Index: lib/Target/AMDGPU/SIShrinkInstructions.cpp
===================================================================
--- lib/Target/AMDGPU/SIShrinkInstructions.cpp
+++ lib/Target/AMDGPU/SIShrinkInstructions.cpp
@@ -431,6 +431,84 @@
   return TargetInstrInfo::RegSubRegPair(Reg, Sub);
 }
 
+// Match:
+// bb0:
+// ..
+// mov r, imm
+// ..
+// branch bb1
+//
+// bb1:
+// ; predecessors: %bb.0
+// ..
+// mov r, imm <== redundant mov
+//
+//
+// Returns true if the mov can be removed.
+//
+static bool isMovRedundant(MachineInstr &Mov, MachineRegisterInfo &MRI,
+                           const SIInstrInfo *TII) {
+
+  assert(Mov.getOpcode() == AMDGPU::V_MOV_B32_e32 ||
+         Mov.getOpcode() == AMDGPU::S_MOV_B32 ||
+         Mov.getOpcode() == AMDGPU::S_MOV_B64);
+  assert(Mov.getParent()->pred_size() == 1);
+
+  auto DstOperand = Mov.getOpcode() == AMDGPU::V_MOV_B32_e32
+                        ? TII->getNamedOperand(Mov, AMDGPU::OpName::vdst)
+                        : TII->getNamedOperand(Mov, AMDGPU::OpName::sdst);
+
+  unsigned R = DstOperand->getReg();
+  unsigned Rsub = DstOperand->getSubReg();
+  auto MBB = Mov.getParent();
+  const SIRegisterInfo &TRI = TII->getRegisterInfo();
+
+  // Make sure that 'R' is not modified between the MOVs in 'MBB'.
+  auto I = std::next(Mov.getReverseIterator()), E = MBB->instr_rend();
+  for (; I != E; ++I) {
+    if (instModifiesReg(&*I, R, Rsub, TRI))
+      return false;
+  }
+
+  unsigned Op = Mov.getOpcode();
+  auto SrcOperand = TII->getNamedOperand(Mov, AMDGPU::OpName::src0);
+  assert(SrcOperand->isImm());
+  const int64_t Imm = SrcOperand->getImm();
+
+  // Look for the same MOV in the predecessor.
+  auto Pred = *MBB->pred_begin();
+  I = Pred->instr_rbegin(), E = Pred->instr_rend();
+  for (; I != E; ++I) {
+
+    MachineInstr *Instr = &*I;
+    auto InstrSrcOp = TII->getNamedOperand(*Instr, AMDGPU::OpName::src0);
+    auto InstrDstOp = Instr->getOpcode() == AMDGPU::V_MOV_B32_e32
+                          ? TII->getNamedOperand(*Instr, AMDGPU::OpName::vdst)
+                          : TII->getNamedOperand(*Instr, AMDGPU::OpName::sdst);
+
+    if (Instr->getOpcode() == Op &&
+        InstrDstOp->getReg() == R &&
+        InstrDstOp->getSubReg() == Rsub &&
+        InstrSrcOp->isImm() &&
+        InstrSrcOp->getImm() == Imm) {
+      break;
+    }
+
+    // Make sure that 'R' is not modified between the MOVs in 'Pred'.
+    if (instModifiesReg(Instr, R, Rsub, TRI))
+      return false;
+  }
+
+  // If the same MOV was not found in the predecessor, bail out.
+  if (I == E)
+    return false;
+
+  if (MRI.tracksLiveness() && !MBB->isLiveIn(R))
+    MBB->addLiveIn(R);
+
+  return true;
+}
+
 // Match:
 // mov t, x
 // mov x, y
@@ -593,6 +671,23 @@
         }
       }
 
+      if (MI.getOpcode() == AMDGPU::V_MOV_B32_e32 ||
+          MI.getOpcode() == AMDGPU::S_MOV_B32 ||
+          MI.getOpcode() == AMDGPU::S_MOV_B64) {
+        // If the MOV is identical to a MOV in the immediate predecessor
+        // of MBB and also no instruction between them modifies the destination
+        // register, then remove the MOV.
+        MachineOperand &Src = MI.getOperand(1);
+        if (Src.isImm() &&
+            TargetRegisterInfo::isPhysicalRegister(MI.getOperand(0).getReg())) {
+
+          if (MBB.pred_size() == 1 && isMovRedundant(MI, MRI, TII)) {
+            MI.eraseFromParent();
+            continue;
+          }
+        }
+      }
+
       // Combine adjacent s_nops to use the immediate operand encoding how long
       // to wait.
