[clang] [CIR] Add canonicalizer for CleanupScopeOp (PR #191084)

[Andy Kaylor via cfe-commits]

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@@ -1449,6 +1449,41 @@ cir::CleanupScopeOp::getSuccessorInputs(RegionSuccessor successor) {
   return ValueRange();
 }
 
+LogicalResult cir::CleanupScopeOp::canonicalize(CleanupScopeOp op,
+                                                PatternRewriter &rewriter) {
+  auto isRegionTrivial = [](Region &region) {
+    if (!region.hasOneBlock())
+      return false;
+    Block &block = region.front();
+    return llvm::hasSingleElement(block) && isa<cir::YieldOp>(block.front());
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andykaylor wrote:

An added benefit of `getSingleElement` is that it asserts that there is one and only one element. I changed `region.front()` to use that too.

https://github.com/llvm/llvm-project/pull/191084