Index: llvm/lib/Transforms/Scalar/IndVarSimplify.cpp =================================================================== --- llvm/lib/Transforms/Scalar/IndVarSimplify.cpp +++ llvm/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -1418,6 +1418,22 @@ auto *NewCond = ConstantInt::get(OldCond->getType(), IsTaken ? ExitIfTrue : !ExitIfTrue); ReplaceExitCond(BI, NewCond); + + // Some nested loops may share the same ExitingBB. So we need to + // forgetTopmostLoop to notify the OuterLoop that the + // ExitCount has been changed. + Loop *Parent = L->getParentLoop(); + bool HasSharedExit = false; + while (Parent && !HasSharedExit) { + SmallVector ParentExitingBlocks; + Parent->getExitingBlocks(ParentExitingBlocks); + if (std::any_of(ParentExitingBlocks.begin(), ParentExitingBlocks.end(), + [&](BasicBlock *BB) { return BB == ExitingBB; })) { + SE->forgetTopmostLoop(Parent); + HasSharedExit = true; + } + Parent = Parent->getParentLoop(); + } }; bool Changed = false; Index: llvm/test/Transforms/IndVarSimplify/shared-exit-between-nested-loop.ll =================================================================== --- /dev/null +++ llvm/test/Transforms/IndVarSimplify/shared-exit-between-nested-loop.ll @@ -0,0 +1,64 @@ +; RUN: opt -indvars -S < %s | FileCheck %s + +@__const.e.f = private unnamed_addr constant <{ <{ [2 x i32], [2 x i32], [8 x [2 x i32]] }>, [10 x [2 x i32]] }> <{ <{ [2 x i32], [2 x i32], [8 x [2 x i32]] }> <{ [2 x i32] [i32 4, i32 8], [2 x i32] [i32 3, i32 10], [8 x [2 x i32]] zeroinitializer }>, [10 x [2 x i32]] [[2 x i32] zeroinitializer, [2 x i32] zeroinitializer, [2 x i32] [i32 1, i32 5], [2 x i32] [i32 2080555007, i32 0], [2 x i32] zeroinitializer, [2 x i32] zeroinitializer, [2 x i32] zeroinitializer, [2 x i32] zeroinitializer, [2 x i32] zeroinitializer, [2 x i32] zeroinitializer] }>, align 4 + +define dso_local i8 @main() local_unnamed_addr { +entry: + br label %for.cond1.preheader + +for.cond1.preheader: ; preds = %for.inc15, %entry + %storemerge32 = phi i32 [ 0, %entry ], [ %inc16, %for.inc15 ] + br label %for.cond4 + +for.cond4: ; preds = %for.inc, %for.cond1.preheader + %storemerge2531 = phi i32 [ 0, %for.cond1.preheader ], [ %inc, %for.inc ] + %tobool = icmp eq i32 1, 0 + br i1 %tobool, label %cleanup, label %if.then + +if.then: ; preds = %for.cond4 +; CHECK: if.then: ; preds = %for.cond4 +; CHECK-NEXT: br i1 false, label %cleanup, label %for.inc + %add = add nuw nsw i32 %storemerge2531, 2 + %idxprom8 = zext i32 %add to i64 + %arrayidx10 = getelementptr inbounds <{ <{ [2 x i32], [2 x i32], [8 x [2 x i32]] }>, [10 x [2 x i32]] }>, <{ <{ [2 x i32], [2 x i32], [8 x [2 x i32]] }>, [10 x [2 x i32]] }>* @__const.e.f, i64 0, i32 1, i64 %idxprom8, i64 0 + %0 = load i32, i32* %arrayidx10, align 4 + %tobool11 = icmp eq i32 %0, 0 + br i1 %tobool11, label %cleanup, label %for.inc + +for.inc: ; preds = %if.then + %inc = add nuw nsw i32 %storemerge2531, 1 + %cmp2 = icmp ult i32 %inc, 2 + br i1 %cmp2, label %for.cond4, label %for.inc15 + +cleanup: ; preds = %if.then, %for.cond4 + br label %return + +for.inc15: ; preds = %for.inc +; CHECK: for.inc15: +; CHECK-NEXT: %inc16 = add nuw nsw i32 %storemerge32, 1 +; CHECK-NEXT: %cmp = icmp eq i32 %inc16, 4 +; CHECK-NEXT: br i1 %cmp, label %for.cond18thread-pre-split, label %for.cond1.preheader + %inc16 = add nuw nsw i32 %storemerge32, 1 + %cmp = icmp eq i32 %inc16, 4 + br i1 %cmp, label %for.cond18thread-pre-split, label %for.cond1.preheader + +for.cond18thread-pre-split: ; preds = %for.inc15 + br i1 1, label %return.loopexit, label %for.inc21.lr.ph + +for.inc21.lr.ph: ; preds = %for.cond18thread-pre-split + br label %for.inc21 + +for.inc21: ; preds = %for.inc21, %for.inc21.lr.ph + %1 = phi i32 [ undef, %for.inc21.lr.ph ], [ %inc22, %for.inc21 ] + %inc22 = add nsw i32 %1, 1 + br i1 true, label %for.cond18.return.loopexit_crit_edge, label %for.inc21 + +for.cond18.return.loopexit_crit_edge: ; preds = %for.inc21 + br label %return.loopexit + +return.loopexit: ; preds = %for.cond18.return.loopexit_crit_edge, %for.cond18thread-pre-split + br label %return + +return: ; preds = %return.loopexit, %cleanup + ret i8 undef +}