       //
Index: test/CodeGen/AMDGPU/control-flow-fastregalloc.ll
===================================================================
--- test/CodeGen/AMDGPU/control-flow-fastregalloc.ll
+++ test/CodeGen/AMDGPU/control-flow-fastregalloc.ll
@@ -38,7 +38,6 @@
 ; GCN: mask branch [[ENDIF:BB[0-9]+_[0-9]+]]
 
 ; GCN: {{^}}BB{{[0-9]+}}_1: ; %if
-; GCN: s_mov_b32 m0, -1
 ; GCN: ds_read_b32 [[LOAD1:v[0-9]+]]
 ; GCN: buffer_load_dword [[RELOAD_LOAD0:v[0-9]+]], off, s[0:3], s7 offset:[[LOAD0_OFFSET]] ; 4-byte Folded Reload
 ; GCN: s_waitcnt vmcnt(0) lgkmcnt(0)
Index: test/CodeGen/AMDGPU/mov-opt.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AMDGPU/mov-opt.ll
@@ -0,0 +1,83 @@
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=gfx900 -verify-machineinstrs | FileCheck %s
+
+; Check that the redundant immediate MOV instruction
+; (by-product of handling phi nodes) is optimized away
+; and not found in bb1.
+
+; CHECK-LABEL: {{^}}mov_opt:
+; CHECK: v_mov_b32_e32 {{v[0-9]+}}, 1.0
+; CHECK: %bb.1:
+; CHECK-NOT: v_mov_b32_e32 {{v[0-9]+}}, 1.0
+; CHECK: %bb.2:
+
+define void @mov_opt(i32, i32) local_unnamed_addr #0 {
+.entry:
+  %2 = add i32 %1, %0
+  br i1 undef, label %3, label %.critedge
+
+3:                                                ; preds = %.entry
+  br i1 undef, label %4, label %.critedge
+
+4:                                                ; preds = %3
+  switch i32 undef, label %8 [
+    i32 0, label %5
+    i32 1, label %6
+    i32 2, label %7
+  ]
+
+5:                                                ; preds = %4
+  br label %8
+
+6:                                                ; preds = %4
+  br label %8
+
+7:                                                ; preds = %4
+  br label %8
+
+8:                                                ; preds = %7, %6, %5, %4
+  %9 = add i32 0, %2
+  %10 = lshr i32 %9, 1
+  %11 = getelementptr <{ [4294967295 x i32] }>, <{ [4294967295 x i32] }> addrspace(6)* null, i32 0, i32 0, i32 %10
+  %12 = ptrtoint i32 addrspace(6)* %11 to i32
+  %13 = call i32 @llvm.amdgcn.s.buffer.load.i32(<4 x i32> undef, i32 %12, i32 0)
+  %14 = lshr i32 %13, 0
+  %15 = lshr i32 %14, 3
+  %16 = and i32 %15, 7
+  switch i32 %16, label %17 [
+    i32 0, label %17
+    i32 1, label %18
+    i32 2, label %20
+    i32 3, label %21
+  ]
+
+17:                                               ; preds = %8, %8
+  br label %.critedge
+
+18:                                               ; preds = %8
+  %19 = fsub reassoc nnan nsz arcp contract float 1.000000e+00, undef
+  br label %.critedge
+
+20:                                               ; preds = %8
+  br label %.critedge
+
+21:                                               ; preds = %8
+  %22 = fsub reassoc nnan nsz arcp contract float 1.000000e+00, undef
+  br label %.critedge
+
+.critedge:                                        ; preds = %21, %20, %18, %17, %3, %.entry
+  %__llpc_output_proxy_.3.0 = phi float [ 1.000000e+00, %3 ], [ undef, %21 ], [ undef, %20 ], [ undef, %18 ], [ 0.000000e+00, %17 ], [ 1.000000e+00, %.entry ]
+  %__llpc_output_proxy_.3.1 = phi float [ 0.000000e+00, %3 ], [ 0.000000e+00, %21 ], [ 0.000000e+00, %20 ], [ %19, %18 ], [ 0.000000e+00, %17 ], [ 0.000000e+00, %.entry ]
+  %__llpc_output_proxy_.3.3 = phi float [ 0.000000e+00, %3 ], [ %22, %21 ], [ undef, %20 ], [ undef, %18 ], [ undef, %17 ], [ 0.000000e+00, %.entry ]
+  call void @llvm.amdgcn.exp.f32(i32 immarg 40, i32 immarg 15, float %__llpc_output_proxy_.3.0, float %__llpc_output_proxy_.3.1, float undef, float %__llpc_output_proxy_.3.3, i1 immarg false, i1 immarg false) #2
+  ret void
+}
+
