forked from OSchip/llvm-project
1298 lines
48 KiB
C++
1298 lines
48 KiB
C++
//===-- InstSelectSimple.cpp - A simple instruction selector for x86 ------===//
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//
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// This file defines a simple peephole instruction selector for the x86 platform
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//
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//===----------------------------------------------------------------------===//
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#include "X86.h"
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#include "X86InstrInfo.h"
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#include "X86InstrBuilder.h"
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#include "llvm/Function.h"
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#include "llvm/iTerminators.h"
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#include "llvm/iOperators.h"
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#include "llvm/iOther.h"
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#include "llvm/iPHINode.h"
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#include "llvm/iMemory.h"
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#include "llvm/Type.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Constants.h"
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#include "llvm/Pass.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/SSARegMap.h"
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#include "llvm/CodeGen/FunctionFrameInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Support/InstVisitor.h"
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#include "llvm/Target/MRegisterInfo.h"
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#include <map>
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/// BMI - A special BuildMI variant that takes an iterator to insert the
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/// instruction at as well as a basic block.
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/// this is the version for when you have a destination register in mind.
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inline static MachineInstrBuilder BMI(MachineBasicBlock *MBB,
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MachineBasicBlock::iterator &I,
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MachineOpCode Opcode,
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unsigned NumOperands,
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unsigned DestReg) {
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assert(I >= MBB->begin() && I <= MBB->end() && "Bad iterator!");
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MachineInstr *MI = new MachineInstr(Opcode, NumOperands+1, true, true);
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I = MBB->insert(I, MI)+1;
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return MachineInstrBuilder(MI).addReg(DestReg, MOTy::Def);
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}
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/// BMI - A special BuildMI variant that takes an iterator to insert the
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/// instruction at as well as a basic block.
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inline static MachineInstrBuilder BMI(MachineBasicBlock *MBB,
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MachineBasicBlock::iterator &I,
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MachineOpCode Opcode,
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unsigned NumOperands) {
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assert(I > MBB->begin() && I <= MBB->end() && "Bad iterator!");
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MachineInstr *MI = new MachineInstr(Opcode, NumOperands, true, true);
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I = MBB->insert(I, MI)+1;
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return MachineInstrBuilder(MI);
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}
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namespace {
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struct ISel : public FunctionPass, InstVisitor<ISel> {
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TargetMachine &TM;
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MachineFunction *F; // The function we are compiling into
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MachineBasicBlock *BB; // The current MBB we are compiling
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unsigned CurReg;
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std::map<Value*, unsigned> RegMap; // Mapping between Val's and SSA Regs
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// MBBMap - Mapping between LLVM BB -> Machine BB
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std::map<const BasicBlock*, MachineBasicBlock*> MBBMap;
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ISel(TargetMachine &tm)
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: TM(tm), F(0), BB(0), CurReg(MRegisterInfo::FirstVirtualRegister) {}
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/// runOnFunction - Top level implementation of instruction selection for
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/// the entire function.
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///
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bool runOnFunction(Function &Fn) {
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F = &MachineFunction::construct(&Fn, TM);
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// Create all of the machine basic blocks for the function...
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for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
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F->getBasicBlockList().push_back(MBBMap[I] = new MachineBasicBlock(I));
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BB = &F->front();
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LoadArgumentsToVirtualRegs(Fn);
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// Instruction select everything except PHI nodes
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visit(Fn);
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// Select the PHI nodes
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SelectPHINodes();
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RegMap.clear();
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MBBMap.clear();
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CurReg = MRegisterInfo::FirstVirtualRegister;
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F = 0;
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return false; // We never modify the LLVM itself.
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}
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virtual const char *getPassName() const {
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return "X86 Simple Instruction Selection";
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}
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/// visitBasicBlock - This method is called when we are visiting a new basic
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/// block. This simply creates a new MachineBasicBlock to emit code into
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/// and adds it to the current MachineFunction. Subsequent visit* for
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/// instructions will be invoked for all instructions in the basic block.
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///
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void visitBasicBlock(BasicBlock &LLVM_BB) {
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BB = MBBMap[&LLVM_BB];
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}
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/// LoadArgumentsToVirtualRegs - Load all of the arguments to this function
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/// from the stack into virtual registers.
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///
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void LoadArgumentsToVirtualRegs(Function &F);
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/// SelectPHINodes - Insert machine code to generate phis. This is tricky
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/// because we have to generate our sources into the source basic blocks,
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/// not the current one.
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///
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void SelectPHINodes();
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// Visitation methods for various instructions. These methods simply emit
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// fixed X86 code for each instruction.
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//
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// Control flow operators
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void visitReturnInst(ReturnInst &RI);
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void visitBranchInst(BranchInst &BI);
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void visitCallInst(CallInst &I);
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// Arithmetic operators
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void visitSimpleBinary(BinaryOperator &B, unsigned OpcodeClass);
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void visitAdd(BinaryOperator &B) { visitSimpleBinary(B, 0); }
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void visitSub(BinaryOperator &B) { visitSimpleBinary(B, 1); }
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void doMultiply(MachineBasicBlock *MBB, MachineBasicBlock::iterator &MBBI,
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unsigned destReg, const Type *resultType,
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unsigned op0Reg, unsigned op1Reg);
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void visitMul(BinaryOperator &B);
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void visitDiv(BinaryOperator &B) { visitDivRem(B); }
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void visitRem(BinaryOperator &B) { visitDivRem(B); }
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void visitDivRem(BinaryOperator &B);
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// Bitwise operators
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void visitAnd(BinaryOperator &B) { visitSimpleBinary(B, 2); }
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void visitOr (BinaryOperator &B) { visitSimpleBinary(B, 3); }
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void visitXor(BinaryOperator &B) { visitSimpleBinary(B, 4); }
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// Binary comparison operators
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void visitSetCCInst(SetCondInst &I, unsigned OpNum);
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void visitSetEQ(SetCondInst &I) { visitSetCCInst(I, 0); }
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void visitSetNE(SetCondInst &I) { visitSetCCInst(I, 1); }
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void visitSetLT(SetCondInst &I) { visitSetCCInst(I, 2); }
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void visitSetGT(SetCondInst &I) { visitSetCCInst(I, 3); }
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void visitSetLE(SetCondInst &I) { visitSetCCInst(I, 4); }
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void visitSetGE(SetCondInst &I) { visitSetCCInst(I, 5); }
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// Memory Instructions
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void visitLoadInst(LoadInst &I);
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void visitStoreInst(StoreInst &I);
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void visitGetElementPtrInst(GetElementPtrInst &I);
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void visitAllocaInst(AllocaInst &I);
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// We assume that by this point, malloc instructions have been
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// lowered to calls, and dlsym will magically find malloc for us.
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void visitMallocInst(MallocInst &I) { visitInstruction (I); }
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void visitFreeInst(FreeInst &I) { visitInstruction(I); }
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// Other operators
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void visitShiftInst(ShiftInst &I);
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void visitPHINode(PHINode &I) {} // PHI nodes handled by second pass
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void visitCastInst(CastInst &I);
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void visitInstruction(Instruction &I) {
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std::cerr << "Cannot instruction select: " << I;
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abort();
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}
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/// promote32 - Make a value 32-bits wide, and put it somewhere.
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void promote32 (const unsigned targetReg, Value *v);
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// emitGEPOperation - Common code shared between visitGetElementPtrInst and
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// constant expression GEP support.
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//
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void emitGEPOperation(MachineBasicBlock *BB, MachineBasicBlock::iterator&IP,
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Value *Src, User::op_iterator IdxBegin,
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User::op_iterator IdxEnd, unsigned TargetReg);
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/// copyConstantToRegister - Output the instructions required to put the
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/// specified constant into the specified register.
