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 */
# 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