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x86 -- disassemble the REP/REPNE prefix when needed

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This fixes Apple bug: 13493622

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177887 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dave Zarzycki 2013-03-25 18:59:38 +00:00
parent 301a9c0db7
commit 97a80092d3
2 changed files with 35 additions and 7 deletions
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27
lib/Target/X86/Disassembler/X86DisassemblerDecoder.c
View File

@ -318,14 +318,27 @@ static int readPrefixes(struct InternalInstruction* insn) {
return -1;
/*
* If the first byte is a LOCK prefix break and let it be disassembled
* as a lock "instruction", by creating an <MCInst #xxxx LOCK_PREFIX>.
* FIXME there is currently no way to get the disassembler to print the
* lock prefix if it is not the first byte.
* If the byte is a LOCK/REP/REPNE prefix and not a part of the opcode, then
* break and let it be disassembled as a normal "instruction".
*/
if (insn->readerCursor - 1 == insn->startLocation && byte == 0xf0)
break;
if (insn->readerCursor - 1 == insn->startLocation
&& (byte == 0xf0 || byte == 0xf2 || byte == 0xf3)) {
if (byte == 0xf0)
break;
uint8_t nextByte;
if (lookAtByte(insn, &nextByte))
return -1;
if (insn->mode == MODE_64BIT && (nextByte & 0xf0) == 0x40) {
if (consumeByte(insn, &nextByte))
return -1;
if (lookAtByte(insn, &nextByte))
return -1;
unconsumeByte(insn);
}
if (nextByte != 0x0f && nextByte != 0x90)
break;
}
switch (byte) {
case 0xf0: /* LOCK */
case 0xf2: /* REPNE/REPNZ */

15
test/MC/Disassembler/X86/simple-tests.txt
View File

@ -753,3 +753,18 @@
# CHECK: lock
# CHECK-NEXT: xaddq %rcx, %rbx
0xf0 0x48 0x0f 0xc1 0xcb
# rdar://13493622 lldb doesn't print the x86 rep/repne prefix when disassembling
# CHECK: repne
# CHECK-NEXT: movsd
0xf2 0xa5
# CHECK: repne
# CHECK-NEXT: movsq
0xf2 0x48 0xa5
# CHECK: repne
# CHECK-NEXT: movb $0, (%rax)
0xf2 0xc6 0x0 0x0
# CHECK: rep
# CHECK-NEXT: lock
# CHECK-NEXT: incl (%rax)
0xf3 0xf0 0xff 0x00