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///
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void copyConstantToRegister(MachineBasicBlock *MBB,
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MachineBasicBlock::iterator &MBBI,
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Constant *C, unsigned Reg);
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/// makeAnotherReg - This method returns the next register number
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/// we haven't yet used.
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unsigned makeAnotherReg(const Type *Ty) {
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// Add the mapping of regnumber => reg class to MachineFunction
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const TargetRegisterClass *RC =
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TM.getRegisterInfo()->getRegClassForType(Ty);
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F->getSSARegMap()->addRegMap(CurReg, RC);
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return CurReg++;
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}
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/// getReg - This method turns an LLVM value into a register number. This
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/// is guaranteed to produce the same register number for a particular value
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/// every time it is queried.
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///
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unsigned getReg(Value &V) { return getReg(&V); } // Allow references
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unsigned getReg(Value *V) {
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// Just append to the end of the current bb.
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MachineBasicBlock::iterator It = BB->end();
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return getReg(V, BB, It);
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}
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unsigned getReg(Value *V, MachineBasicBlock *MBB,
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MachineBasicBlock::iterator &IPt) {
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unsigned &Reg = RegMap[V];
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if (Reg == 0) {
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Reg = makeAnotherReg(V->getType());
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RegMap[V] = Reg;
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}
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// If this operand is a constant, emit the code to copy the constant into
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// the register here...
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//
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if (Constant *C = dyn_cast<Constant>(V)) {
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copyConstantToRegister(MBB, IPt, C, Reg);
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RegMap.erase(V); // Assign a new name to this constant if ref'd again
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} else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
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// Move the address of the global into the register
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BMI(MBB, IPt, X86::MOVir32, 1, Reg).addReg(GV);
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RegMap.erase(V); // Assign a new name to this address if ref'd again
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}
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return Reg;
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}
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};
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}
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/// TypeClass - Used by the X86 backend to group LLVM types by their basic X86
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/// Representation.
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///
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enum TypeClass {
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cByte, cShort, cInt, cFP, cLong
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};
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/// getClass - Turn a primitive type into a "class" number which is based on the
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/// size of the type, and whether or not it is floating point.
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///
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static inline TypeClass getClass(const Type *Ty) {
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switch (Ty->getPrimitiveID()) {
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case Type::SByteTyID:
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case Type::UByteTyID: return cByte; // Byte operands are class #0
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case Type::ShortTyID:
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case Type::UShortTyID: return cShort; // Short operands are class #1
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case Type::IntTyID:
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case Type::UIntTyID:
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case Type::PointerTyID: return cInt; // Int's and pointers are class #2
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case Type::FloatTyID:
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case Type::DoubleTyID: return cFP; // Floating Point is #3
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case Type::LongTyID:
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case Type::ULongTyID: //return cLong; // Longs are class #3
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return cInt; // FIXME: LONGS ARE TREATED AS INTS!
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default:
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assert(0 && "Invalid type to getClass!");
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return cByte; // not reached
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}
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}
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// getClassB - Just like getClass, but treat boolean values as bytes.
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static inline TypeClass getClassB(const Type *Ty) {
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if (Ty == Type::BoolTy) return cByte;
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return getClass(Ty);
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}
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/// copyConstantToRegister - Output the instructions required to put the
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/// specified constant into the specified register.
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///
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void ISel::copyConstantToRegister(MachineBasicBlock *MBB,
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MachineBasicBlock::iterator &IP,
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Constant *C, unsigned R) {
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if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
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if (CE->getOpcode() == Instruction::GetElementPtr) {
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emitGEPOperation(MBB, IP, CE->getOperand(0),
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CE->op_begin()+1, CE->op_end(), R);
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return;
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}
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std::cerr << "Offending expr: " << C << "\n";
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assert(0 && "Constant expressions not yet handled!\n");
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}
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if (C->getType()->isIntegral()) {
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unsigned Class = getClassB(C->getType());
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assert(Class <= cInt && "Type not handled yet!");
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static const unsigned IntegralOpcodeTab[] = {
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X86::MOVir8, X86::MOVir16, X86::MOVir32
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};
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if (C->getType() == Type::BoolTy) {
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BMI(MBB, IP, X86::MOVir8, 1, R).addZImm(C == ConstantBool::True);
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} else if (C->getType()->isSigned()) {
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ConstantSInt *CSI = cast<ConstantSInt>(C);
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BMI(MBB, IP, IntegralOpcodeTab[Class], 1, R).addSImm(CSI->getValue());
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} else {
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ConstantUInt *CUI = cast<ConstantUInt>(C);
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BMI(MBB, IP, IntegralOpcodeTab[Class], 1, R).addZImm(CUI->getValue());
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}
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} else if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
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double Value = CFP->getValue();
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if (Value == +0.0)
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BMI(MBB, IP, X86::FLD0, 0, R);
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else if (Value == +1.0)
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BMI(MBB, IP, X86::FLD1, 0, R);
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else {
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std::cerr << "Cannot load constant '" << Value << "'!\n";
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assert(0);
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}
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} else if (isa<ConstantPointerNull>(C)) {
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// Copy zero (null pointer) to the register.
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BMI(MBB, IP, X86::MOVir32, 1, R).addZImm(0);
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} else if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C)) {
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unsigned SrcReg = getReg(CPR->getValue(), MBB, IP);
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BMI(MBB, IP, X86::MOVrr32, 1, R).addReg(SrcReg);
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} else {
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std::cerr << "Offending constant: " << C << "\n";
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assert(0 && "Type not handled yet!");
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}
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}
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/// LoadArgumentsToVirtualRegs - Load all of the arguments to this function from
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/// the stack into virtual registers.
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///
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void ISel::LoadArgumentsToVirtualRegs(Function &Fn) {
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// Emit instructions to load the arguments... On entry to a function on the
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// X86, the stack frame looks like this:
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//
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// [ESP] -- return address
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// [ESP + 4] -- first argument (leftmost lexically) if four bytes in size
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// [ESP + 8] -- second argument, if four bytes in size
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// ...
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//
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unsigned ArgOffset = 0;
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FunctionFrameInfo *FFI = F->getFrameInfo();
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for (Function::aiterator I = Fn.abegin(), E = Fn.aend(); I != E; ++I) {
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unsigned Reg = getReg(*I);
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ArgOffset += 4; // Each argument takes at least 4 bytes on the stack...
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int FI; // Frame object index
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switch (getClassB(I->getType())) {
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case cByte:
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FI = FFI->CreateFixedObject(1, ArgOffset);
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addFrameReference(BuildMI(BB, X86::MOVmr8, 4, Reg), FI);
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break;
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case cShort:
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FI = FFI->CreateFixedObject(2, ArgOffset);
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addFrameReference(BuildMI(BB, X86::MOVmr16, 4, Reg), FI);
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break;
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case cInt:
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FI = FFI->CreateFixedObject(4, ArgOffset);
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addFrameReference(BuildMI(BB, X86::MOVmr32, 4, Reg), FI);
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break;
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case cFP:
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unsigned Opcode;
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if (I->getType() == Type::FloatTy) {
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Opcode = X86::FLDr32;
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FI = FFI->CreateFixedObject(4, ArgOffset);
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} else {
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Opcode = X86::FLDr64;
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ArgOffset += 4; // doubles require 4 additional bytes
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FI = FFI->CreateFixedObject(8, ArgOffset);
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}
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addFrameReference(BuildMI(BB, Opcode, 4, Reg), FI);
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break;
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default:
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assert(0 && "Unhandled argument type!");
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}
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}
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}
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/// SelectPHINodes - Insert machine code to generate phis. This is tricky
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/// because we have to generate our sources into the source basic blocks, not
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/// the current one.
