Index: llvm/lib/Target/AMDGPU/FLATInstructions.td
===================================================================
--- llvm/lib/Target/AMDGPU/FLATInstructions.td
+++ llvm/lib/Target/AMDGPU/FLATInstructions.td
@@ -783,6 +783,11 @@
   (inst VReg_64:$vaddr, getVregSrcForVT<vt>.ret:$data, $offset)
 >;
 
+class FlatSignedAtomicPatNoRtn <FLAT_Pseudo inst, SDPatternOperator node, ValueType vt> : GCNPat <
+  (node (FLATOffsetSigned i64:$vaddr, i16:$offset), vt:$data),
+  (inst VReg_64:$vaddr, getVregSrcForVT<vt>.ret:$data, $offset)
+>;
+
 class FlatSignedAtomicPat <FLAT_Pseudo inst, SDPatternOperator node, ValueType vt,
                      ValueType data_vt = vt> : GCNPat <
   (vt (node (FLATOffsetSigned i64:$vaddr, i16:$offset), data_vt:$data)),
@@ -971,8 +976,8 @@
 def : FlatSignedAtomicPat <GLOBAL_ATOMIC_CMPSWAP_X2_RTN, AMDGPUatomic_cmp_swap_global_64, i64, v2i64>;
 def : FlatSignedAtomicPat <GLOBAL_ATOMIC_XOR_X2_RTN, atomic_load_xor_global_64, i64>;
 
-def : FlatAtomicPatNoRtn <GLOBAL_ATOMIC_ADD_F32,    atomic_fadd_global_noret, f32>;
-def : FlatAtomicPatNoRtn <GLOBAL_ATOMIC_PK_ADD_F16, atomic_fadd_global_noret, v2f16>;
+def : FlatSignedAtomicPatNoRtn <GLOBAL_ATOMIC_ADD_F32,    atomic_fadd_global_noret, f32>;
+def : FlatSignedAtomicPatNoRtn <GLOBAL_ATOMIC_PK_ADD_F16, atomic_fadd_global_noret, v2f16>;
 
 } // End OtherPredicates = [HasFlatGlobalInsts], AddedComplexity = 10
 
Index: llvm/test/CodeGen/AMDGPU/llvm.amdgcn.atomic.fadd.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/llvm.amdgcn.atomic.fadd.ll
+++ llvm/test/CodeGen/AMDGPU/llvm.amdgcn.atomic.fadd.ll
@@ -54,6 +54,15 @@
   ret void
 }
 
+; GCN-LABEL: {{^}}global_atomic_add_f32_offneg4:
+; GCN: global_atomic_add_f32 v[{{[0-9:]+}}], v{{[0-9]+}}, off offset:-4
+define amdgpu_kernel void @global_atomic_add_f32_offneg4(float addrspace(1)* %ptr, float %data) {
+main_body:
+  %p = getelementptr float, float addrspace(1)* %ptr, i64 -1
+  call void @llvm.amdgcn.global.atomic.fadd.p1f32.f32(float addrspace(1)* %p, float %data)
+  ret void
+}
+
 ; GCN-LABEL: {{^}}global_atomic_pk_add_v2f16:
 ; GCN: global_atomic_pk_add_f16 v[{{[0-9:]+}}], v{{[0-9]+}}, off
 define amdgpu_kernel void @global_atomic_pk_add_v2f16(<2 x half> addrspace(1)* %ptr, <2 x half> %data) {
@@ -71,6 +80,15 @@
   ret void
 }
 
+; GCN-LABEL: {{^}}global_atomic_pk_add_v2f16_offneg4:
+; GCN: global_atomic_pk_add_f16 v[{{[0-9:]+}}], v{{[0-9]+}}, off offset:-4
+define amdgpu_kernel void @global_atomic_pk_add_v2f16_offneg4(<2 x half> addrspace(1)* %ptr, <2 x half> %data) {
+main_body:
+  %p = getelementptr <2 x half>, <2 x half> addrspace(1)* %ptr, i64 -1
+  call void @llvm.amdgcn.global.atomic.fadd.p1v2f16.v2f16(<2 x half> addrspace(1)* %p, <2 x half> %data)
+  ret void
+}
+
 ; Make sure this artificially selects with an incorrect subtarget, but
 ; the feature set.
 ; GCN-LABEL: {{^}}global_atomic_fadd_f32_wrong_subtarget: