diff --git a/llvm/test/CodeGen/AMDGPU/bit-op-reduce-width-known-bits.ll b/llvm/test/CodeGen/AMDGPU/bit-op-reduce-width-known-bits.ll
new file mode 100644
index 0000000000000..ac5f9b6b483eb
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/bit-op-reduce-width-known-bits.ll
@@ -0,0 +1,162 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 < %s | FileCheck %s
+
+; Check for situations where we could reduce the width of bitwise
+; operations.
+
+
+; Should be able to reduce this to a 32-bit or plus a copy
+; https://alive2.llvm.org/ce/z/9LddFX
+define i64 @v_xor_i64_known_hi_i32_from_arg_range(i64 range(i64 0, 4294967296) %arg0, i64 %arg1) {
+; CHECK-LABEL: v_xor_i64_known_hi_i32_from_arg_range:
+; CHECK:       ; %bb.0:
+; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; CHECK-NEXT:    v_xor_b32_e32 v1, v1, v3
+; CHECK-NEXT:    v_xor_b32_e32 v0, v0, v2
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+  %xor = xor i64 %arg0, %arg1
+  ret i64 %xor
+}
+
+; Should be able to reduce this to a 32-bit or plus a copy
+; https://alive2.llvm.org/ce/z/HaXnBJ
+define i64 @v_or_i64_known_hi_i32_from_arg_range(i64 range(i64 0, 4294967296) %arg0, i64 %arg1) {
+; CHECK-LABEL: v_or_i64_known_hi_i32_from_arg_range:
+; CHECK:       ; %bb.0:
+; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; CHECK-NEXT:    v_or_b32_e32 v1, v1, v3
+; CHECK-NEXT:    v_or_b32_e32 v0, v0, v2
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+  %or = or i64 %arg0, %arg1
+  ret i64 %or
+}
+
+; https://alive2.llvm.org/ce/z/M96Ror
+; Should be able to reduce this to a 32-bit plus a copy
+define i64 @v_and_i64_known_i32_from_arg_range(i64 range(i64 -4294967296, 0) %arg0, i64 %arg1) {
+; CHECK-LABEL: v_and_i64_known_i32_from_arg_range:
+; CHECK:       ; %bb.0:
+; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; CHECK-NEXT:    v_and_b32_e32 v1, v1, v3
+; CHECK-NEXT:    v_and_b32_e32 v0, v0, v2
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+  %and = and i64 %arg0, %arg1
+  ret i64 %and
+}
+
+define i64 @s_xor_i64_known_i32_from_arg_range(i64 range(i64 0, 65) inreg %arg) {
+; CHECK-LABEL: s_xor_i64_known_i32_from_arg_range:
+; CHECK:       ; %bb.0:
+; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; CHECK-NEXT:    s_not_b64 s[4:5], s[16:17]
+; CHECK-NEXT:    v_mov_b32_e32 v0, s4
+; CHECK-NEXT:    v_mov_b32_e32 v1, s5
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+  %xor = xor i64 %arg, -1
+  ret i64 %xor
+}
+
+define i64 @v_xor_i64_known_i32_from_call_range() {
+; CHECK-LABEL: v_xor_i64_known_i32_from_call_range:
+; CHECK:       ; %bb.0:
+; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; CHECK-NEXT:    ;;#ASMSTART
+; CHECK-NEXT:    ; def v[0:1]
+; CHECK-NEXT:    ;;#ASMEND
+; CHECK-NEXT:    v_not_b32_e32 v1, v1
+; CHECK-NEXT:    v_not_b32_e32 v0, v0
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+  %call = call range(i64 0, 65) i64 asm "; def $0", "=v"()
+  %xor = xor i64 %call, -1
+  ret i64 %xor
+}
+
+define i64 @s_xor_i64_known_i32_from_call_range() {
+; CHECK-LABEL: s_xor_i64_known_i32_from_call_range:
+; CHECK:       ; %bb.0:
+; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; CHECK-NEXT:    ;;#ASMSTART
+; CHECK-NEXT:    ; def s[4:5]
+; CHECK-NEXT:    ;;#ASMEND
+; CHECK-NEXT:    s_not_b64 s[4:5], s[4:5]
+; CHECK-NEXT:    v_mov_b32_e32 v0, s4
+; CHECK-NEXT:    v_mov_b32_e32 v1, s5
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+  %call = call range(i64 0, 65) i64 asm "; def $0", "=s"()
+  %xor = xor i64 %call, -1
+  ret i64 %xor
+}
+
+; Reduced from -amdgpu-codegenprepare-expand-div64 output, produces a
+; not of 0 which ideally would fold out.