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///
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void ISel::SelectPHINodes() {
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const Function &LF = *F->getFunction(); // The LLVM function...
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for (Function::const_iterator I = LF.begin(), E = LF.end(); I != E; ++I) {
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const BasicBlock *BB = I;
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MachineBasicBlock *MBB = MBBMap[I];
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// Loop over all of the PHI nodes in the LLVM basic block...
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unsigned NumPHIs = 0;
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for (BasicBlock::const_iterator I = BB->begin();
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PHINode *PN = (PHINode*)dyn_cast<PHINode>(&*I); ++I) {
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// Create a new machine instr PHI node, and insert it.
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MachineInstr *MI = BuildMI(X86::PHI, PN->getNumOperands(), getReg(*PN));
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MBB->insert(MBB->begin()+NumPHIs++, MI); // Insert it at the top of the BB
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for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
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MachineBasicBlock *PredMBB = MBBMap[PN->getIncomingBlock(i)];
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// Get the incoming value into a virtual register. If it is not already
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// available in a virtual register, insert the computation code into
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// PredMBB
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//
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// FIXME: This should insert the code into the BOTTOM of the block, not
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// the top of the block. This just makes for huge live ranges...
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MachineBasicBlock::iterator PI = PredMBB->begin();
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while ((*PI)->getOpcode() == X86::PHI) ++PI;
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MI->addRegOperand(getReg(PN->getIncomingValue(i), PredMBB, PI));
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MI->addMachineBasicBlockOperand(PredMBB);
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}
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}
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}
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}
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/// SetCC instructions - Here we just emit boilerplate code to set a byte-sized
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/// register, then move it to wherever the result should be.
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/// We handle FP setcc instructions by pushing them, doing a
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/// compare-and-pop-twice, and then copying the concodes to the main
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/// processor's concodes (I didn't make this up, it's in the Intel manual)
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///
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void ISel::visitSetCCInst(SetCondInst &I, unsigned OpNum) {
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// The arguments are already supposed to be of the same type.
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const Type *CompTy = I.getOperand(0)->getType();
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unsigned reg1 = getReg(I.getOperand(0));
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unsigned reg2 = getReg(I.getOperand(1));
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unsigned Class = getClass(CompTy);
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switch (Class) {
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// Emit: cmp <var1>, <var2> (do the comparison). We can
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// compare 8-bit with 8-bit, 16-bit with 16-bit, 32-bit with
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// 32-bit.
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case cByte:
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BuildMI (BB, X86::CMPrr8, 2).addReg (reg1).addReg (reg2);
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break;
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case cShort:
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BuildMI (BB, X86::CMPrr16, 2).addReg (reg1).addReg (reg2);
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break;
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case cInt:
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BuildMI (BB, X86::CMPrr32, 2).addReg (reg1).addReg (reg2);
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break;
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#if 0
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// Push the variables on the stack with fldl opcodes.
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// FIXME: assuming var1, var2 are in memory, if not, spill to
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// stack first
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case cFP: // Floats
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BuildMI (BB, X86::FLDr32, 1).addReg (reg1);
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BuildMI (BB, X86::FLDr32, 1).addReg (reg2);
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break;
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case cFP (doubles): // Doubles
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BuildMI (BB, X86::FLDr64, 1).addReg (reg1);
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BuildMI (BB, X86::FLDr64, 1).addReg (reg2);
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break;
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#endif
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case cLong:
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default:
|
|
visitInstruction(I);
|
|
}
|
|
|
|
#if 0
|
|
if (CompTy->isFloatingPoint()) {
|
|
// (Non-trapping) compare and pop twice.
|
|
BuildMI (BB, X86::FUCOMPP, 0);
|
|
// Move fp status word (concodes) to ax.
|
|
BuildMI (BB, X86::FNSTSWr8, 1, X86::AX);
|
|
// Load real concodes from ax.
|
|
BuildMI (BB, X86::SAHF, 1).addReg(X86::AH);
|
|
}
|
|
#endif
|
|
|
|
// Emit setOp instruction (extract concode; clobbers ax),
|
|
// using the following mapping:
|
|
// LLVM -> X86 signed X86 unsigned
|
|
// ----- ----- -----
|
|
// seteq -> sete sete
|
|
// setne -> setne setne
|
|
// setlt -> setl setb
|
|
// setgt -> setg seta
|
|
// setle -> setle setbe
|
|
// setge -> setge setae
|
|
|
|
static const unsigned OpcodeTab[2][6] = {
|
|
{X86::SETEr, X86::SETNEr, X86::SETBr, X86::SETAr, X86::SETBEr, X86::SETAEr},
|
|
{X86::SETEr, X86::SETNEr, X86::SETLr, X86::SETGr, X86::SETLEr, X86::SETGEr},
|
|
};
|
|
|
|
BuildMI(BB, OpcodeTab[CompTy->isSigned()][OpNum], 0, getReg(I));
|
|
}
|
|
|
|
/// promote32 - Emit instructions to turn a narrow operand into a 32-bit-wide
|
|
/// operand, in the specified target register.
|
|
void ISel::promote32 (unsigned targetReg, Value *v) {
|
|
unsigned vReg = getReg(v);
|
|
bool isUnsigned = v->getType()->isUnsigned();
|
|
switch (getClass(v->getType())) {
|
|
case cByte:
|
|
// Extend value into target register (8->32)
|
|
if (isUnsigned)
|
|
BuildMI(BB, X86::MOVZXr32r8, 1, targetReg).addReg(vReg);
|
|
else
|
|
BuildMI(BB, X86::MOVSXr32r8, 1, targetReg).addReg(vReg);
|
|
break;
|
|
case cShort:
|
|
// Extend value into target register (16->32)
|
|
if (isUnsigned)
|
|
BuildMI(BB, X86::MOVZXr32r16, 1, targetReg).addReg(vReg);
|
|
else
|
|
BuildMI(BB, X86::MOVSXr32r16, 1, targetReg).addReg(vReg);
|
|
break;
|
|
case cInt:
|
|
// Move value into target register (32->32)
|
|
BuildMI(BB, X86::MOVrr32, 1, targetReg).addReg(vReg);
|
|
break;
|
|
default:
|
|
assert(0 && "Unpromotable operand class in promote32");
|
|
}
|
|
}
|
|
|
|
/// 'ret' instruction - Here we are interested in meeting the x86 ABI. As such,
|
|
/// we have the following possibilities:
|
|
///
|
|
/// ret void: No return value, simply emit a 'ret' instruction
|
|
/// ret sbyte, ubyte : Extend value into EAX and return
|
|
/// ret short, ushort: Extend value into EAX and return
|
|
/// ret int, uint : Move value into EAX and return
|
|
/// ret pointer : Move value into EAX and return
|
|
/// ret long, ulong : Move value into EAX/EDX and return
|
|
/// ret float/double : Top of FP stack
|
|
///
|
|
void ISel::visitReturnInst (ReturnInst &I) {
|
|
if (I.getNumOperands() == 0) {
|
|
BuildMI(BB, X86::RET, 0); // Just emit a 'ret' instruction
|
|
return;
|
|
}
|
|
|
|
Value *RetVal = I.getOperand(0);
|
|
switch (getClass(RetVal->getType())) {
|
|
case cByte: // integral return values: extend or move into EAX and return
|
|
case cShort:
|
|
case cInt:
|
|
promote32(X86::EAX, RetVal);
|
|
break;
|
|
case cFP: // Floats & Doubles: Return in ST(0)
|
|
BuildMI(BB, X86::FpMOV, 1, X86::ST0).addReg(getReg(RetVal));
|
|
break;
|
|
case cLong:
|
|
// ret long: use EAX(least significant 32 bits)/EDX (most
|
|
// significant 32)...
