IRBuilder - add a CreateShuffleVector function that takes an ArrayRef of int

[spatel]

Summary

Adding this convenience function was suggested in D8086 as a way to ease creation of ShuffleVectors in AutoUpgrade and other places.

I changed one instance in AutoUpgrade as an example of the intended usage.

[craig.topper]

Patch looks fine to me other than my one comment. But I've never really looked at this file so I'm not sure I'm the best reviewer.

[spatel]

In D8184#138603, @craig.topper wrote:

Patch looks fine to me other than my one comment. But I've never really looked at this file so I'm not sure I'm the best reviewer.

Thanks, Craig. Was that an inline comment? I'm not seeing anything posted here in the review.

[andreadb]

Hi Sanjay,

the patch looks good to me too.

[craig.topper]

Yeah it was inline comment not sure why it disappeared. I just said to make the Idxs array in AutoUpgrade a 'const' array.

[spatel]

In D8184#139781, @craig.topper wrote:

Yeah it was inline comment not sure why it disappeared. I just said to make the Idxs array in AutoUpgrade a 'const' array.

Thanks! Checked in at r232056.

include/llvm/IR/IRBuilder.h

Value *CreateShuffleVector(Value *V1, Value *V2, Value *Mask,
                              const Twine &Name = "") {
     if (Constant *V1C = dyn_cast<Constant>(V1))
       if (Constant *V2C = dyn_cast<Constant>(V2))
         if (Constant *MC = dyn_cast<Constant>(Mask))
           return Insert(Folder.CreateShuffleVector(V1C, V2C, MC), Name);
     return Insert(new ShuffleVectorInst(V1, V2, Mask), Name);
   }
 
+  Value *CreateShuffleVector(Value *V1, Value *V2, ArrayRef<int> IntMask,
+                             const Twine &Name = "") {
+    size_t MaskSize = IntMask.size();
+    SmallVector<Constant*, 8> MaskVec(MaskSize);
+    for (size_t i = 0; i != MaskSize; ++i)
+      MaskVec[i] = getInt32(IntMask[i]);
+    Value *Mask = ConstantVector::get(MaskVec);
+    return CreateShuffleVector(V1, V2, Mask, Name);
+  }
+
   Value *CreateExtractValue(Value *Agg,
                             ArrayRef<unsigned> Idxs,
                             const Twine &Name = "") {
     if (Constant *AggC = dyn_cast<Constant>(Agg))
       return Insert(Folder.CreateExtractValue(AggC, Idxs), Name);
     return Insert(ExtractValueInst::Create(Agg, Idxs), Name);
   }
 

lib/IR/AutoUpgrade.cpp

if (Name.startswith("llvm.x86.sse2.pcmpeq.") ||
         Rep = Builder.CreateInsertElement(Rep, Load,
                                           ConstantInt::get(I32Ty, I));
     } else if (Name == "llvm.x86.avx2.vbroadcasti128") {
       // Replace vbroadcasts with a vector shuffle.
       Value *Op = Builder.CreatePointerCast(
           CI->getArgOperand(0),
           PointerType::getUnqual(VectorType::get(Type::getInt64Ty(C), 2)));
       Value *Load = Builder.CreateLoad(Op);
-      SmallVector<Constant *, 4> Idxs; // 0, 1, 0, 1.
-      for (unsigned i = 0; i != 4; ++i)
-        Idxs.push_back(Builder.getInt32(i & 1));
+      int Idxs[4] = { 0, 1, 0, 1 };
       Rep = Builder.CreateShuffleVector(Load, UndefValue::get(Load->getType()),
-                                        ConstantVector::get(Idxs));
+                                        Idxs);
     } else if (Name == "llvm.x86.sse2.psll.dq") {
       // 128-bit shift left specified in bits.
       unsigned Shift = cast<ConstantInt>(CI->getArgOperand(1))->getZExtValue();
       Rep = UpgradeX86PSLLDQIntrinsics(Builder, C, CI->getArgOperand(0), 1,
                                        Shift / 8); // Shift is in bits.
     } else if (Name == "llvm.x86.sse2.psrl.dq") {
       // 128-bit shift right specified in bits.
       unsigned Shift = cast<ConstantInt>(CI->getArgOperand(1))->getZExtValue();