+; FIXME: Produces not of constant 0
+define i64 @v_xor_i64_known_i32_from_range_use_out_of_block(i64 %x) {
+; CHECK-LABEL: v_xor_i64_known_i32_from_range_use_out_of_block:
+; CHECK:       ; %bb.0: ; %entry
+; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; CHECK-NEXT:    v_ffbh_u32_e32 v2, v0
+; CHECK-NEXT:    v_add_u32_e32 v2, 32, v2
+; CHECK-NEXT:    v_ffbh_u32_e32 v3, v1
+; CHECK-NEXT:    v_min_u32_e32 v4, v2, v3
+; CHECK-NEXT:    v_mov_b32_e32 v5, 0
+; CHECK-NEXT:    v_cmp_eq_u64_e32 vcc, v[4:5], v[0:1]
+; CHECK-NEXT:    v_mov_b32_e32 v2, 0
+; CHECK-NEXT:    v_mov_b32_e32 v3, 0
+; CHECK-NEXT:    s_and_saveexec_b64 s[4:5], vcc
+; CHECK-NEXT:  ; %bb.1: ; %inc
+; CHECK-NEXT:    v_not_b32_e32 v2, v4
+; CHECK-NEXT:    v_not_b32_e32 v3, 0
+; CHECK-NEXT:    v_add_co_u32_e32 v2, vcc, v0, v2
+; CHECK-NEXT:    v_addc_co_u32_e32 v3, vcc, v1, v3, vcc
+; CHECK-NEXT:  ; %bb.2: ; %UnifiedReturnBlock
+; CHECK-NEXT:    s_or_b64 exec, exec, s[4:5]
+; CHECK-NEXT:    v_mov_b32_e32 v0, v2
+; CHECK-NEXT:    v_mov_b32_e32 v1, v3
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+entry:
+  %ctlz = tail call range(i64 0, 65) i64 @llvm.ctlz.i64(i64 %x, i1 true)
+  %cmp.entry.not = icmp eq i64 %ctlz, %x
+  br i1 %cmp.entry.not, label %inc, label %ret
+
+inc:                                              ; preds = %entry
+  %i1 = xor i64 %ctlz, -1
+  %i2 = add i64 %x, %i1
+  ret i64 %i2
+
+ret:                                              ; preds = %loop, %entry
+  ret i64 0
+}
+
+define i64 @s_xor_i64_known_i32_from_range_use_out_of_block(i64 inreg %x) {
+; CHECK-LABEL: s_xor_i64_known_i32_from_range_use_out_of_block:
+; CHECK:       ; %bb.0: ; %entry
+; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; CHECK-NEXT:    s_flbit_i32_b64 s4, s[16:17]
+; CHECK-NEXT:    s_mov_b32 s5, 0
+; CHECK-NEXT:    s_cmp_lg_u64 s[4:5], s[16:17]
+; CHECK-NEXT:    s_cbranch_scc1 .LBB7_2
+; CHECK-NEXT:  ; %bb.1: ; %inc
+; CHECK-NEXT:    s_not_b64 s[4:5], s[4:5]
+; CHECK-NEXT:    s_add_u32 s4, s16, s4
+; CHECK-NEXT:    s_addc_u32 s5, s17, s5
+; CHECK-NEXT:    v_mov_b32_e32 v0, s4
+; CHECK-NEXT:    v_mov_b32_e32 v1, s5
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+; CHECK-NEXT:  .LBB7_2: ; %ret
+; CHECK-NEXT:    v_mov_b32_e32 v0, 0
+; CHECK-NEXT:    v_mov_b32_e32 v1, 0
+; CHECK-NEXT:    s_setpc_b64 s[30:31]
+entry:
+  %ctlz = tail call range(i64 0, 65) i64 @llvm.ctlz.i64(i64 %x, i1 true)
+  %cmp.entry.not = icmp eq i64 %ctlz, %x
+  br i1 %cmp.entry.not, label %inc, label %ret
+
+inc:                                              ; preds = %entry
+  %i1 = xor i64 %ctlz, -1
+  %i2 = add i64 %x, %i1
+  ret i64 %i2
+
+ret:                                              ; preds = %loop, %entry
+  ret i64 0
+}
+