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[X86] Fix PR23271 - RIP-relative decoding bug in disassembler.

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Differential Revision: http://reviews.llvm.org/D9110

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237310 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Douglas Katzman
2015-05-13 22:44:52 +00:00
parent 393c054cd2
commit a8a342bb41
2 changed files with 46 additions and 9 deletions
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17
lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
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@@ -1366,16 +1366,17 @@ static int readModRM(struct InternalInstruction* insn) {
switch (mod) {
case 0x0:
insn->eaDisplacement = EA_DISP_NONE; /* readSIB may override this */
switch (rm) {
case 0x14:
case 0x4:
case 0xc: /* in case REXW.b is set */
// In determining whether RIP-relative mode is used (rm=5),
// or whether a SIB byte is present (rm=4),
// the extension bits (REX.b and EVEX.x) are ignored.
switch (rm & 7) {
case 0x4: // SIB byte is present
insn->eaBase = (insn->addressSize == 4 ?
EA_BASE_sib : EA_BASE_sib64);
if (readSIB(insn) || readDisplacement(insn))
return -1;
break;
case 0x5:
case 0x5: // RIP-relative
insn->eaBase = EA_BASE_NONE;
insn->eaDisplacement = EA_DISP_32;
if (readDisplacement(insn))
@@ -1391,10 +1392,8 @@ static int readModRM(struct InternalInstruction* insn) {
/* FALLTHROUGH */
case 0x2:
insn->eaDisplacement = (mod == 0x1 ? EA_DISP_8 : EA_DISP_32);
switch (rm) {
case 0x14:
case 0x4:
case 0xc: /* in case REXW.b is set */
switch (rm & 7) {
case 0x4: // SIB byte is present
insn->eaBase = EA_BASE_sib;
if (readSIB(insn) || readDisplacement(insn))
return -1;