[Mlir-commits] [mlir] [mlir][gpu][spirv] Remove rotation semantics of gpu.shuffle up/down (PR #139105)

[Jakub Kuderski]

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@@ -1332,7 +1332,8 @@ def GPU_ShuffleOp : GPU_Op<
     %3, %4 = gpu.shuffle down %0, %cst1, %width : f32
     ```
 
-    For lane `k`, returns the value from lane `(k + 1) % width`.
+    For lane `k`, returns the value from lane `(k + cst1)`. The resulting value
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kuhar wrote:

Could we say that the oob values are poison? We want to avoid using handwavey terms like `unspecified`/`undefined` that don't have precise meaning. For example, what happens when you try to perform arithmetic or branch on them?

https://github.com/llvm/llvm-project/pull/139105