From 7135686104c0414c5f2b0817ac1e7f6508ab4b97 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Sat, 2 Dec 2017 08:27:46 +0000
Subject: [PATCH] [X86] Teach the assembler to support %db8-%db15 as aliases
 for %dr8-%dr15.

llvm-svn: 319612
---
 lib/Target/X86/AsmParser/X86AsmParser.cpp | 38 +++++++++++++++--------
 test/MC/X86/x86-64.s                      |  3 ++
 2 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/lib/Target/X86/AsmParser/X86AsmParser.cpp b/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 4dc0466344b..87c65347e33 100644
--- a/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -1098,19 +1098,31 @@ bool X86AsmParser::ParseRegister(unsigned &RegNo,
 
   EndLoc = Parser.getTok().getEndLoc();
 
-  // If this is "db[0-7]", match it as an alias
-  // for dr[0-7].
-  if (RegNo == 0 && Tok.getString().size() == 3 &&
-      Tok.getString().startswith("db")) {
-    switch (Tok.getString()[2]) {
-    case '0': RegNo = X86::DR0; break;
-    case '1': RegNo = X86::DR1; break;
-    case '2': RegNo = X86::DR2; break;
-    case '3': RegNo = X86::DR3; break;
-    case '4': RegNo = X86::DR4; break;
-    case '5': RegNo = X86::DR5; break;
-    case '6': RegNo = X86::DR6; break;
-    case '7': RegNo = X86::DR7; break;
+  // If this is "db[0-15]", match it as an alias
+  // for dr[0-15].
+  if (RegNo == 0 && Tok.getString().startswith("db")) {
+    if (Tok.getString().size() == 3) {
+      switch (Tok.getString()[2]) {
+      case '0': RegNo = X86::DR0; break;
+      case '1': RegNo = X86::DR1; break;
+      case '2': RegNo = X86::DR2; break;
+      case '3': RegNo = X86::DR3; break;
+      case '4': RegNo = X86::DR4; break;
+      case '5': RegNo = X86::DR5; break;
+      case '6': RegNo = X86::DR6; break;
+      case '7': RegNo = X86::DR7; break;
+      case '8': RegNo = X86::DR8; break;
+      case '9': RegNo = X86::DR9; break;
+      }
+    } else if (Tok.getString().size() == 4 && Tok.getString()[2] == '1') {
+      switch (Tok.getString()[3]) {
+      case '0': RegNo = X86::DR10; break;
+      case '1': RegNo = X86::DR11; break;
+      case '2': RegNo = X86::DR12; break;
+      case '3': RegNo = X86::DR13; break;
+      case '4': RegNo = X86::DR14; break;
+      case '5': RegNo = X86::DR15; break;
+      }
     }
 
     if (RegNo != 0) {
diff --git a/test/MC/X86/x86-64.s b/test/MC/X86/x86-64.s
index 326e58c409d..27d68f173ea 100644
--- a/test/MC/X86/x86-64.s
+++ b/test/MC/X86/x86-64.s
@@ -455,6 +455,9 @@ mov %rdx, %cr15
 mov %rdx, %dr15
 // CHECK: movq	%rdx, %dr15
 // CHECK: encoding: [0x44,0x0f,0x23,0xfa]
+mov %rdx, %db15
+// CHECK: movq	%rdx, %db15
+// CHECK: encoding: [0x44,0x0f,0x23,0xfa]
 
 // rdar://8456371 - Handle commutable instructions written backward.
 // CHECK: 	faddp	%st(1)