#include "llvm/iPHINode.h"
#include "llvm/iMemory.h"
#include "llvm/Type.h"
+#include "llvm/DerivedTypes.h"
#include "llvm/Constants.h"
#include "llvm/Pass.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Target/MRegisterInfo.h"
#include <map>
+#include <iostream>
using namespace MOTy; // Get Use, Def, UseAndDef
void visitSimpleBinary(BinaryOperator &B, unsigned OpcodeClass);
void visitAdd(BinaryOperator &B) { visitSimpleBinary(B, 0); }
void visitSub(BinaryOperator &B) { visitSimpleBinary(B, 1); }
+ void doMultiply(unsigned destReg, const Type *resultType,
+ unsigned op0Reg, unsigned op1Reg);
void visitMul(BinaryOperator &B);
void visitDiv(BinaryOperator &B) { visitDivRem(B); }
// Memory Instructions
void visitLoadInst(LoadInst &I);
void visitStoreInst(StoreInst &I);
-
+ void visitGetElementPtrInst(GetElementPtrInst &I);
+ void visitMallocInst(MallocInst &I);
+ void visitAllocaInst(AllocaInst &I);
+
// Other operators
void visitShiftInst(ShiftInst &I);
void visitPHINode(PHINode &I);
///
void copyConstantToRegister(Constant *C, unsigned Reg);
+ /// makeAnotherReg - This method returns the next register number
+ /// we haven't yet used.
+ unsigned makeAnotherReg (void) {
+ unsigned Reg = CurReg++;
+ return Reg;
+ }
+
/// getReg - This method turns an LLVM value into a register number. This
/// is guaranteed to produce the same register number for a particular value
/// every time it is queried.
unsigned getReg(Value *V) {
unsigned &Reg = RegMap[V];
if (Reg == 0) {
- Reg = CurReg++;
+ Reg = makeAnotherReg ();
RegMap[V] = Reg;
// Add the mapping of regnumber => reg class to MachineFunction
// If this operand is a constant, emit the code to copy the constant into
// the register here...
//
- if (Constant *C = dyn_cast<Constant>(V))
+ if (Constant *C = dyn_cast<Constant>(V)) {
copyConstantToRegister(C, Reg);
+ } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
+ // Move the address of the global into the register
+ BuildMI(BB, X86::MOVir32, 1, Reg).addReg(GV);
+ } else if (Argument *A = dyn_cast<Argument>(V)) {
+ std::cerr << "ERROR: Arguments not implemented in SimpleInstSel\n";
+ }
return Reg;
}
/// specified constant into the specified register.
///
void ISel::copyConstantToRegister(Constant *C, unsigned R) {
+ if (isa<ConstantExpr> (C)) {
+ // FIXME: We really need to handle getelementptr exprs, among
+ // other things.
+ std::cerr << "Offending expr: " << C << "\n";
+ }
assert (!isa<ConstantExpr>(C) && "Constant expressions not yet handled!\n");
if (C->getType()->isIntegral()) {
ConstantUInt *CUI = cast<ConstantUInt>(C);
BuildMI(BB, IntegralOpcodeTab[Class], 1, R).addZImm(CUI->getValue());
}
+ } else if (isa <ConstantPointerNull> (C)) {
+ // Copy zero (null pointer) to the register.
+ BuildMI (BB, X86::MOVir32, 1, R).addZImm(0);
} else {
+ std::cerr << "Offending constant: " << C << "\n";
assert(0 && "Type not handled yet!");
}
}
// FIXME: assuming var1, var2 are in memory, if not, spill to
// stack first
case cFloat: // Floats
- BuildMI (BB, X86::FLDr4, 1).addReg (reg1);
- BuildMI (BB, X86::FLDr4, 1).addReg (reg2);
+ BuildMI (BB, X86::FLDr32, 1).addReg (reg1);
+ BuildMI (BB, X86::FLDr32, 1).addReg (reg2);
break;
case cDouble: // Doubles
- BuildMI (BB, X86::FLDr8, 1).addReg (reg1);
- BuildMI (BB, X86::FLDr8, 1).addReg (reg2);
+ BuildMI (BB, X86::FLDr64, 1).addReg (reg1);
+ BuildMI (BB, X86::FLDr64, 1).addReg (reg2);
break;
case cLong:
default:
// ret float/double: top of FP stack
// FLD <val>
case cFloat: // Floats
- BuildMI (BB, X86::FLDr4, 1).addReg (getReg (rv));
+ BuildMI (BB, X86::FLDr32, 1).addReg (getReg (rv));
break;
case cDouble: // Doubles
- BuildMI (BB, X86::FLDr8, 1).addReg (getReg (rv));
+ BuildMI (BB, X86::FLDr64, 1).addReg (getReg (rv));
break;
case cLong:
// ret long: use EAX(least significant 32 bits)/EDX (most
void
ISel::visitCallInst (CallInst & CI)
{
+ // keep a counter of how many bytes we pushed on the stack
+ unsigned bytesPushed = 0;
+
// Push the arguments on the stack in reverse order, as specified by
// the ABI.
