diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -388,6 +388,7 @@
   }
 
   setOperationAction(ISD::BITREVERSE, MVT::i32, Legal);
+  setOperationAction(ISD::BITREVERSE, MVT::i64, Legal);
 
   // FIXME: This should be narrowed to i32, but that only happens if i64 is
   // illegal.
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.h b/llvm/lib/Target/AMDGPU/SIInstrInfo.h
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.h
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.h
@@ -96,7 +96,8 @@
                           unsigned Opcode) const;
 
   void splitScalar64BitUnaryOp(SetVectorType &Worklist,
-                               MachineInstr &Inst, unsigned Opcode) const;
+                               MachineInstr &Inst, unsigned Opcode,
+                               bool Swap = false) const;
 
   void splitScalar64BitAddSub(SetVectorType &Worklist, MachineInstr &Inst,
                               MachineDominatorTree *MDT = nullptr) const;
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -5742,6 +5742,11 @@
       Inst.eraseFromParent();
       continue;
 
+    case AMDGPU::S_BREV_B64:
+      splitScalar64BitUnaryOp(Worklist, Inst, AMDGPU::S_BREV_B32, true);
+      Inst.eraseFromParent();
+      continue;
+
     case AMDGPU::S_NOT_B64:
       splitScalar64BitUnaryOp(Worklist, Inst, AMDGPU::S_NOT_B32);
       Inst.eraseFromParent();
@@ -6292,7 +6297,7 @@
 
 void SIInstrInfo::splitScalar64BitUnaryOp(
     SetVectorType &Worklist, MachineInstr &Inst,
-    unsigned Opcode) const {
+    unsigned Opcode, bool Swap) const {
   MachineBasicBlock &MBB = *Inst.getParent();
   MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
 
@@ -6325,6 +6330,9 @@
   Register DestSub1 = MRI.createVirtualRegister(NewDestSubRC);
   MachineInstr &HiHalf = *BuildMI(MBB, MII, DL, InstDesc, DestSub1).add(SrcReg0Sub1);
 
+  if (Swap)
+    std::swap(DestSub0, DestSub1);
+
   Register FullDestReg = MRI.createVirtualRegister(NewDestRC);
   BuildMI(MBB, MII, DL, get(TargetOpcode::REG_SEQUENCE), FullDestReg)
     .addReg(DestSub0)
diff --git a/llvm/lib/Target/AMDGPU/SOPInstructions.td b/llvm/lib/Target/AMDGPU/SOPInstructions.td
--- a/llvm/lib/Target/AMDGPU/SOPInstructions.td
+++ b/llvm/lib/Target/AMDGPU/SOPInstructions.td
@@ -195,7 +195,9 @@
 def S_BREV_B32 : SOP1_32 <"s_brev_b32",
   [(set i32:$sdst, (bitreverse i32:$src0))]
 >;
-def S_BREV_B64 : SOP1_64 <"s_brev_b64">;
+def S_BREV_B64 : SOP1_64 <"s_brev_b64",
+  [(set i64:$sdst, (bitreverse i64:$src0))]
+>;
 
 let Defs = [SCC] in {
 def S_BCNT0_I32_B32 : SOP1_32 <"s_bcnt0_i32_b32">;
diff --git a/llvm/test/CodeGen/AMDGPU/bitreverse.ll b/llvm/test/CodeGen/AMDGPU/bitreverse.ll
--- a/llvm/test/CodeGen/AMDGPU/bitreverse.ll
+++ b/llvm/test/CodeGen/AMDGPU/bitreverse.ll
@@ -235,92 +235,28 @@
 define amdgpu_kernel void @s_brev_i64(i64 addrspace(1)* noalias %out, i64 %val) #0 {
 ; SI-LABEL: s_brev_i64:
 ; SI:       ; %bb.0:
-; SI-NEXT:    s_load_dwordx2 s[2:3], s[0:1], 0xb
-; SI-NEXT:    s_mov_b32 s4, 0xff00ff
-; SI-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x9
+; SI-NEXT:    s_load_dwordx2 s[4:5], s[0:1], 0x9
