Index: llvm/trunk/lib/Target/ARM/ARM.td
===================================================================
--- llvm/trunk/lib/Target/ARM/ARM.td
+++ llvm/trunk/lib/Target/ARM/ARM.td
@@ -83,6 +83,9 @@
 def FeatureV7Clrex        : SubtargetFeature<"v7clrex", "HasV7Clrex", "true",
                                              "Has v7 clrex instruction">;
 
+def FeatureDFB  : SubtargetFeature<"dfb", "HasFullDataBarrier", "true",
+                                   "Has full data barrier (dfb) instruction">;
+
 def FeatureAcquireRelease : SubtargetFeature<"acquire-release",
                                              "HasAcquireRelease", "true",
                                              "Has v8 acquire/release (lda/ldaex "
@@ -617,6 +620,7 @@
 def ARMv8r    : Architecture<"armv8-r",   "ARMv8r",   [HasV8Ops,
                                                        FeatureRClass,
                                                        FeatureDB,
+                                                       FeatureDFB,
                                                        FeatureDSP,
                                                        FeatureCRC,
                                                        FeatureMP,
Index: llvm/trunk/lib/Target/ARM/ARMInstrInfo.td
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMInstrInfo.td
+++ llvm/trunk/lib/Target/ARM/ARMInstrInfo.td
@@ -280,6 +280,9 @@
 def HasDB            : Predicate<"Subtarget->hasDataBarrier()">,
                                  AssemblerPredicate<"FeatureDB",
                                                     "data-barriers">;
+def HasDFB           : Predicate<"Subtarget->hasFullDataBarrier()">,
+                                 AssemblerPredicate<"FeatureDFB",
+                                                    "full-data-barrier">;
 def HasV7Clrex  : Predicate<"Subtarget->hasV7Clrex()">,
                             AssemblerPredicate<"FeatureV7Clrex",
                                                "v7 clrex">;
@@ -5850,6 +5853,8 @@
 def : InstAlias<"dmb", (DMB 0xf), 0>, Requires<[IsARM, HasDB]>;
 def : InstAlias<"dsb", (DSB 0xf), 0>, Requires<[IsARM, HasDB]>;
 def : InstAlias<"isb", (ISB 0xf), 0>, Requires<[IsARM, HasDB]>;
+// Armv8-R 'Data Full Barrier'
+def : InstAlias<"dfb", (DSB 0xc), 1>, Requires<[IsARM, HasDFB]>;
 
 // System instructions
 def : MnemonicAlias<"swi", "svc">;
Index: llvm/trunk/lib/Target/ARM/ARMInstrThumb2.td
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMInstrThumb2.td
+++ llvm/trunk/lib/Target/ARM/ARMInstrThumb2.td
@@ -4508,6 +4508,8 @@
 def : InstAlias<"dmb${p}", (t2DMB 0xf, pred:$p), 0>, Requires<[HasDB]>;
 def : InstAlias<"dsb${p}", (t2DSB 0xf, pred:$p), 0>, Requires<[HasDB]>;
 def : InstAlias<"isb${p}", (t2ISB 0xf, pred:$p), 0>, Requires<[HasDB]>;
+// Armv8-R 'Data Full Barrier'
+def : InstAlias<"dfb${p}", (t2DSB 0xc, pred:$p), 1>, Requires<[HasDFB]>;
 
 // Alias for LDR, LDRB, LDRH, LDRSB, and LDRSH without the ".w" optional
 // width specifier.
Index: llvm/trunk/lib/Target/ARM/ARMSubtarget.h
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMSubtarget.h
+++ llvm/trunk/lib/Target/ARM/ARMSubtarget.h
@@ -236,6 +236,10 @@
   /// instructions.
   bool HasDataBarrier = false;
 
+  /// HasFullDataBarrier - True if the subtarget supports DFB data barrier
+  /// instruction.
+  bool HasFullDataBarrier = false;
+
   /// HasV7Clrex - True if the subtarget supports CLREX instructions
   bool HasV7Clrex = false;
 
@@ -544,6 +548,7 @@
   bool hasDivideInThumbMode() const { return HasHardwareDivideInThumb; }
   bool hasDivideInARMMode() const { return HasHardwareDivideInARM; }
   bool hasDataBarrier() const { return HasDataBarrier; }
+  bool hasFullDataBarrier() const { return HasFullDataBarrier; }
   bool hasV7Clrex() const { return HasV7Clrex; }
   bool hasAcquireRelease() const { return HasAcquireRelease; }
 
