[CIR][FlattenCFG] Exceptions: move cir.eh.selector up to dominate more uses

Author: bcardosolopes

clang/lib/CIR/Dialect/Transforms/FlattenCFG.cpp

@@ -234,6 +234,7 @@ class CIRTryOpFlattening : public mlir::OpRewritePattern<mlir::cir::TryOp> {
     rewriter.setInsertionPointToEnd(catchBegin);
     auto exception = rewriter.create<mlir::cir::EhInflightOp>(
         loc, mlir::cir::ExceptionInfoType::get(rewriter.getContext()));
+    auto selector = rewriter.create<mlir::cir::EhSelectorOp>(loc, exception);
 
     // TODO: direct catch all needs no dispatch?
 
@@ -247,7 +248,6 @@ class CIRTryOpFlattening : public mlir::OpRewritePattern<mlir::cir::TryOp> {
 
     // Fill in dispatcher.
     rewriter.setInsertionPointToEnd(dispatchBlock);
-    auto selector = rewriter.create<mlir::cir::EhSelectorOp>(loc, exception);
 
     // FIXME: we should have an extra block for the dispatcher, just in case
     // there isn't one later.

clang/test/CIR/Lowering/try-catch.cpp

@@ -26,9 +26,9 @@ unsigned long long tc() {
 
     // CIR_FLAT: ^[[LPAD]]:  // pred: ^bb2
     // CIR_FLAT:   %[[EH:.*]] = cir.eh.inflight_exception
+    // CIR_FLAT:   %[[SEL:.*]] = cir.eh.selector %[[EH]]
     // CIR_FLAT:   cir.br ^[[BB_INT_IDX_SEL:.*]] loc
     // CIR_FLAT: ^[[BB_INT_IDX_SEL]]:  // pred: ^[[LPAD]]
-    // CIR_FLAT:   %[[SEL:.*]] = cir.eh.selector %[[EH]]
   } catch (int idx) {
     // CIR_FLAT:   %[[INT_IDX_ID:.*]] = cir.eh.typeid @_ZTIi
     // CIR_FLAT:   %[[MATCH_CASE_INT_IDX:.*]] = cir.cmp(eq, %[[SEL]], %[[INT_IDX_ID]]) : !u32i, !cir.bool