[MLIR] Harden gpu.func verification

[csigg]

Summary

GPUFuncOpLowering moves the body out of gpu.func op and erases it. An empty gpu.func may fail verification but should not crash it. Verification of an erased op is triggered e.g. with debug printing on.

[csigg]

Format.

mlir/lib/Dialect/GPU/IR/GPUDialect.cpp

if (type.getMemorySpaceAsInt() != memorySpace) {
              << "expected memory space " << memorySpace << " in attribution";
     }
   }
   return success();
 }
 
 /// Verifies the body of the function.
 LogicalResult GPUFuncOp::verifyBody() {
+  if (empty())
+    return emitOpError() << "expected body with at least one block";
   unsigned numFuncArguments = getNumArguments();
   unsigned numWorkgroupAttributions = getNumWorkgroupAttributions();
   unsigned numBlockArguments = front().getNumArguments();
   if (numBlockArguments < numFuncArguments + numWorkgroupAttributions)
     return emitOpError() << "expected at least "
                          << numFuncArguments + numWorkgroupAttributions
                          << " arguments to body region";
 

mlir/test/Dialect/GPU/invalid.mlir

gpu.module @gpu_funcs {
     ^bb0(%arg0: f32, %arg1: memref<?xf32>, %arg2: memref<5xf32, 3>, %arg3: memref<5xf32, 5>):
       "gpu.return"() : () -> ()
     } ) {function_type = (f32, memref<?xf32>) -> (), gpu.kernel, sym_name = "kernel_1", workgroup_attributions = 3: i64} : () -> ()
   }
 }
 
 // -----
 
+module {
+  gpu.module @gpu_funcs {
+    // expected-error @+1 {{expected body with at least one block}}
+    "gpu.func"() ({}) {function_type = () -> (), gpu.kernel, sym_name = "kernel"} : () -> ()
+  }
+}
+
+// -----
+
 func.func @sync_wait_with_result() {
   // expected-error @+1 {{cannot name an operation with no results}}
   %t = gpu.wait
 }
 
 // -----
 
 func.func @async_wait_without_result() {