[llvm] [MLIR] Update convert-gpu-to-spirv pass to prepare using GPU compilat… (PR #69941)

[Sang Ik Lee via llvm-commits]

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@@ -108,6 +138,25 @@ void GPUToSPIRVPass::runOnOperation() {
     if (failed(applyFullConversion(gpuModule, *target, std::move(patterns))))
       return signalPassFailure();
   }
+
+  // For OpenCL, the gpu.func op in the original gpu.module op needs to be
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silee2 wrote:

Keeping the original gpu.func causes legality check error later in the gpu compile pipeline. 
If target attr is set for a gpu.module, gpu-to-llvm pass doesn't lower gpu.launch_func 
Instead, it is replaced with another gpu.launch_func that has lowered argument types (llvm ptrs).
If a gpu.func remains as an input to gpu-to-llvm pass, there is an argument mismatch between the new gpu.launch_func and the gpu.func. And a error is fired.
The reason for putting a dummy func.func here is to work around that check.
For func types other than gpu.func, argument types are not checked against gpu.launch_func.
But a func.func is still need as there will be a symbol check.


https://github.com/llvm/llvm-project/pull/69941