Implement variable-width shifts.

No testcase yet - it seems we're exposing generic codegen bugs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91221 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 170 insertions, 7 deletions

diff --git a/lib/Target/MSP430/MSP430ISelLowering.cpp b/lib/Target/MSP430/MSP430ISelLowering.cpp
index 4bd6006964..5fe9b20bd3 100644
--- a/lib/Target/MSP430/MSP430ISelLowering.cpp
+++ b/lib/Target/MSP430/MSP430ISelLowering.cpp
@@ -592,9 +592,21 @@ SDValue MSP430TargetLowering::LowerShifts(SDValue Op,
   EVT VT = Op.getValueType();
   DebugLoc dl = N->getDebugLoc();
 
-  // We currently only lower shifts of constant argument.
+  // Expand non-constant shifts to loops:
   if (!isa<ConstantSDNode>(N->getOperand(1)))
-    return SDValue();
+    switch (Opc) {
+    default:
+      assert(0 && "Invalid shift opcode!");
+    case ISD::SHL:
+      return DAG.getNode(MSP430ISD::SHL, dl,
+                         VT, N->getOperand(0), N->getOperand(1));
+    case ISD::SRA:
+      return DAG.getNode(MSP430ISD::SRA, dl,
+                         VT, N->getOperand(0), N->getOperand(1));
+    case ISD::SRL:
+      return DAG.getNode(MSP430ISD::SRL, dl,
+                         VT, N->getOperand(0), N->getOperand(1));
+    }
 
   uint64_t ShiftAmount = cast<ConstantSDNode>(N->getOperand(1))->getZExtValue();
 
@@ -916,6 +928,8 @@ const char *MSP430TargetLowering::getTargetNodeName(unsigned Opcode) const {
   case MSP430ISD::BR_CC:              return "MSP430ISD::BR_CC";
   case MSP430ISD::CMP:                return "MSP430ISD::CMP";
   case MSP430ISD::SELECT_CC:          return "MSP430ISD::SELECT_CC";
+  case MSP430ISD::SHL:                return "MSP430ISD::SHL";
+  case MSP430ISD::SRA:                return "MSP430ISD::SRA";
   }
 }
 
@@ -924,13 +938,131 @@ const char *MSP430TargetLowering::getTargetNodeName(unsigned Opcode) const {
 //===----------------------------------------------------------------------===//
 