+; SI-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0xb
+; SI-NEXT:    s_mov_b32 s7, 0xf000
+; SI-NEXT:    s_mov_b32 s6, -1
 ; SI-NEXT:    s_waitcnt lgkmcnt(0)
-; SI-NEXT:    v_alignbit_b32 v0, s2, s2, 8
-; SI-NEXT:    v_alignbit_b32 v1, s2, s2, 24
-; SI-NEXT:    v_alignbit_b32 v2, s3, s3, 8
-; SI-NEXT:    v_alignbit_b32 v3, s3, s3, 24
-; SI-NEXT:    v_bfi_b32 v4, s4, v1, v0
-; SI-NEXT:    s_mov_b32 s2, 0xf0f0f0f
-; SI-NEXT:    v_bfi_b32 v2, s4, v3, v2
-; SI-NEXT:    v_and_b32_e32 v1, s2, v4
-; SI-NEXT:    v_and_b32_e32 v0, s2, v2
-; SI-NEXT:    s_mov_b32 s2, 0xf0f0f0f0
-; SI-NEXT:    v_and_b32_e32 v3, s2, v4
-; SI-NEXT:    v_and_b32_e32 v2, s2, v2
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 4
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 4
-; SI-NEXT:    s_mov_b32 s2, 0x33333333
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_and_b32_e32 v1, s2, v3
-; SI-NEXT:    v_and_b32_e32 v0, s2, v2
-; SI-NEXT:    s_mov_b32 s2, 0xcccccccc
-; SI-NEXT:    v_and_b32_e32 v3, s2, v3
-; SI-NEXT:    v_and_b32_e32 v2, s2, v2
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 2
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 2
-; SI-NEXT:    s_mov_b32 s2, 0x55555555
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_and_b32_e32 v1, s2, v3
-; SI-NEXT:    v_and_b32_e32 v0, s2, v2
-; SI-NEXT:    s_mov_b32 s2, 0xaaaaaaaa
-; SI-NEXT:    v_and_b32_e32 v3, s2, v3
-; SI-NEXT:    v_and_b32_e32 v2, s2, v2
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 1
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 1
-; SI-NEXT:    s_mov_b32 s3, 0xf000
-; SI-NEXT:    s_mov_b32 s2, -1
-; SI-NEXT:    v_or_b32_e32 v0, v2, v0
-; SI-NEXT:    v_or_b32_e32 v1, v3, v1
-; SI-NEXT:    buffer_store_dwordx2 v[0:1], off, s[0:3], 0
+; SI-NEXT:    s_brev_b64 s[0:1], s[0:1]
+; SI-NEXT:    v_mov_b32_e32 v0, s0
+; SI-NEXT:    v_mov_b32_e32 v1, s1
+; SI-NEXT:    buffer_store_dwordx2 v[0:1], off, s[4:7], 0
 ; SI-NEXT:    s_endpgm
 ;
 ; FLAT-LABEL: s_brev_i64:
 ; FLAT:       ; %bb.0:
-; FLAT-NEXT:    s_load_dwordx2 s[2:3], s[0:1], 0x2c
-; FLAT-NEXT:    v_mov_b32_e32 v0, 0x10203
-; FLAT-NEXT:    s_mov_b32 s4, 0xf0f0f0f
-; FLAT-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x24
+; FLAT-NEXT:    s_load_dwordx2 s[4:5], s[0:1], 0x24
+; FLAT-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x2c
+; FLAT-NEXT:    s_mov_b32 s7, 0xf000
+; FLAT-NEXT:    s_mov_b32 s6, -1
 ; FLAT-NEXT:    s_waitcnt lgkmcnt(0)
-; FLAT-NEXT:    v_perm_b32 v2, 0, s2, v0
-; FLAT-NEXT:    v_perm_b32 v4, 0, s3, v0
-; FLAT-NEXT:    s_mov_b32 s2, 0xf0f0f0f0
-; FLAT-NEXT:    v_and_b32_e32 v1, s4, v2
-; FLAT-NEXT:    v_and_b32_e32 v0, s4, v4
-; FLAT-NEXT:    v_and_b32_e32 v3, s2, v2
-; FLAT-NEXT:    v_and_b32_e32 v2, s2, v4
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 4, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 4, v[2:3]
-; FLAT-NEXT:    s_mov_b32 s2, 0x33333333
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_and_b32_e32 v1, s2, v3
-; FLAT-NEXT:    v_and_b32_e32 v0, s2, v2
-; FLAT-NEXT:    s_mov_b32 s2, 0xcccccccc
-; FLAT-NEXT:    v_and_b32_e32 v3, s2, v3
-; FLAT-NEXT:    v_and_b32_e32 v2, s2, v2
