Index: llvm/lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -870,6 +870,8 @@
   setTargetDAGCombine(ISD::ATOMIC_LOAD_UMIN);
   setTargetDAGCombine(ISD::ATOMIC_LOAD_UMAX);
   setTargetDAGCombine(ISD::ATOMIC_LOAD_FADD);
+  setTargetDAGCombine(ISD::INTRINSIC_VOID);
+  setTargetDAGCombine(ISD::INTRINSIC_W_CHAIN);
 
   // FIXME: In other contexts we pretend this is a per-function property.
   setStackPointerRegisterToSaveRestore(AMDGPU::SGPR32);
@@ -8563,14 +8565,28 @@
   return DAG.getNode(ISD::ADD, SL, VT, ShlX, COffset, Flags);
 }
 
+/// MemSDNode::getBasePtr() does not work for intrinsics, which needs to offset
+/// by the chain and intrinsic ID. Theoretically we would also need to check the
+/// specific intrinsic.
+static unsigned getBasePtrIndex(const MemSDNode *N) {
+  switch (N->getOpcode()) {
+  case ISD::STORE:
+  case ISD::INTRINSIC_W_CHAIN:
+  case ISD::INTRINSIC_VOID:
+    return 2;
+  default:
+    return 1;
+  }
+}
+
 SDValue SITargetLowering::performMemSDNodeCombine(MemSDNode *N,
                                                   DAGCombinerInfo &DCI) const {
-  // FIXME: getBasePtr does not work correctly for intrinsic nodes and will find
-  // the intrinsic ID, not the pointer.
-  SDValue Ptr = N->getBasePtr();
   SelectionDAG &DAG = DCI.DAG;
   SDLoc SL(N);
 
+  unsigned PtrIdx = getBasePtrIndex(N);
+  SDValue Ptr = N->getOperand(PtrIdx);
+
   // TODO: We could also do this for multiplies.
   if (Ptr.getOpcode() == ISD::SHL) {
     SDValue NewPtr = performSHLPtrCombine(Ptr.getNode(),  N->getAddressSpace(),
@@ -8578,7 +8594,7 @@
     if (NewPtr) {
       SmallVector<SDValue, 8> NewOps(N->op_begin(), N->op_end());
 
-      NewOps[N->getOpcode() == ISD::STORE ? 2 : 1] = NewPtr;
+      NewOps[PtrIdx] = NewPtr;
       return SDValue(DAG.UpdateNodeOperands(N, NewOps), 0);
     }
   }
Index: llvm/test/CodeGen/AMDGPU/shl_add_ptr_csub.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/shl_add_ptr_csub.ll
@@ -0,0 +1,22 @@
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx1030 -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefixes=GCN,GFX10 %s
+
+; GCN-LABEL: {{^}}shl_base_atomicrmw_global_atomic_csub_ptr:
+; GCN-DAG: v_lshlrev_b64 v{{\[}}[[LO:[0-9]+]]:[[HI:[0-9]+]]{{\]}}, 2, v[4:5]
+; GCN-DAG: v_mov_b32_e32 [[K:v[0-9]+]], 43
+; GCN: v_add_co_u32_e64 v[[EXTRA_LO:[0-9]+]], vcc_lo, 0x80, v4
+; GCN: v_add_co_ci_u32_e32 v[[EXTRA_HI:[0-9]+]], vcc_lo, 0, v5, vcc_lo
+; GCN: global_atomic_csub v{{[0-9]+}}, v{{\[}}[[LO]]:[[HI]]{{\]}}, [[K]], off offset:512 glc
+; GCN: global_store_dwordx2 v{{\[[0-9]+:[0-9]+\]}}, v{{\[}}[[EXTRA_LO]]:[[EXTRA_HI]]{{\]}}
+define i32 @shl_base_atomicrmw_global_atomic_csub_ptr(i32 addrspace(1)* %out, i64 addrspace(1)* %extra.use, [512 x i32] addrspace(1)* %ptr) #0 {
+  %arrayidx0 = getelementptr inbounds [512 x i32], [512 x i32] addrspace(1)* %ptr, i64 0, i64 32
+  %cast = ptrtoint i32 addrspace(1)* %arrayidx0 to i64
+  %shl = shl i64 %cast, 2
+  %castback = inttoptr i64 %shl to i32 addrspace(1)*
+  %val = call i32 @llvm.amdgcn.global.atomic.csub.p1i32(i32 addrspace(1)* %castback, i32 43)
+  store volatile i64 %cast, i64 addrspace(1)* %extra.use, align 4
+  ret i32 %val
+}
+
+declare i32 @llvm.amdgcn.global.atomic.csub.p1i32(i32 addrspace(1)* nocapture, i32) #0
+
+attributes #0 = { argmemonly nounwind }
Index: llvm/test/CodeGen/AMDGPU/shl_add_ptr_global.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/shl_add_ptr_global.ll
+++ llvm/test/CodeGen/AMDGPU/shl_add_ptr_global.ll
@@ -1,13 +1,13 @@
-; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefixes=GCN,GFX9 %s
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefixes=GCN,GFX9 %s
 
