llvm-mirror/test/Transforms/LoopRotate/pr33701.ll
Jakub Kuderski 892202cb99 [LoopRotate] Fix DomTree update logic for unreachable nodes. Fix PR33701.
Summary:
LoopRotate manually updates the DoomTree by iterating over all predecessors of a basic block and computing the Nearest Common Dominator.

When a predecessor happens to be unreachable, `DT.findNearestCommonDominator` returns nullptr.

This patch teaches LoopRotate to handle this case and fixes [[ https://bugs.llvm.org/show_bug.cgi?id=33701 | PR33701 ]].

In the future, LoopRotate should be taught to use the new incremental API for updating the DomTree.

Reviewers: dberlin, davide, uabelho, grosser

Subscribers: efriedma, mzolotukhin

Differential Revision: https://reviews.llvm.org/D35074

llvm-svn: 307828
2017-07-12 18:42:16 +00:00

28 lines
770 B
LLVM

; RUN: opt < %s -loop-rotate -verify-dom-info -verify-loop-info -disable-output
define void @func() {
bb0:
br label %bb1
bb1: ; preds = %bb4, %bb0
%0 = phi i16 [ %2, %bb4 ], [ 0, %bb0 ]
%1 = icmp sle i16 %0, 2
br i1 %1, label %bb2, label %bb5
bb2: ; preds = %bb1
br i1 undef, label %bb6, label %bb4
bb3: ; No predecessors!
br label %bb6
bb4: ; preds = %bb2
%2 = add i16 undef, 1
br label %bb1
bb5: ; preds = %bb1
br label %bb6
bb6: ; preds = %bb5, %bb3, %bb2
unreachable
}