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 2, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 2, v[2:3]
-; FLAT-NEXT:    s_mov_b32 s2, 0x55555555
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_and_b32_e32 v1, s2, v3
-; FLAT-NEXT:    v_and_b32_e32 v0, s2, v2
-; FLAT-NEXT:    s_mov_b32 s2, 0xaaaaaaaa
-; FLAT-NEXT:    v_and_b32_e32 v3, s2, v3
-; FLAT-NEXT:    v_and_b32_e32 v2, s2, v2
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 1, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 1, v[2:3]
-; FLAT-NEXT:    s_mov_b32 s3, 0xf000
-; FLAT-NEXT:    s_mov_b32 s2, -1
-; FLAT-NEXT:    v_or_b32_e32 v0, v2, v0
-; FLAT-NEXT:    v_or_b32_e32 v1, v3, v1
-; FLAT-NEXT:    buffer_store_dwordx2 v[0:1], off, s[0:3], 0
+; FLAT-NEXT:    s_brev_b64 s[0:1], s[0:1]
+; FLAT-NEXT:    v_mov_b32_e32 v0, s0
+; FLAT-NEXT:    v_mov_b32_e32 v1, s1
+; FLAT-NEXT:    buffer_store_dwordx2 v[0:1], off, s[4:7], 0
 ; FLAT-NEXT:    s_endpgm
   %brev = call i64 @llvm.bitreverse.i64(i64 %val) #1
   store i64 %brev, i64 addrspace(1)* %out
@@ -339,46 +275,11 @@
 ; SI-NEXT:    v_mov_b32_e32 v1, 0
 ; SI-NEXT:    s_waitcnt lgkmcnt(0)
 ; SI-NEXT:    buffer_load_dwordx2 v[0:1], v[0:1], s[0:3], 0 addr64
-; SI-NEXT:    s_mov_b32 s0, 0xff00ff
-; SI-NEXT:    s_mov_b32 s1, 0xf0f0f0f
-; SI-NEXT:    s_mov_b32 s2, 0xf0f0f0f0
-; SI-NEXT:    s_mov_b32 s3, 0x33333333
-; SI-NEXT:    s_mov_b32 s6, 0xcccccccc
-; SI-NEXT:    s_waitcnt vmcnt(0)
-; SI-NEXT:    v_alignbit_b32 v2, v0, v0, 8
-; SI-NEXT:    v_alignbit_b32 v0, v0, v0, 24
-; SI-NEXT:    v_alignbit_b32 v3, v1, v1, 8
-; SI-NEXT:    v_alignbit_b32 v1, v1, v1, 24
-; SI-NEXT:    v_bfi_b32 v2, s0, v0, v2
-; SI-NEXT:    v_bfi_b32 v4, s0, v1, v3
-; SI-NEXT:    v_and_b32_e32 v1, s1, v2
-; SI-NEXT:    v_and_b32_e32 v0, s1, v4
-; SI-NEXT:    v_and_b32_e32 v3, s2, v2
-; SI-NEXT:    v_and_b32_e32 v2, s2, v4
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 4
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 4
-; SI-NEXT:    s_mov_b32 s0, 0x55555555
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_and_b32_e32 v1, s3, v3
-; SI-NEXT:    v_and_b32_e32 v0, s3, v2
-; SI-NEXT:    v_and_b32_e32 v3, s6, v3
-; SI-NEXT:    v_and_b32_e32 v2, s6, v2
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 2
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 2
-; SI-NEXT:    s_mov_b32 s1, 0xaaaaaaaa
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_and_b32_e32 v1, s0, v3
-; SI-NEXT:    v_and_b32_e32 v0, s0, v2
-; SI-NEXT:    v_and_b32_e32 v3, s1, v3
-; SI-NEXT:    v_and_b32_e32 v2, s1, v2
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 1
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 1
 ; SI-NEXT:    s_mov_b32 s6, -1
-; SI-NEXT:    v_or_b32_e32 v1, v3, v1
-; SI-NEXT:    v_or_b32_e32 v0, v2, v0
-; SI-NEXT:    buffer_store_dwordx2 v[0:1], off, s[4:7], 0
+; SI-NEXT:    s_waitcnt vmcnt(0)
+; SI-NEXT:    v_bfrev_b32_e32 v2, v0
+; SI-NEXT:    v_bfrev_b32_e32 v1, v1
+; SI-NEXT:    buffer_store_dwordx2 v[1:2], off, s[4:7], 0
 ; SI-NEXT:    s_endpgm
 ;
 ; FLAT-LABEL: v_brev_i64:
@@ -386,48 +287,17 @@
 ; FLAT-NEXT:    s_load_dwordx2 s[4:5], s[0:1], 0x24
