Fix shift legalization and lowering for big constants.

Summary: If shift amount is a constant value > 64 bit it is handled incorrectly during type legalization and X86 lowering. This patch the type of shift amount argument in function DAGTypeLegalizer::ExpandShiftByConstant from unsigned to APInt.

Reviewers: nadav, majnemer, sanjoy, RKSimon

Subscribers: RKSimon, llvm-commits

Differential Revision: http://reviews.llvm.org/D10767

llvm-svn: 241790

2 files changed, 17 insertions, 18 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index f97e0d6fb06..f234e005b32 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -1358,9 +1358,9 @@ std::pair <SDValue, SDValue> DAGTypeLegalizer::ExpandAtomic(SDNode *Node) {
   return ExpandChainLibCall(LC, Node, false);
 }
 
-/// ExpandShiftByConstant - N is a shift by a value that needs to be expanded,
+/// N is a shift by a value that needs to be expanded,
 /// and the shift amount is a constant 'Amt'.  Expand the operation.
-void DAGTypeLegalizer::ExpandShiftByConstant(SDNode *N, unsigned Amt,
+void DAGTypeLegalizer::ExpandShiftByConstant(SDNode *N, const APInt &Amt,
                                              SDValue &Lo, SDValue &Hi) {
   SDLoc DL(N);
   // Expand the incoming operand to be shifted, so that we have its parts
@@ -1381,12 +1381,12 @@ void DAGTypeLegalizer::ExpandShiftByConstant(SDNode *N, unsigned Amt,
   EVT ShTy = N->getOperand(1).getValueType();
 
   if (N->getOpcode() == ISD::SHL) {
-    if (Amt > VTBits) {
+    if (Amt.ugt(VTBits)) {
       Lo = Hi = DAG.getConstant(0, DL, NVT);
-    } else if (Amt > NVTBits) {
+    } else if (Amt.ugt(NVTBits)) {
       Lo = DAG.getConstant(0, DL, NVT);
       Hi = DAG.getNode(ISD::SHL, DL,
-                       NVT, InL, DAG.getConstant(Amt - NVTBits, DL, ShTy));
+                       NVT, InL, DAG.getConstant(-Amt + NVTBits, DL, ShTy));
     } else if (Amt == NVTBits) {
       Lo = DAG.getConstant(0, DL, NVT);
       Hi = InL;
@@ -1405,16 +1405,15 @@ void DAGTypeLegalizer::ExpandShiftByConstant(SDNode *N, unsigned Amt,
                        DAG.getNode(ISD::SHL, DL, NVT, InH,
                                    DAG.getConstant(Amt, DL, ShTy)),
                        DAG.getNode(ISD::SRL, DL, NVT, InL,
-                                   DAG.getConstant(NVTBits - Amt, DL, ShTy)));
+                                   DAG.getConstant(-Amt + NVTBits, DL, ShTy)));
     }
     return;
   }
 
   if (N->getOpcode() == ISD::SRL) {
-    if (Amt > VTBits) {
-      Lo = DAG.getConstant(0, DL, NVT);
-      Hi = DAG.getConstant(0, DL, NVT);
-    } else if (Amt > NVTBits) {
+    if (Amt.ugt(VTBits)) {
+      Lo = Hi = DAG.getConstant(0, DL, NVT);
+    } else if (Amt.ugt(NVTBits)) {
       Lo = DAG.getNode(ISD::SRL, DL,
                        NVT, InH, DAG.getConstant(Amt - NVTBits, DL, ShTy));
       Hi = DAG.getConstant(0, DL, NVT);
@@ -1426,19 +1425,19 @@ void DAGTypeLegalizer::ExpandShiftByConstant(SDNode *N, unsigned Amt,
                        DAG.getNode(ISD::SRL, DL, NVT, InL,
                                    DAG.getConstant(Amt, DL, ShTy)),
                        DAG.getNode(ISD::SHL, DL, NVT, InH,
-                                   DAG.getConstant(NVTBits - Amt, DL, ShTy)));
+                                   DAG.getConstant(-Amt + NVTBits, DL, ShTy)));
       Hi = DAG.getNode(ISD::SRL, DL, NVT, InH, DAG.getConstant(Amt, DL, ShTy));
     }
     return;
   }
 
   assert(N->getOpcode() == ISD::SRA && "Unknown shift!");
-  if (Amt > VTBits) {
+  if (Amt.ugt(VTBits)) {
     Hi = Lo = DAG.getNode(ISD::SRA, DL, NVT, InH,
                           DAG.getConstant(NVTBits - 1, DL, ShTy));
-  } else if (Amt > NVTBits) {
+  } else if (Amt.ugt(NVTBits)) {
     Lo = DAG.getNode(ISD::SRA, DL, NVT, InH,
-                     DAG.getConstant(Amt-NVTBits, DL, ShTy));
+                     DAG.getConstant(Amt - NVTBits, DL, ShTy));
     Hi = DAG.getNode(ISD::SRA, DL, NVT, InH,
                      DAG.getConstant(NVTBits - 1, DL, ShTy));
   } else if (Amt == NVTBits) {
@@ -1450,7 +1449,7 @@ void DAGTypeLegalizer::ExpandShiftByConstant(SDNode *N, unsigned Amt,
                      DAG.getNode(ISD::SRL, DL, NVT, InL,
                                  DAG.getConstant(Amt, DL, ShTy)),
                      DAG.getNode(ISD::SHL, DL, NVT, InH,
-                                 DAG.getConstant(NVTBits - Amt, DL, ShTy)));
+                                 DAG.getConstant(-Amt + NVTBits, DL, ShTy)));
     Hi = DAG.getNode(ISD::SRA, DL, NVT, InH, DAG.getConstant(Amt, DL, ShTy));
   }
 }
@@ -2178,7 +2177,7 @@ void DAGTypeLegalizer::ExpandIntRes_Shift(SDNode *N,
   // If we can emit an efficient shift operation, do so now.  Check to see if
   // the RHS is a constant.
   if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N->getOperand(1)))
-    return ExpandShiftByConstant(N, CN->getZExtValue(), Lo, Hi);
+    return ExpandShiftByConstant(N, CN->getAPIntValue(), Lo, Hi);
 
   // If we can determine that the high bit of the shift is zero or one, even if
   // the low bits are variable, emit this shift in an optimized form.
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
index 496639b5fb8..d1131a74cf1 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
@@ -167,7 +167,7 @@ private:
   SDValue GetVectorElementPointer(SDValue VecPtr, EVT EltVT, SDValue Index);
   SDValue JoinIntegers(SDValue Lo, SDValue Hi);
   SDValue LibCallify(RTLIB::Libcall LC, SDNode *N, bool isSigned);
-  
+
   std::pair<SDValue, SDValue> ExpandChainLibCall(RTLIB::Libcall LC,
                                                  SDNode *Node, bool isSigned);
   std::pair<SDValue, SDValue> ExpandAtomic(SDNode *Node);
@@ -347,7 +347,7 @@ private:
 
   void ExpandIntRes_ATOMIC_LOAD       (SDNode *N, SDValue &Lo, SDValue &Hi);
 
-  void ExpandShiftByConstant(SDNode *N, unsigned Amt,
+  void ExpandShiftByConstant(SDNode *N, const APInt &Amt,
                              SDValue &Lo, SDValue &Hi);
   bool ExpandShiftWithKnownAmountBit(SDNode *N, SDValue &Lo, SDValue &Hi);
   bool ExpandShiftWithUnknownAmountBit(SDNode *N, SDValue &Lo, SDValue &Hi);