+; Function Attrs: inaccessiblememonly nounwind
+declare void @llvm.amdgcn.exp.f32(i32 immarg, i32 immarg, float, float, float, float, i1 immarg, i1 immarg) #0
+
+; Function Attrs: nounwind readnone
+declare i32 @llvm.amdgcn.s.buffer.load.i32(<4 x i32>, i32, i32 immarg) #1
+
+attributes #0 = { inaccessiblememonly nounwind }
+attributes #1 = { nounwind readnone }
+attributes #2 = { nounwind }
Index: test/CodeGen/AMDGPU/remove-redundant-mov.mir
===================================================================
--- /dev/null
+++ test/CodeGen/AMDGPU/remove-redundant-mov.mir
@@ -0,0 +1,284 @@
+# RUN: llc -march=amdgcn -mcpu=gfx900 -run-pass si-shrink-instructions -verify-machineinstrs %s -o - | FileCheck -check-prefix=GCN %s
+
+# GCN-LABEL: name: v_mov_redundant_move_single
+# GCN: bb.1:
+# GCN-NOT: $vgpr2 = V_MOV_B32_e32 1065353216
+# GCN: $vgpr3 = V_MOV_B32_e32 $vgpr2
+---
+name:            v_mov_redundant_move_single
+body:             |
+  bb.0:
+    renamable $vgpr2 = V_MOV_B32_e32 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $vgpr2 = V_MOV_B32_e32 1065353216, implicit $exec
+    $vgpr3 = V_MOV_B32_e32 $vgpr2, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: v_mov_redundant_move_liveness
+# GCN: bb.1:
+# GCN: liveins: $vgpr2
+# GCN-NOT: $vgpr2 = V_MOV_B32_e32 1065353216
+# GCN: $vgpr3 = V_MOV_B32_e32 $vgpr2
+---
+name:            v_mov_redundant_move_liveness
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    renamable $vgpr2 = V_MOV_B32_e32 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $vgpr2 = V_MOV_B32_e32 1065353216, implicit $exec
+    $vgpr3 = V_MOV_B32_e32 $vgpr2, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: v_mov_redundant_move_multiple
+# GCN: bb.1:
+# GCN-NOT: $vgpr2 = V_MOV_B32_e32 0
+# GCN-NOT: $vgpr1 = V_MOV_B32_e32 1065353216
+# GCN-NOT: $vgpr4 = V_MOV_B32_e32 3204448256
+# GCN-NOT: $vgpr3 = V_MOV_B32_e32 1056964608
+# GCN: $vgpr3 = V_MOV_B32_e32 $vgpr2
+---
+name:            v_mov_redundant_move_multiple
+body:             |
+  bb.0:
+    renamable $vgpr1 = V_MOV_B32_e32 1065353216, implicit $exec
+    renamable $vgpr2 = V_MOV_B32_e32 0, implicit $exec
+    renamable $vgpr3 = V_MOV_B32_e32 1056964608, implicit $exec
+    renamable $vgpr4 = V_MOV_B32_e32 3204448256, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $vgpr2 = V_MOV_B32_e32 0, implicit $exec
+    renamable $vgpr1 = V_MOV_B32_e32 1065353216, implicit $exec
+    renamable $vgpr4 = V_MOV_B32_e32 3204448256, implicit $exec
+    renamable $vgpr3 = V_MOV_B32_e32 1056964608, implicit $exec
+    $vgpr3 = V_MOV_B32_e32 $vgpr2, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: v_mov_necessary_move_not_removed_1
+# GCN: bb.1:
+# GCN: $vgpr2 = V_MOV_B32_e32 1065353216
+# GCN: $vgpr3 = V_MOV_B32_e32 $vgpr2
+---
+name:            v_mov_necessary_move_not_removed_1
+body:             |
+  bb.0:
+    renamable $vgpr2 = V_MOV_B32_e32 1065353216, implicit $exec
+    renamable $vgpr2 = V_MOV_B32_e32 0, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $vgpr2 = V_MOV_B32_e32 1065353216, implicit $exec
+    $vgpr3 = V_MOV_B32_e32 $vgpr2, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: v_mov_necessary_move_not_removed_2
+# GCN: bb.1:
+# GCN: $vgpr2 = V_MOV_B32_e32 1065353216
+# GCN: $vgpr3 = V_MOV_B32_e32 $vgpr2
+---
+name:            v_mov_necessary_move_not_removed_2
+body:             |
+  bb.0:
+    renamable $vgpr2 = V_MOV_B32_e32 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $vgpr2 = V_MOV_B32_e32 0, implicit $exec
+    renamable $vgpr2 = V_MOV_B32_e32 1065353216, implicit $exec
+    $vgpr3 = V_MOV_B32_e32 $vgpr2, implicit $exec, implicit $exec
+...