Index: llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
===================================================================
--- llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -5581,11 +5581,11 @@
     CanAcceptPredicationCode =
         Mnemonic != "cdp2" && Mnemonic != "clrex" && Mnemonic != "mcr2" &&
         Mnemonic != "mcrr2" && Mnemonic != "mrc2" && Mnemonic != "mrrc2" &&
-        Mnemonic != "dmb" && Mnemonic != "dsb" && Mnemonic != "isb" &&
-        Mnemonic != "pld" && Mnemonic != "pli" && Mnemonic != "pldw" &&
-        Mnemonic != "ldc2" && Mnemonic != "ldc2l" && Mnemonic != "stc2" &&
-        Mnemonic != "stc2l" && !Mnemonic.startswith("rfe") &&
-        !Mnemonic.startswith("srs");
+        Mnemonic != "dmb" && Mnemonic != "dfb" && Mnemonic != "dsb" &&
+        Mnemonic != "isb" && Mnemonic != "pld" && Mnemonic != "pli" &&
+        Mnemonic != "pldw" && Mnemonic != "ldc2" && Mnemonic != "ldc2l" &&
+        Mnemonic != "stc2" && Mnemonic != "stc2l" &&
+        !Mnemonic.startswith("rfe") && !Mnemonic.startswith("srs");
   } else if (isThumbOne()) {
     if (hasV6MOps())
       CanAcceptPredicationCode = Mnemonic != "movs";
Index: llvm/trunk/test/MC/ARM/dfb-neg.s
===================================================================
--- llvm/trunk/test/MC/ARM/dfb-neg.s
+++ llvm/trunk/test/MC/ARM/dfb-neg.s
@@ -0,0 +1,10 @@
+@ RUN: not llvm-mc -triple armv8-none-eabi -mcpu=cortex-r52 -mattr=-dfb -show-encoding < %s 2>&1 | FileCheck %s
+@ RUN: not llvm-mc -triple thumbv8-none-eabi -mcpu=cortex-r52 -mattr=-dfb -show-encoding < %s 2>&1 | FileCheck %s
+
+        dfb
+@ CHECK: error: instruction requires: full-data-barrier
+
+        dfb sy
+        dfb #0
+@ CHECK: error: invalid instruction
+@ CHECK: error: invalid instruction
Index: llvm/trunk/test/MC/ARM/dfb.s
===================================================================
--- llvm/trunk/test/MC/ARM/dfb.s
+++ llvm/trunk/test/MC/ARM/dfb.s
@@ -0,0 +1,6 @@
+@ RUN: llvm-mc -triple armv8-none-eabi -mcpu=cortex-r52 -show-encoding < %s | FileCheck %s --check-prefix=CHECK-ARM
+@ RUN: llvm-mc -triple thumbv8-none-eabi -mcpu=cortex-r52 -show-encoding < %s | FileCheck %s --check-prefix=CHECK-THUMB
+
+        dfb
+@ CHECK-ARM:   dfb                             @ encoding: [0x4c,0xf0,0x7f,0xf5]
+@ CHECK-THUMB: dfb                             @ encoding: [0xbf,0xf3,0x4c,0x8f]
Index: llvm/trunk/test/MC/Disassembler/ARM/dfb-arm.txt
===================================================================
--- llvm/trunk/test/MC/Disassembler/ARM/dfb-arm.txt
+++ llvm/trunk/test/MC/Disassembler/ARM/dfb-arm.txt
@@ -0,0 +1,6 @@
+# RUN: llvm-mc -disassemble -triple armv8-none-eabi -mcpu=cortex-r52 -show-encoding < %s | FileCheck %s --check-prefix=CHECK-DFB
+# RUN: llvm-mc -disassemble -triple armv8-none-eabi -mcpu=cortex-r52 -mattr=-dfb -show-encoding < %s | FileCheck %s --check-prefix=CHECK-NODFB
+
+# CHECK-DFB:   dfb                             @ encoding: [0x4c,0xf0,0x7f,0xf5]
+# CHECK-NODFB: dsb     #0xc                    @ encoding: [0x4c,0xf0,0x7f,0xf5]
+[0x4c,0xf0,0x7f,0xf5]
Index: llvm/trunk/test/MC/Disassembler/ARM/dfb-thumb.txt
===================================================================
--- llvm/trunk/test/MC/Disassembler/ARM/dfb-thumb.txt
+++ llvm/trunk/test/MC/Disassembler/ARM/dfb-thumb.txt
@@ -0,0 +1,6 @@
+# RUN: llvm-mc -disassemble -triple thumbv8-none-eabi -mcpu=cortex-r52 -show-encoding < %s | FileCheck %s --check-prefix=CHECK-DFB
+# RUN: llvm-mc -disassemble -triple thumbv8-none-eabi -mcpu=cortex-r52 -mattr=-dfb -show-encoding < %s | FileCheck %s --check-prefix=CHECK-NODFB
+
+# CHECK-DFB:   dfb                             @ encoding: [0xbf,0xf3,0x4c,0x8f]
+# CHECK-NODFB: dsb     #0xc                    @ encoding: [0xbf,0xf3,0x4c,0x8f]
+[0xbf,0xf3,0x4c,0x8f]