[X86][AVX512] Fixed decoding of permd/permpd variable mask shuffles + enabled them for target shuffle combining

Corrected element mask masking to extract the bottom index bits (now matches the perm2 implementation but for unary inputs).

llvm-svn: 274571

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/Target/X86/X86ShuffleDecodeConstantPool.cpp b/llvm/lib/Target/X86/X86ShuffleDecodeConstantPool.cpp
index 856a2bc..8c700e3 100644
--- a/llvm/lib/Target/X86/X86ShuffleDecodeConstantPool.cpp
+++ b/llvm/lib/Target/X86/X86ShuffleDecodeConstantPool.cpp
@@ -300,6 +300,7 @@ void DecodeVPERMVMask(const Constant *C, MVT VT,
   if (MaskTy->isVectorTy()) {
     unsigned NumElements = MaskTy->getVectorNumElements();
     if (NumElements == VT.getVectorNumElements()) {
+      unsigned EltMaskSize = Log2_64(NumElements);
       for (unsigned i = 0; i < NumElements; ++i) {
         Constant *COp = C->getAggregateElement(i);
         if (!COp || (!isa<UndefValue>(COp) && !isa<ConstantInt>(COp))) {
@@ -309,9 +310,9 @@ void DecodeVPERMVMask(const Constant *C, MVT VT,
         if (isa<UndefValue>(COp))
           ShuffleMask.push_back(SM_SentinelUndef);
         else {
-          uint64_t Element = cast<ConstantInt>(COp)->getZExtValue();
-          Element &= (1 << NumElements) - 1;
-          ShuffleMask.push_back(Element);
+          APInt Element = cast<ConstantInt>(COp)->getValue();
+          Element = Element.getLoBits(EltMaskSize);
+          ShuffleMask.push_back(Element.getZExtValue());
         }
       }
     }