+
+
+
+# GCN-LABEL: name: s_mov_32_redundant_move_single
+# GCN: bb.1:
+# GCN-NOT: $sgpr11 = S_MOV_B32 1065353216
+# GCN: $sgpr12 = S_MOV_B32 $sgpr11
+---
+name:            s_mov_32_redundant_move_single
+body:             |
+  bb.0:
+    renamable $sgpr11 = S_MOV_B32 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr11 = S_MOV_B32 1065353216, implicit $exec
+    $sgpr12 = S_MOV_B32 $sgpr11, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: s_mov_32_redundant_move_liveness
+# GCN: bb.1:
+# GCN: liveins: $sgpr11
+# GCN-NOT: $sgpr11 = S_MOV_B32 1065353216
+# GCN: $sgpr12 = S_MOV_B32 $sgpr11
+---
+name:            s_mov_32_redundant_move_liveness
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    renamable $sgpr11 = S_MOV_B32 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr11 = S_MOV_B32 1065353216, implicit $exec
+    $sgpr12 = S_MOV_B32 $sgpr11, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: s_mov_32_redundant_move_multiple
+# GCN: bb.1:
+# GCN-NOT: $sgpr11 = S_MOV_B32 0
+# GCN-NOT: $sgpr10 = S_MOV_B32 1065353216
+# GCN-NOT: $sgpr13 = S_MOV_B32 3204448256
+# GCN-NOT: $sgpr12 = S_MOV_B32 1056964608
+# GCN: $sgpr12 = S_MOV_B32 $sgpr11
+---
+name:            s_mov_32_redundant_move_multiple
+body:             |
+  bb.0:
+    renamable $sgpr10 = S_MOV_B32 1065353216, implicit $exec
+    renamable $sgpr11 = S_MOV_B32 0, implicit $exec
+    renamable $sgpr12 = S_MOV_B32 1056964608, implicit $exec
+    renamable $sgpr13 = S_MOV_B32 3204448256, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr11 = S_MOV_B32 0, implicit $exec
+    renamable $sgpr10 = S_MOV_B32 1065353216, implicit $exec
+    renamable $sgpr13 = S_MOV_B32 3204448256, implicit $exec
+    renamable $sgpr12 = S_MOV_B32 1056964608, implicit $exec
+    $sgpr12 = S_MOV_B32 $sgpr11, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: s_mov_32_necessary_move_not_removed_1
+# GCN: bb.1:
+# GCN: $sgpr11 = S_MOV_B32 1065353216
+# GCN: $sgpr12 = S_MOV_B32 $sgpr11
+---
+name:            s_mov_32_necessary_move_not_removed_1
+body:             |
+  bb.0:
+    renamable $sgpr11 = S_MOV_B32 1065353216, implicit $exec
+    renamable $sgpr11 = S_MOV_B32 0, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr11 = S_MOV_B32 1065353216, implicit $exec
+    $sgpr12 = S_MOV_B32 $sgpr11, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: s_mov_32_necessary_move_not_removed_2
+# GCN: bb.1:
+# GCN: $sgpr11 = S_MOV_B32 1065353216
+# GCN: $sgpr12 = S_MOV_B32 $sgpr11
+---
+name:            s_mov_32_necessary_move_not_removed_2
+body:             |
+  bb.0:
+    renamable $sgpr11 = S_MOV_B32 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr11 = S_MOV_B32 0, implicit $exec
+    renamable $sgpr11 = S_MOV_B32 1065353216, implicit $exec
+    $sgpr12 = S_MOV_B32 $sgpr11, implicit $exec, implicit $exec
+...
