[llvm] r200576 - [SLPV] Recognize vectorizable intrinsics during SLP vectorization and

Reid Kleckner rnk at google.com
Fri Jan 31 17:40:32 PST 2014


Hey Raul,

This patch broke the 32-bit self-host build.  The x86 backend claims that
the legalizer knows how to expand bswap intrinsics on vector types, but
this is not the case.  Running llc the test case I gave produces:
Unhandled Expand type in BSWAP!
UNREACHABLE executed at ..\lib\CodeGen\SelectionDAG\LegalizeDAG.cpp:2537!

I'm going to revert this for now, but what should happen is that we should
learn how to expand bswap on vectors.

Reid



On Fri, Jan 31, 2014 at 5:17 PM, Reid Kleckner <rnk at google.com> wrote:

> This change caused us to vectorize bswap, which we then try to expand on
> i686, which hits an unreachable.  Running llc on this repros:
>
> declare <2 x i64> @llvm.bswap.v2i64(<2 x i64>) #8
> define <2 x i64> @foo(<2 x i64> %v) {
>   %s = call <2 x i64> @llvm.bswap.v2i64(<2 x i64> %v)
>   ret <2 x i64> %s
> }
> attributes #8 = { nounwind readnone }
>
> I don't have a reduced test case of input to the SLP vectorizer yet
> because I'm new to reducing LLVM IR.
>
>
> On Fri, Jan 31, 2014 at 1:14 PM, Chandler Carruth <chandlerc at gmail.com>wrote:
>
>> Author: chandlerc
>> Date: Fri Jan 31 15:14:40 2014
>> New Revision: 200576
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=200576&view=rev
>> Log:
>> [SLPV] Recognize vectorizable intrinsics during SLP vectorization and
>> transform accordingly. Based on similar code from Loop vectorization.
>> Subsequent commits will include vectorization of function calls to
>> vector intrinsics and form function calls to vector library calls.
>>
>> Patch by Raul Silvera! (Much delayed due to my not running dcommit)
>>
>> Added:
>>     llvm/trunk/test/Transforms/SLPVectorizer/X86/intrinsic.ll
>> Modified:
>>     llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
>>
>> Modified: llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp?rev=200576&r1=200575&r2=200576&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp Fri Jan 31
>> 15:14:40 2014
>> @@ -947,6 +947,39 @@ void BoUpSLP::buildTree_rec(ArrayRef<Val
>>        buildTree_rec(Operands, Depth + 1);
>>        return;
>>      }
>> +    case Instruction::Call: {
>> +      // Check if the calls are all to the same vectorizable intrinsic.
>> +      IntrinsicInst *II = dyn_cast<IntrinsicInst>(VL[0]);
>> +      if (II==NULL) {
>> +        newTreeEntry(VL, false);
>> +        DEBUG(dbgs() << "SLP: Non-vectorizable call.\n");
>> +        return;
>> +      }
>> +
>> +      Intrinsic::ID ID = II->getIntrinsicID();
>> +
>> +      for (unsigned i = 1, e = VL.size(); i != e; ++i) {
>> +        IntrinsicInst *II2 = dyn_cast<IntrinsicInst>(VL[i]);
>> +        if (!II2 || II2->getIntrinsicID() != ID) {
>> +          newTreeEntry(VL, false);
>> +          DEBUG(dbgs() << "SLP: mismatched calls:" << *II << "!=" <<
>> *VL[i]
>> +                       << "\n");
>> +          return;
>> +        }
>> +      }
>> +
>> +      newTreeEntry(VL, true);
>> +      for (unsigned i = 0, e = II->getNumArgOperands(); i != e; ++i) {
>> +        ValueList Operands;
>> +        // Prepare the operand vector.
>> +        for (unsigned j = 0; j < VL.size(); ++j) {
>> +          IntrinsicInst *II2 = dyn_cast<IntrinsicInst>(VL[j]);
>> +          Operands.push_back(II2->getArgOperand(i));
>> +        }
