https://github.com/xlauko updated https://github.com/llvm/llvm-project/pull/231449
>From 174be027152561ef72c4fd9ab257414202bbd63f Mon Sep 17 00:00:00 2001 From: Henrich Lauko <[email protected]> Date: Tue, 13 Oct 2026 10:40:32 +0000 Subject: [PATCH] [CIR] Fix cir.try successor regions `TryOp::getSuccessorRegions` sent every exit from the try region back to the parent, so nothing led from the try region to the handlers. A `cir.resume` ending the try region, left there once FlattenCFG has flattened an inner cleanup scope, unwinds into a handler, and `CIRTryOpFlattening` branches it to the handler dispatch block. Now every exit from the try region can enter the handlers, and a `cir.resume` leaves the op only when there are none. The parent keeps its edges to the handlers. An unwind out of a call in the try region is not a region branch point, so these edges stand in for it, and without them -remove-dead-values empties a handler that is reached only that way. Co-Authored-By: Claude Opus 5.5 <[email protected]> --- clang/lib/CIR/Dialect/IR/CIRDialect.cpp | 30 +++-- .../CIR/Transforms/remove-dead-values-try.cir | 40 ++++++ clang/unittests/CIR/ControlFlowTest.cpp | 115 +++++++++++++++++- 3 files changed, 173 insertions(+), 12 deletions(-) create mode 100644 clang/test/CIR/Transforms/remove-dead-values-try.cir diff --git a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp index 15f5ccaef130b7..1012827cdcc6e8 100644 --- a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp +++ b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp @@ -807,7 +807,7 @@ cir::ConditionOp::getMutableSuccessorOperands(RegionSuccessor point) { MutableOperandRange cir::ResumeOp::getMutableSuccessorOperands(RegionSuccessor point) { - // The eh_token operand is not forwarded to the parent region. + // The eh_token operand is not modeled as forwarded to any successor. return MutableOperandRange(getOperation(), 0, 0); } @@ -5147,18 +5147,30 @@ LogicalResult cir::TypeInfoAttr::verify( void cir::TryOp::getSuccessorRegions( mlir::RegionBranchPoint point, llvm::SmallVectorImpl<mlir::RegionSuccessor> ®ions) { - // The `try` and the `catchers` region branch back to the parent operation. - if (!point.isParent()) { - regions.emplace_back(getOperation()); - return; + if (point.isParent()) { + regions.emplace_back(&getTryRegion()); + } else { + // A handler exit leaves the operation. + mlir::Operation *term = point.getTerminatorPredecessorOrNull(); + if (term->getParentRegion() != &getTryRegion()) { + regions.emplace_back(getOperation()); + return; + } + // A cir.resume ending the try region unwinds into a handler, so it leaves + // the operation only when there is none. Every other exit can leave it. + if (!isa<cir::ResumeOp>(term) || getHandlerRegions().empty()) + regions.emplace_back(getOperation()); } - regions.push_back(mlir::RegionSuccessor(&getTryRegion())); - + // Most handlers are entered by an unwind out of a call in the try region, + // which is not a branch point, so the handlers are successors of the parent + // and of every exit from the try region to stand in for it. + // // TODO(CIR): If we know a target function never throws a specific type, we // can remove the catch handler. - for (mlir::Region &handlerRegion : this->getHandlerRegions()) - regions.push_back(mlir::RegionSuccessor(&handlerRegion)); + regions.reserve(regions.size() + getHandlerRegions().size()); + for (mlir::Region &handlerRegion : getHandlerRegions()) + regions.emplace_back(&handlerRegion); } /// Verify that each cir.init_catch_param in \p handlerRegion, outside any diff --git a/clang/test/CIR/Transforms/remove-dead-values-try.cir b/clang/test/CIR/Transforms/remove-dead-values-try.cir new file mode 100644 index 00000000000000..446f0355183b04 --- /dev/null +++ b/clang/test/CIR/Transforms/remove-dead-values-try.cir @@ -0,0 +1,40 @@ +// RUN: cir-opt %s -remove-dead-values -o - | FileCheck %s + +// The handler runs only when @may_throw throws, which is not a region branch +// point. The handler region must still count as reachable, or generic passes +// such as -remove-dead-values erase its contents. + +!s32i = !cir.int<s, 32> +!void = !cir.void + +module { + cir.func private @may_throw() + + cir.func @catch_all(%p : !cir.ptr<!s32i>) { + cir.scope { + cir.try { + cir.call @may_throw() : () -> () + cir.yield + } catch all (%eh : !cir.eh_token) { + %ct, %exn = cir.begin_catch %eh : !cir.eh_token -> (!cir.catch_token, !cir.ptr<!void>) + %c = cir.const #cir.int<7> : !s32i + cir.store %c, %p : !s32i, !cir.ptr<!s32i> + cir.end_catch %ct : !cir.catch_token + cir.yield + } + } + cir.return + } + + // CHECK-LABEL: cir.func @catch_all + // CHECK: cir.try { + // CHECK-NEXT: cir.call @may_throw() : () -> () + // CHECK-NEXT: cir.yield + // CHECK-NEXT: } catch all (%[[EH:.*]]: !cir.eh_token) { + // CHECK-NEXT: %[[CT:.*]], %{{.*}} = cir.begin_catch %[[EH]] + // CHECK-NEXT: %[[C:.*]] = cir.const #cir.int<7> : !s32i + // CHECK-NEXT: cir.store %[[C]], %{{.*}} : !s32i, !cir.ptr<!s32i> + // CHECK-NEXT: cir.end_catch %[[CT]] : !cir.catch_token + // CHECK-NEXT: cir.yield + // CHECK-NEXT: } +} diff --git a/clang/unittests/CIR/ControlFlowTest.cpp b/clang/unittests/CIR/ControlFlowTest.cpp index a83d1098a17cbc..92fa33b16708ac 100644 --- a/clang/unittests/CIR/ControlFlowTest.cpp +++ b/clang/unittests/CIR/ControlFlowTest.cpp @@ -733,15 +733,124 @@ TEST_F(CIRControlFlowTest, TryOpWithCatchAll) { MutableArrayRef<Region> handlerRegions = tryOp.getHandlerRegions(); ASSERT_EQ(handlerRegions.size(), 1u); + // A throw from the middle of the body is not a branch point, so the handler + // is a successor of both the parent and the body's cir.yield. expectSuccessors(tryOp, RegionBranchPoint::parent(), {&tryRegion, &handlerRegions[0]}); - expectTerminatorSuccessors(tryRegion, {nullptr}); + expectTerminatorSuccessors(tryRegion, {&handlerRegions[0], nullptr}); expectTerminatorSuccessors(handlerRegions[0], {nullptr}); EXPECT_FALSE(asRegionBranch(tryOp).hasLoop()); - // TODO: TryOp::getSuccessorInputs returns empty for handler regions that - // have block arguments, so verifyControlFlowInterfaceConsistency fails. + verifyControlFlowInterfaceConsistency(tryOp); +} + +TEST_F(CIRControlFlowTest, TryOpResumeInBody) { + // A cir.resume left behind in the body by an already-flattened inner + // cleanup scope unwinds into the handlers. + OwningOpRef<ModuleOp> module = parse(R"CIR( + !u8i = !cir.int<u, 8> + !void = !cir.void + cir.func @f() { + cir.scope { + cir.try { + %tok = cir.eh.initiate cleanup : !cir.eh_token + cir.resume %tok : !cir.eh_token + } catch [type #cir.global_view<@_ZTIi> : !cir.ptr<!u8i>] + (%eh : !cir.eh_token) { + %ct, %exn = cir.begin_catch %eh + : !cir.eh_token -> (!cir.catch_token, !cir.ptr<!void>) + cir.end_catch %ct : !cir.catch_token + cir.yield + } unwind (%eh : !cir.eh_token) { + cir.resume %eh : !cir.eh_token + } + } + cir.return + } + )CIR"); + auto tryOp = findFirstOp<cir::TryOp>(*module); + + Region &tryRegion = tryOp.getTryRegion(); + MutableArrayRef<Region> handlerRegions = tryOp.getHandlerRegions(); + ASSERT_EQ(handlerRegions.size(), 2u); + + expectSuccessors(tryOp, RegionBranchPoint::parent(), + {&tryRegion, &handlerRegions[0], &handlerRegions[1]}); + expectTerminatorSuccessors(tryRegion, + {&handlerRegions[0], &handlerRegions[1]}); + // A cir.resume in the unwind handler leaves the op like any handler exit. + expectTerminatorSuccessors(handlerRegions[0], {nullptr}); + expectTerminatorSuccessors(handlerRegions[1], {nullptr}); + + EXPECT_FALSE(asRegionBranch(tryOp).hasLoop()); + + verifyControlFlowInterfaceConsistency(tryOp); +} + +TEST_F(CIRControlFlowTest, TryOpMultiBlockBody) { + // One block leaves the try body normally and another unwinds. Only the + // normal exit can leave the op. + OwningOpRef<ModuleOp> module = parse(R"CIR( + !void = !cir.void + cir.func @f() { + cir.scope { + cir.try { + %cond = cir.const #cir.bool<true> : !cir.bool + cir.brcond %cond ^bb_normal, ^bb_unwind + ^bb_normal: + cir.yield + ^bb_unwind: + %tok = cir.eh.initiate cleanup : !cir.eh_token + cir.resume %tok : !cir.eh_token + } catch all (%eh : !cir.eh_token) { + %ct, %exn = cir.begin_catch %eh + : !cir.eh_token -> (!cir.catch_token, !cir.ptr<!void>) + cir.end_catch %ct : !cir.catch_token + cir.yield + } + } + cir.return + } + )CIR"); + auto tryOp = findFirstOp<cir::TryOp>(*module); + Region &tryRegion = tryOp.getTryRegion(); + Region &handler = tryOp.getHandlerRegions()[0]; + + SmallVector<RegionBranchTerminatorOpInterface> bodyTerms = + getExitTerminators(tryRegion); + ASSERT_EQ(bodyTerms.size(), 2u); + EXPECT_TRUE(isa<cir::YieldOp>(*bodyTerms[0])); + EXPECT_TRUE(isa<cir::ResumeOp>(*bodyTerms[1])); + + expectSuccessors(tryOp, RegionBranchPoint(bodyTerms[0]), {&handler, nullptr}); + expectSuccessors(tryOp, RegionBranchPoint(bodyTerms[1]), {&handler}); + expectTerminatorSuccessors(handler, {nullptr}); + + EXPECT_FALSE(asRegionBranch(tryOp).hasLoop()); + + verifyControlFlowInterfaceConsistency(tryOp); +} + +TEST_F(CIRControlFlowTest, TryOpResumeInBodyWithoutHandlers) { + OwningOpRef<ModuleOp> module = parse(R"CIR( + cir.func @f() { + cir.scope { + cir.try { + %tok = cir.eh.initiate cleanup : !cir.eh_token + cir.resume %tok : !cir.eh_token + } + } + cir.return + } + )CIR"); + auto tryOp = findFirstOp<cir::TryOp>(*module); + + // With no handler to unwind into, the cir.resume leaves the op. + expectSuccessors(tryOp, RegionBranchPoint::parent(), {&tryOp.getTryRegion()}); + expectTerminatorSuccessors(tryOp.getTryRegion(), {nullptr}); + + verifyControlFlowInterfaceConsistency(tryOp); } TEST_F(CIRControlFlowTest, CoroutineOp) { _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
