[Mlir-commits] [mlir] [RFC][mlir][func] Enforce func.return as sole terminator in func.func regions (PR #184778)

[Jakub Kuderski]

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@@ -42,6 +42,24 @@ class ReturnOpPattern final : public OpConversionPattern<func::ReturnOp> {
     if (returnOp.getNumOperands() > 1)
       return failure();
 
+    // Only convert func.return when the enclosing func.func is being converted
+    // to spirv.func. Check that all argument and result types of the parent
+    // function are convertible; if not, leave this op unconverted so the
+    // func.func stays in the Func dialect with a valid func.return terminator.
+    if (auto funcOp = returnOp->getParentOfType<func::FuncOp>()) {
+      FunctionType fnType = funcOp.getFunctionType();
+      if (fnType.getNumResults() > 1)
+        return failure();
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kuhar wrote:

I think it would be cleared to bail out one more than 2 args here but do a for loop below, so that it's clear we are handling zero or more return values.

RE signature conversion, I'm also unsure if this is required here -- is it because spirv.func won't convert if the type converter fails alter on, and you always want the return op to be in sync with the function op?

https://github.com/llvm/llvm-project/pull/184778