when legalizing extremely wide shifts, make sure that

the shift amounts are in a suitably wide type so that
we don't generate out of range constant shift amounts.

This fixes PR9028.

llvm-svn: 125458

2 files changed, 9 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index 007f8d658e1..4c8cb5253a6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -1167,13 +1167,19 @@ void DAGTypeLegalizer::ExpandShiftByConstant(SDNode *N, unsigned Amt,
   unsigned NVTBits = NVT.getSizeInBits();
   EVT ShTy = N->getOperand(1).getValueType();
 
+  // If this is a large integer being legalized (e.g. an i512) then plop the
+  // shift amount down as a fixed i32.  The target shift amount may be something
+  // like i8, but this isn't enough to represent the shift amount.
+  if (NVTBits > 256)
+    ShTy = MVT::i32;
+  
   if (N->getOpcode() == ISD::SHL) {
     if (Amt > VTBits) {
       Lo = Hi = DAG.getConstant(0, NVT);
     } else if (Amt > NVTBits) {
       Lo = DAG.getConstant(0, NVT);
       Hi = DAG.getNode(ISD::SHL, dl,
-                       NVT, InL, DAG.getConstant(Amt-NVTBits,ShTy));
+                       NVT, InL, DAG.getConstant(Amt-NVTBits, ShTy));
     } else if (Amt == NVTBits) {
       Lo = DAG.getConstant(0, NVT);
       Hi = InL;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index d9faea12476..696cd24f0a7 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2426,11 +2426,11 @@ void SelectionDAGBuilder::visitShift(const User &I, unsigned Opcode) {
   SDValue Op2 = getValue(I.getOperand(1));
   
   MVT ShiftTy = TLI.getShiftAmountTy();
-  unsigned ShiftSize = ShiftTy.getSizeInBits();
-  unsigned Op2Size = Op2.getValueType().getSizeInBits();
   
   // Coerce the shift amount to the right type if we can.
   if (!I.getType()->isVectorTy() && Op2.getValueType() != ShiftTy) {
+    unsigned ShiftSize = ShiftTy.getSizeInBits();
+    unsigned Op2Size = Op2.getValueType().getSizeInBits();
     DebugLoc DL = getCurDebugLoc();
     
     // If the operand is smaller than the shift count type, promote it.