>> +        buildTree_rec(Operands, Depth + 1);
>> +      }
>> +      return;
>> +    }
>>      default:
>>        newTreeEntry(VL, false);
>>        DEBUG(dbgs() << "SLP: Gathering unknown instruction.\n");
>> @@ -1072,6 +1105,30 @@ int BoUpSLP::getEntryCost(TreeEntry *E)
>>        int VecStCost = TTI->getMemoryOpCost(Instruction::Store, VecTy, 1,
>> 0);
>>        return VecStCost - ScalarStCost;
>>      }
>> +    case Instruction::Call: {
>> +      CallInst *CI = cast<CallInst>(VL0);
>> +      IntrinsicInst *II = cast<IntrinsicInst>(CI);
>> +      Intrinsic::ID ID = II->getIntrinsicID();
>> +
>> +      // Calculate the cost of the scalar and vector calls.
>> +      SmallVector<Type*, 4> ScalarTys, VecTys;
>> +      for (unsigned op = 0, opc = II->getNumArgOperands(); op!= opc;
>> ++op) {
>> +        ScalarTys.push_back(CI->getArgOperand(op)->getType());
>> +
>>  VecTys.push_back(VectorType::get(CI->getArgOperand(op)->getType(),
>> +                                         VecTy->getNumElements()));
>> +      }
>> +
>> +      int ScalarCallCost = VecTy->getNumElements() *
>> +          TTI->getIntrinsicInstrCost(ID, ScalarTy, ScalarTys);
>> +
>> +      int VecCallCost = TTI->getIntrinsicInstrCost(ID, VecTy, VecTys);
>> +
>> +      DEBUG(dbgs() << "SLP: Call cost "<< VecCallCost - ScalarCallCost
>> +            << " (" << VecCallCost  << "-" <<  ScalarCallCost << ")"
>> +            << " for " << *II << "\n");
>> +
>> +      return VecCallCost - ScalarCallCost;
>> +    }
>>      default:
>>        llvm_unreachable("Unknown instruction");
>>    }
>> @@ -1086,10 +1143,10 @@ bool BoUpSLP::isFullyVectorizableTinyTre
>>      return false;
>>
>>    // Gathering cost would be too much for tiny trees.
>> -  if (VectorizableTree[0].NeedToGather ||
>> VectorizableTree[1].NeedToGather)
>> -    return false;
>> +  if (VectorizableTree[0].NeedToGather ||
>> VectorizableTree[1].NeedToGather)
>> +    return false;
>>
>> -  return true;
>> +  return true;
>>  }
>>
>>  int BoUpSLP::getTreeCost() {
>> @@ -1555,6 +1612,32 @@ Value *BoUpSLP::vectorizeTree(TreeEntry
>>        E->VectorizedValue = S;
>>        return propagateMetadata(S, E->Scalars);
>>      }
>> +    case Instruction::Call: {
>> +      CallInst *CI = cast<CallInst>(VL0);
>> +
>> +      setInsertPointAfterBundle(E->Scalars);
>> +      std::vector<Value *> OpVecs;
>> +      for (int j = 0, e = CI->getNumArgOperands(); j < e; ++j) {
>> +        ValueList OpVL;
>> +        for (int i = 0, e = E->Scalars.size(); i < e; ++i) {
>> +          CallInst *CEI = cast<CallInst>(E->Scalars[i]);
>> +          OpVL.push_back(CEI->getArgOperand(j));
>> +        }
>> +
>> +        Value *OpVec = vectorizeTree(OpVL);
>> +        DEBUG(dbgs() << "SLP: OpVec[" << j << "]: " << *OpVec << "\n");
>> +        OpVecs.push_back(OpVec);
>> +      }
>> +
>> +      Module *M = F->getParent();
>> +      IntrinsicInst *II = cast<IntrinsicInst>(CI);
>> +      Intrinsic::ID ID = II->getIntrinsicID();
>> +      Type *Tys[] = { VectorType::get(CI->getType(), E->Scalars.size())
>> };
>> +      Function *CF = Intrinsic::getDeclaration(M, ID, Tys);
>> +      Value *V = Builder.CreateCall(CF, OpVecs);
>> +      E->VectorizedValue = V;
>> +      return V;
>> +    }
>>      default:
>>      llvm_unreachable("unknown inst");
>>    }
>>
>> Added: llvm/trunk/test/Transforms/SLPVectorizer/X86/intrinsic.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/intrinsic.ll?rev=200576&view=auto
