[Mlir-commits] [mlir] [mlir][x86] Support multiple result uses in AMX nanokernel (PR #236811)

[Adam Siemieniuk]

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@@ -45,10 +45,13 @@ static bool isZeroVectorConstant(Operation *op) {
 }
 
 // Recursively follows single-use values through scf.yield operations
-// and returns the first non-yield user result in the contraction chain.
-static Value contractionUsersAfterYield(Value v) {
-  if (v.getNumUses() != 1)
+// and returns the first value that has more than one user, or is not used by a
+// yield operation. Returns nullptr if the chain is ultimately unused.
+static Value contractionResultAfterYield(Value v) {
+  if (v.hasNUses(0))
     return nullptr;
+  if (v.hasNUsesOrMore(2))
+    return v;
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adam-smnk wrote:

I found this helper's behavior always a bit confusing.
Why return itself with multiple uses but null without uses? Does it help with current usage?
If you're simply retaining previous behavior that's fine too.

https://github.com/llvm/llvm-project/pull/236811