[AMDGPU][SDAG] Add test for ISD::PTRADD handling in SelectionDAGAddressAnalysis

Pre-committing test to show improvements in a follow-up PR.

Author: ritter-x2a

llvm/test/CodeGen/AMDGPU/ptradd-sdag-optimizations.ll

@@ -132,3 +132,32 @@ declare noalias ptr addrspace(4) @llvm.amdgcn.implicitarg.ptr()
 declare i64 @llvm.amdgcn.dispatch.id()
 declare noalias ptr addrspace(4) @llvm.amdgcn.dispatch.ptr()
 
+
+; Taken from memcpy-param-combinations.ll, tests PTRADD handling in
+; SelectionDAGAddressAnalysis.
+define void @memcpy_p1_p4_sz16_align_1_1(ptr addrspace(1) align 1 %dst, ptr addrspace(4) align 1 readonly %src) {
+; GFX942_PTRADD-LABEL: memcpy_p1_p4_sz16_align_1_1:
+; GFX942_PTRADD:       ; %bb.0: ; %entry
+; GFX942_PTRADD-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX942_PTRADD-NEXT:    global_load_dwordx2 v[4:5], v[2:3], off
+; GFX942_PTRADD-NEXT:    s_waitcnt vmcnt(0)
+; GFX942_PTRADD-NEXT:    global_store_dwordx2 v[0:1], v[4:5], off
+; GFX942_PTRADD-NEXT:    global_load_dwordx2 v[2:3], v[2:3], off offset:8
+; GFX942_PTRADD-NEXT:    s_waitcnt vmcnt(0)
+; GFX942_PTRADD-NEXT:    global_store_dwordx2 v[0:1], v[2:3], off offset:8
+; GFX942_PTRADD-NEXT:    s_waitcnt vmcnt(0)
+; GFX942_PTRADD-NEXT:    s_setpc_b64 s[30:31]
+;
+; GFX942_LEGACY-LABEL: memcpy_p1_p4_sz16_align_1_1:
+; GFX942_LEGACY:       ; %bb.0: ; %entry
+; GFX942_LEGACY-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX942_LEGACY-NEXT:    global_load_dwordx4 v[2:5], v[2:3], off
+; GFX942_LEGACY-NEXT:    s_waitcnt vmcnt(0)
+; GFX942_LEGACY-NEXT:    global_store_dwordx4 v[0:1], v[2:5], off
+; GFX942_LEGACY-NEXT:    s_waitcnt vmcnt(0)
+; GFX942_LEGACY-NEXT:    s_setpc_b64 s[30:31]
+entry:
+  tail call void @llvm.memcpy.p1.p4.i64(ptr addrspace(1) noundef nonnull align 1 %dst, ptr addrspace(4) noundef nonnull align 1 %src, i64 16, i1 false)
+  ret void
+}
+