 ; FLAT-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x2c
 ; FLAT-NEXT:    v_lshlrev_b32_e32 v0, 3, v0
-; FLAT-NEXT:    s_mov_b32 s2, 0xf0f0f0f0
-; FLAT-NEXT:    s_mov_b32 s3, 0x33333333
-; FLAT-NEXT:    s_mov_b32 s6, 0xcccccccc
+; FLAT-NEXT:    s_mov_b32 s7, 0xf000
+; FLAT-NEXT:    s_mov_b32 s6, -1
 ; FLAT-NEXT:    s_waitcnt lgkmcnt(0)
 ; FLAT-NEXT:    v_mov_b32_e32 v1, s1
 ; FLAT-NEXT:    v_add_u32_e32 v0, vcc, s0, v0
 ; FLAT-NEXT:    v_addc_u32_e32 v1, vcc, 0, v1, vcc
 ; FLAT-NEXT:    flat_load_dwordx2 v[0:1], v[0:1]
-; FLAT-NEXT:    s_mov_b32 s0, 0x10203
-; FLAT-NEXT:    s_mov_b32 s1, 0xf0f0f0f
-; FLAT-NEXT:    s_mov_b32 s7, 0xf000
 ; FLAT-NEXT:    s_waitcnt vmcnt(0)
-; FLAT-NEXT:    v_perm_b32 v2, 0, v0, s0
-; FLAT-NEXT:    v_perm_b32 v4, 0, v1, s0
-; FLAT-NEXT:    v_and_b32_e32 v1, s1, v2
-; FLAT-NEXT:    v_and_b32_e32 v0, s1, v4
-; FLAT-NEXT:    v_and_b32_e32 v3, s2, v2
-; FLAT-NEXT:    v_and_b32_e32 v2, s2, v4
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 4, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 4, v[2:3]
-; FLAT-NEXT:    s_mov_b32 s0, 0x55555555
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_and_b32_e32 v1, s3, v3
-; FLAT-NEXT:    v_and_b32_e32 v0, s3, v2
-; FLAT-NEXT:    v_and_b32_e32 v3, s6, v3
-; FLAT-NEXT:    v_and_b32_e32 v2, s6, v2
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 2, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 2, v[2:3]
-; FLAT-NEXT:    s_mov_b32 s1, 0xaaaaaaaa
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_and_b32_e32 v1, s0, v3
-; FLAT-NEXT:    v_and_b32_e32 v0, s0, v2
-; FLAT-NEXT:    v_and_b32_e32 v3, s1, v3
-; FLAT-NEXT:    v_and_b32_e32 v2, s1, v2
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 1, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 1, v[2:3]
-; FLAT-NEXT:    s_mov_b32 s6, -1
-; FLAT-NEXT:    v_or_b32_e32 v1, v3, v1
-; FLAT-NEXT:    v_or_b32_e32 v0, v2, v0
-; FLAT-NEXT:    buffer_store_dwordx2 v[0:1], off, s[4:7], 0
+; FLAT-NEXT:    v_bfrev_b32_e32 v2, v0
+; FLAT-NEXT:    v_bfrev_b32_e32 v1, v1
+; FLAT-NEXT:    buffer_store_dwordx2 v[1:2], off, s[4:7], 0
 ; FLAT-NEXT:    s_endpgm
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep = getelementptr i64, i64 addrspace(1)* %valptr, i32 %tid
@@ -442,76 +312,15 @@
 ; SI:       ; %bb.0:
 ; SI-NEXT:    s_load_dwordx2 s[4:5], s[0:1], 0x9
 ; SI-NEXT:    s_load_dwordx4 s[0:3], s[0:1], 0xd
-; SI-NEXT:    s_mov_b32 s8, 0xff00ff
-; SI-NEXT:    s_mov_b32 s9, 0x33333333
-; SI-NEXT:    s_mov_b32 s10, 0xcccccccc
-; SI-NEXT:    s_mov_b32 s11, 0x55555555
-; SI-NEXT:    s_waitcnt lgkmcnt(0)
-; SI-NEXT:    v_alignbit_b32 v0, s2, s2, 8
-; SI-NEXT:    v_alignbit_b32 v1, s2, s2, 24
-; SI-NEXT:    v_bfi_b32 v3, s8, v1, v0
-; SI-NEXT:    v_alignbit_b32 v2, s3, s3, 8
-; SI-NEXT:    v_alignbit_b32 v0, s3, s3, 24
-; SI-NEXT:    s_mov_b32 s2, 0xf0f0f0f
-; SI-NEXT:    v_bfi_b32 v2, s8, v0, v2
-; SI-NEXT:    s_mov_b32 s3, 0xf0f0f0f0
-; SI-NEXT:    v_and_b32_e32 v0, s2, v2
-; SI-NEXT:    v_and_b32_e32 v1, s2, v3
-; SI-NEXT:    v_and_b32_e32 v2, s3, v2
-; SI-NEXT:    v_and_b32_e32 v3, s3, v3
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 4