 MachineBasicBlock*
+MSP430TargetLowering::EmitShiftInstr(MachineInstr *MI,
+                                     MachineBasicBlock *BB,
+                   DenseMap<MachineBasicBlock*, MachineBasicBlock*> *EM) const {
+  MachineFunction *F = BB->getParent();
+  MachineRegisterInfo &RI = F->getRegInfo();
+  DebugLoc dl = MI->getDebugLoc();
+  const TargetInstrInfo &TII = *getTargetMachine().getInstrInfo();
+
+  unsigned Opc;
+  const TargetRegisterClass * RC;
+  switch (MI->getOpcode()) {
+  default:
+    assert(0 && "Invalid shift opcode!");
+  case MSP430::Shl8:
+   Opc = MSP430::SHL8r1;
+   RC = MSP430::GR8RegisterClass;
+   break;
+  case MSP430::Shl16:
+   Opc = MSP430::SHL16r1;
+   RC = MSP430::GR16RegisterClass;
+   break;
+  case MSP430::Sra8:
+   Opc = MSP430::SAR8r1;
+   RC = MSP430::GR8RegisterClass;
+   break;
+  case MSP430::Sra16:
+   Opc = MSP430::SAR16r1;
+   RC = MSP430::GR16RegisterClass;
+   break;
+  case MSP430::Srl8:
+   Opc = MSP430::SAR8r1c;
+   RC = MSP430::GR8RegisterClass;
+   break;
+  case MSP430::Srl16:
+   Opc = MSP430::SAR16r1c;
+   RC = MSP430::GR16RegisterClass;
+   break;
+  }
+
+  const BasicBlock *LLVM_BB = BB->getBasicBlock();
+  MachineFunction::iterator I = BB;
+  ++I;
+
+  // Create loop block
+  MachineBasicBlock *LoopBB = F->CreateMachineBasicBlock(LLVM_BB);
+  MachineBasicBlock *RemBB  = F->CreateMachineBasicBlock(LLVM_BB);
+
+  F->insert(I, LoopBB);
+  F->insert(I, RemBB);
+
+  // Update machine-CFG edges by transferring all successors of the current
+  // block to the block containing instructions after shift.
+  RemBB->transferSuccessors(BB);
+
+  // Inform sdisel of the edge changes.
+  for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
+         SE = BB->succ_end(); SI != SE; ++SI)
+    EM->insert(std::make_pair(*SI, RemBB));
+
+  // Add adges BB => LoopBB => RemBB, BB => RemBB, LoopBB => LoopBB
+  BB->addSuccessor(LoopBB);
+  BB->addSuccessor(RemBB);
+  LoopBB->addSuccessor(RemBB);
+  LoopBB->addSuccessor(LoopBB);
+
+  unsigned ShiftAmtReg = RI.createVirtualRegister(MSP430::GR8RegisterClass);
+  unsigned ShiftAmtReg2 = RI.createVirtualRegister(MSP430::GR8RegisterClass);
+  unsigned ShiftReg = RI.createVirtualRegister(RC);
+  unsigned ShiftReg2 = RI.createVirtualRegister(RC);
+  unsigned ShiftAmtSrcReg = MI->getOperand(2).getReg();
+  unsigned SrcReg = MI->getOperand(1).getReg();
+  unsigned DstReg = MI->getOperand(0).getReg();
+
+  // BB:
+  // cmp 0, N
+  // je RemBB
+  BuildMI(BB, dl, TII.get(MSP430::CMP8ir))
+    .addImm(0).addReg(ShiftAmtSrcReg);
+  BuildMI(BB, dl, TII.get(MSP430::JCC))
+    .addMBB(RemBB)
+    .addImm(MSP430CC::COND_E);
+
+  // LoopBB:
+  // ShiftReg = phi [%SrcReg, BB], [%ShiftReg2, LoopBB]
+  // ShiftAmt = phi [%N, BB],      [%ShiftAmt2, LoopBB]
+  // ShiftReg2 = shift ShiftReg
+  // ShiftAmt2 = ShiftAmt - 1;
+  BuildMI(LoopBB, dl, TII.get(MSP430::PHI), ShiftReg)
+    .addReg(SrcReg).addMBB(BB)
+    .addReg(ShiftReg2).addMBB(LoopBB);
+  BuildMI(LoopBB, dl, TII.get(MSP430::PHI), ShiftAmtReg)
+    .addReg(ShiftAmtSrcReg).addMBB(BB)
+    .addReg(ShiftAmtReg2).addMBB(LoopBB);
+  BuildMI(LoopBB, dl, TII.get(Opc), ShiftReg2)
+    .addReg(ShiftReg);
+  BuildMI(LoopBB, dl, TII.get(MSP430::SUB8ri), ShiftAmtReg2)
+    .addReg(ShiftAmtReg).addImm(1);
+  BuildMI(LoopBB, dl, TII.get(MSP430::JCC))
+    .addMBB(LoopBB)
+    .addImm(MSP430CC::COND_NE);
+
+  // RemBB:
+  // DestReg = phi [%SrcReg, BB], [%ShiftReg, LoopBB]
+  BuildMI(RemBB, dl, TII.get(MSP430::PHI), DstReg)
+    .addReg(SrcReg).addMBB(BB)
+    .addReg(ShiftReg2).addMBB(LoopBB);
+
+  return RemBB;
+}
+
+MachineBasicBlock*
 MSP430TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
                                                   MachineBasicBlock *BB,
                    DenseMap<MachineBasicBlock*, MachineBasicBlock*> *EM) const {
+  unsigned Opc = MI->getOpcode();
+
+  if (Opc == MSP430::Shl8 || Opc == MSP430::Shl16 ||
+      Opc == MSP430::Sra8 || Opc == MSP430::Sra16 ||
+      Opc == MSP430::Srl8 || Opc == MSP430::Srl16)
+    return EmitShiftInstr(MI, BB, EM);
+
   const TargetInstrInfo &TII = *getTargetMachine().getInstrInfo();
   DebugLoc dl = MI->getDebugLoc();
-  assert((MI->getOpcode() == MSP430::Select16 ||
-          MI->getOpcode() == MSP430::Select8) &&
+
+  assert((Opc == MSP430::Select16 || Opc == MSP430::Select8) &&
          "Unexpected instr type to insert");
 
   // To "insert" a SELECT instruction, we actually have to insert the diamond
diff --git a/lib/Target/MSP430/MSP430ISelLowering.h b/lib/Target/MSP430/MSP430ISelLowering.h
index b126d8e431..4921500d39 100644
--- a/lib/Target/MSP430/MSP430ISelLowering.h
+++ b/lib/Target/MSP430/MSP430ISelLowering.h
@@ -47,7 +47,7 @@ namespace llvm {
       /// CMP - Compare instruction.
       CMP,
 
-      /// SetCC. Operand 0 is condition code, and operand 1 is the flag
+      /// SetCC - Operand 0 is condition code, and operand 1 is the flag
       /// operand produced by a CMP instruction.
       SETCC,
 
@@ -57,9 +57,12 @@ namespace llvm {
       /// instruction.
       BR_CC,
 
-      /// SELECT_CC. Operand 0 and operand 1 are selection variable, operand 3
+      /// SELECT_CC - Operand 0 and operand 1 are selection variable, operand 3
       /// is condition code and operand 4 is flag operand.
-      SELECT_CC
+      SELECT_CC,
+
+      /// SHL, SRA, SRL - Non-constant shifts.
+      SHL, SRA, SRL
     };
   }
 
