[Mlir-commits] [mlir] [mlir][tosa] Fix check for isolated regions in `tosa.cond_if` (PR #143772)

[Jack Frankland]

================
@@ -1193,32 +1193,55 @@ bool checkErrorIfPad(Operation *op) {
   return true;
 }
 
-// Returns true if the operation takes no input operands, excluding attributes.
-static bool isNullaryOperation(Operation *op) {
-  if (isa<tosa::ConstOp>(op) || isa<tosa::ConstShapeOp>(op) ||
-      isa<tosa::YieldOp>(op) || isa<tosa::VariableOp>(op))
-    return true;
-  return false;
+static bool isOpIsolatedFromAbove(Operation *op, Region *region) {
+  return llvm::all_of(op->getOperands(), [&](auto operand) {
+    Region *operandRegion = operand.getParentRegion();
+    return region->isAncestor(operandRegion);
+  });
 }
 
 bool checkErrorIfCondIf(Operation *op) {
   auto ifOp = dyn_cast<tosa::IfOp>(op);
   if (!ifOp)
     return true;
 
-  // Whether the types and shapes of operands between the input/output list and
-  // internal regions are validated by the operation verifier. However, with
-  // support for the simplified form - where redundant operand notations are
-  // omitted - is not conformant to the specification. According to the
-  // specification, all operands passed into an operation must be explicitly
-  // declared at each operation's structure. This code section verify that the
-  // operation's form complies with this requirement.
+  // Currently the dialect supports declaring cond_if operations that
+  // have then/else regions that reference values from outside these
+  // regions. According to the specification, all values used by the
+  // then/else regions must be explicitly declared within the regions.
+  // Therefore we must check that the then/else regions are
+  // "isolated from above", in order to be conformant to the
+  // specification.
+  //
+  // Note: the dialect currently supports two styles of syntax for
+  // declaring "cond_if" operations. We'll refer to these as follows:
+  //
+  // Generic:
+  // %0 = "tosa.cond_if"(%arg0, %arg1, %arg2) ({
+  //   ^bb0(%arg3, %arg4):
----------------
FranklandJack wrote:

Both blocks here use the label `bb0`, is that expected? This is also the case for the lit tests below.

https://github.com/llvm/llvm-project/pull/143772