[X86] getFauxShuffleMask/getTargetShuffleInputs - make SelectionDAG const (PR45974).

Try to prevent future node creation issues (as detailed in PR45974) by making the SelectionDAG reference const, so it can still be used for analysis, but not node creation.

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 95c9312..89559ad 100644 (file)
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -7271,7 +7271,7 @@ static void resolveZeroablesFromTargetShuffle(const SmallVectorImpl<int> &Mask,
 // TODO: Use DemandedElts variant.
 static bool getTargetShuffleInputs(SDValue Op, SmallVectorImpl<SDValue> &Inputs,
                                    SmallVectorImpl<int> &Mask,
-                                   SelectionDAG &DAG, unsigned Depth,
+                                   const SelectionDAG &DAG, unsigned Depth,
                                    bool ResolveKnownElts);
 
 // Attempt to decode ops that could be represented as a shuffle mask.
@@ -7280,7 +7280,7 @@ static bool getTargetShuffleInputs(SDValue Op, SmallVectorImpl<SDValue> &Inputs,
 static bool getFauxShuffleMask(SDValue N, const APInt &DemandedElts,
                                SmallVectorImpl<int> &Mask,
                                SmallVectorImpl<SDValue> &Ops,
-                               SelectionDAG &DAG, unsigned Depth,
+                               const SelectionDAG &DAG, unsigned Depth,
                                bool ResolveKnownElts) {
   Mask.clear();
   Ops.clear();
@@ -7734,7 +7734,7 @@ static bool getTargetShuffleInputs(SDValue Op, const APInt &DemandedElts,
                                    SmallVectorImpl<SDValue> &Inputs,
                                    SmallVectorImpl<int> &Mask,
                                    APInt &KnownUndef, APInt &KnownZero,
-                                   SelectionDAG &DAG, unsigned Depth,
+                                   const SelectionDAG &DAG, unsigned Depth,
                                    bool ResolveKnownElts) {
   EVT VT = Op.getValueType();
   if (!VT.isSimple() || !VT.isVector())
@@ -7755,7 +7755,7 @@ static bool getTargetShuffleInputs(SDValue Op, const APInt &DemandedElts,
 
 static bool getTargetShuffleInputs(SDValue Op, SmallVectorImpl<SDValue> &Inputs,
                                    SmallVectorImpl<int> &Mask,
-                                   SelectionDAG &DAG, unsigned Depth = 0,
+                                   const SelectionDAG &DAG, unsigned Depth = 0,
                                    bool ResolveKnownElts = true) {
   EVT VT = Op.getValueType();
   if (!VT.isSimple() || !VT.isVector())