From 3e74ac0d93797747e2d374d5985265c635ef66e9 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@gmail.com>
Date: Mon, 17 Feb 2014 10:03:43 +0000
Subject: [PATCH] Fix diassembler handling of rex.b when mod=00/01/10 and
 bbb=101. Mod=00 should ignore the base register entirely. Mod=01/10 should
 treat this as R13 plus displacment. Fixes PR18860.

llvm-svn: 201507
---
 .../X86/Disassembler/X86DisassemblerDecoder.c |  7 +++---
 test/MC/Disassembler/X86/x86-64.txt           | 24 +++++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/lib/Target/X86/Disassembler/X86DisassemblerDecoder.c b/lib/Target/X86/Disassembler/X86DisassemblerDecoder.c
index 75d255fe7e7..a2b5e63fd12 100644
--- a/lib/Target/X86/Disassembler/X86DisassemblerDecoder.c
+++ b/lib/Target/X86/Disassembler/X86DisassemblerDecoder.c
@@ -1167,6 +1167,7 @@ static int readSIB(struct InternalInstruction* insn) {
 
   switch (base) {
   case 0x5:
+  case 0xd:
     switch (modFromModRM(insn->modRM)) {
     case 0x0:
       insn->eaDisplacement = EA_DISP_32;
@@ -1174,13 +1175,11 @@ static int readSIB(struct InternalInstruction* insn) {
       break;
     case 0x1:
       insn->eaDisplacement = EA_DISP_8;
-      insn->sibBase = (insn->addressSize == 4 ?
-                       SIB_BASE_EBP : SIB_BASE_RBP);
+      insn->sibBase = (SIBBase)(sibBaseBase + base);
       break;
     case 0x2:
       insn->eaDisplacement = EA_DISP_32;
-      insn->sibBase = (insn->addressSize == 4 ?
-                       SIB_BASE_EBP : SIB_BASE_RBP);
+      insn->sibBase = (SIBBase)(sibBaseBase + base);
       break;
     case 0x3:
       debug("Cannot have Mod = 0b11 and a SIB byte");
diff --git a/test/MC/Disassembler/X86/x86-64.txt b/test/MC/Disassembler/X86/x86-64.txt
index 8c6bc0e2964..6f072df7e4b 100644
--- a/test/MC/Disassembler/X86/x86-64.txt
+++ b/test/MC/Disassembler/X86/x86-64.txt
@@ -241,3 +241,27 @@
 
 # CHECK: pextrw $3, %xmm3, (%rax)
 0x66 0x0f 0x3a 0x15 0x18 0x03
+
+# CHECK: $0, 305419896(,%r8)
+0x43 0x80 0x04 0x05 0x78 0x56 0x34 0x12 0x00
+
+# CHECK: $0, 305419896(%r13,%r8)
+0x43 0x80 0x84 0x05 0x78 0x56 0x34 0x12 0x00
+
+# CHECK: $0, 305419896(,%r8)
+0x42 0x80 0x04 0x05 0x78 0x56 0x34 0x12 0x00
+
+# CHECK: $0, 305419896(%rbp,%r8)
+0x42 0x80 0x84 0x05 0x78 0x56 0x34 0x12 0x00
+
+# CHECK: $0, 305419896(,%r12)
+0x42 0x80 0x04 0x25 0x78 0x56 0x34 0x12 0x00
+
+# CHECK: $0, 305419896(%rbp,%r12)
+0x42 0x80 0x84 0x25 0x78 0x56 0x34 0x12 0x00
+
+# CHECK: $0, 305419896
+0x80 0x04 0x25 0x78 0x56 0x34 0x12 0x00
+
+# CHECK: $0, 305419896(%rbp)
+0x80 0x84 0x25 0x78 0x56 0x34 0x12 0x00