-; GCN-LABEL: {{^}}shl_base_global_ptr:
+; GCN-LABEL: {{^}}shl_base_atomicrmw_global_ptr:
 ; GCN: v_add_co_u32_e32 v[[EXTRA_LO:[0-9]+]], vcc, 0x80, v4
 ; GCN: v_addc_co_u32_e32 v[[EXTRA_HI:[0-9]+]], vcc, 0, v5, vcc
 ; GCN: v_lshlrev_b64 v{{\[}}[[LO:[0-9]+]]:[[HI:[0-9]+]]{{\]}}, 2, v[4:5]
 ; GCN: v_mov_b32_e32 [[THREE:v[0-9]+]], 3
 ; GCN: global_atomic_and v{{\[}}[[LO]]:[[HI]]{{\]}}, [[THREE]], off offset:512
 ; GCN: global_store_dwordx2 v{{\[[0-9]+:[0-9]+\]}}, v{{\[}}[[EXTRA_LO]]:[[EXTRA_HI]]{{\]}}
-define void @shl_base_global_ptr(i32 addrspace(1)* %out, i64 addrspace(1)* %extra.use, [512 x i32] addrspace(1)* %ptr) #0 {
+define void @shl_base_atomicrmw_global_ptr(i32 addrspace(1)* %out, i64 addrspace(1)* %extra.use, [512 x i32] addrspace(1)* %ptr) #0 {
   %arrayidx0 = getelementptr inbounds [512 x i32], [512 x i32] addrspace(1)* %ptr, i64 0, i64 32
   %cast = ptrtoint i32 addrspace(1)* %arrayidx0 to i64
   %shl = shl i64 %cast, 2
@@ -17,5 +17,24 @@
   ret void
 }
 
+; GCN-LABEL: {{^}}shl_base_global_ptr_global_atomic_fadd:
+; GCN: v_add_co_u32_e32 v[[EXTRA_LO:[0-9]+]], vcc, 0x80, v4
+; GCN: v_addc_co_u32_e32 v[[EXTRA_HI:[0-9]+]], vcc, 0, v5, vcc
+; GCN: v_lshlrev_b64 v{{\[}}[[LO:[0-9]+]]:[[HI:[0-9]+]]{{\]}}, 2, v[4:5]
+; GCN: v_mov_b32_e32 [[K:v[0-9]+]], 0x42c80000
+; GCN: global_atomic_add_f32 v{{\[}}[[LO]]:[[HI]]{{\]}}, [[K]], off offset:512
+; GCN: global_store_dwordx2 v{{\[[0-9]+:[0-9]+\]}}, v{{\[}}[[EXTRA_LO]]:[[EXTRA_HI]]{{\]}}
+define void @shl_base_global_ptr_global_atomic_fadd(i32 addrspace(1)* %out, i64 addrspace(1)* %extra.use, [512 x i32] addrspace(1)* %ptr) #0 {
+  %arrayidx0 = getelementptr inbounds [512 x i32], [512 x i32] addrspace(1)* %ptr, i64 0, i64 32
+  %cast = ptrtoint i32 addrspace(1)* %arrayidx0 to i64
+  %shl = shl i64 %cast, 2
+  %castback = inttoptr i64 %shl to float addrspace(1)*
+  call void @llvm.amdgcn.global.atomic.fadd.p1f32.f32(float addrspace(1)* %castback, float 100.0)
+  store volatile i64 %cast, i64 addrspace(1)* %extra.use, align 4
+  ret void
+}
+
+declare void @llvm.amdgcn.global.atomic.fadd.p1f32.f32(float addrspace(1)* nocapture, float) #1
+
 attributes #0 = { nounwind }
-attributes #1 = { nounwind readnone }
+attributes #1 = { argmemonly nounwind willreturn }