diff --git a/llvm/lib/Transforms/Scalar/LoopFuse.cpp b/llvm/lib/Transforms/Scalar/LoopFuse.cpp index 19eccb9e17020..9ffa602416b05 100644 --- a/llvm/lib/Transforms/Scalar/LoopFuse.cpp +++ b/llvm/lib/Transforms/Scalar/LoopFuse.cpp @@ -1796,14 +1796,16 @@ struct LoopFuser { // mergeLatch may remove the only block in FC1. SE.forgetLoop(FC1.L); SE.forgetLoop(FC0.L); - // Forget block dispositions as well, so that there are no dangling - // pointers to erased/free'ed blocks. - SE.forgetBlockAndLoopDispositions(); // Move instructions from FC0.Latch to FC1.Latch. // Note: mergeLatch requires an updated DT. mergeLatch(FC0, FC1); + // Forget block dispositions as well, so that there are no dangling + // pointers to erased/free'ed blocks. It should be done after mergeLatch() + // since merging the latches may affect the dispositions. + SE.forgetBlockAndLoopDispositions(); + // Merge the loops. SmallVector Blocks(FC1.L->blocks()); for (BasicBlock *BB : Blocks) { @@ -2092,14 +2094,16 @@ struct LoopFuser { // mergeLatch may remove the only block in FC1. SE.forgetLoop(FC1.L); SE.forgetLoop(FC0.L); - // Forget block dispositions as well, so that there are no dangling - // pointers to erased/free'ed blocks. - SE.forgetBlockAndLoopDispositions(); // Move instructions from FC0.Latch to FC1.Latch. // Note: mergeLatch requires an updated DT. mergeLatch(FC0, FC1); + // Forget block dispositions as well, so that there are no dangling + // pointers to erased/free'ed blocks. It should be done after mergeLatch() + // since merging the latches may affect the dispositions. + SE.forgetBlockAndLoopDispositions(); + // Merge the loops. SmallVector Blocks(FC1.L->blocks()); for (BasicBlock *BB : Blocks) { diff --git a/llvm/test/Transforms/LoopFusion/pr164082.ll b/llvm/test/Transforms/LoopFusion/pr164082.ll new file mode 100644 index 0000000000000..652557cef48f8 --- /dev/null +++ b/llvm/test/Transforms/LoopFusion/pr164082.ll @@ -0,0 +1,65 @@ +; REQUIRES: asserts +; RUN: opt -passes=loop-fusion -disable-output -stats < %s 2>&1 | FileCheck -check-prefix=STAT %s +; STAT: 1 loop-fusion - Loops fused + +; C Code +; +;; for (int i = 0; i < 100; ++i) +;; Array[i][i] = -i; +;; for (int row = 0; row < 100; ++row) +;; for (int col = 0; col < 100; ++col) +;; if (col != row) +;; Array[row][col] = row + col; +; +; Loop fusion should not crash anymore as now forgetBlockAndLoopDispositions() +; is trigerred after mergeLatch() during the fusion. + +define i32 @forget_dispositions() nounwind { +entry: + %Array = alloca [100 x [100 x i32]], align 4 + br label %for.body + +for.body: ; preds = %for.body, %entry + %indvars.iv33 = phi i64 [ 0, %entry ], [ %indvars.iv.next34, %for.body ] + %0 = trunc i64 %indvars.iv33 to i32 + %sub = sub i32 0, %0 + %arrayidx2 = getelementptr inbounds [100 x [100 x i32]], ptr %Array, i64 0, i64 %indvars.iv33, i64 %indvars.iv33 + store i32 %sub, ptr %arrayidx2, align 4 + %indvars.iv.next34 = add i64 %indvars.iv33, 1 + %lftr.wideiv35 = trunc i64 %indvars.iv.next34 to i32 + %exitcond36 = icmp eq i32 %lftr.wideiv35, 100 + br i1 %exitcond36, label %for.cond6.preheader, label %for.body + +for.cond6.preheader: ; preds = %for.body, %for.inc17 + %indvars.iv29 = phi i64 [ %indvars.iv.next30, %for.inc17 ], [ 0, %for.body ] + br label %for.body8 + +for.body8: ; preds = %for.inc14, %for.cond6.preheader + %indvars.iv = phi i64 [ 0, %for.cond6.preheader ], [ %indvars.iv.next, %for.inc14 ] + %1 = trunc i64 %indvars.iv to i32 + %2 = trunc i64 %indvars.iv29 to i32 + %cmp9 = icmp eq i32 %1, %2 + br i1 %cmp9, label %for.inc14, label %if.then + +if.then: ; preds = %for.body8 + %3 = add i64 %indvars.iv, %indvars.iv29 + %arrayidx13 = getelementptr inbounds [100 x [100 x i32]], ptr %Array, i64 0, i64 %indvars.iv29, i64 %indvars.iv + %4 = trunc i64 %3 to i32 + store i32 %4, ptr %arrayidx13, align 4 + br label %for.inc14 + +for.inc14: ; preds = %for.body8, %if.then + %indvars.iv.next = add i64 %indvars.iv, 1 + %lftr.wideiv27 = trunc i64 %indvars.iv.next to i32 + %exitcond28 = icmp eq i32 %lftr.wideiv27, 100 + br i1 %exitcond28, label %for.inc17, label %for.body8 + +for.inc17: ; preds = %for.inc14 + %indvars.iv.next30 = add i64 %indvars.iv29, 1 + %lftr.wideiv31 = trunc i64 %indvars.iv.next30 to i32 + %exitcond32 = icmp eq i32 %lftr.wideiv31, 100 + br i1 %exitcond32, label %for.exit, label %for.cond6.preheader + +for.exit: ; preds = %for.inc17 + ret i32 0 +}