@@ -99,6 +102,9 @@ namespace llvm {
     MachineBasicBlock* EmitInstrWithCustomInserter(MachineInstr *MI,
                                                    MachineBasicBlock *BB,
                     DenseMap<MachineBasicBlock*, MachineBasicBlock*> *EM) const;
+    MachineBasicBlock* EmitShiftInstr(MachineInstr *MI,
+                                      MachineBasicBlock *BB,
+                    DenseMap<MachineBasicBlock*, MachineBasicBlock*> *EM) const;
 
   private:
     SDValue LowerCCCCallTo(SDValue Chain, SDValue Callee,
diff --git a/lib/Target/MSP430/MSP430InstrInfo.td b/lib/Target/MSP430/MSP430InstrInfo.td
index 321018e958..d67ba90a4c 100644
--- a/lib/Target/MSP430/MSP430InstrInfo.td
+++ b/lib/Target/MSP430/MSP430InstrInfo.td
@@ -31,6 +31,7 @@ def SDT_MSP430BrCC         : SDTypeProfile<0, 2, [SDTCisVT<0, OtherVT>,
                                                   SDTCisVT<1, i8>]>;
 def SDT_MSP430SelectCC     : SDTypeProfile<1, 3, [SDTCisSameAs<0, 1>, SDTCisSameAs<1, 2>, 
                                                   SDTCisVT<3, i8>]>;
+def SDT_MSP430Shift        : SDTypeProfile<1, 2, [SDTCisSameAs<0, 1>, SDTCisI8<2>]>;
 
 //===----------------------------------------------------------------------===//
 // MSP430 Specific Node Definitions.
@@ -56,6 +57,9 @@ def MSP430Wrapper : SDNode<"MSP430ISD::Wrapper", SDT_MSP430Wrapper>;
 def MSP430cmp     : SDNode<"MSP430ISD::CMP", SDT_MSP430Cmp, [SDNPOutFlag]>;
 def MSP430brcc    : SDNode<"MSP430ISD::BR_CC", SDT_MSP430BrCC, [SDNPHasChain, SDNPInFlag]>;
 def MSP430selectcc: SDNode<"MSP430ISD::SELECT_CC", SDT_MSP430SelectCC, [SDNPInFlag]>;
+def MSP430shl     : SDNode<"MSP430ISD::SHL", SDT_MSP430Shift, []>;
+def MSP430sra     : SDNode<"MSP430ISD::SRA", SDT_MSP430Shift, []>;
+def MSP430srl     : SDNode<"MSP430ISD::SRL", SDT_MSP430Shift, []>;
 
 //===----------------------------------------------------------------------===//
 // MSP430 Operand Definitions.
@@ -121,6 +125,27 @@ let usesCustomInserter = 1 in {
                         "# Select16 PSEUDO",
                         [(set GR16:$dst,
                           (MSP430selectcc GR16:$src1, GR16:$src2, imm:$cc))]>;
+  let Defs = [SRW] in {
+  def Shl8     : Pseudo<(outs GR8:$dst), (ins GR8:$src, GR8:$cnt),
+                        "# Shl8 PSEUDO",
+                        [(set GR8:$dst, (MSP430shl GR8:$src, GR8:$cnt))]>;
+  def Shl16    : Pseudo<(outs GR16:$dst), (ins GR16:$src, GR8:$cnt),
+                        "# Shl16 PSEUDO",
+                        [(set GR16:$dst, (MSP430shl GR16:$src, GR8:$cnt))]>;
+  def Sra8     : Pseudo<(outs GR8:$dst), (ins GR8:$src, GR8:$cnt),
+                        "# Sra8 PSEUDO",
+                        [(set GR8:$dst, (MSP430sra GR8:$src, GR8:$cnt))]>;
+  def Sra16    : Pseudo<(outs GR16:$dst), (ins GR16:$src, GR8:$cnt),
+                        "# Sra16 PSEUDO",
+                        [(set GR16:$dst, (MSP430sra GR16:$src, GR8:$cnt))]>;
+  def Srl8     : Pseudo<(outs GR8:$dst), (ins GR8:$src, GR8:$cnt),
+                        "# Srl8 PSEUDO",
+                        [(set GR8:$dst, (MSP430srl GR8:$src, GR8:$cnt))]>;
+  def Srl16    : Pseudo<(outs GR16:$dst), (ins GR16:$src, GR8:$cnt),
+                        "# Srl16 PSEUDO",
+                        [(set GR16:$dst, (MSP430srl GR16:$src, GR8:$cnt))]>;
+
+  }
 }
 
 let neverHasSideEffects = 1 in