[Mlir-commits] [mlir] [mlir][XeGPU] Fix crash in getUArch for unsupported architectures (PR #179173)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir-gpu

Author: puneeth_aditya_5656 (mugiwaraluffy56)

<details>
<summary>Changes</summary>

## Summary
- Return nullptr from getUArch() instead of crashing with llvm_unreachable when the architecture name is not recognized
- Callers already check for nullptr and handle it gracefully (e.g., returning match failure)

Fixes #<!-- -->179167

## Test plan
- Added test case that runs xegpu subgroup distribute without a target attribute

---
Full diff: https://github.com/llvm/llvm-project/pull/179173.diff


2 Files Affected:

- (modified) mlir/include/mlir/Dialect/XeGPU/uArch/IntelGpuXe2.h (+1-4) 
- (added) mlir/test/Dialect/XeGPU/subgroup-distribute-no-target.mlir (+14) 


``````````diff
diff --git a/mlir/include/mlir/Dialect/XeGPU/uArch/IntelGpuXe2.h b/mlir/include/mlir/Dialect/XeGPU/uArch/IntelGpuXe2.h
index 29e75b57f4a5f..5a1fcb42b53ee 100644
--- a/mlir/include/mlir/Dialect/XeGPU/uArch/IntelGpuXe2.h
+++ b/mlir/include/mlir/Dialect/XeGPU/uArch/IntelGpuXe2.h
@@ -296,11 +296,8 @@ struct BMGuArch : public Xe2Plus {
 inline const uArch *getUArch(llvm::StringRef archName) {
   if (archName.equals_insensitive("pvc"))
     return PVCuArch::getInstance();
-  else if (archName.equals_insensitive("bmg"))
+  if (archName.equals_insensitive("bmg"))
     return BMGuArch::getInstance();
-  else
-    llvm_unreachable("No matching uArch found");
-
   return nullptr;
 }
 
diff --git a/mlir/test/Dialect/XeGPU/subgroup-distribute-no-target.mlir b/mlir/test/Dialect/XeGPU/subgroup-distribute-no-target.mlir
new file mode 100644
index 0000000000000..0df69a14d44f5
--- /dev/null
+++ b/mlir/test/Dialect/XeGPU/subgroup-distribute-no-target.mlir
@@ -0,0 +1,14 @@
+// RUN: mlir-opt -xegpu-subgroup-distribute -split-input-file %s 2>&1 | FileCheck %s
+
+// Test that the pass gracefully handles a GPU module without a target attribute
+// instead of crashing with "UNREACHABLE executed".
+
+// CHECK-LABEL: gpu.module @no_target_module
+// The function body should remain unchanged since no target is attached.
+// CHECK: gpu.func @simple_func
+// CHECK: gpu.return
+gpu.module @no_target_module {
+  gpu.func @simple_func(%arg0: memref<8x16xf16>) {
+    gpu.return
+  }
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/179173