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The MONITOR and MWAIT instructions have insufficient information for

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decoding. Essentially, they both map to the same column in the "opcode
extensions for one- and two-byte opcodes" table in the x86 manual. The RawFrm
complicates decoding this.

Instead, use opcode 0x01, prefix 0x01, and form MRM1r. Then have the code
emitter special case these, a la [SML]FENCE.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72556 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2009-05-28 23:40:46 +00:00
parent 056dbd0645
commit 2265ba0717
3 changed files with 27 additions and 10 deletions
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19
lib/Target/X86/X86CodeEmitter.cpp
View File

@ -671,13 +671,26 @@ void Emitter::emitInstruction(const MachineInstr &MI,
case X86II::MRM6r: case X86II::MRM7r: {
MCE.emitByte(BaseOpcode);
// Special handling of lfence and mfence.
// Special handling of lfence, mfence, monitor, and mwait.
if (Desc->getOpcode() == X86::LFENCE ||
Desc->getOpcode() == X86::MFENCE)
Desc->getOpcode() == X86::MFENCE ||
Desc->getOpcode() == X86::MONITOR ||
Desc->getOpcode() == X86::MWAIT) {
emitRegModRMByte((Desc->TSFlags & X86II::FormMask)-X86II::MRM0r);
else
switch (Desc->getOpcode()) {
default: break;
case X86::MONITOR:
MCE.emitByte(0xC8);
break;
case X86::MWAIT:
MCE.emitByte(0xC9);
break;
}
} else {
emitRegModRMByte(MI.getOperand(CurOp++).getReg(),
(Desc->TSFlags & X86II::FormMask)-X86II::MRM0r);
}
if (CurOp != NumOps) {
const MachineOperand &MO1 = MI.getOperand(CurOp++);

12
lib/Target/X86/X86InstrInfo.cpp
View File

@ -2885,7 +2885,7 @@ static unsigned GetInstSizeWithDesc(const MachineInstr &MI,
// Emit the lock opcode prefix as needed.
if (Desc->TSFlags & X86II::LOCK) ++FinalSize;
// Emit segment overrid opcode prefix as needed.
// Emit segment override opcode prefix as needed.
switch (Desc->TSFlags & X86II::SegOvrMask) {
case X86II::FS:
case X86II::GS:
@ -3087,11 +3087,15 @@ static unsigned GetInstSizeWithDesc(const MachineInstr &MI,
case X86II::MRM4r: case X86II::MRM5r:
case X86II::MRM6r: case X86II::MRM7r:
++FinalSize;
// Special handling of lfence and mfence.
if (Desc->getOpcode() == X86::LFENCE ||
Desc->getOpcode() == X86::MFENCE)
Desc->getOpcode() == X86::MFENCE) {
// Special handling of lfence and mfence;
FinalSize += sizeRegModRMByte();
else {
} else if (Desc->getOpcode() == X86::MONITOR ||
Desc->getOpcode() == X86::MWAIT) {
// Special handling of monitor and mwait.
FinalSize += sizeRegModRMByte() + 1; // +1 for the opcode.
} else {
++CurOp;
FinalSize += sizeRegModRMByte();
}

4
lib/Target/X86/X86InstrSSE.td
View File

@ -2504,9 +2504,9 @@ let Constraints = "$src1 = $dst" in {
}
// Thread synchronization
def MONITOR : I<0xC8, RawFrm, (outs), (ins), "monitor",
def MONITOR : I<0x01, MRM1r, (outs), (ins), "monitor",
[(int_x86_sse3_monitor EAX, ECX, EDX)]>,TB, Requires<[HasSSE3]>;
def MWAIT : I<0xC9, RawFrm, (outs), (ins), "mwait",
def MWAIT : I<0x01, MRM1r, (outs), (ins), "mwait",
[(int_x86_sse3_mwait ECX, EAX)]>, TB, Requires<[HasSSE3]>;
// vector_shuffle v1, <undef> <1, 1, 3, 3>