- for (unsigned i = CI.getNumOperands (); i >= 1; --i)
+ for (unsigned i = CI.getNumOperands()-1; i >= 1; --i)
{
Value *v = CI.getOperand (i);
- unsigned argReg = getReg (v);
switch (getClass (v->getType ()))
{
case cByte:
case cShort:
+ // Promote V to 32 bits wide, and move the result into EAX,
+ // then push EAX.
promote32 (X86::EAX, v);
BuildMI (BB, X86::PUSHr32, 1).addReg (X86::EAX);
+ bytesPushed += 4;
break;
case cInt:
- case cFloat:
- BuildMI (BB, X86::PUSHr32, 1).addReg (argReg);
+ case cFloat: {
+ unsigned Reg = getReg(v);
+ BuildMI (BB, X86::PUSHr32, 1).addReg(Reg);
+ bytesPushed += 4;
break;
+ }
default:
- // FIXME
+ // FIXME: long/ulong/double args not handled.
visitInstruction (CI);
break;
}
}
// Emit a CALL instruction with PC-relative displacement.
BuildMI (BB, X86::CALLpcrel32, 1).addPCDisp (CI.getCalledValue ());
+
+ // Adjust the stack by `bytesPushed' amount if non-zero
+ if (bytesPushed > 0)
+ BuildMI (BB, X86::ADDri32, 2).addReg(X86::ESP).addZImm(bytesPushed);
+
+ // 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 cFloat:
+ // Floating-point return values live in %st(0) (i.e., the top of
+ // the FP stack.) The general way to approach this is to do a
+ // FSTP to save the top of the FP stack on the real stack, then
+ // do a MOV to load the top of the real stack into the target
+ // register.
+ visitInstruction (CI); // FIXME: add the right args for the calls below
+ // BuildMI (BB, X86::FSTPm32, 0);
+ // BuildMI (BB, X86::MOVmr32, 0);
+ 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...
BuildMI(BB, Opcode, 2, getReg(B)).addReg(Op0r).addReg(Op1r);
}
-/// visitMul - Multiplies are not simple binary operators because they must deal
-/// with the EAX register explicitly.
-///
-void ISel::visitMul(BinaryOperator &I) {
- unsigned Class = getClass(I.getType());
- if (Class > 2) // FIXME: Handle longs
- visitInstruction(I);
+/// 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(unsigned destReg, const Type *resultType,
+ unsigned op0Reg, unsigned op1Reg)
+{
+ unsigned Class = getClass (resultType);
+ // FIXME:
+ assert (Class <= 2 && "Someday, we will learn how to multiply"
+ "longs and floating-point numbers. This is not that day.");
+
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];
- unsigned Op0Reg = getReg(I.getOperand(0));
- unsigned Op1Reg = getReg(I.getOperand(1));
- // Put the first operand into one of the A registers...
- BuildMI(BB, MovOpcode[Class], 1, Reg).addReg(Op0Reg);
+ // Emit a MOV to put the first operand into the appropriately-sized
+ // subreg of EAX.
+ BuildMI (BB, MovOpcode[Class], 1, Reg).addReg (op0Reg);
- // Emit the appropriate multiply instruction...
- BuildMI(BB, MulOpcode[Class], 1).addReg(Op1Reg);
+ // Emit the appropriate multiply instruction.
+ BuildMI (BB, MulOpcode[Class], 1).addReg (op1Reg);
- // Put the result into the destination register...
- BuildMI(BB, MovOpcode[Class], 1, getReg(I)).addReg(Reg);
+ // Emit another MOV to put the result into the destination register.
