[AMDGPU][LowerModuleLDS] Avoid crash on zero-sized types

Author: Pierre-vh

llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp

@@ -1398,6 +1398,10 @@ class AMDGPULowerModuleLDS {
           LDSVarsToTransform.begin(), LDSVarsToTransform.end()));
 
       for (GlobalVariable *GV : Sorted) {
+        if (DL.getTypeAllocSize(GV->getValueType()) == 0)
+          report_fatal_error("cannot lower LDS '" + GV->getName() +
+                             "' because it has a zero-sized type");
+
         OptimizedStructLayoutField F(GV,
                                      DL.getTypeAllocSize(GV->getValueType()),
                                      AMDGPU::getAlign(DL, GV));

llvm/test/CodeGen/AMDGPU/lower-module-lds-zero-size-type.ll

@@ -0,0 +1,10 @@
+; RUN: not --crash opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds --amdgpu-lower-module-lds-strategy=module < %s 2>&1 | FileCheck %s
+; RUN: not --crash opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-module-lds --amdgpu-lower-module-lds-strategy=module < %s 2>&1 | FileCheck %s
+
+; CHECK: LLVM ERROR: cannot lower LDS 'var0' because it has a zero-sized type
+@var0 = internal addrspace(3) global [0 x float] poison, align 4
+
+define amdgpu_kernel void @kernel() {
+  load float, ptr addrspace(3) @var0
+  ret void
+}