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Two changes: 

1. If an incoming argument is dead, don't load it from the stack
  2. Do not code gen noop copies at all (ie, cast int -> uint), not even to
     a move.  This should reduce register pressure for allocators that are
     unable to coallesce away these copies in some cases.

llvm-svn: 12835
This commit is contained in:
Chris Lattner 2004-04-11 19:21:59 +00:00
parent 5ec93a8678
commit 3f912a6f43
1 changed files with 92 additions and 70 deletions
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162
llvm/lib/Target/X86/InstSelectSimple.cpp
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@ -35,6 +35,43 @@ using namespace llvm;
namespace {
Statistic<>
NumFPKill("x86-codegen", "Number of FP_REG_KILL instructions added");
/// TypeClass - Used by the X86 backend to group LLVM types by their basic X86
/// Representation.
///
enum TypeClass {
cByte, cShort, cInt, cFP, cLong
};
}
/// getClass - Turn a primitive type into a "class" number which is based on the
/// size of the type, and whether or not it is floating point.
///
static inline TypeClass getClass(const Type *Ty) {
switch (Ty->getPrimitiveID()) {
case Type::SByteTyID:
case Type::UByteTyID: return cByte; // Byte operands are class #0
case Type::ShortTyID:
case Type::UShortTyID: return cShort; // Short operands are class #1
case Type::IntTyID:
case Type::UIntTyID:
case Type::PointerTyID: return cInt; // Int's and pointers are class #2
case Type::FloatTyID:
case Type::DoubleTyID: return cFP; // Floating Point is #3
case Type::LongTyID:
case Type::ULongTyID: return cLong; // Longs are class #4
default:
assert(0 && "Invalid type to getClass!");
return cByte; // not reached
}
}
// getClassB - Just like getClass, but treat boolean values as bytes.
static inline TypeClass getClassB(const Type *Ty) {
if (Ty == Type::BoolTy) return cByte;
return getClass(Ty);
}
namespace {
@ -315,67 +352,35 @@ namespace {
}
unsigned getReg(Value *V, MachineBasicBlock *MBB,
MachineBasicBlock::iterator IPt) {
// If this operand is a constant, emit the code to copy the constant into
// the register here...
//
if (Constant *C = dyn_cast<Constant>(V)) {
unsigned Reg = makeAnotherReg(V->getType());
copyConstantToRegister(MBB, IPt, C, Reg);
return Reg;
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
unsigned Reg = makeAnotherReg(V->getType());
// Move the address of the global into the register
BuildMI(*MBB, IPt, X86::MOV32ri, 1, Reg).addGlobalAddress(GV);
return Reg;
} else if (CastInst *CI = dyn_cast<CastInst>(V)) {
// Do not emit noop casts at all.
if (getClassB(CI->getType()) == getClassB(CI->getOperand(0)->getType()))
return getReg(CI->getOperand(0), MBB, IPt);
}
unsigned &Reg = RegMap[V];
if (Reg == 0) {
Reg = makeAnotherReg(V->getType());
RegMap[V] = Reg;
}
// If this operand is a constant, emit the code to copy the constant into
// the register here...
//
if (Constant *C = dyn_cast<Constant>(V)) {
copyConstantToRegister(MBB, IPt, C, Reg);
RegMap.erase(V); // Assign a new name to this constant if ref'd again
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
// Move the address of the global into the register
BuildMI(*MBB, IPt, X86::MOV32ri, 1, Reg).addGlobalAddress(GV);
RegMap.erase(V); // Assign a new name to this address if ref'd again
}
return Reg;
}
};
}
/// TypeClass - Used by the X86 backend to group LLVM types by their basic X86
/// Representation.
///
enum TypeClass {
cByte, cShort, cInt, cFP, cLong
};
/// getClass - Turn a primitive type into a "class" number which is based on the
/// size of the type, and whether or not it is floating point.