+ BuildMI (BB, 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) {
+ doMultiply (getReg (I), I.getType (),
+ getReg (I.getOperand (0)), getReg (I.getOperand (1)));
}
void
ISel::visitCastInst (CastInst &CI)
{
-//> cast larger int to smaller int --> copy least significant byte/word w/ mov?
-//
-//I'm not really sure what to do with this. We could insert a pseudo-op
-//that says take the low X bits of a Y bit register, but for now we can just
-//force the value into, say, EAX, then rip out AL or AX. The advantage of
-//the former is that the register allocator could use any register it wants,
-//but for now this obviously doesn't matter. :)
-
-// if target type is bool
-// Emit Compare
-// Emit Set-if-not-zero
-
-// if size of target type == size of source type
-// Emit Mov reg(target) <- reg(source)
-
-// if size of target type > size of source type
-// if both types are integer types
-// if source type is signed
-// sbyte to short, ushort: Emit movsx 8->16
-// sbyte to int, uint: Emit movsx 8->32
-// short to int, uint: Emit movsx 16->32
-// else if source type is unsigned
-// ubyte to short, ushort: Emit movzx 8->16
-// ubyte to int, uint: Emit movzx 8->32
-// ushort to int, uint: Emit movzx 16->32
-// if both types are fp types
-// float to double: Emit fstp, fld (???)
-
+ const Type *targetType = CI.getType ();
+ Value *operand = CI.getOperand (0);
+ unsigned int operandReg = getReg (operand);
+ const Type *sourceType = operand->getType ();
+ unsigned int 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 int srcClass = getClass (sourceType);
+ unsigned int targClass = getClass (targetType);
+ static const unsigned regRegMove[] = {
+ X86::MOVrr8, X86::MOVrr16, X86::MOVrr32
+ };
+ if ((srcClass < 3) && (targClass < 3) && (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 < 3) && (targClass < 3) && (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 < 3) && (targClass < 3) && (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);
}
+/// 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)
+{
+ Value *basePtr = I.getPointerOperand ();
+ const TargetData &TD = TM.DataLayout;
+ unsigned basePtrReg = getReg (basePtr);
+ unsigned resultReg = getReg (I);
+ const Type *Ty = basePtr->getType();
+ // GEPs have zero or more indices; we must perform a struct access
+ // or array access for each one.
+ for (GetElementPtrInst::op_iterator oi = I.idx_begin (),
+ oe = I.idx_end (); oi != oe; ++oi) {
+ Value *idx = *oi;
+ unsigned nextBasePtrReg = makeAnotherReg ();
+ 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.
+ BuildMI (BB, 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].
+ // The documentation does not seem to match the code on the type
+ // of array indices. The code seems to use long, and the docs
+ // (and the comments) say uint. If it is long, I don't know what
+ // we are going to do, because the X86 loves 64-bit types.
+ const Type *typeOfSequentialTypeIndex = SqTy->getIndexType ();
+ // 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 () == typeOfSequentialTypeIndex
+ && "Funny-looking array index in GEP");
+ // 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);
+ unsigned elementSizeReg = makeAnotherReg ();
+ copyConstantToRegister (ConstantInt::get (typeOfSequentialTypeIndex,
+ elementSize),
+ elementSizeReg);
+ unsigned idxReg = getReg (idx);
+ // Emit a MUL to multiply the register holding the index by
+ // elementSize, putting the result in memberOffsetReg.
+ unsigned memberOffsetReg = makeAnotherReg ();
+ doMultiply (memberOffsetReg, typeOfSequentialTypeIndex,
+ elementSizeReg, idxReg);
+ // Emit an ADD to add memberOffsetReg to the basePtr.
+ BuildMI (BB, X86::ADDrr32, 2,
+ nextBasePtrReg).addReg (basePtrReg).addReg (memberOffsetReg);
+ }
+ // 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.
+ BuildMI (BB, X86::MOVrr32, 1, getReg (I)).addReg (basePtrReg);
+}
+
+
+/// visitMallocInst - I know that personally, whenever I want to remember
+/// something, I have to clear off some space in my brain.
+void
+ISel::visitMallocInst (MallocInst &I)
+{
+ visitInstruction (I);
+}
+
+
+/// visitAllocaInst - I want some stack space. Come on, man, I said I
+/// want some freakin' stack space.
+void
+ISel::visitAllocaInst (AllocaInst &I)
+{
+ visitInstruction (I);
+}
+
+
/// 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.
projects / oota-llvm.git / blobdiff