[llvm] r344936 - Revert rL344933 from llvm/trunk: [X86][SSE] Tidyup DecodeVPERMILPMask shuffle mask decoding

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Mon Oct 22 11:58:32 2018
New Revision: 344936

URL: http://llvm.org/viewvc/llvm-project?rev=344936&view=rev
Log:
Revert rL344933 from llvm/trunk: [X86][SSE] Tidyup DecodeVPERMILPMask shuffle mask decoding
We can't safely assume that certain RawMask entries are UNDEF as most variable shuffles ignore non-index bits.
........
Add support for UNDEF raw mask elements and remove the ConstantPool DecodeVPERMILPMask usage in X86ISelLowering.cpp


Modified:
    llvm/trunk/lib/Target/X86/Utils/X86ShuffleDecode.cpp
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/Utils/X86ShuffleDecode.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/Utils/X86ShuffleDecode.cpp?rev=344936&r1=344935&r2=344936&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/Utils/X86ShuffleDecode.cpp (original)
+++ llvm/trunk/lib/Target/X86/Utils/X86ShuffleDecode.cpp Mon Oct 22 11:58:32 2018
@@ -501,10 +501,6 @@ void DecodeVPERMILPMask(unsigned NumElts
 
   for (unsigned i = 0, e = RawMask.size(); i < e; ++i) {
     uint64_t M = RawMask[i];
-    if (M == (uint64_t)SM_SentinelUndef) {
-      ShuffleMask.push_back(M);
-      continue;
-    }
     M = (ScalarBits == 64 ? ((M >> 1) & 0x1) : (M & 0x3));
     unsigned LaneOffset = i & ~(NumEltsPerLane - 1);
     ShuffleMask.push_back((int)(LaneOffset + M));

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=344936&r1=344935&r2=344936&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon Oct 22 11:58:32 2018
@@ -6043,10 +6043,14 @@ static bool getTargetShuffleMask(SDNode
     IsUnary = true;
     SDValue MaskNode = N->getOperand(1);
     SmallVector<uint64_t, 32> RawMask;
-    if (getTargetShuffleMaskIndices(MaskNode, MaskEltSize, RawMask, true)) {
+    if (getTargetShuffleMaskIndices(MaskNode, MaskEltSize, RawMask)) {
       DecodeVPERMILPMask(NumElems, MaskEltSize, RawMask, Mask);
       break;
     }
+    if (auto *C = getTargetConstantFromNode(MaskNode)) {
+      DecodeVPERMILPMask(C, MaskEltSize, Mask);
+      break;
+    }
     return false;
   }
   case X86ISD::PSHUFB: {