diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp index 7192efe3f16b9..f68cbf62b9825 100644 --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -1028,7 +1028,13 @@ CanRedirectPredsOfEmptyBBToSucc(BasicBlock *BB, BasicBlock *Succ, if (!BB->hasNPredecessorsOrMore(2)) return false; - // Get single common predecessors of both BB and Succ + if (any_of(BBPreds, [](const BasicBlock *Pred) { + return isa(Pred->getTerminator()); + })) + return false; + + // Get the single common predecessor of both BB and Succ. Return false + // when there are more than one common predecessors. for (BasicBlock *SuccPred : SuccPreds) { if (BBPreds.count(SuccPred)) { if (CommonPred) @@ -1133,7 +1139,7 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB, bool BBKillable = CanPropagatePredecessorsForPHIs(BB, Succ, BBPreds); - // Even if we can not fold bB into Succ, we may be able to redirect the + // Even if we can not fold BB into Succ, we may be able to redirect the // predecessors of BB to Succ. bool BBPhisMergeable = BBKillable || diff --git a/llvm/test/Transforms/SimplifyCFG/switch-branch-fold-indirectbr-102351.ll b/llvm/test/Transforms/SimplifyCFG/switch-branch-fold-indirectbr-102351.ll new file mode 100644 index 0000000000000..d3713be8358db --- /dev/null +++ b/llvm/test/Transforms/SimplifyCFG/switch-branch-fold-indirectbr-102351.ll @@ -0,0 +1,81 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --prefix-filecheck-ir-name pref --version 5 +; RUN: opt < %s -passes=simplifycfg -S | FileCheck %s + +define i32 @foo.1(i32 %arg, ptr %arg1) { +; CHECK-LABEL: define i32 @foo.1( +; CHECK-SAME: i32 [[ARG:%.*]], ptr [[ARG1:%.*]]) { +; CHECK-NEXT: [[BB:.*]]: +; CHECK-NEXT: [[ALLOCA:%.*]] = alloca [2 x ptr], align 16 +; CHECK-NEXT: store ptr blockaddress(@foo.1, %[[BB8:.*]]), ptr [[ALLOCA]], align 16 +; CHECK-NEXT: [[GETELEMENTPTR:%.*]] = getelementptr inbounds [2 x ptr], ptr [[ALLOCA]], i64 0, i64 1 +; CHECK-NEXT: store ptr blockaddress(@foo.1, %[[BB16:.*]]), ptr [[GETELEMENTPTR]], align 8 +; CHECK-NEXT: br label %[[PREFBB2:.*]] +; CHECK: [[PREFBB2]]: +; CHECK-NEXT: [[PHI:%.*]] = phi i32 [ 0, %[[BB]] ], [ [[PHI14:%.*]], %[[BB13:.*]] ] +; CHECK-NEXT: [[PHI3:%.*]] = phi i32 [ 0, %[[BB]] ], [ [[PHI15:%.*]], %[[BB13]] ] +; CHECK-NEXT: switch i32 [[PHI]], label %[[BB13]] [ +; CHECK-NEXT: i32 0, label %[[PREFBB18:.*]] +; CHECK-NEXT: i32 1, label %[[BB8]] +; CHECK-NEXT: i32 2, label %[[PREFBB11:.*]] +; CHECK-NEXT: ] +; CHECK: [[BB8]]: +; CHECK-NEXT: [[PHI10:%.*]] = phi i32 [ [[ARG]], %[[PREFBB18]] ], [ [[PHI3]], %[[PREFBB2]] ] +; CHECK-NEXT: br label %[[BB13]] +; CHECK: [[PREFBB11]]: +; CHECK-NEXT: [[CALL:%.*]] = call i32 @wombat(i32 noundef [[PHI3]]) +; CHECK-NEXT: [[ADD:%.*]] = add nsw i32 [[PHI3]], 1 +; CHECK-NEXT: br label %[[PREFBB18]] +; CHECK: [[BB13]]: +; CHECK-NEXT: [[PHI14]] = phi i32 [ [[PHI]], %[[PREFBB2]] ], [ 2, %[[BB8]] ] +; CHECK-NEXT: [[PHI15]] = phi i32 [ [[PHI3]], %[[PREFBB2]] ], [ [[PHI10]], %[[BB8]] ] +; CHECK-NEXT: br label %[[PREFBB2]] +; CHECK: [[BB16]]: +; CHECK-NEXT: [[CALL17:%.*]] = call i32 @wombat(i32 noundef [[ARG]]) +; CHECK-NEXT: ret i32 0 +; CHECK: [[PREFBB18]]: +; CHECK-NEXT: [[LOAD:%.*]] = load ptr, ptr [[ARG1]], align 8 +; CHECK-NEXT: indirectbr ptr [[LOAD]], [label %[[BB8]], label %bb16] +; +bb: + %alloca = alloca [2 x ptr], align 16 + store ptr blockaddress(@foo.1, %bb8), ptr %alloca, align 16 + %getelementptr = getelementptr inbounds [2 x ptr], ptr %alloca, i64 0, i64 1 + store ptr blockaddress(@foo.1, %bb16), ptr %getelementptr, align 8 + br label %bb2 + +bb2: ; preds = %bb13, %bb + %phi = phi i32 [ 0, %bb ], [ %phi14, %bb13 ] + %phi3 = phi i32 [ 0, %bb ], [ %phi15, %bb13 ] + switch i32 %phi, label %bb13 [ + i32 0, label %bb5 + i32 1, label %bb8 + i32 2, label %bb11 + ] + +bb5: ; preds = %bb2 + br label %bb18 + +bb8: ; preds = %bb18, %bb2 + %phi10 = phi i32 [ %arg, %bb18 ], [ %phi3, %bb2 ] + br label %bb13 + +bb11: ; preds = %bb2 + %call = call i32 @wombat(i32 noundef %phi3) + %add = add nsw i32 %phi3, 1 + br label %bb18 + +bb13: ; preds = %bb8, %bb2 + %phi14 = phi i32 [ %phi, %bb2 ], [ 2, %bb8 ] + %phi15 = phi i32 [ %phi3, %bb2 ], [ %phi10, %bb8 ] + br label %bb2 + +bb16: ; preds = %bb18 + %call17 = call i32 @wombat(i32 noundef %arg) + ret i32 0 + +bb18: ; preds = %bb11, %bb5 + %load = load ptr, ptr %arg1, align 8 + indirectbr ptr %load, [label %bb8, label %bb16] +} + +declare i32 @wombat(i32)