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 4
-; SI-NEXT:    v_alignbit_b32 v4, s0, s0, 8
-; SI-NEXT:    v_alignbit_b32 v5, s0, s0, 24
-; SI-NEXT:    v_bfi_b32 v7, s8, v5, v4
-; SI-NEXT:    v_alignbit_b32 v4, s1, s1, 8
-; SI-NEXT:    v_alignbit_b32 v5, s1, s1, 24
-; SI-NEXT:    v_bfi_b32 v6, s8, v5, v4
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_and_b32_e32 v0, s9, v2
-; SI-NEXT:    v_and_b32_e32 v1, s9, v3
-; SI-NEXT:    v_and_b32_e32 v4, s2, v6
-; SI-NEXT:    v_and_b32_e32 v5, s2, v7
-; SI-NEXT:    v_and_b32_e32 v2, s10, v2
-; SI-NEXT:    v_and_b32_e32 v3, s10, v3
-; SI-NEXT:    v_and_b32_e32 v6, s3, v6
-; SI-NEXT:    v_and_b32_e32 v7, s3, v7
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 2
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 2
-; SI-NEXT:    v_lshl_b64 v[4:5], v[4:5], 4
-; SI-NEXT:    v_lshr_b64 v[6:7], v[6:7], 4
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_or_b32_e32 v6, v6, v4
-; SI-NEXT:    v_or_b32_e32 v7, v7, v5
-; SI-NEXT:    s_mov_b32 s12, 0xaaaaaaaa
-; SI-NEXT:    v_and_b32_e32 v0, s11, v2
-; SI-NEXT:    v_and_b32_e32 v1, s11, v3
-; SI-NEXT:    v_and_b32_e32 v4, s9, v6
-; SI-NEXT:    v_and_b32_e32 v5, s9, v7
-; SI-NEXT:    v_and_b32_e32 v2, s12, v2
-; SI-NEXT:    v_and_b32_e32 v3, s12, v3
-; SI-NEXT:    v_and_b32_e32 v6, s10, v6
-; SI-NEXT:    v_and_b32_e32 v7, s10, v7
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 1
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 1
-; SI-NEXT:    v_lshl_b64 v[4:5], v[4:5], 2
-; SI-NEXT:    v_lshr_b64 v[6:7], v[6:7], 2
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_or_b32_e32 v0, v6, v4
-; SI-NEXT:    v_or_b32_e32 v7, v7, v5
-; SI-NEXT:    v_and_b32_e32 v5, s11, v7
-; SI-NEXT:    v_and_b32_e32 v4, s11, v0
-; SI-NEXT:    v_and_b32_e32 v6, s12, v0
-; SI-NEXT:    v_and_b32_e32 v7, s12, v7
-; SI-NEXT:    v_lshl_b64 v[4:5], v[4:5], 1
-; SI-NEXT:    v_lshr_b64 v[6:7], v[6:7], 1
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
 ; SI-NEXT:    s_mov_b32 s7, 0xf000
 ; SI-NEXT:    s_mov_b32 s6, -1
-; SI-NEXT:    v_or_b32_e32 v0, v6, v4
-; SI-NEXT:    v_or_b32_e32 v1, v7, v5
+; SI-NEXT:    s_waitcnt lgkmcnt(0)
+; SI-NEXT:    s_brev_b64 s[2:3], s[2:3]
+; SI-NEXT:    s_brev_b64 s[0:1], s[0:1]
+; SI-NEXT:    v_mov_b32_e32 v0, s0
+; SI-NEXT:    v_mov_b32_e32 v1, s1
+; SI-NEXT:    v_mov_b32_e32 v2, s2
+; SI-NEXT:    v_mov_b32_e32 v3, s3
 ; SI-NEXT:    buffer_store_dwordx4 v[0:3], off, s[4:7], 0
 ; SI-NEXT:    s_endpgm
 ;
@@ -519,68 +328,15 @@
 ; FLAT:       ; %bb.0:
 ; FLAT-NEXT:    s_load_dwordx2 s[4:5], s[0:1], 0x24
 ; FLAT-NEXT:    s_load_dwordx4 s[0:3], s[0:1], 0x34
-; FLAT-NEXT:    v_mov_b32_e32 v4, 0x10203
-; FLAT-NEXT:    s_mov_b32 s8, 0xf0f0f0f
-; FLAT-NEXT:    s_mov_b32 s9, 0xcccccccc
-; FLAT-NEXT:    s_mov_b32 s10, 0x55555555
-; FLAT-NEXT:    s_waitcnt lgkmcnt(0)
-; FLAT-NEXT:    v_perm_b32 v3, 0, s2, v4
-; FLAT-NEXT:    v_perm_b32 v2, 0, s3, v4
-; FLAT-NEXT:    s_mov_b32 s2, 0xf0f0f0f0
-; FLAT-NEXT:    v_and_b32_e32 v0, s8, v2
-; FLAT-NEXT:    v_and_b32_e32 v1, s8, v3
-; FLAT-NEXT:    v_and_b32_e32 v2, s2, v2
-; FLAT-NEXT:    v_and_b32_e32 v3, s2, v3
