ARM: fix CodeGen for 64-bit shifts.

One half of the shifts obviously needed conditional selection based on whether
the shift amount is more than 32-bits, but leaving the other half as the
natural shift isn't acceptable either: it's undefined behaviour to shift a
32-bit value by more than 31.

llvm-svn: 287149

1 files changed, 31 insertions, 17 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 143c6d9c543..20406ef350e 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -4893,6 +4893,7 @@ SDValue ARMTargetLowering::LowerShiftRightParts(SDValue Op,
   SDValue ShOpHi = Op.getOperand(1);
   SDValue ShAmt  = Op.getOperand(2);
   SDValue ARMcc;
+  SDValue CCR = DAG.getRegister(ARM::CPSR, MVT::i32);
   unsigned Opc = (Op.getOpcode() == ISD::SRA_PARTS) ? ISD::SRA : ISD::SRL;
 
   assert(Op.getOpcode() == ISD::SRA_PARTS || Op.getOpcode() == ISD::SRL_PARTS);
@@ -4903,15 +4904,23 @@ SDValue ARMTargetLowering::LowerShiftRightParts(SDValue Op,
   SDValue ExtraShAmt = DAG.getNode(ISD::SUB, dl, MVT::i32, ShAmt,
                                    DAG.getConstant(VTBits, dl, MVT::i32));
   SDValue Tmp2 = DAG.getNode(ISD::SHL, dl, VT, ShOpHi, RevShAmt);
-  SDValue FalseVal = DAG.getNode(ISD::OR, dl, VT, Tmp1, Tmp2);
-  SDValue TrueVal = DAG.getNode(Opc, dl, VT, ShOpHi, ExtraShAmt);
-
-  SDValue CCR = DAG.getRegister(ARM::CPSR, MVT::i32);
-  SDValue Cmp = getARMCmp(ExtraShAmt, DAG.getConstant(0, dl, MVT::i32),
-                          ISD::SETGE, ARMcc, DAG, dl);
-  SDValue Hi = DAG.getNode(Opc, dl, VT, ShOpHi, ShAmt);
-  SDValue Lo = DAG.getNode(ARMISD::CMOV, dl, VT, FalseVal, TrueVal, ARMcc,
-                           CCR, Cmp);
+  SDValue LoSmallShift = DAG.getNode(ISD::OR, dl, VT, Tmp1, Tmp2);
+  SDValue LoBigShift = DAG.getNode(Opc, dl, VT, ShOpHi, ExtraShAmt);
+  SDValue CmpLo = getARMCmp(ExtraShAmt, DAG.getConstant(0, dl, MVT::i32),
+                            ISD::SETGE, ARMcc, DAG, dl);
+  SDValue Lo = DAG.getNode(ARMISD::CMOV, dl, VT, LoSmallShift, LoBigShift,
+                           ARMcc, CCR, CmpLo);
+
+
+  SDValue HiSmallShift = DAG.getNode(Opc, dl, VT, ShOpHi, ShAmt);
+  SDValue HiBigShift = Opc == ISD::SRA
+                           ? DAG.getNode(Opc, dl, VT, ShOpHi,
+                                         DAG.getConstant(VTBits - 1, dl, VT))
+                           : DAG.getConstant(0, dl, VT);
+  SDValue CmpHi = getARMCmp(ExtraShAmt, DAG.getConstant(0, dl, MVT::i32),
+                            ISD::SETGE, ARMcc, DAG, dl);
+  SDValue Hi = DAG.getNode(ARMISD::CMOV, dl, VT, HiSmallShift, HiBigShift,
+                           ARMcc, CCR, CmpHi);
 
   SDValue Ops[2] = { Lo, Hi };
   return DAG.getMergeValues(Ops, dl);
@@ -4929,23 +4938,28 @@ SDValue ARMTargetLowering::LowerShiftLeftParts(SDValue Op,
   SDValue ShOpHi = Op.getOperand(1);
   SDValue ShAmt  = Op.getOperand(2);
   SDValue ARMcc;
+  SDValue CCR = DAG.getRegister(ARM::CPSR, MVT::i32);
 
   assert(Op.getOpcode() == ISD::SHL_PARTS);
   SDValue RevShAmt = DAG.getNode(ISD::SUB, dl, MVT::i32,
                                  DAG.getConstant(VTBits, dl, MVT::i32), ShAmt);
   SDValue Tmp1 = DAG.getNode(ISD::SRL, dl, VT, ShOpLo, RevShAmt);
+  SDValue Tmp2 = DAG.getNode(ISD::SHL, dl, VT, ShOpHi, ShAmt);
+  SDValue HiSmallShift = DAG.getNode(ISD::OR, dl, VT, Tmp1, Tmp2);
+
   SDValue ExtraShAmt = DAG.getNode(ISD::SUB, dl, MVT::i32, ShAmt,
                                    DAG.getConstant(VTBits, dl, MVT::i32));
-  SDValue Tmp2 = DAG.getNode(ISD::SHL, dl, VT, ShOpHi, ShAmt);
-  SDValue Tmp3 = DAG.getNode(ISD::SHL, dl, VT, ShOpLo, ExtraShAmt);
+  SDValue HiBigShift = DAG.getNode(ISD::SHL, dl, VT, ShOpLo, ExtraShAmt);
+  SDValue CmpHi = getARMCmp(ExtraShAmt, DAG.getConstant(0, dl, MVT::i32),
+                            ISD::SETGE, ARMcc, DAG, dl);
+  SDValue Hi = DAG.getNode(ARMISD::CMOV, dl, VT, HiSmallShift, HiBigShift,
+                           ARMcc, CCR, CmpHi);
 
-  SDValue FalseVal = DAG.getNode(ISD::OR, dl, VT, Tmp1, Tmp2);
-  SDValue CCR = DAG.getRegister(ARM::CPSR, MVT::i32);
-  SDValue Cmp = getARMCmp(ExtraShAmt, DAG.getConstant(0, dl, MVT::i32),
+  SDValue CmpLo = getARMCmp(ExtraShAmt, DAG.getConstant(0, dl, MVT::i32),
                           ISD::SETGE, ARMcc, DAG, dl);
-  SDValue Lo = DAG.getNode(ISD::SHL, dl, VT, ShOpLo, ShAmt);
-  SDValue Hi = DAG.getNode(ARMISD::CMOV, dl, VT, FalseVal, Tmp3, ARMcc,
-                           CCR, Cmp);
+  SDValue LoSmallShift = DAG.getNode(ISD::SHL, dl, VT, ShOpLo, ShAmt);
+  SDValue Lo = DAG.getNode(ARMISD::CMOV, dl, VT, LoSmallShift,
+                           DAG.getConstant(0, dl, VT), ARMcc, CCR, CmpLo);
 
   SDValue Ops[2] = { Lo, Hi };
   return DAG.getMergeValues(Ops, dl);