|
|
default:
|
|
visitInstruction (I);
|
|
}
|
|
// Emit a 'ret' instruction
|
|
BuildMI(BB, X86::RET, 0);
|
|
}
|
|
|
|
/// visitBranchInst - Handle conditional and unconditional branches here. Note
|
|
/// that since code layout is frozen at this point, that if we are trying to
|
|
/// jump to a block that is the immediate successor of the current block, we can
|
|
/// just make a fall-through. (but we don't currently).
|
|
///
|
|
void ISel::visitBranchInst(BranchInst &BI) {
|
|
if (BI.isConditional()) {
|
|
BasicBlock *ifTrue = BI.getSuccessor(0);
|
|
BasicBlock *ifFalse = BI.getSuccessor(1);
|
|
|
|
// Compare condition with zero, followed by jump-if-equal to ifFalse, and
|
|
// jump-if-nonequal to ifTrue
|
|
unsigned condReg = getReg(BI.getCondition());
|
|
BuildMI(BB, X86::CMPri8, 2).addReg(condReg).addZImm(0);
|
|
BuildMI(BB, X86::JNE, 1).addPCDisp(BI.getSuccessor(0));
|
|
BuildMI(BB, X86::JE, 1).addPCDisp(BI.getSuccessor(1));
|
|
} else { // unconditional branch
|
|
BuildMI(BB, X86::JMP, 1).addPCDisp(BI.getSuccessor(0));
|
|
}
|
|
}
|
|
|
|
/// visitCallInst - Push args on stack and do a procedure call instruction.
|
|
void ISel::visitCallInst(CallInst &CI) {
|
|
// Count how many bytes are to be pushed on the stack...
|
|
unsigned NumBytes = 0;
|
|
|
|
if (CI.getNumOperands() > 1) {
|
|
for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
|
|
switch (getClass(CI.getOperand(i)->getType())) {
|
|
case cByte: case cShort: case cInt:
|
|
NumBytes += 4;
|
|
break;
|
|
case cLong:
|
|
NumBytes += 8;
|
|
break;
|
|
case cFP:
|
|
NumBytes += CI.getOperand(i)->getType() == Type::FloatTy ? 4 : 8;
|
|
break;
|
|
default: assert(0 && "Unknown class!");
|
|
}
|
|
|
|
// Adjust the stack pointer for the new arguments...
|
|
BuildMI(BB, X86::ADJCALLSTACKDOWN, 1).addZImm(NumBytes);
|
|
|
|
// Arguments go on the stack in reverse order, as specified by the ABI.
|
|
unsigned ArgOffset = 0;
|
|
for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i) {
|
|
Value *Arg = CI.getOperand(i);
|
|
switch (getClass(Arg->getType())) {
|
|
case cByte:
|
|
case cShort: {
|
|
// Promote arg to 32 bits wide into a temporary register...
|
|
unsigned R = makeAnotherReg(Type::UIntTy);
|
|
promote32(R, Arg);
|
|
addRegOffset(BuildMI(BB, X86::MOVrm32, 5),
|
|
X86::ESP, ArgOffset).addReg(R);
|
|
break;
|
|
}
|
|
case cInt:
|
|
addRegOffset(BuildMI(BB, X86::MOVrm32, 5),
|
|
X86::ESP, ArgOffset).addReg(getReg(Arg));
|
|
break;
|
|
|
|
case cFP:
|
|
if (Arg->getType() == Type::FloatTy) {
|
|
addRegOffset(BuildMI(BB, X86::FSTr32, 5),
|
|
X86::ESP, ArgOffset).addReg(getReg(Arg));
|
|
} else {
|
|
assert(Arg->getType() == Type::DoubleTy && "Unknown FP type!");
|
|
ArgOffset += 4;
|
|
addRegOffset(BuildMI(BB, X86::FSTr32, 5),
|
|
X86::ESP, ArgOffset).addReg(getReg(Arg));
|
|
}
|
|
break;
|
|
|
|
default:
|
|
// FIXME: long/ulong/float/double args not handled.
|
|
visitInstruction(CI);
|
|
break;
|
|
}
|
|
ArgOffset += 4;
|
|
}
|
|
}
|
|
|
|
if (Function *F = CI.getCalledFunction()) {
|
|
// Emit a CALL instruction with PC-relative displacement.
|
|
BuildMI(BB, X86::CALLpcrel32, 1).addPCDisp(F);
|
|
} else {
|
|
unsigned Reg = getReg(CI.getCalledValue());
|
|
BuildMI(BB, X86::CALLr32, 1).addReg(Reg);
|
|
}
|
|
|
|
BuildMI(BB, X86::ADJCALLSTACKUP, 1).addZImm(NumBytes);
|
|
|
|
// If there is a return value, scavenge the result from the location the call
|
|
// leaves it in...
|
|
//
|
|
if (CI.getType() != Type::VoidTy) {
|
|
unsigned resultTypeClass = getClass(CI.getType());
|
|
switch (resultTypeClass) {
|
|
case cByte:
|
|
case cShort:
|
|
case cInt: {
|
|
// Integral results are in %eax, or the appropriate portion
|
|
// thereof.
|
|
static const unsigned regRegMove[] = {
|
|
X86::MOVrr8, X86::MOVrr16, X86::MOVrr32
|
|
};
|
|
static const unsigned AReg[] = { X86::AL, X86::AX, X86::EAX };
|
|
BuildMI(BB, regRegMove[resultTypeClass], 1, getReg(CI))
|
|
.addReg(AReg[resultTypeClass]);
|
|
break;
|
|
}
|
|
case cFP: // Floating-point return values live in %ST(0)
|
|
BuildMI(BB, X86::FpMOV, 1, getReg(CI)).addReg(X86::ST0);
|
|
break;
|
|
default:
|
|
std::cerr << "Cannot get return value for call of type '"
|
|
<< *CI.getType() << "'\n";
|
|
visitInstruction(CI);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// visitSimpleBinary - Implement simple binary operators for integral types...
|
|
/// OperatorClass is one of: 0 for Add, 1 for Sub, 2 for And, 3 for Or,
|
|
/// 4 for Xor.
|
|
///
|
|
void ISel::visitSimpleBinary(BinaryOperator &B, unsigned OperatorClass) {
|
|
if (B.getType() == Type::BoolTy) // FIXME: Handle bools for logicals
|
|
visitInstruction(B);
|
|
|
|
unsigned Class = getClass(B.getType());
|
|
if (Class > cFP) // FIXME: Handle longs
|
|
visitInstruction(B);
|
|
|
|
static const unsigned OpcodeTab[][4] = {
|
|
// Arithmetic operators
|
|
{ X86::ADDrr8, X86::ADDrr16, X86::ADDrr32, X86::FpADD }, // ADD
|
|
{ X86::SUBrr8, X86::SUBrr16, X86::SUBrr32, X86::FpSUB }, // SUB
|
|
|
|
// Bitwise operators
|
|
{ X86::ANDrr8, X86::ANDrr16, X86::ANDrr32, 0 }, // AND
|
|
{ X86:: ORrr8, X86:: ORrr16, X86:: ORrr32, 0 }, // OR
|
|
{ X86::XORrr8, X86::XORrr16, X86::XORrr32, 0 }, // XOR
|
|
};
|
|
|
|
unsigned Opcode = OpcodeTab[OperatorClass][Class];
|
|
assert(Opcode && "Floating point arguments to logical inst?");
|
|
unsigned Op0r = getReg(B.getOperand(0));
|
|
unsigned Op1r = getReg(B.getOperand(1));
|
|
BuildMI(BB, Opcode, 2, getReg(B)).addReg(Op0r).addReg(Op1r);
|
|
}
|
|
|
|
/// doMultiply - Emit appropriate instructions to multiply together
|
|
/// the registers op0Reg and op1Reg, and put the result in destReg.
