[Mlir-commits] [mlir] [mlir][gpu][spirv] Add patterns for gpu.shuffle up/down (PR #139105)

[Jakub Kuderski]

================
@@ -430,10 +430,12 @@ LogicalResult GPUShuffleConversion::matchAndRewrite(
   unsigned subgroupSize =
       targetEnv.getAttr().getResourceLimits().getSubgroupSize();
   IntegerAttr widthAttr;
+  // The width argument specifies the number of lanes that participate in the
+  // shuffle. The width value should not exceed the subgroup limit.
   if (!matchPattern(shuffleOp.getWidth(), m_Constant(&widthAttr)) ||
-      widthAttr.getValue().getZExtValue() != subgroupSize)
+      widthAttr.getValue().getZExtValue() > subgroupSize)
     return rewriter.notifyMatchFailure(
-        shuffleOp, "shuffle width and target subgroup size mismatch");
+        shuffleOp, "shuffle width is larger than target subgroup size");
----------------
kuhar wrote:

The comment above says:
```c++
  // Require the shuffle width to be the same as the target's subgroup size,
  // given that for SPIR-V non-uniform subgroup ops, we cannot select
  // participating invocations.
```

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