+
+
+
+# GCN-LABEL: name: s_mov_64_redundant_move_single
+# GCN: bb.1:
+# GCN-NOT: $sgpr8_sgpr9 = S_MOV_B64 1065353216
+# GCN: $sgpr6_sgpr7 = S_MOV_B64 $sgpr8_sgpr9
+---
+name:            s_mov_64_redundant_move_single
+body:             |
+  bb.0:
+    renamable $sgpr8_sgpr9 = S_MOV_B64 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr8_sgpr9 = S_MOV_B64 1065353216, implicit $exec
+    $sgpr6_sgpr7 = S_MOV_B64 $sgpr8_sgpr9, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: s_mov_64_redundant_move_liveness
+# GCN: bb.1:
+# GCN: liveins: $sgpr10_sgpr11
+# GCN-NOT: $sgpr10_sgpr11 = S_MOV_B64 1065353216
+# GCN: $sgpr6_sgpr7 = S_MOV_B64 $sgpr10_sgpr11
+---
+name:            s_mov_64_redundant_move_liveness
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    renamable $sgpr10_sgpr11 = S_MOV_B64 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr10_sgpr11 = S_MOV_B64 1065353216, implicit $exec
+    $sgpr6_sgpr7 = S_MOV_B64 $sgpr10_sgpr11, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: s_mov_64_redundant_move_multiple
+# GCN: bb.1:
+# GCN-NOT: $sgpr10_sgpr11 = S_MOV_B64 0
+# GCN-NOT: $sgpr12_sgpr13 = S_MOV_B64 1065353216
+# GCN-NOT: $sgpr6_sgpr7 = S_MOV_B64 3204448256
+# GCN-NOT: $sgpr8_sgpr9 = S_MOV_B64 1056964608
+# GCN: $sgpr14_sgpr15 = S_MOV_B64 $sgpr8_sgpr9
+---
+name:            s_mov_64_redundant_move_multiple
+body:             |
+  bb.0:
+    renamable $sgpr12_sgpr13 = S_MOV_B64 1065353216, implicit $exec
+    renamable $sgpr10_sgpr11 = S_MOV_B64 0, implicit $exec
+    renamable $sgpr8_sgpr9 = S_MOV_B64 1056964608, implicit $exec
+    renamable $sgpr6_sgpr7 = S_MOV_B64 3204448256, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr10_sgpr11 = S_MOV_B64 0, implicit $exec
+    renamable $sgpr12_sgpr13 = S_MOV_B64 1065353216, implicit $exec
+    renamable $sgpr6_sgpr7 = S_MOV_B64 3204448256, implicit $exec
+    renamable $sgpr8_sgpr9 = S_MOV_B64 1056964608, implicit $exec
+    $sgpr14_sgpr15 = S_MOV_B64 $sgpr8_sgpr9, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: s_mov_64_necessary_move_not_removed_1
+# GCN: bb.1:
+# GCN: $sgpr10_sgpr11 = S_MOV_B64 1065353216
+# GCN: $sgpr6_sgpr7 = S_MOV_B64 $sgpr10_sgpr11
+---
+name:            s_mov_64_necessary_move_not_removed_1
+body:             |
+  bb.0:
+    renamable $sgpr10_sgpr11 = S_MOV_B64 1065353216, implicit $exec
+    renamable $sgpr10_sgpr11 = S_MOV_B64 0, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr10_sgpr11 = S_MOV_B64 1065353216, implicit $exec
+    $sgpr6_sgpr7 = S_MOV_B64 $sgpr10_sgpr11, implicit $exec, implicit $exec
+...
+
+# GCN-LABEL: name: s_mov_64_necessary_move_not_removed_2
+# GCN: bb.1:
+# GCN: $sgpr10_sgpr11 = S_MOV_B64 1065353216
+# GCN: $sgpr6_sgpr7 = S_MOV_B64 $sgpr10_sgpr11
+---
+name:            s_mov_64_necessary_move_not_removed_2
+body:             |
+  bb.0:
+    renamable $sgpr10_sgpr11 = S_MOV_B64 1065353216, implicit $exec
+    S_BRANCH %bb.1
+
+  bb.1:
+    renamable $sgpr10_sgpr11 = S_MOV_B64 0, implicit $exec
+    renamable $sgpr10_sgpr11 = S_MOV_B64 1065353216, implicit $exec
+    $sgpr6_sgpr7 = S_MOV_B64 $sgpr10_sgpr11, implicit $exec, implicit $exec
+...