|
|
/// The type of the result should be given as resultType.
|
|
void ISel::doMultiply(MachineBasicBlock *MBB, MachineBasicBlock::iterator &MBBI,
|
|
unsigned destReg, const Type *resultType,
|
|
unsigned op0Reg, unsigned op1Reg) {
|
|
unsigned Class = getClass(resultType);
|
|
switch (Class) {
|
|
case cFP: // Floating point multiply
|
|
BuildMI(BB, X86::FpMUL, 2, destReg).addReg(op0Reg).addReg(op1Reg);
|
|
return;
|
|
default:
|
|
case cLong:
|
|
assert(0 && "doMultiply not implemented for this class yet!");
|
|
case cByte:
|
|
case cShort:
|
|
case cInt: // Small integerals, handled below...
|
|
break;
|
|
}
|
|
|
|
static const unsigned Regs[] ={ X86::AL , X86::AX , X86::EAX };
|
|
static const unsigned MulOpcode[]={ X86::MULrr8, X86::MULrr16, X86::MULrr32 };
|
|
static const unsigned MovOpcode[]={ X86::MOVrr8, X86::MOVrr16, X86::MOVrr32 };
|
|
unsigned Reg = Regs[Class];
|
|
|
|
// Emit a MOV to put the first operand into the appropriately-sized
|
|
// subreg of EAX.
|
|
BMI(MBB, MBBI, MovOpcode[Class], 1, Reg).addReg (op0Reg);
|
|
|
|
// Emit the appropriate multiply instruction.
|
|
BMI(MBB, MBBI, MulOpcode[Class], 1).addReg (op1Reg);
|
|
|
|
// Emit another MOV to put the result into the destination register.
|
|
BMI(MBB, MBBI, MovOpcode[Class], 1, destReg).addReg (Reg);
|
|
}
|
|
|
|
/// visitMul - Multiplies are not simple binary operators because they must deal
|
|
/// with the EAX register explicitly.
|
|
///
|
|
void ISel::visitMul(BinaryOperator &I) {
|
|
unsigned DestReg = getReg(I);
|
|
unsigned Op0Reg = getReg(I.getOperand(0));
|
|
unsigned Op1Reg = getReg(I.getOperand(1));
|
|
MachineBasicBlock::iterator MBBI = BB->end();
|
|
doMultiply(BB, MBBI, DestReg, I.getType(), Op0Reg, Op1Reg);
|
|
}
|
|
|
|
|
|
/// visitDivRem - Handle division and remainder instructions... these
|
|
/// instruction both require the same instructions to be generated, they just
|
|
/// select the result from a different register. Note that both of these
|
|
/// instructions work differently for signed and unsigned operands.
|
|
///
|
|
void ISel::visitDivRem(BinaryOperator &I) {
|
|
unsigned Class = getClass(I.getType());
|
|
unsigned Op0Reg = getReg(I.getOperand(0));
|
|
unsigned Op1Reg = getReg(I.getOperand(1));
|
|
unsigned ResultReg = getReg(I);
|
|
|
|
switch (Class) {
|
|
case cFP: // Floating point multiply
|
|
if (I.getOpcode() == Instruction::Div)
|
|
BuildMI(BB, X86::FpDIV, 2, ResultReg).addReg(Op0Reg).addReg(Op1Reg);
|
|
else
|
|
BuildMI(BB, X86::FpREM, 2, ResultReg).addReg(Op0Reg).addReg(Op1Reg);
|
|
return;
|
|
default:
|
|
case cLong:
|
|
assert(0 && "div/rem not implemented for this class yet!");
|
|
case cByte:
|
|
case cShort:
|
|
case cInt: // Small integerals, handled below...
|
|
break;
|
|
}
|
|
|
|
static const unsigned Regs[] ={ X86::AL , X86::AX , X86::EAX };
|
|
static const unsigned MovOpcode[]={ X86::MOVrr8, X86::MOVrr16, X86::MOVrr32 };
|
|
static const unsigned ExtOpcode[]={ X86::CBW , X86::CWD , X86::CDQ };
|
|
static const unsigned ClrOpcode[]={ X86::XORrr8, X86::XORrr16, X86::XORrr32 };
|
|
static const unsigned ExtRegs[] ={ X86::AH , X86::DX , X86::EDX };
|
|
|
|
static const unsigned DivOpcode[][4] = {
|
|
{ X86::DIVrr8 , X86::DIVrr16 , X86::DIVrr32 , 0 }, // Unsigned division
|
|
{ X86::IDIVrr8, X86::IDIVrr16, X86::IDIVrr32, 0 }, // Signed division
|
|
};
|
|
|
|
bool isSigned = I.getType()->isSigned();
|
|
unsigned Reg = Regs[Class];
|
|
unsigned ExtReg = ExtRegs[Class];
|
|
|
|
// Put the first operand into one of the A registers...
|
|
BuildMI(BB, MovOpcode[Class], 1, Reg).addReg(Op0Reg);
|
|
|
|
if (isSigned) {
|
|
// Emit a sign extension instruction...
|
|
BuildMI(BB, ExtOpcode[Class], 0);
|
|
} else {
|
|
// If unsigned, emit a zeroing instruction... (reg = xor reg, reg)
|
|
BuildMI(BB, ClrOpcode[Class], 2, ExtReg).addReg(ExtReg).addReg(ExtReg);
|
|
}
|
|
|
|
// Emit the appropriate divide or remainder instruction...
|
|
BuildMI(BB, DivOpcode[isSigned][Class], 1).addReg(Op1Reg);
|
|
|
|
// Figure out which register we want to pick the result out of...
|
|
unsigned DestReg = (I.getOpcode() == Instruction::Div) ? Reg : ExtReg;
|
|
|
|
// Put the result into the destination register...
|
|
BuildMI(BB, MovOpcode[Class], 1, ResultReg).addReg(DestReg);
|
|
}
|
|
|
|
|
|
/// Shift instructions: 'shl', 'sar', 'shr' - Some special cases here
|
|
/// for constant immediate shift values, and for constant immediate
|
|
/// shift values equal to 1. Even the general case is sort of special,
|
|
/// because the shift amount has to be in CL, not just any old register.
|
|
///
|
|
void ISel::visitShiftInst (ShiftInst &I) {
|
|
unsigned Op0r = getReg (I.getOperand(0));
|
|
unsigned DestReg = getReg(I);
|
|
bool isLeftShift = I.getOpcode() == Instruction::Shl;
|
|
bool isOperandSigned = I.getType()->isUnsigned();
|
|
unsigned OperandClass = getClass(I.getType());
|
|
|
|
if (OperandClass > cInt)
|
|
visitInstruction(I); // Can't handle longs yet!
|
|
|
|
if (ConstantUInt *CUI = dyn_cast<ConstantUInt> (I.getOperand (1)))
|
|
{
|
|
// The shift amount is constant, guaranteed to be a ubyte. Get its value.
