Everything it could do can be implemented with the generic vector_shuffle
instruction and/or using ConstantAggregateZero input.
Here's the code from lib/IR/AutoUpgrade.cpp that we use to upgrade it if we
see it in IR input to opt or llc
uint8_t Imm =
cast<ConstantInt>(CI->getArgOperand(2))->getZExtValue();
unsigned NumElts = CI->getType()->getVectorNumElements();
unsigned HalfSize = NumElts / 2;
SmallVector<uint32_t, 8> ShuffleMask(NumElts);
// Determine which operand(s) are actually in use for this
instruction.
Value *V0 = (Imm & 0x02) ? CI->getArgOperand(1) :
CI->getArgOperand(0);
Value *V1 = (Imm & 0x20) ? CI->getArgOperand(1) :
CI->getArgOperand(0);
// If needed, replace operands based on zero mask.
V0 = (Imm & 0x08) ? ConstantAggregateZero::get(CI->getType()) : V0;
V1 = (Imm & 0x80) ? ConstantAggregateZero::get(CI->getType()) : V1;
// Permute low half of result.
unsigned StartIndex = (Imm & 0x01) ? HalfSize : 0;
for (unsigned i = 0; i < HalfSize; ++i)
ShuffleMask[i] = StartIndex + i;
// Permute high half of result.
StartIndex = (Imm & 0x10) ? HalfSize : 0;
for (unsigned i = 0; i < HalfSize; ++i)
ShuffleMask[i + HalfSize] = NumElts + StartIndex + i;
Rep = Builder.CreateShuffleVector(V0, V1, ShuffleMask);
~Craig
On Sun, Nov 12, 2017 at 12:55 PM, Rob Cameron via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi, there. I am unable to use the above intrinsic
> with LLVM 6.0svn. Is there a substitute?
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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