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/SLPVectorizer/X86/intrinsic.ll (added)
>> +++ llvm/trunk/test/Transforms/SLPVectorizer/X86/intrinsic.ll Fri Jan 31
>> 15:14:40 2014
>> @@ -0,0 +1,75 @@
>> +; RUN: opt < %s -basicaa -slp-vectorizer -slp-threshold=-999 -dce -S
>> -mtriple=x86_64-apple-macosx10.8.0 -mcpu=corei7-avx | FileCheck %s
>> +
>> +target datalayout =
>> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
>> +target triple = "x86_64-apple-macosx10.8.0"
>> +
>> +declare double @llvm.fabs.f64(double) nounwind readnone
>> +
>> +;CHECK-LABEL: @vec_fabs_f64(
>> +;CHECK: load <2 x double>
>> +;CHECK: load <2 x double>
>> +;CHECK: call <2 x double> @llvm.fabs.v2f64
>> +;CHECK: store <2 x double>
>> +;CHECK: ret
>> +define void @vec_fabs_f64(double* %a, double* %b, double* %c) {
>> +entry:
>> +  %i0 = load double* %a, align 8
>> +  %i1 = load double* %b, align 8
>> +  %mul = fmul double %i0, %i1
>> +  %call = tail call double @llvm.fabs.f64(double %mul) nounwind readnone
>> +  %arrayidx3 = getelementptr inbounds double* %a, i64 1
>> +  %i3 = load double* %arrayidx3, align 8
>> +  %arrayidx4 = getelementptr inbounds double* %b, i64 1
>> +  %i4 = load double* %arrayidx4, align 8
>> +  %mul5 = fmul double %i3, %i4
>> +  %call5 = tail call double @llvm.fabs.f64(double %mul5) nounwind
>> readnone
>> +  store double %call, double* %c, align 8
>> +  %arrayidx5 = getelementptr inbounds double* %c, i64 1
>> +  store double %call5, double* %arrayidx5, align 8
>> +  ret void
>> +}
>> +
>> +declare float @llvm.copysign.f32(float, float) nounwind readnone
>> +
>> +;CHECK-LABEL: @vec_copysign_f32(
>> +;CHECK: load <4 x float>
>> +;CHECK: load <4 x float>
>> +;CHECK: call <4 x float> @llvm.copysign.v4f32
>> +;CHECK: store <4 x float>
>> +;CHECK: ret
>> +define void @vec_copysign_f32(float* %a, float* %b, float* noalias %c) {
>> +entry:
>> +  %0 = load float* %a, align 4
>> +  %1 = load float* %b, align 4
>> +  %call0 = tail call float @llvm.copysign.f32(float %0, float %1)
>> nounwind readnone
>> +  store float %call0, float* %c, align 4
>> +
>> +  %ix2 = getelementptr inbounds float* %a, i64 1
>> +  %2 = load float* %ix2, align 4
>> +  %ix3 = getelementptr inbounds float* %b, i64 1
>> +  %3 = load float* %ix3, align 4
>> +  %call1 = tail call float @llvm.copysign.f32(float %2, float %3)
>> nounwind readnone
>> +  %c1 = getelementptr inbounds float* %c, i64 1
>> +  store float %call1, float* %c1, align 4
>> +
>> +  %ix4 = getelementptr inbounds float* %a, i64 2
>> +  %4 = load float* %ix4, align 4
>> +  %ix5 = getelementptr inbounds float* %b, i64 2
>> +  %5 = load float* %ix5, align 4
>> +  %call2 = tail call float @llvm.copysign.f32(float %4, float %5)
>> nounwind readnone
>> +  %c2 = getelementptr inbounds float* %c, i64 2
>> +  store float %call2, float* %c2, align 4
>> +
>> +  %ix6 = getelementptr inbounds float* %a, i64 3
>> +  %6 = load float* %ix6, align 4
>> +  %ix7 = getelementptr inbounds float* %b, i64 3
>> +  %7 = load float* %ix7, align 4
>> +  %call3 = tail call float @llvm.copysign.f32(float %6, float %7)
>> nounwind readnone
>> +  %c3 = getelementptr inbounds float* %c, i64 3
>> +  store float %call3, float* %c3, align 4
>> +
>> +  ret void
>> +}
>> +
>> +
>> +
>>
>>
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>
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