|
|
assert(CUI->getType() == Type::UByteTy && "Shift amount not a ubyte?");
|
|
unsigned char shAmt = CUI->getValue();
|
|
|
|
static const unsigned ConstantOperand[][4] = {
|
|
{ X86::SHRir8, X86::SHRir16, X86::SHRir32, 0 }, // SHR
|
|
{ X86::SARir8, X86::SARir16, X86::SARir32, 0 }, // SAR
|
|
{ X86::SHLir8, X86::SHLir16, X86::SHLir32, 0 }, // SHL
|
|
{ X86::SHLir8, X86::SHLir16, X86::SHLir32, 0 }, // SAL = SHL
|
|
};
|
|
|
|
const unsigned *OpTab = // Figure out the operand table to use
|
|
ConstantOperand[isLeftShift*2+isOperandSigned];
|
|
|
|
// Emit: <insn> reg, shamt (shift-by-immediate opcode "ir" form.)
|
|
BuildMI(BB, OpTab[OperandClass], 2, DestReg).addReg(Op0r).addZImm(shAmt);
|
|
}
|
|
else
|
|
{
|
|
// The shift amount is non-constant.
|
|
//
|
|
// In fact, you can only shift with a variable shift amount if
|
|
// that amount is already in the CL register, so we have to put it
|
|
// there first.
|
|
//
|
|
|
|
// Emit: move cl, shiftAmount (put the shift amount in CL.)
|
|
BuildMI(BB, X86::MOVrr8, 1, X86::CL).addReg(getReg(I.getOperand(1)));
|
|
|
|
// This is a shift right (SHR).
|
|
static const unsigned NonConstantOperand[][4] = {
|
|
{ X86::SHRrr8, X86::SHRrr16, X86::SHRrr32, 0 }, // SHR
|
|
{ X86::SARrr8, X86::SARrr16, X86::SARrr32, 0 }, // SAR
|
|
{ X86::SHLrr8, X86::SHLrr16, X86::SHLrr32, 0 }, // SHL
|
|
{ X86::SHLrr8, X86::SHLrr16, X86::SHLrr32, 0 }, // SAL = SHL
|
|
};
|
|
|
|
const unsigned *OpTab = // Figure out the operand table to use
|
|
NonConstantOperand[isLeftShift*2+isOperandSigned];
|
|
|
|
BuildMI(BB, OpTab[OperandClass], 1, DestReg).addReg(Op0r);
|
|
}
|
|
}
|
|
|
|
|
|
/// visitLoadInst - Implement LLVM load instructions in terms of the x86 'mov'
|
|
/// instruction. The load and store instructions are the only place where we
|
|
/// need to worry about the memory layout of the target machine.
|
|
///
|
|
void ISel::visitLoadInst(LoadInst &I) {
|
|
bool isLittleEndian = TM.getTargetData().isLittleEndian();
|
|
bool hasLongPointers = TM.getTargetData().getPointerSize() == 8;
|
|
unsigned SrcAddrReg = getReg(I.getOperand(0));
|
|
unsigned DestReg = getReg(I);
|
|
|
|
unsigned Class = getClass(I.getType());
|
|
switch (Class) {
|
|
default: visitInstruction(I); // FIXME: Handle longs...
|
|
case cFP: {
|
|
// FIXME: Handle endian swapping for FP values.
|
|
unsigned Opcode = I.getType() == Type::FloatTy ? X86::FLDr32 : X86::FLDr64;
|
|
addDirectMem(BuildMI(BB, Opcode, 4, DestReg), SrcAddrReg);
|
|
return;
|
|
}
|
|
case cInt: // Integers of various sizes handled below
|
|
case cShort:
|
|
case cByte: break;
|
|
}
|
|
|
|
// We need to adjust the input pointer if we are emulating a big-endian
|
|
// long-pointer target. On these systems, the pointer that we are interested
|
|
// in is in the upper part of the eight byte memory image of the pointer. It
|
|
// also happens to be byte-swapped, but this will be handled later.
|
|
//
|
|
if (!isLittleEndian && hasLongPointers && isa<PointerType>(I.getType())) {
|
|
unsigned R = makeAnotherReg(Type::UIntTy);
|
|
BuildMI(BB, X86::ADDri32, 2, R).addReg(SrcAddrReg).addZImm(4);
|
|
SrcAddrReg = R;
|
|
}
|
|
|
|
unsigned IReg = DestReg;
|
|
if (!isLittleEndian) { // If big endian we need an intermediate stage
|
|
IReg = makeAnotherReg(I.getType());
|
|
std::swap(IReg, DestReg);
|
|
}
|
|
|
|
static const unsigned Opcode[] = { X86::MOVmr8, X86::MOVmr16, X86::MOVmr32 };
|
|
addDirectMem(BuildMI(BB, Opcode[Class], 4, DestReg), SrcAddrReg);
|
|
|
|
if (!isLittleEndian) {
|
|
// Emit the byte swap instruction...
|
|
switch (Class) {
|
|
case cByte:
|
|
// No byteswap neccesary for 8 bit value...
|
|
BuildMI(BB, X86::MOVrr8, 1, IReg).addReg(DestReg);
|
|
break;
|
|
case cInt:
|
|
// Use the 32 bit bswap instruction to do a 32 bit swap...
|
|
BuildMI(BB, X86::BSWAPr32, 1, IReg).addReg(DestReg);
|
|
break;
|
|
|
|
case cShort:
|
|
// For 16 bit we have to use an xchg instruction, because there is no
|
|
// 16-bit bswap. XCHG is neccesarily not in SSA form, so we force things
|
|
// into AX to do the xchg.
|
|
//
|
|
BuildMI(BB, X86::MOVrr16, 1, X86::AX).addReg(DestReg);
|
|
BuildMI(BB, X86::XCHGrr8, 2).addReg(X86::AL, MOTy::UseAndDef)
|
|
.addReg(X86::AH, MOTy::UseAndDef);
|
|
BuildMI(BB, X86::MOVrr16, 1, DestReg).addReg(X86::AX);
|
|
break;
|
|
default: assert(0 && "Class not handled yet!");
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/// visitStoreInst - Implement LLVM store instructions in terms of the x86 'mov'
|
|
/// instruction.
|
|
///
|
|
void ISel::visitStoreInst(StoreInst &I) {
|
|
bool isLittleEndian = TM.getTargetData().isLittleEndian();
|
|
bool hasLongPointers = TM.getTargetData().getPointerSize() == 8;
|
|
unsigned ValReg = getReg(I.getOperand(0));
|
|
unsigned AddressReg = getReg(I.getOperand(1));
|
|
|
|
unsigned Class = getClass(I.getOperand(0)->getType());
|
|
switch (Class) {
|
|
default: visitInstruction(I); // FIXME: Handle longs...
|
|
case cFP: {
|
|
// FIXME: Handle endian swapping for FP values.
|
|
unsigned Opcode = I.getOperand(0)->getType() == Type::FloatTy ?
|
|
X86::FSTr32 : X86::FSTr64;
|
|
addDirectMem(BuildMI(BB, Opcode, 1+4), AddressReg).addReg(ValReg);
|
|
return;
|
|
}
|
|
case cInt: // Integers of various sizes handled below
|
|
case cShort:
|
|
case cByte: break;
|
|
}
|
|
|
|
if (!isLittleEndian && hasLongPointers &&
|
|
isa<PointerType>(I.getOperand(0)->getType())) {
|
|
unsigned R = makeAnotherReg(Type::UIntTy);
|
|
BuildMI(BB, X86::ADDri32, 2, R).addReg(AddressReg).addZImm(4);
|
|
AddressReg = R;
|
|
}
|
|
|
|
if (!isLittleEndian && Class != cByte) {
|
|
// Emit a byte swap instruction...
|
|
switch (Class) {
|
|
case cInt: {
|
|
unsigned R = makeAnotherReg(I.getOperand(0)->getType());
|
|
BuildMI(BB, X86::BSWAPr32, 1, R).addReg(ValReg);
|
|
ValReg = R;
|
|
break;
|
|
}
|
|
case cShort:
|
|
// For 16 bit we have to use an xchg instruction, because there is no
|
|
// 16-bit bswap. XCHG is neccesarily not in SSA form, so we force things
|
|
// into AX to do the xchg.
