From 842f58f9be82e1a0d2751e7982ef3641829acf87 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@gmail.com>
Date: Sun, 11 Sep 2011 20:23:20 +0000
Subject: [PATCH] Fix disassembling of PAUSE instruction. Fixes PR10900. Also
 fixed NOP disassembling to ignore OpSize and REX.W.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139484 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/MC/Disassembler/X86/simple-tests.txt | 3 +++
 utils/TableGen/X86DisassemblerTables.cpp  | 6 ++++--
 utils/TableGen/X86RecognizableInstr.cpp   | 3 ++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/test/MC/Disassembler/X86/simple-tests.txt b/test/MC/Disassembler/X86/simple-tests.txt
index ef36a6b80d0..62f3464d830 100644
--- a/test/MC/Disassembler/X86/simple-tests.txt
+++ b/test/MC/Disassembler/X86/simple-tests.txt
@@ -158,3 +158,6 @@
 
 # CHECK: vinsertps $129, %xmm3, %xmm2, %xmm1
 0xc4 0xe3 0x69 0x21 0xcb 0x81
+
+# CHECK: pause
+0xf3 0x90
diff --git a/utils/TableGen/X86DisassemblerTables.cpp b/utils/TableGen/X86DisassemblerTables.cpp
index e0cbb18a4b8..aed27279a51 100644
--- a/utils/TableGen/X86DisassemblerTables.cpp
+++ b/utils/TableGen/X86DisassemblerTables.cpp
@@ -613,8 +613,10 @@ void DisassemblerTables::setTableFields(ModRMDecision     &decision,
         if(newInfo.filtered)
           continue; // filtered instructions get lowest priority
         
-        if(previousInfo.name == "NOOP")
-          continue; // special case for XCHG32ar and NOOP
+        if(previousInfo.name == "NOOP" && (newInfo.name == "XCHG16ar" ||
+                                           newInfo.name == "XCHG32ar" ||
+                                           newInfo.name == "XCHG64ar"))
+          continue; // special case for XCHG*ar and NOOP
 
         if (outranks(previousInfo.insnContext, newInfo.insnContext))
           continue;
diff --git a/utils/TableGen/X86RecognizableInstr.cpp b/utils/TableGen/X86RecognizableInstr.cpp
index 5f8fe6ee4cc..f43a93938bb 100644
--- a/utils/TableGen/X86RecognizableInstr.cpp
+++ b/utils/TableGen/X86RecognizableInstr.cpp
@@ -325,7 +325,7 @@ InstructionContext RecognizableInstr::insnContext() const {
       insnContext = IC_OPSIZE;
     else if (Prefix == X86Local::XD)
       insnContext = IC_XD;
-    else if (Prefix == X86Local::XS)
+    else if (Prefix == X86Local::XS || Prefix == X86Local::REP)
       insnContext = IC_XS;
     else
       insnContext = IC;
@@ -882,6 +882,7 @@ void RecognizableInstr::emitDecodePath(DisassemblerTables &tables) const {
     }
     opcodeToSet = 0xd8 + (Prefix - X86Local::D8);
     break;
+  case X86Local::REP:
   default:
     opcodeType = ONEBYTE;
     switch (Opcode) {