[llvm] r374732 - [X86] getTargetShuffleInputs - Control KnownUndef mask element resolution as well as KnownZero.

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Sun Oct 13 12:35:35 2019
New Revision: 374732

URL: http://llvm.org/viewvc/llvm-project?rev=374732&view=rev
Log:
[X86] getTargetShuffleInputs - Control KnownUndef mask element resolution as well as KnownZero.

We were already controlling whether the KnownZero elements were being written to the target mask, this extends it to the KnownUndef elements as well so we can prevent the target shuffle mask being manipulated at all.

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

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=374732&r1=374731&r2=374732&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Sun Oct 13 12:35:35 2019
@@ -6812,7 +6812,7 @@ static bool getTargetShuffleAndZeroables
 static bool getTargetShuffleInputs(SDValue Op, SmallVectorImpl<SDValue> &Inputs,
                                    SmallVectorImpl<int> &Mask,
                                    SelectionDAG &DAG, unsigned Depth,
-                                   bool ResolveZero);
+                                   bool ResolveKnownElts);
 
 // Attempt to decode ops that could be represented as a shuffle mask.
 // The decoded shuffle mask may contain a different number of elements to the
@@ -6821,7 +6821,7 @@ static bool getFauxShuffleMask(SDValue N
                                SmallVectorImpl<int> &Mask,
                                SmallVectorImpl<SDValue> &Ops,
                                SelectionDAG &DAG, unsigned Depth,
-                               bool ResolveZero) {
+                               bool ResolveKnownElts) {
   Mask.clear();
   Ops.clear();
 
@@ -6916,9 +6916,9 @@ static bool getFauxShuffleMask(SDValue N
     SmallVector<int, 64> SrcMask0, SrcMask1;
     SmallVector<SDValue, 2> SrcInputs0, SrcInputs1;
     if (!getTargetShuffleInputs(N0, SrcInputs0, SrcMask0, DAG, Depth + 1,
-                                ResolveZero) ||
+                                ResolveKnownElts) ||
         !getTargetShuffleInputs(N1, SrcInputs1, SrcMask1, DAG, Depth + 1,
-                                ResolveZero))
+                                ResolveKnownElts))
       return false;
     size_t MaskSize = std::max(SrcMask0.size(), SrcMask1.size());
     SmallVector<int, 64> Mask0, Mask1;
@@ -6966,7 +6966,7 @@ static bool getFauxShuffleMask(SDValue N
     SmallVector<int, 64> SubMask;
     SmallVector<SDValue, 2> SubInputs;
     if (!getTargetShuffleInputs(peekThroughOneUseBitcasts(Sub), SubInputs,
-                                SubMask, DAG, Depth + 1, ResolveZero))
+                                SubMask, DAG, Depth + 1, ResolveKnownElts))
       return false;
     if (SubMask.size() != NumSubElts) {
       assert(((SubMask.size() % NumSubElts) == 0 ||
@@ -7250,7 +7250,7 @@ static bool getTargetShuffleInputs(SDVal
                                    SmallVectorImpl<int> &Mask,
                                    APInt &KnownUndef, APInt &KnownZero,
                                    SelectionDAG &DAG, unsigned Depth,
-                                   bool ResolveZero) {
+                                   bool ResolveKnownElts) {
   EVT VT = Op.getValueType();
   if (!VT.isSimple() || !VT.isVector())
     return false;
@@ -7258,17 +7258,17 @@ static bool getTargetShuffleInputs(SDVal
   if (getTargetShuffleAndZeroables(Op, Mask, Inputs, KnownUndef, KnownZero)) {
     for (int i = 0, e = Mask.size(); i != e; ++i) {
       int &M = Mask[i];
-      if (M < 0)
+      if (M < 0 || !ResolveKnownElts)
         continue;
       if (KnownUndef[i])
         M = SM_SentinelUndef;
-      else if (ResolveZero && KnownZero[i])
+      else if (KnownZero[i])
         M = SM_SentinelZero;
     }
     return true;
   }
   if (getFauxShuffleMask(Op, DemandedElts, Mask, Inputs, DAG, Depth,
-                         ResolveZero)) {
+                         ResolveKnownElts)) {
     KnownUndef = KnownZero = APInt::getNullValue(Mask.size());
     for (int i = 0, e = Mask.size(); i != e; ++i) {
       int M = Mask[i];
@@ -7285,7 +7285,7 @@ static bool getTargetShuffleInputs(SDVal
 static bool getTargetShuffleInputs(SDValue Op, SmallVectorImpl<SDValue> &Inputs,
                                    SmallVectorImpl<int> &Mask,
                                    SelectionDAG &DAG, unsigned Depth = 0,
-                                   bool ResolveZero = true) {
+                                   bool ResolveKnownElts = true) {
   EVT VT = Op.getValueType();
   if (!VT.isSimple() || !VT.isVector())
     return false;
@@ -7294,7 +7294,7 @@ static bool getTargetShuffleInputs(SDVal
   unsigned NumElts = Op.getValueType().getVectorNumElements();
   APInt DemandedElts = APInt::getAllOnesValue(NumElts);
   return getTargetShuffleInputs(Op, DemandedElts, Inputs, Mask, KnownUndef,
-                                KnownZero, DAG, Depth, ResolveZero);
+                                KnownZero, DAG, Depth, ResolveKnownElts);
 }
 
 /// Returns the scalar element that will make up the ith