diff --git a/llvm/lib/Target/AMDGPU/FLATInstructions.td b/llvm/lib/Target/AMDGPU/FLATInstructions.td
--- a/llvm/lib/Target/AMDGPU/FLATInstructions.td
+++ b/llvm/lib/Target/AMDGPU/FLATInstructions.td
@@ -725,11 +725,12 @@
   defm FLAT_ATOMIC_ADD_F64   : FLAT_Atomic_Pseudo<"flat_atomic_add_f64", VReg_64, f64>;
   defm FLAT_ATOMIC_MIN_F64   : FLAT_Atomic_Pseudo<"flat_atomic_min_f64", VReg_64, f64>;
   defm FLAT_ATOMIC_MAX_F64   : FLAT_Atomic_Pseudo<"flat_atomic_max_f64", VReg_64, f64>;
-  defm GLOBAL_ATOMIC_ADD_F64 : FLAT_Global_Atomic_Pseudo<"global_atomic_add_f64", VReg_64, f64>;
-  defm GLOBAL_ATOMIC_MIN_F64 : FLAT_Global_Atomic_Pseudo<"global_atomic_min_f64", VReg_64, f64>;
-  defm GLOBAL_ATOMIC_MAX_F64 : FLAT_Global_Atomic_Pseudo<"global_atomic_max_f64", VReg_64, f64>;
 } // End SubtargetPredicate = isGFX90APlus
 
+defm GLOBAL_ATOMIC_ADD_F64 : FLAT_Global_Atomic_Pseudo<"global_atomic_add_f64", VReg_64, f64>;
+defm GLOBAL_ATOMIC_MIN_F64 : FLAT_Global_Atomic_Pseudo<"global_atomic_min_f64", VReg_64, f64>;
+defm GLOBAL_ATOMIC_MAX_F64 : FLAT_Global_Atomic_Pseudo<"global_atomic_max_f64", VReg_64, f64>;
+
 let SubtargetPredicate = HasAtomicFlatPkAdd16Insts in {
   defm FLAT_ATOMIC_PK_ADD_F16    : FLAT_Atomic_Pseudo<"flat_atomic_pk_add_f16",  VGPR_32, v2f16>;
   let FPAtomic = 1 in
@@ -1943,22 +1944,24 @@
 }
 
 let SubtargetPredicate = isGFX940Plus in {
-  // These instructions are encoded differently on gfx90* and gfx940.
-  defm GLOBAL_ATOMIC_ADD_F32     : FLAT_Global_Real_Atomics_gfx940 <0x04d>;
-  defm GLOBAL_ATOMIC_PK_ADD_F16  : FLAT_Global_Real_Atomics_gfx940 <0x04e>;
 
   defm FLAT_ATOMIC_ADD_F64       : FLAT_Real_Atomics_gfx940<0x4f, FLAT_ATOMIC_ADD_F64>;
   defm FLAT_ATOMIC_MIN_F64       : FLAT_Real_Atomics_gfx940<0x50, FLAT_ATOMIC_MIN_F64>;
   defm FLAT_ATOMIC_MAX_F64       : FLAT_Real_Atomics_gfx940<0x51, FLAT_ATOMIC_MAX_F64>;
-  defm GLOBAL_ATOMIC_ADD_F64     : FLAT_Global_Real_Atomics_gfx940<0x4f>;
-  defm GLOBAL_ATOMIC_MIN_F64     : FLAT_Global_Real_Atomics_gfx940<0x50>;
-  defm GLOBAL_ATOMIC_MAX_F64     : FLAT_Global_Real_Atomics_gfx940<0x51>;
   defm FLAT_ATOMIC_ADD_F32       : FLAT_Real_Atomics_vi<0x4d, FLAT_ATOMIC_ADD_F32>;
   defm FLAT_ATOMIC_PK_ADD_F16    : FLAT_Real_Atomics_vi<0x4e, FLAT_ATOMIC_PK_ADD_F16>;
   defm FLAT_ATOMIC_PK_ADD_BF16   : FLAT_Real_Atomics_vi<0x52, FLAT_ATOMIC_PK_ADD_BF16>;
   defm GLOBAL_ATOMIC_PK_ADD_BF16 : FLAT_Global_Real_Atomics_vi<0x52>;
 } // End SubtargetPredicate = isGFX940Plus
 
+// These instructions are encoded differently on gfx90* and gfx940.
+defm GLOBAL_ATOMIC_ADD_F32     : FLAT_Global_Real_Atomics_gfx940<0x04d>;
+defm GLOBAL_ATOMIC_PK_ADD_F16  : FLAT_Global_Real_Atomics_gfx940<0x04e>;
+
+defm GLOBAL_ATOMIC_ADD_F64     : FLAT_Global_Real_Atomics_gfx940<0x4f>;
+defm GLOBAL_ATOMIC_MIN_F64     : FLAT_Global_Real_Atomics_gfx940<0x50>;
+defm GLOBAL_ATOMIC_MAX_F64     : FLAT_Global_Real_Atomics_gfx940<0x51>;
+
 //===----------------------------------------------------------------------===//
 // GFX10.
 //===----------------------------------------------------------------------===//
diff --git a/llvm/test/MC/AMDGPU/gfx908_unsupported.s b/llvm/test/MC/AMDGPU/gfx908_unsupported.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/AMDGPU/gfx908_unsupported.s
@@ -0,0 +1,11 @@
+// RUN: not llvm-mc -arch=amdgcn -mcpu=gfx908 -mattr=+wavefrontsize32,-wavefrontsize64 %s 2>&1 | FileCheck --implicit-check-not=error: %s
+// RUN: not llvm-mc -arch=amdgcn -mcpu=gfx908 -mattr=-wavefrontsize32,+wavefrontsize64 %s 2>&1 | FileCheck --implicit-check-not=error: %s
+
+global_atomic_add_f64 v[0:1], v[0:1], v[2:3], off glc
+// CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: instruction not supported on this GPU
+
+global_atomic_min_f64 v[0:1], v[0:1], v[2:3], off glc
+// CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: instruction not supported on this GPU
+
+global_atomic_max_f64 v[0:1], v[0:1], v[2:3], off glc
+// CHECK: :[[@LINE-1]]:{{[0-9]+}}: error: instruction not supported on this GPU