[CIR][CIRGen][NFCI] Exceptions: change getEHDispatchBlock to create blocks inside calls

getEHDispatchBlock result isn't really used to track anything just yet, so this change
isn't supposed to affect anything. This is building block for having a cleanup per call.

Author: bcardosolopes

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -893,7 +893,7 @@ def ConditionOp : CIR_Op<"condition", [
 def YieldOp : CIR_Op<"yield", [ReturnLike, Terminator,
     ParentOneOf<["IfOp", "ScopeOp", "SwitchOp", "WhileOp", "ForOp", "AwaitOp",
                  "TernaryOp", "GlobalOp", "DoWhileOp", "TryOp", "ArrayCtor",
-                 "ArrayDtor"]>]> {
+                 "ArrayDtor", "CallOp"]>]> {
   let summary = "Represents the default branching behaviour of a region";
   let description = [{
     The `cir.yield` operation terminates regions on different CIR operations,

clang/lib/CIR/CodeGen/CIRGenCall.cpp

@@ -505,8 +505,10 @@ buildCallLikeOp(CIRGenFunction &CGF, mlir::Location callLoc,
     }
     callOpWithExceptions->setAttr("extra_attrs", extraFnAttrs);
 
+    CGF.callWithExceptionCtx = callOpWithExceptions;
     auto *invokeDest = CGF.getInvokeDest(tryOp);
     (void)invokeDest;
+    CGF.callWithExceptionCtx = nullptr;
 
     if (tryOp.getSynthetic()) {
       builder.create<mlir::cir::YieldOp>(tryOp.getLoc());

clang/lib/CIR/CodeGen/CIRGenException.cpp

@@ -742,7 +742,9 @@ mlir::Operation *CIRGenFunction::buildLandingPad(mlir::cir::TryOp tryOp) {
     // landing pad by generating a branch to the dispatch block. In CIR the same
     // function is called to gather some state, but this block info it's not
     // useful per-se.
-    (void)getEHDispatchBlock(EHStack.getInnermostEHScope(), tryOp);
+    mlir::Block *dispatch =
+        getEHDispatchBlock(EHStack.getInnermostEHScope(), tryOp);
+    (void)dispatch;
   }
 
   return tryOp;
@@ -789,9 +791,12 @@ CIRGenFunction::getEHDispatchBlock(EHScopeStack::stable_iterator si,
 
     case EHScope::Cleanup: {
       assert(tryOp && "expected cir.try available");
-      llvm::MutableArrayRef<mlir::Region> regions = tryOp.getCatchRegions();
-      assert(regions.size() == 1 && "expected only one region");
-      dispatchBlock = &regions[0].getBlocks().back();
+      assert(callWithExceptionCtx && "expected call information");
+      {
+        mlir::OpBuilder::InsertionGuard guard(getBuilder());
+        dispatchBlock = builder.createBlock(&callWithExceptionCtx.getCleanup());
+        builder.createYield(callWithExceptionCtx.getLoc());
+      }
       break;
     }
 

clang/lib/CIR/CodeGen/CIRGenFunction.h

@@ -1748,6 +1748,7 @@ class CIRGenFunction : public CIRGenTypeCache {
   };
 
   /// Emits try/catch information for the current EH stack.
+  mlir::cir::CallOp callWithExceptionCtx = nullptr;
   mlir::Operation *buildLandingPad(mlir::cir::TryOp tryOp);
   mlir::Block *getEHResumeBlock(bool isCleanup, mlir::cir::TryOp tryOp);
   mlir::Block *getEHDispatchBlock(EHScopeStack::stable_iterator scope,

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

@@ -111,6 +111,30 @@ struct RemoveTrivialTry : public OpRewritePattern<TryOp> {
   }
 };
 
+// Remove call exception with empty cleanups
+struct SimplifyCallOp : public OpRewritePattern<CallOp> {
+  using OpRewritePattern<CallOp>::OpRewritePattern;
+
+  LogicalResult match(CallOp op) const final {
+    // Applicable to cir.call exception ... clean { cir.yield }
+    mlir::Region *r = &op.getCleanup();
+    if (r->empty() || !r->hasOneBlock())
+      return failure();
+
+    mlir::Block *b = &r->getBlocks().back();
+    if (&b->back() != &b->front())
+      return failure();
+
+    return success(isa<YieldOp>(&b->getOperations().back()));
+  }
+
+  void rewrite(CallOp op, PatternRewriter &rewriter) const final {
+    mlir::Block *b = &op.getCleanup().back();
+    rewriter.eraseOp(&b->back());
+    rewriter.eraseBlock(b);
+  }
+};
+
 /// Simplify suitable ternary operations into select operations.
 ///
 /// For now we only simplify those ternary operations whose true and false
@@ -255,7 +279,8 @@ void populateMergeCleanupPatterns(RewritePatternSet &patterns) {
     RemoveEmptySwitch,
     RemoveTrivialTry,
     SimplifyTernary,
-    SimplifySelect
+    SimplifySelect,
+    SimplifyCallOp
   >(patterns.getContext());
   // clang-format on
 }
@@ -271,8 +296,8 @@ void CIRSimplifyPass::runOnOperation() {
     // CastOp here is to perform a manual `fold` in
     // applyOpPatternsAndFold
     if (isa<BrOp, BrCondOp, ScopeOp, SwitchOp, CastOp, TryOp, UnaryOp,
-            TernaryOp, SelectOp, ComplexCreateOp, ComplexRealOp, ComplexImagOp>(
-            op))
+            TernaryOp, SelectOp, ComplexCreateOp, ComplexRealOp, ComplexImagOp,
+            CallOp>(op))
       ops.push_back(op);
   });