///
static inline TypeClass getClass(const Type *Ty) {
switch (Ty->getPrimitiveID()) {
case Type::SByteTyID:
case Type::UByteTyID: return cByte; // Byte operands are class #0
case Type::ShortTyID:
case Type::UShortTyID: return cShort; // Short operands are class #1
case Type::IntTyID:
case Type::UIntTyID:
case Type::PointerTyID: return cInt; // Int's and pointers are class #2
case Type::FloatTyID:
case Type::DoubleTyID: return cFP; // Floating Point is #3
case Type::LongTyID:
case Type::ULongTyID: return cLong; // Longs are class #4
default:
assert(0 && "Invalid type to getClass!");
return cByte; // not reached
}
}
// getClassB - Just like getClass, but treat boolean values as bytes.
static inline TypeClass getClassB(const Type *Ty) {
if (Ty == Type::BoolTy) return cByte;
return getClass(Ty);
}
/// copyConstantToRegister - Output the instructions required to put the
/// specified constant into the specified register.
///
@ -511,39 +516,51 @@ void ISel::LoadArgumentsToVirtualRegs(Function &Fn) {
MachineFrameInfo *MFI = F->getFrameInfo();
for (Function::aiterator I = Fn.abegin(), E = Fn.aend(); I != E; ++I) {
unsigned Reg = getReg(*I);
bool ArgLive = !I->use_empty();
unsigned Reg = ArgLive ? getReg(*I) : 0;
int FI; // Frame object index
switch (getClassB(I->getType())) {
case cByte:
FI = MFI->CreateFixedObject(1, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOV8rm, 4, Reg), FI);
if (ArgLive) {
FI = MFI->CreateFixedObject(1, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOV8rm, 4, Reg), FI);
}
break;
case cShort:
FI = MFI->CreateFixedObject(2, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOV16rm, 4, Reg), FI);
if (ArgLive) {
FI = MFI->CreateFixedObject(2, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOV16rm, 4, Reg), FI);
}
break;
case cInt:
FI = MFI->CreateFixedObject(4, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOV32rm, 4, Reg), FI);
if (ArgLive) {
FI = MFI->CreateFixedObject(4, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOV32rm, 4, Reg), FI);
}
break;
case cLong:
FI = MFI->CreateFixedObject(8, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOV32rm, 4, Reg), FI);
addFrameReference(BuildMI(BB, X86::MOV32rm, 4, Reg+1), FI, 4);
if (ArgLive) {
FI = MFI->CreateFixedObject(8, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOV32rm, 4, Reg), FI);
addFrameReference(BuildMI(BB, X86::MOV32rm, 4, Reg+1), FI, 4);
}
ArgOffset += 4; // longs require 4 additional bytes
break;
case cFP:
unsigned Opcode;
if (I->getType() == Type::FloatTy) {
Opcode = X86::FLD32m;
FI = MFI->CreateFixedObject(4, ArgOffset);
} else {
Opcode = X86::FLD64m;
FI = MFI->CreateFixedObject(8, ArgOffset);
ArgOffset += 4; // doubles require 4 additional bytes
if (ArgLive) {
unsigned Opcode;
if (I->getType() == Type::FloatTy) {
Opcode = X86::FLD32m;
FI = MFI->CreateFixedObject(4, ArgOffset);
} else {
Opcode = X86::FLD64m;
FI = MFI->CreateFixedObject(8, ArgOffset);
}
addFrameReference(BuildMI(BB, Opcode, 4, Reg), FI);
}
addFrameReference(BuildMI(BB, Opcode, 4, Reg), FI);
if (I->getType() == Type::DoubleTy)
ArgOffset += 4; // doubles require 4 additional bytes
break;
default:
assert(0 && "Unhandled argument type!");
@ -2525,6 +2542,11 @@ void ISel::visitStoreInst(StoreInst &I) {
///
void ISel::visitCastInst(CastInst &CI) {
Value *Op = CI.getOperand(0);
// Noop casts are not even emitted.
if (getClassB(CI.getType()) == getClassB(Op->getType()))
return;
// If this is a cast from a 32-bit integer to a Long type, and the only uses
// of the case are GEP instructions, then the cast does not need to be
// generated explicitly, it will be folded into the GEP.