Remove "mask" operand from shufflevector.

Instead, represent the mask as out-of-line data in the instruction. This
should be more efficient in the places that currently use
getShuffleVector(), and paves the way for further changes to add new
shuffles for scalable vectors.

This doesn't change the syntax in textual IR. And I don't currently plan
to change the bitcode encoding in this patch, although we'll probably
need to do something once we extend shufflevector for scalable types.

I expect that once this is finished, we can then replace the raw "mask"
with something more appropriate for scalable vectors.  Not sure exactly
what this looks like at the moment, but there are a few different ways
we could handle it.  Maybe we could try to describe specific shuffles.
Or maybe we could define it in terms of a function to convert a fixed-length
array into an appropriate scalable vector, using a "step", or something
like that.

Differential Revision: https://reviews.llvm.org/D72467

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 0075130..6a4d596 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -168,16 +168,16 @@ static bool getShuffleDemandedElts(const ShuffleVectorInst *Shuf,
                                    APInt &DemandedLHS, APInt &DemandedRHS) {
   // The length of scalable vectors is unknown at compile time, thus we
   // cannot check their values
-  if (Shuf->getMask()->getType()->getVectorElementCount().Scalable)
+  if (Shuf->getType()->getVectorElementCount().Scalable)
     return false;
 
   int NumElts = Shuf->getOperand(0)->getType()->getVectorNumElements();
-  int NumMaskElts = Shuf->getMask()->getType()->getVectorNumElements();
+  int NumMaskElts = Shuf->getType()->getVectorNumElements();
   DemandedLHS = DemandedRHS = APInt::getNullValue(NumElts);
   if (DemandedElts.isNullValue())
     return true;
   // Simple case of a shuffle with zeroinitializer.
-  if (isa<ConstantAggregateZero>(Shuf->getMask())) {
+  if (all_of(Shuf->getShuffleMask(), [](int Elt) { return Elt == 0; })) {
     DemandedLHS.setBit(0);
     return true;
   }