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 4, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 4, v[2:3]
-; FLAT-NEXT:    v_perm_b32 v7, 0, s0, v4
-; FLAT-NEXT:    v_perm_b32 v6, 0, s1, v4
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    s_mov_b32 s3, 0x33333333
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_and_b32_e32 v0, s3, v2
-; FLAT-NEXT:    v_and_b32_e32 v1, s3, v3
-; FLAT-NEXT:    v_and_b32_e32 v4, s8, v6
-; FLAT-NEXT:    v_and_b32_e32 v5, s8, v7
-; FLAT-NEXT:    v_and_b32_e32 v2, s9, v2
-; FLAT-NEXT:    v_and_b32_e32 v3, s9, v3
-; FLAT-NEXT:    v_and_b32_e32 v6, s2, v6
-; FLAT-NEXT:    v_and_b32_e32 v7, s2, v7
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 2, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 2, v[2:3]
-; FLAT-NEXT:    v_lshlrev_b64 v[4:5], 4, v[4:5]
-; FLAT-NEXT:    v_lshrrev_b64 v[6:7], 4, v[6:7]
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_or_b32_e32 v6, v6, v4
-; FLAT-NEXT:    v_or_b32_e32 v7, v7, v5
-; FLAT-NEXT:    s_mov_b32 s11, 0xaaaaaaaa
-; FLAT-NEXT:    v_and_b32_e32 v0, s10, v2
-; FLAT-NEXT:    v_and_b32_e32 v1, s10, v3
-; FLAT-NEXT:    v_and_b32_e32 v4, s3, v6
-; FLAT-NEXT:    v_and_b32_e32 v5, s3, v7
-; FLAT-NEXT:    v_and_b32_e32 v2, s11, v2
-; FLAT-NEXT:    v_and_b32_e32 v3, s11, v3
-; FLAT-NEXT:    v_and_b32_e32 v6, s9, v6
-; FLAT-NEXT:    v_and_b32_e32 v7, s9, v7
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 1, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 1, v[2:3]
-; FLAT-NEXT:    v_lshlrev_b64 v[4:5], 2, v[4:5]
-; FLAT-NEXT:    v_lshrrev_b64 v[6:7], 2, v[6:7]
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_or_b32_e32 v0, v6, v4
-; FLAT-NEXT:    v_or_b32_e32 v7, v7, v5
-; FLAT-NEXT:    v_and_b32_e32 v5, s10, v7
-; FLAT-NEXT:    v_and_b32_e32 v4, s10, v0
-; FLAT-NEXT:    v_and_b32_e32 v6, s11, v0
-; FLAT-NEXT:    v_and_b32_e32 v7, s11, v7
-; FLAT-NEXT:    v_lshlrev_b64 v[4:5], 1, v[4:5]
-; FLAT-NEXT:    v_lshrrev_b64 v[6:7], 1, v[6:7]
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
 ; FLAT-NEXT:    s_mov_b32 s7, 0xf000
 ; FLAT-NEXT:    s_mov_b32 s6, -1
-; FLAT-NEXT:    v_or_b32_e32 v0, v6, v4
-; FLAT-NEXT:    v_or_b32_e32 v1, v7, v5
+; FLAT-NEXT:    s_waitcnt lgkmcnt(0)
+; FLAT-NEXT:    s_brev_b64 s[2:3], s[2:3]
+; FLAT-NEXT:    s_brev_b64 s[0:1], s[0:1]
+; FLAT-NEXT:    v_mov_b32_e32 v0, s0
+; FLAT-NEXT:    v_mov_b32_e32 v1, s1
+; FLAT-NEXT:    v_mov_b32_e32 v2, s2
+; FLAT-NEXT:    v_mov_b32_e32 v3, s3
 ; FLAT-NEXT:    buffer_store_dwordx4 v[0:3], off, s[4:7], 0
 ; FLAT-NEXT:    s_endpgm
   %brev = call <2 x i64> @llvm.bitreverse.v2i64(<2 x i64> %val) #1
@@ -600,76 +356,13 @@
 ; SI-NEXT:    v_mov_b32_e32 v1, 0
 ; SI-NEXT:    s_waitcnt lgkmcnt(0)
 ; SI-NEXT:    buffer_load_dwordx4 v[0:3], v[0:1], s[0:3], 0 addr64
-; SI-NEXT:    s_mov_b32 s0, 0xff00ff
-; SI-NEXT:    s_mov_b32 s1, 0xf0f0f0f
-; SI-NEXT:    s_mov_b32 s2, 0xf0f0f0f0
-; SI-NEXT:    s_mov_b32 s3, 0x33333333
-; SI-NEXT:    s_mov_b32 s8, 0xcccccccc
-; SI-NEXT:    s_mov_b32 s9, 0x55555555
-; SI-NEXT:    s_mov_b32 s10, 0xaaaaaaaa
 ; SI-NEXT:    s_mov_b32 s6, -1
 ; SI-NEXT:    s_waitcnt vmcnt(0)
-; SI-NEXT:    v_alignbit_b32 v4, v2, v2, 8
