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Avoid unneeded SIB byte encoding. Patch by Zoltan Varga.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71520 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2009-05-12 00:07:35 +00:00
parent bc12c2be18
commit 6ed34918eb
2 changed files with 4 additions and 2 deletions
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3
lib/Target/X86/X86CodeEmitter.cpp
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@@ -338,7 +338,8 @@ void Emitter::emitMemModRMByte(const MachineInstr &MI,
unsigned BaseReg = Base.getReg();
// Is a SIB byte needed?
if ((!Is64BitMode || DispForReloc) && IndexReg.getReg() == 0 &&
if ((!Is64BitMode || DispForReloc || BaseReg != 0) &&
IndexReg.getReg() == 0 &&
(BaseReg == 0 || getX86RegNum(BaseReg) != N86::ESP)) {
if (BaseReg == 0) { // Just a displacement?
// Emit special case [disp32] encoding

3
lib/Target/X86/X86InstrInfo.cpp
View File

@@ -2811,7 +2811,8 @@ static unsigned getMemModRMByteSize(const MachineInstr &MI, unsigned Op,
unsigned BaseReg = Base.getReg();
// Is a SIB byte needed?
if ((!Is64BitMode || DispForReloc) && IndexReg.getReg() == 0 &&
if ((!Is64BitMode || DispForReloc || BaseReg != 0) &&
IndexReg.getReg() == 0 &&
(BaseReg == 0 || X86RegisterInfo::getX86RegNum(BaseReg) != N86::ESP)) {
if (BaseReg == 0) { // Just a displacement?
// Emit special case [disp32] encoding