|
|
//
|
|
BuildMI(BB, X86::MOVrr16, 1, X86::AX).addReg(ValReg);
|
|
BuildMI(BB, X86::XCHGrr8, 2).addReg(X86::AL, MOTy::UseAndDef)
|
|
.addReg(X86::AH, MOTy::UseAndDef);
|
|
ValReg = X86::AX;
|
|
break;
|
|
default: assert(0 && "Unknown class!");
|
|
}
|
|
}
|
|
|
|
static const unsigned Opcode[] = { X86::MOVrm8, X86::MOVrm16, X86::MOVrm32 };
|
|
addDirectMem(BuildMI(BB, Opcode[Class], 1+4), AddressReg).addReg(ValReg);
|
|
}
|
|
|
|
|
|
/// visitCastInst - Here we have various kinds of copying with or without
|
|
/// sign extension going on.
|
|
void
|
|
ISel::visitCastInst (CastInst &CI)
|
|
{
|
|
const Type *targetType = CI.getType ();
|
|
Value *operand = CI.getOperand (0);
|
|
unsigned operandReg = getReg (operand);
|
|
const Type *sourceType = operand->getType ();
|
|
unsigned destReg = getReg (CI);
|
|
//
|
|
// Currently we handle:
|
|
//
|
|
// 1) cast * to bool
|
|
//
|
|
// 2) cast {sbyte, ubyte} to {sbyte, ubyte}
|
|
// cast {short, ushort} to {ushort, short}
|
|
// cast {int, uint, ptr} to {int, uint, ptr}
|
|
//
|
|
// 3) cast {sbyte, ubyte} to {ushort, short}
|
|
// cast {sbyte, ubyte} to {int, uint, ptr}
|
|
// cast {short, ushort} to {int, uint, ptr}
|
|
//
|
|
// 4) cast {int, uint, ptr} to {short, ushort}
|
|
// cast {int, uint, ptr} to {sbyte, ubyte}
|
|
// cast {short, ushort} to {sbyte, ubyte}
|
|
|
|
// 1) Implement casts to bool by using compare on the operand followed
|
|
// by set if not zero on the result.
|
|
if (targetType == Type::BoolTy)
|
|
{
|
|
BuildMI (BB, X86::CMPri8, 2).addReg (operandReg).addZImm (0);
|
|
BuildMI (BB, X86::SETNEr, 1, destReg);
|
|
return;
|
|
}
|
|
|
|
// 2) Implement casts between values of the same type class (as determined
|
|
// by getClass) by using a register-to-register move.
|
|
unsigned srcClass = getClassB(sourceType);
|
|
unsigned targClass = getClass(targetType);
|
|
static const unsigned regRegMove[] = {
|
|
X86::MOVrr8, X86::MOVrr16, X86::MOVrr32
|
|
};
|
|
|
|
if (srcClass <= cInt && targClass <= cInt && srcClass == targClass) {
|
|
BuildMI(BB, regRegMove[srcClass], 1, destReg).addReg(operandReg);
|
|
return;
|
|
}
|
|
// 3) Handle cast of SMALLER int to LARGER int using a move with sign
|
|
// extension or zero extension, depending on whether the source type
|
|
// was signed.
|
|
if ((srcClass <= cInt) && (targClass <= cInt) && (srcClass < targClass))
|
|
{
|
|
static const unsigned ops[] = {
|
|
X86::MOVSXr16r8, X86::MOVSXr32r8, X86::MOVSXr32r16,
|
|
X86::MOVZXr16r8, X86::MOVZXr32r8, X86::MOVZXr32r16
|
|
};
|
|
unsigned srcSigned = sourceType->isSigned ();
|
|
BuildMI (BB, ops[3 * srcSigned + srcClass + targClass - 1], 1,
|
|
destReg).addReg (operandReg);
|
|
return;
|
|
}
|
|
// 4) Handle cast of LARGER int to SMALLER int using a move to EAX
|
|
// followed by a move out of AX or AL.
|
|
if ((srcClass <= cInt) && (targClass <= cInt) && (srcClass > targClass))
|
|
{
|
|
static const unsigned AReg[] = { X86::AL, X86::AX, X86::EAX };
|
|
BuildMI (BB, regRegMove[srcClass], 1,
|
|
AReg[srcClass]).addReg (operandReg);
|
|
BuildMI (BB, regRegMove[targClass], 1, destReg).addReg (AReg[srcClass]);
|
|
return;
|
|
}
|
|
// Anything we haven't handled already, we can't (yet) handle at all.
|
|
//
|
|
// FP to integral casts can be handled with FISTP to store onto the
|
|
// stack while converting to integer, followed by a MOV to load from
|
|
// the stack into the result register. Integral to FP casts can be
|
|
// handled with MOV to store onto the stack, followed by a FILD to
|
|
// load from the stack while converting to FP. For the moment, I
|
|
// can't quite get straight in my head how to borrow myself some
|
|
// stack space and write on it. Otherwise, this would be trivial.
|
|
visitInstruction (CI);
|
|
}
|
|
|
|
// ExactLog2 - This function solves for (Val == 1 << (N-1)) and returns N. It
|
|
// returns zero when the input is not exactly a power of two.
|
|
static unsigned ExactLog2(unsigned Val) {
|
|
if (Val == 0) return 0;
|
|
unsigned Count = 0;
|
|
while (Val != 1) {
|
|
if (Val & 1) return 0;
|
|
Val >>= 1;
|
|
++Count;
|
|
}
|
|
return Count+1;
|
|
}
|
|
|
|
/// visitGetElementPtrInst - I don't know, most programs don't have
|
|
/// getelementptr instructions, right? That means we can put off
|
|
/// implementing this, right? Right. This method emits machine
|
|
/// instructions to perform type-safe pointer arithmetic. I am
|
|
/// guessing this could be cleaned up somewhat to use fewer temporary
|
|
/// registers.
|
|
void
|
|
ISel::visitGetElementPtrInst (GetElementPtrInst &I)
|
|
{
|
|
unsigned outputReg = getReg (I);
|
|
MachineBasicBlock::iterator MI = BB->end();
|
|
emitGEPOperation(BB, MI, I.getOperand(0),
|
|
I.op_begin()+1, I.op_end(), outputReg);
|
|
}
|
|
|
|
void ISel::emitGEPOperation(MachineBasicBlock *MBB,
|
|
MachineBasicBlock::iterator &IP,
|
|
Value *Src, User::op_iterator IdxBegin,
|
|
User::op_iterator IdxEnd, unsigned TargetReg) {
|
|
const TargetData &TD = TM.getTargetData();
|
|
const Type *Ty = Src->getType();
|
|
unsigned basePtrReg = getReg(Src, MBB, IP);
|
|
|
|
// GEPs have zero or more indices; we must perform a struct access
|
|
// or array access for each one.
|
|
for (GetElementPtrInst::op_iterator oi = IdxBegin,
|
|
oe = IdxEnd; oi != oe; ++oi) {
|
|
Value *idx = *oi;
|
|
unsigned nextBasePtrReg = makeAnotherReg(Type::UIntTy);
|
|
if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
|
|
// It's a struct access. idx is the index into the structure,
|
|
// which names the field. This index must have ubyte type.
|
|
const ConstantUInt *CUI = cast<ConstantUInt>(idx);
|
|
assert(CUI->getType() == Type::UByteTy
|
|
&& "Funny-looking structure index in GEP");
|
|
// Use the TargetData structure to pick out what the layout of
|
|
// the structure is in memory. Since the structure index must
|
|
// be constant, we can get its value and use it to find the
|
|
// right byte offset from the StructLayout class's list of
|
|
// structure member offsets.