-; SI-NEXT:    v_alignbit_b32 v2, v2, v2, 24
-; SI-NEXT:    v_alignbit_b32 v5, v3, v3, 8
-; SI-NEXT:    v_alignbit_b32 v6, v0, v0, 8
-; SI-NEXT:    v_alignbit_b32 v0, v0, v0, 24
-; SI-NEXT:    v_alignbit_b32 v7, v1, v1, 8
-; SI-NEXT:    v_alignbit_b32 v1, v1, v1, 24
-; SI-NEXT:    v_alignbit_b32 v3, v3, v3, 24
-; SI-NEXT:    v_bfi_b32 v2, s0, v2, v4
-; SI-NEXT:    v_bfi_b32 v4, s0, v3, v5
-; SI-NEXT:    v_bfi_b32 v6, s0, v0, v6
-; SI-NEXT:    v_bfi_b32 v8, s0, v1, v7
-; SI-NEXT:    v_and_b32_e32 v1, s1, v2
-; SI-NEXT:    v_and_b32_e32 v0, s1, v4
-; SI-NEXT:    v_and_b32_e32 v3, s2, v2
-; SI-NEXT:    v_and_b32_e32 v2, s2, v4
-; SI-NEXT:    v_and_b32_e32 v5, s1, v6
-; SI-NEXT:    v_and_b32_e32 v4, s1, v8
-; SI-NEXT:    v_and_b32_e32 v7, s2, v6
-; SI-NEXT:    v_and_b32_e32 v6, s2, v8
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 4
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 4
-; SI-NEXT:    v_lshl_b64 v[4:5], v[4:5], 4
-; SI-NEXT:    v_lshr_b64 v[6:7], v[6:7], 4
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_or_b32_e32 v7, v7, v5
-; SI-NEXT:    v_or_b32_e32 v6, v6, v4
-; SI-NEXT:    v_and_b32_e32 v1, s3, v3
-; SI-NEXT:    v_and_b32_e32 v0, s3, v2
-; SI-NEXT:    v_and_b32_e32 v5, s3, v7
-; SI-NEXT:    v_and_b32_e32 v4, s3, v6
-; SI-NEXT:    v_and_b32_e32 v3, s8, v3
-; SI-NEXT:    v_and_b32_e32 v2, s8, v2
-; SI-NEXT:    v_and_b32_e32 v7, s8, v7
-; SI-NEXT:    v_and_b32_e32 v6, s8, v6
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 2
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 2
-; SI-NEXT:    v_lshl_b64 v[4:5], v[4:5], 2
-; SI-NEXT:    v_lshr_b64 v[6:7], v[6:7], 2
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_or_b32_e32 v7, v7, v5
-; SI-NEXT:    v_or_b32_e32 v6, v6, v4
-; SI-NEXT:    v_and_b32_e32 v1, s9, v3
-; SI-NEXT:    v_and_b32_e32 v0, s9, v2
-; SI-NEXT:    v_and_b32_e32 v5, s9, v7
-; SI-NEXT:    v_and_b32_e32 v4, s9, v6
-; SI-NEXT:    v_and_b32_e32 v3, s10, v3
-; SI-NEXT:    v_and_b32_e32 v2, s10, v2
-; SI-NEXT:    v_and_b32_e32 v7, s10, v7
-; SI-NEXT:    v_and_b32_e32 v6, s10, v6
-; SI-NEXT:    v_lshl_b64 v[0:1], v[0:1], 1
-; SI-NEXT:    v_lshr_b64 v[2:3], v[2:3], 1
-; SI-NEXT:    v_lshl_b64 v[4:5], v[4:5], 1
-; SI-NEXT:    v_lshr_b64 v[6:7], v[6:7], 1
-; SI-NEXT:    v_or_b32_e32 v3, v3, v1
-; SI-NEXT:    v_or_b32_e32 v2, v2, v0
-; SI-NEXT:    v_or_b32_e32 v1, v7, v5
-; SI-NEXT:    v_or_b32_e32 v0, v6, v4
-; SI-NEXT:    buffer_store_dwordx4 v[0:3], off, s[4:7], 0
+; SI-NEXT:    v_bfrev_b32_e32 v4, v2
+; SI-NEXT:    v_bfrev_b32_e32 v3, v3
+; SI-NEXT:    v_bfrev_b32_e32 v2, v0
+; SI-NEXT:    v_bfrev_b32_e32 v1, v1
+; SI-NEXT:    buffer_store_dwordx4 v[1:4], off, s[4:7], 0
 ; SI-NEXT:    s_endpgm
 ;
 ; FLAT-LABEL: v_brev_v2i64:
@@ -677,74 +370,19 @@
 ; FLAT-NEXT:    s_load_dwordx2 s[4:5], s[0:1], 0x24
 ; FLAT-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x2c
 ; FLAT-NEXT:    v_lshlrev_b32_e32 v0, 4, v0
-; FLAT-NEXT:    s_mov_b32 s2, 0xf0f0f0f0
-; FLAT-NEXT:    s_mov_b32 s3, 0x33333333
-; FLAT-NEXT:    s_mov_b32 s8, 0xcccccccc
+; FLAT-NEXT:    s_mov_b32 s7, 0xf000
+; FLAT-NEXT:    s_mov_b32 s6, -1
