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Two changes:

Browse Source 
* In promote32, if we can just promote a constant value, do so instead of
    promoting a constant dynamically.
  * In visitReturn inst, actually USE the promote32 argument that takes a
    Value*

The end result of this is that we now generate this:

test:
        mov %EAX, 0
        ret

instead of...

test:
        mov %AX, 0
        movzx %EAX, %AX
        ret

for:

ushort %test() {
        ret ushort 0
}


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12679 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-04-06 01:21:00 +00:00
parent a57d86b436
commit 29bf0623e5
2 changed files with 36 additions and 14 deletions
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25
lib/Target/X86/InstSelectSimple.cpp
View File

@ -1107,10 +1107,18 @@ void ISel::emitSelectOperation(MachineBasicBlock *MBB,
void ISel::promote32(unsigned targetReg, const ValueRecord &VR) {
bool isUnsigned = VR.Ty->isUnsigned();
// Make sure we have the register number for this value...
unsigned Reg = VR.Val ? getReg(VR.Val) : VR.Reg;
Value *Val = VR.Val;
const Type *Ty = VR.Ty;
if (Val)
if (Constant *C = dyn_cast<Constant>(Val)) {
Val = ConstantExpr::getCast(C, Type::IntTy);
Ty = Type::IntTy;
}
switch (getClassB(VR.Ty)) {
// Make sure we have the register number for this value...
unsigned Reg = Val ? getReg(Val) : VR.Reg;
switch (getClassB(Ty)) {
case cByte:
// Extend value into target register (8->32)
if (isUnsigned)
@ -1152,27 +1160,30 @@ void ISel::visitReturnInst(ReturnInst &I) {
}
Value *RetVal = I.getOperand(0);
unsigned RetReg = getReg(RetVal);
switch (getClassB(RetVal->getType())) {
case cByte: // integral return values: extend or move into EAX and return
case cShort:
case cInt:
promote32(X86::EAX, ValueRecord(RetReg, RetVal->getType()));
promote32(X86::EAX, ValueRecord(RetVal));
// Declare that EAX is live on exit
BuildMI(BB, X86::IMPLICIT_USE, 2).addReg(X86::EAX).addReg(X86::ESP);
break;
case cFP: // Floats & Doubles: Return in ST(0)
case cFP: { // Floats & Doubles: Return in ST(0)
unsigned RetReg = getReg(RetVal);
BuildMI(BB, X86::FpSETRESULT, 1).addReg(RetReg);
// Declare that top-of-stack is live on exit
BuildMI(BB, X86::IMPLICIT_USE, 2).addReg(X86::ST0).addReg(X86::ESP);
break;
case cLong:
}
case cLong: {
unsigned RetReg = getReg(RetVal);
BuildMI(BB, X86::MOV32rr, 1, X86::EAX).addReg(RetReg);
BuildMI(BB, X86::MOV32rr, 1, X86::EDX).addReg(RetReg+1);
// Declare that EAX & EDX are live on exit
BuildMI(BB, X86::IMPLICIT_USE, 3).addReg(X86::EAX).addReg(X86::EDX)
.addReg(X86::ESP);
break;
}
default:
visitInstruction(I);
}

25
lib/Target/X86/X86ISelSimple.cpp
View File

@ -1107,10 +1107,18 @@ void ISel::emitSelectOperation(MachineBasicBlock *MBB,
void ISel::promote32(unsigned targetReg, const ValueRecord &VR) {
bool isUnsigned = VR.Ty->isUnsigned();
// Make sure we have the register number for this value...
unsigned Reg = VR.Val ? getReg(VR.Val) : VR.Reg;
Value *Val = VR.Val;
const Type *Ty = VR.Ty;
if (Val)
if (Constant *C = dyn_cast<Constant>(Val)) {
Val = ConstantExpr::getCast(C, Type::IntTy);
Ty = Type::IntTy;
}
switch (getClassB(VR.Ty)) {
// Make sure we have the register number for this value...
unsigned Reg = Val ? getReg(Val) : VR.Reg;
switch (getClassB(Ty)) {
case cByte:
// Extend value into target register (8->32)
if (isUnsigned)
@ -1152,27 +1160,30 @@ void ISel::visitReturnInst(ReturnInst &I) {
}
Value *RetVal = I.getOperand(0);
unsigned RetReg = getReg(RetVal);
switch (getClassB(RetVal->getType())) {
case cByte: // integral return values: extend or move into EAX and return
case cShort:
case cInt:
promote32(X86::EAX, ValueRecord(RetReg, RetVal->getType()));
promote32(X86::EAX, ValueRecord(RetVal));
// Declare that EAX is live on exit
BuildMI(BB, X86::IMPLICIT_USE, 2).addReg(X86::EAX).addReg(X86::ESP);
break;
case cFP: // Floats & Doubles: Return in ST(0)
case cFP: { // Floats & Doubles: Return in ST(0)
unsigned RetReg = getReg(RetVal);
BuildMI(BB, X86::FpSETRESULT, 1).addReg(RetReg);
// Declare that top-of-stack is live on exit
BuildMI(BB, X86::IMPLICIT_USE, 2).addReg(X86::ST0).addReg(X86::ESP);
break;
case cLong:
}
case cLong: {
unsigned RetReg = getReg(RetVal);
BuildMI(BB, X86::MOV32rr, 1, X86::EAX).addReg(RetReg);
BuildMI(BB, X86::MOV32rr, 1, X86::EDX).addReg(RetReg+1);
// Declare that EAX & EDX are live on exit
BuildMI(BB, X86::IMPLICIT_USE, 3).addReg(X86::EAX).addReg(X86::EDX)
.addReg(X86::ESP);
break;
}
default:
visitInstruction(I);
}