Fix for Bug 30718 - Failure to disassemble certain MOV with rex.R. The issue was...

Differential Revision: https://reviews.llvm.org/D38786

llvm-svn: 316319

diff --git a/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp b/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
index 80acff2..709fc63 100644 (file)
--- a/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
+++ b/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
@@ -1453,9 +1453,9 @@ static int readModRM(struct InternalInstruction* insn) {
     case TYPE_MM64:                                       \
       return prefix##_MM0 + (index & 0x7);                \
     case TYPE_SEGMENTREG:                                 \
-      if (index > 5)                                      \
+      if ((index & 7) > 5)                                \
         *valid = 0;                                       \
-      return prefix##_ES + index;                         \
+      return prefix##_ES + (index & 7);                   \
     case TYPE_DEBUGREG:                                   \
       return prefix##_DR0 + index;                        \
     case TYPE_CONTROLREG:                                 \

diff --git a/llvm/test/MC/Disassembler/X86/x86-64.txt b/llvm/test/MC/Disassembler/X86/x86-64.txt
index 965d713..9302668 100644 (file)
--- a/llvm/test/MC/Disassembler/X86/x86-64.txt
+++ b/llvm/test/MC/Disassembler/X86/x86-64.txt
@@ -482,6 +482,9 @@
 # CHECK:  xchgw   %di, %ax
 0x66 0x3e 0x97
 
+# CHECK: movq    %rdx, %cs
+0x4c 0x8e 0xca
+
 # CHECK: movw    %bx, %cs:(%rsi,%rbp)
 0x2e 0x66 0x89 0x1c 0x2e
 # CHECK: movl    %ebx, %cs:(%esi,%ebp)