocapture %a, i32 %n) nounwind uwta
 
 
 ;CHECK: @read_mod_i64
-;CHECK: load <8 x i64>
+;CHECK: load <4 x i64>
 ;CHECK: ret i32
 define i32 @read_mod_i64(i64* nocapture %a, i32 %n) nounwind uwtable ssp {
   %1 = icmp sgt i32 %n, 0

test/Transforms/LoopVectorize/X86/conversion-cost.ll

@@ -4,7 +4,7 @@ target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f3
 target triple = "x86_64-apple-macosx10.8.0"
 
 ;CHECK: @conversion_cost1
-;CHECK: store <8 x i8>
+;CHECK: store <32 x i8>
 ;CHECK: ret
 define i32 @conversion_cost1(i32 %n, i8* nocapture %A, float* nocapture %B) nounwind uwtable ssp {
   %1 = icmp sgt i32 %n, 3