 ; FLAT-NEXT:    s_waitcnt lgkmcnt(0)
 ; FLAT-NEXT:    v_mov_b32_e32 v1, s1
 ; FLAT-NEXT:    v_add_u32_e32 v0, vcc, s0, v0
 ; FLAT-NEXT:    v_addc_u32_e32 v1, vcc, 0, v1, vcc
 ; FLAT-NEXT:    flat_load_dwordx4 v[0:3], v[0:1]
-; FLAT-NEXT:    s_mov_b32 s0, 0x10203
-; FLAT-NEXT:    s_mov_b32 s1, 0xf0f0f0f
-; FLAT-NEXT:    s_mov_b32 s9, 0x55555555
-; FLAT-NEXT:    s_mov_b32 s10, 0xaaaaaaaa
-; FLAT-NEXT:    s_mov_b32 s7, 0xf000
-; FLAT-NEXT:    s_mov_b32 s6, -1
 ; FLAT-NEXT:    s_waitcnt vmcnt(0)
-; FLAT-NEXT:    v_perm_b32 v6, 0, v0, s0
-; FLAT-NEXT:    v_perm_b32 v4, 0, v3, s0
-; FLAT-NEXT:    v_perm_b32 v2, 0, v2, s0
-; FLAT-NEXT:    v_perm_b32 v8, 0, v1, s0
-; FLAT-NEXT:    v_and_b32_e32 v1, s1, v2
-; FLAT-NEXT:    v_and_b32_e32 v0, s1, v4
-; FLAT-NEXT:    v_and_b32_e32 v3, s2, v2
-; FLAT-NEXT:    v_and_b32_e32 v2, s2, v4
-; FLAT-NEXT:    v_and_b32_e32 v5, s1, v6
-; FLAT-NEXT:    v_and_b32_e32 v4, s1, v8
-; FLAT-NEXT:    v_and_b32_e32 v7, s2, v6
-; FLAT-NEXT:    v_and_b32_e32 v6, s2, v8
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 4, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 4, v[2:3]
-; FLAT-NEXT:    v_lshlrev_b64 v[4:5], 4, v[4:5]
-; FLAT-NEXT:    v_lshrrev_b64 v[6:7], 4, v[6:7]
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_or_b32_e32 v7, v7, v5
-; FLAT-NEXT:    v_or_b32_e32 v6, v6, v4
-; FLAT-NEXT:    v_and_b32_e32 v1, s3, v3
-; FLAT-NEXT:    v_and_b32_e32 v0, s3, v2
-; FLAT-NEXT:    v_and_b32_e32 v5, s3, v7
-; FLAT-NEXT:    v_and_b32_e32 v4, s3, v6
-; FLAT-NEXT:    v_and_b32_e32 v3, s8, v3
-; FLAT-NEXT:    v_and_b32_e32 v2, s8, v2
-; FLAT-NEXT:    v_and_b32_e32 v7, s8, v7
-; FLAT-NEXT:    v_and_b32_e32 v6, s8, v6
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 2, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 2, v[2:3]
-; FLAT-NEXT:    v_lshlrev_b64 v[4:5], 2, v[4:5]
-; FLAT-NEXT:    v_lshrrev_b64 v[6:7], 2, v[6:7]
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_or_b32_e32 v7, v7, v5
-; FLAT-NEXT:    v_or_b32_e32 v6, v6, v4
-; FLAT-NEXT:    v_and_b32_e32 v1, s9, v3
-; FLAT-NEXT:    v_and_b32_e32 v0, s9, v2
-; FLAT-NEXT:    v_and_b32_e32 v5, s9, v7
-; FLAT-NEXT:    v_and_b32_e32 v4, s9, v6
-; FLAT-NEXT:    v_and_b32_e32 v3, s10, v3
-; FLAT-NEXT:    v_and_b32_e32 v2, s10, v2
-; FLAT-NEXT:    v_and_b32_e32 v7, s10, v7
-; FLAT-NEXT:    v_and_b32_e32 v6, s10, v6
-; FLAT-NEXT:    v_lshlrev_b64 v[0:1], 1, v[0:1]
-; FLAT-NEXT:    v_lshrrev_b64 v[2:3], 1, v[2:3]
-; FLAT-NEXT:    v_lshlrev_b64 v[4:5], 1, v[4:5]
-; FLAT-NEXT:    v_lshrrev_b64 v[6:7], 1, v[6:7]
-; FLAT-NEXT:    v_or_b32_e32 v3, v3, v1
-; FLAT-NEXT:    v_or_b32_e32 v2, v2, v0
-; FLAT-NEXT:    v_or_b32_e32 v1, v7, v5
-; FLAT-NEXT:    v_or_b32_e32 v0, v6, v4
-; FLAT-NEXT:    buffer_store_dwordx4 v[0:3], off, s[4:7], 0
+; FLAT-NEXT:    v_bfrev_b32_e32 v4, v2
+; FLAT-NEXT:    v_bfrev_b32_e32 v3, v3
+; FLAT-NEXT:    v_bfrev_b32_e32 v2, v0
+; FLAT-NEXT:    v_bfrev_b32_e32 v1, v1
+; FLAT-NEXT:    buffer_store_dwordx4 v[1:4], off, s[4:7], 0
 ; FLAT-NEXT:    s_endpgm
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep = getelementptr <2 x i64> , <2 x i64> addrspace(1)* %valptr, i32 %tid