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- Avoid the longer SIB encoding on x86_64 when it's not needed.

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- Synchronize instruction length computation code in X86InstrInfo with code in X86CodeEmitter.cpp
Patch by Zoltan Varga.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70929 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2009-05-04 22:49:16 +00:00
parent 35738ac150
commit b0030ddca4
2 changed files with 24 additions and 9 deletions
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2
lib/Target/X86/X86CodeEmitter.cpp
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@ -338,7 +338,7 @@ void Emitter::emitMemModRMByte(const MachineInstr &MI,
unsigned BaseReg = Base.getReg();
// Is a SIB byte needed?
if ((!Is64BitMode || DispForReloc) && IndexReg.getReg() == 0 &&
if (IndexReg.getReg() == 0 && (!Is64BitMode || BaseReg != 0) &&
(BaseReg == 0 || getX86RegNum(BaseReg) != N86::ESP)) {
if (BaseReg == 0) { // Just a displacement?
// Emit special case [disp32] encoding

27
lib/Target/X86/X86InstrInfo.cpp
View File

@ -2811,7 +2811,7 @@ static unsigned getMemModRMByteSize(const MachineInstr &MI, unsigned Op,
unsigned BaseReg = Base.getReg();
// Is a SIB byte needed?
if ((!Is64BitMode || DispForReloc) && IndexReg.getReg() == 0 &&
if (IndexReg.getReg() == 0 && (!Is64BitMode || BaseReg != 0) &&
(BaseReg == 0 || X86RegisterInfo::getX86RegNum(BaseReg) != N86::ESP)) {
if (BaseReg == 0) { // Just a displacement?
// Emit special case [disp32] encoding
@ -2932,6 +2932,9 @@ static unsigned GetInstSizeWithDesc(const MachineInstr &MI,
unsigned CurOp = 0;
if (NumOps > 1 && Desc->getOperandConstraint(1, TOI::TIED_TO) != -1)
CurOp++;
else if (NumOps > 2 && Desc->getOperandConstraint(NumOps-1, TOI::TIED_TO)== 0)
// Skip the last source operand that is tied_to the dest reg. e.g. LXADD32
--NumOps;
switch (Desc->TSFlags & X86II::FormMask) {
default: assert(0 && "Unknown FormMask value in X86 MachineCodeEmitter!");
@ -3022,7 +3025,7 @@ static unsigned GetInstSizeWithDesc(const MachineInstr &MI,
case X86II::MRMDestMem: {
++FinalSize;
FinalSize += getMemModRMByteSize(MI, CurOp, IsPIC, Is64BitMode);
CurOp += 5;
CurOp += X86AddrNumOperands + 1;
if (CurOp != NumOps) {
++CurOp;
FinalSize += sizeConstant(X86InstrInfo::sizeOfImm(Desc));
@ -3041,10 +3044,16 @@ static unsigned GetInstSizeWithDesc(const MachineInstr &MI,
break;
case X86II::MRMSrcMem: {
int AddrOperands;
if (Opcode == X86::LEA64r || Opcode == X86::LEA64_32r ||
Opcode == X86::LEA16r || Opcode == X86::LEA32r)
AddrOperands = X86AddrNumOperands - 1; // No segment register
else
AddrOperands = X86AddrNumOperands;
++FinalSize;
FinalSize += getMemModRMByteSize(MI, CurOp+1, IsPIC, Is64BitMode);
CurOp += 5;
CurOp += AddrOperands + 1;
if (CurOp != NumOps) {
++CurOp;
FinalSize += sizeConstant(X86InstrInfo::sizeOfImm(Desc));
@ -3057,8 +3066,14 @@ static unsigned GetInstSizeWithDesc(const MachineInstr &MI,
case X86II::MRM4r: case X86II::MRM5r:
case X86II::MRM6r: case X86II::MRM7r:
++FinalSize;
++CurOp;
FinalSize += sizeRegModRMByte();
// Special handling of lfence and mfence.
if (Desc->getOpcode() == X86::LFENCE ||
Desc->getOpcode() == X86::MFENCE)
FinalSize += sizeRegModRMByte();
else {
++CurOp;
FinalSize += sizeRegModRMByte();
}
if (CurOp != NumOps) {
const MachineOperand &MO1 = MI.getOperand(CurOp++);
@ -3088,7 +3103,7 @@ static unsigned GetInstSizeWithDesc(const MachineInstr &MI,
++FinalSize;
FinalSize += getMemModRMByteSize(MI, CurOp, IsPIC, Is64BitMode);
CurOp += 4;
CurOp += X86AddrNumOperands;
if (CurOp != NumOps) {
const MachineOperand &MO = MI.getOperand(CurOp++);