|
|
unsigned idxValue = CUI->getValue();
|
|
unsigned memberOffset =
|
|
TD.getStructLayout(StTy)->MemberOffsets[idxValue];
|
|
// Emit an ADD to add memberOffset to the basePtr.
|
|
BMI(MBB, IP, X86::ADDri32, 2,
|
|
nextBasePtrReg).addReg(basePtrReg).addZImm(memberOffset);
|
|
// The next type is the member of the structure selected by the
|
|
// index.
|
|
Ty = StTy->getElementTypes()[idxValue];
|
|
} else if (const SequentialType *SqTy = cast<SequentialType>(Ty)) {
|
|
// It's an array or pointer access: [ArraySize x ElementType].
|
|
|
|
// idx is the index into the array. Unlike with structure
|
|
// indices, we may not know its actual value at code-generation
|
|
// time.
|
|
assert(idx->getType() == Type::LongTy && "Bad GEP array index!");
|
|
|
|
// We want to add basePtrReg to(idxReg * sizeof ElementType). First, we
|
|
// must find the size of the pointed-to type (Not coincidentally, the next
|
|
// type is the type of the elements in the array).
|
|
Ty = SqTy->getElementType();
|
|
unsigned elementSize = TD.getTypeSize(Ty);
|
|
|
|
// If idxReg is a constant, we don't need to perform the multiply!
|
|
if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(idx)) {
|
|
if (CSI->isNullValue()) {
|
|
BMI(MBB, IP, X86::MOVrr32, 1, nextBasePtrReg).addReg(basePtrReg);
|
|
} else {
|
|
unsigned Offset = elementSize*CSI->getValue();
|
|
|
|
BMI(MBB, IP, X86::ADDri32, 2,
|
|
nextBasePtrReg).addReg(basePtrReg).addZImm(Offset);
|
|
}
|
|
} else if (elementSize == 1) {
|
|
// If the element size is 1, we don't have to multiply, just add
|
|
unsigned idxReg = getReg(idx, MBB, IP);
|
|
BMI(MBB, IP, X86::ADDrr32, 2,
|
|
nextBasePtrReg).addReg(basePtrReg).addReg(idxReg);
|
|
} else {
|
|
unsigned idxReg = getReg(idx, MBB, IP);
|
|
unsigned OffsetReg = makeAnotherReg(Type::UIntTy);
|
|
if (unsigned Shift = ExactLog2(elementSize)) {
|
|
// If the element size is exactly a power of 2, use a shift to get it.
|
|
|
|
BMI(MBB, IP, X86::SHLir32, 2,
|
|
OffsetReg).addReg(idxReg).addZImm(Shift-1);
|
|
} else {
|
|
// Most general case, emit a multiply...
|
|
unsigned elementSizeReg = makeAnotherReg(Type::LongTy);
|
|
BMI(MBB, IP, X86::MOVir32, 1, elementSizeReg).addZImm(elementSize);
|
|
|
|
// Emit a MUL to multiply the register holding the index by
|
|
// elementSize, putting the result in OffsetReg.
|
|
doMultiply(MBB, IP, OffsetReg, Type::LongTy, idxReg, elementSizeReg);
|
|
}
|
|
// Emit an ADD to add OffsetReg to the basePtr.
|
|
BMI(MBB, IP, X86::ADDrr32, 2,
|
|
nextBasePtrReg).addReg(basePtrReg).addReg(OffsetReg);
|
|
}
|
|
}
|
|
// Now that we are here, further indices refer to subtypes of this
|
|
// one, so we don't need to worry about basePtrReg itself, anymore.
|
|
basePtrReg = nextBasePtrReg;
|
|
}
|
|
// After we have processed all the indices, the result is left in
|
|
// basePtrReg. Move it to the register where we were expected to
|
|
// put the answer. A 32-bit move should do it, because we are in
|
|
// ILP32 land.
|
|
BMI(MBB, IP, X86::MOVrr32, 1, TargetReg).addReg(basePtrReg);
|
|
}
|
|
|
|
|
|
/// visitAllocaInst - If this is a fixed size alloca, allocate space from the
|
|
/// frame manager, otherwise do it the hard way.
|
|
///
|
|
void ISel::visitAllocaInst(AllocaInst &I) {
|
|
// Find the data size of the alloca inst's getAllocatedType.
|
|
const Type *Ty = I.getAllocatedType();
|
|
unsigned TySize = TM.getTargetData().getTypeSize(Ty);
|
|
|
|
// If this is a fixed size alloca in the entry block for the function,
|
|
// statically stack allocate the space.
|
|
//
|
|
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I.getArraySize())) {
|
|
if (I.getParent() == I.getParent()->getParent()->begin()) {
|
|
TySize *= CUI->getValue(); // Get total allocated size...
|
|
unsigned Alignment = TM.getTargetData().getTypeAlignment(Ty);
|
|
|
|
// Create a new stack object using the frame manager...
|
|
int FrameIdx = F->getFrameInfo()->CreateStackObject(TySize, Alignment);
|
|
addFrameReference(BuildMI(BB, X86::LEAr32, 5, getReg(I)), FrameIdx);
|
|
return;
|
|
}
|
|
}
|
|
|
|
// Create a register to hold the temporary result of multiplying the type size
|
|
// constant by the variable amount.
|
|
unsigned TotalSizeReg = makeAnotherReg(Type::UIntTy);
|
|
unsigned SrcReg1 = getReg(I.getArraySize());
|
|
unsigned SizeReg = makeAnotherReg(Type::UIntTy);
|
|
BuildMI(BB, X86::MOVir32, 1, SizeReg).addZImm(TySize);
|
|
|
|
// TotalSizeReg = mul <numelements>, <TypeSize>
|
|
MachineBasicBlock::iterator MBBI = BB->end();
|
|
doMultiply(BB, MBBI, TotalSizeReg, Type::UIntTy, SrcReg1, SizeReg);
|
|
|
|
// AddedSize = add <TotalSizeReg>, 15
|
|
unsigned AddedSizeReg = makeAnotherReg(Type::UIntTy);
|
|
BuildMI(BB, X86::ADDri32, 2, AddedSizeReg).addReg(TotalSizeReg).addZImm(15);
|
|
|
|
// AlignedSize = and <AddedSize>, ~15
|
|
unsigned AlignedSize = makeAnotherReg(Type::UIntTy);
|
|
BuildMI(BB, X86::ANDri32, 2, AlignedSize).addReg(AddedSizeReg).addZImm(~15);
|
|
|
|
// Subtract size from stack pointer, thereby allocating some space.
|
|
BuildMI(BB, X86::SUBri32, 2, X86::ESP).addReg(X86::ESP).addZImm(AlignedSize);
|
|
|
|
// Put a pointer to the space into the result register, by copying
|
|
// the stack pointer.
|
|
BuildMI(BB, X86::MOVrr32, 1, getReg(I)).addReg(X86::ESP);
|
|
|
|
// Inform the Frame Information that we have just allocated a variable sized
|
|
// object.
|
|
F->getFrameInfo()->CreateVariableSizedObject();
|
|
}
|
|
|
|
|
|
/// createSimpleX86InstructionSelector - This pass converts an LLVM function
|
|
/// into a machine code representation is a very simple peep-hole fashion. The
|
|
/// generated code sucks but the implementation is nice and simple.
|
|
///
|
|
Pass *createSimpleX86InstructionSelector(TargetMachine &TM) {
|
|
return new ISel(TM);
|
|
}
|