[llvm-commits] [llvm] r167032 - in /llvm/trunk: lib/Transforms/Vectorize/LoopVectorize.cpp test/Transforms/LoopVectorize/reduction.ll

[Evan Cheng]

On Oct 30, 2012, at 11:12 AM, Nadav Rotem <nrotem at apple.com> wrote:

> Author: nadav
> Date: Tue Oct 30 13:12:36 2012
> New Revision: 167032
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=167032&view=rev
> Log:
> LoopVectorize: Fix a bug in the initialization of reduction variables. AND needs to start at all-one
> while XOR, and OR need to start at zero.
> 
> 
> Modified:
>    llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
>    llvm/trunk/test/Transforms/LoopVectorize/reduction.ll
> 
> Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=167032&r1=167031&r2=167032&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
> +++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Tue Oct 30 13:12:36 2012
> @@ -211,8 +211,6 @@
>   TheLoop(Lp), SE(Se), DL(Dl), Induction(0) { }
> 
>   /// This represents the kinds of reductions that we support.
> -  /// We use the enum values to hold the 'identity' value for
> -  /// each operand. This value does not change the result if applied.
>   enum ReductionKind {
>     NoReduction = -1, /// Not a reduction.
>     IntegerAdd  = 0,  /// Sum of numbers.
> @@ -523,7 +521,7 @@
>   SmallVector<Constant*, 8> Indices;
>   // Create a vector of consecutive numbers from zero to VF.
>   for (unsigned i = 0; i < VF; ++i)
> -    Indices.push_back(ConstantInt::get(ScalarTy, Val));
> +    Indices.push_back(ConstantInt::get(ScalarTy, Val, true));
> 
>   // Add the consecutive indices to the vector value.
>   return ConstantVector::get(Indices);
> @@ -750,6 +748,23 @@
>   LoopBypassBlock = BypassBlock;
> }
> 
> +
> +static unsigned
> +getReductionIdentity(LoopVectorizationLegality::ReductionKind K) {
> +  switch (K) {
> +  case LoopVectorizationLegality::IntegerXor:
> +  case LoopVectorizationLegality::IntegerAdd:
> +  case LoopVectorizationLegality::IntegerOr:
> +    return 0;
> +  case LoopVectorizationLegality::IntegerMult:
> +    return 1;
> +  case LoopVectorizationLegality::IntegerAnd:
> +    return -1;
> +  default:
> +    llvm_unreachable("Unknown reduction kind");
> +  }
> +}
> +

It seems like this function can do with some comments.

Evan

> void
> SingleBlockLoopVectorizer::vectorizeLoop(LoopVectorizationLegality *Legal) {
>   //===------------------------------------------------===//
> @@ -974,10 +989,9 @@
>     Value *VectorExit = getVectorValue(RdxDesc.LoopExitInstr);
>     Type *VecTy = VectorExit->getType();
> 
> -    // Find the reduction identity variable. The value of the enum is the
> -    // identity. Zero for addition. One for Multiplication.
> -    unsigned IdentitySclr =  RdxDesc.Kind;
> -    Constant *Identity = getUniformVector(IdentitySclr,
> +    // Find the reduction identity variable. Zero for addition, or, xor,
> +    // one for multiplication, -1 for And.
> +    Constant *Identity = getUniformVector(getReductionIdentity(RdxDesc.Kind),
>                                           VecTy->getScalarType());
> 
>     // This vector is the Identity vector where the first element is the
> 
> Modified: llvm/trunk/test/Transforms/LoopVectorize/reduction.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/reduction.ll?rev=167032&r1=167031&r2=167032&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/LoopVectorize/reduction.ll (original)
> +++ llvm/trunk/test/Transforms/LoopVectorize/reduction.ll Tue Oct 30 13:12:36 2012
> @@ -151,6 +151,7 @@
> 
> ;CHECK: @reduction_and
> ;CHECK: and <4 x i32>
> +;CHECK: <i32 -1, i32 -1, i32 -1, i32 -1>
> ;CHECK: ret i32
> define i32 @reduction_and(i32 %n, i32* nocapture %A, i32* nocapture %B) nounwind uwtable readonly {
> entry:
> 
> 
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