AMDGPU: Error on LDS global address in functions

[arsenm]

Summary

These won't work as expected now, so error on them to avoid
wasting time debugging this in the future.

Not sure what the best terminology to use in the error message is

[kzhuravl]

LGTM

[t-tye]

lib/Target/AMDGPU/AMDGPUISelLowering.cpp

1279

Should this also give an error for any non-global address space? I think the same issue exists if global private or region address space happens. In that case therror message would be "global variables in non global address space not supported in non-kernel functions".

[arsenm]

lib/Target/AMDGPU/AMDGPUISelLowering.cpp

1279

This works fine for constant

[t-tye]

lib/Target/AMDGPU/AMDGPUISelLowering.cpp

1279

But probably not for private (scratch) or region (GDS).

[arsenm]

r334269

lib/Target/AMDGPU/AMDGPUISelLowering.cpp

 SDValue AMDGPUTargetLowering::LowerGlobalAddress(AMDGPUMachineFunction* MFI,
                                                  SDValue Op,
                                                  SelectionDAG &DAG) const {
 
   const DataLayout &DL = DAG.getDataLayout();
   GlobalAddressSDNode *G = cast<GlobalAddressSDNode>(Op);
   const GlobalValue *GV = G->getGlobal();
 
-  if  (G->getAddressSpace() == AMDGPUASI.LOCAL_ADDRESS) {
+  if (G->getAddressSpace() == AMDGPUASI.LOCAL_ADDRESS) {
+    if (!MFI->isEntryFunction()) {
+      const Function &Fn = DAG.getMachineFunction().getFunction();
+      DiagnosticInfoUnsupported BadLDSDecl(
+        Fn, "local memory global used by non-kernel function", SDLoc(Op).getDebugLoc());
+      DAG.getContext()->diagnose(BadLDSDecl);
+    }
+
     // XXX: What does the value of G->getOffset() mean?
     assert(G->getOffset() == 0 &&
          "Do not know what to do with an non-zero offset");
 
     // TODO: We could emit code to handle the initialization somewhere.
     if (!hasDefinedInitializer(GV)) {
       unsigned Offset = MFI->allocateLDSGlobal(DL, *GV);
       return DAG.getConstant(Offset, SDLoc(Op), Op.getValueType());

test/CodeGen/AMDGPU/lds-global-non-entry-func.ll

+; RUN: not llc -mtriple=amdgcn-amd-amdhsa -o /dev/null %s 2>&1 | FileCheck %s
+
+@lds = internal addrspace(3) global float undef, align 4
+
+; CHECK: error: <unknown>:0:0: in function func_use_lds_global void (): local memory global used by non-kernel function
+define void @func_use_lds_global() {
+  store float 0.0, float addrspace(3)* @lds, align 4
+  ret void
+}