[SelectionDAG][X86] Use stack load/store in PromoteIntRes_BITCAST when the input needs to be be split and the output type is a vector.

We had special case handling here, but it uses a scalar any_extend for the
promotion then bitcasts to the final type. This won't split up the input data
into multiple promoted elements like we need.

This patch falls back to doing the conversion through memory.

Fixes PR41594 which I believe was reflected in the bitcast-vector-bool.ll
changes. The changes to vector-half-conversions.ll are fixing a previously
unknown miscompile from this issue.

Differential Revision: https://reviews.llvm.org/D61114

llvm-svn: 359219

1 files changed, 18 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index ca0f0d69aea..3b05841ac93 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -306,21 +306,24 @@ SDValue DAGTypeLegalizer::PromoteIntRes_BITCAST(SDNode *N) {
                          BitConvertToInteger(GetScalarizedVector(InOp)));
     break;
   case TargetLowering::TypeSplitVector: {
-    // For example, i32 = BITCAST v2i16 on alpha.  Convert the split
-    // pieces of the input into integers and reassemble in the final type.
-    SDValue Lo, Hi;
-    GetSplitVector(N->getOperand(0), Lo, Hi);
-    Lo = BitConvertToInteger(Lo);
-    Hi = BitConvertToInteger(Hi);
-
-    if (DAG.getDataLayout().isBigEndian())
-      std::swap(Lo, Hi);
-
-    InOp = DAG.getNode(ISD::ANY_EXTEND, dl,
-                       EVT::getIntegerVT(*DAG.getContext(),
-                                         NOutVT.getSizeInBits()),
-                       JoinIntegers(Lo, Hi));
-    return DAG.getNode(ISD::BITCAST, dl, NOutVT, InOp);
+    if (!NOutVT.isVector()) {
+      // For example, i32 = BITCAST v2i16 on alpha.  Convert the split
+      // pieces of the input into integers and reassemble in the final type.
+      SDValue Lo, Hi;
+      GetSplitVector(N->getOperand(0), Lo, Hi);
+      Lo = BitConvertToInteger(Lo);
+      Hi = BitConvertToInteger(Hi);
+
+      if (DAG.getDataLayout().isBigEndian())
+        std::swap(Lo, Hi);
+
+      InOp = DAG.getNode(ISD::ANY_EXTEND, dl,
+                         EVT::getIntegerVT(*DAG.getContext(),
+                                           NOutVT.getSizeInBits()),
+                         JoinIntegers(Lo, Hi));
+      return DAG.getNode(ISD::BITCAST, dl, NOutVT, InOp);
+    }
+    break;
   }
   case TargetLowering::TypeWidenVector:
     // The input is widened to the same size. Convert to the widened value.