[llvm] r354547 - [LoopSimplifyCFG] Add missing MSSA edge deletion

[Max Kazantsev via llvm-commits]

Author: mkazantsev
Date: Wed Feb 20 21:51:29 2019
New Revision: 354547

URL: http://llvm.org/viewvc/llvm-project?rev=354547&view=rev
Log:
[LoopSimplifyCFG] Add missing MSSA edge deletion

When we create fictive switch in preheader, we should take
care about MSSA and delete edge between old preheader and
header.

Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
    llvm/trunk/test/Transforms/LoopSimplifyCFG/lcssa.ll

Modified: llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp?rev=354547&r1=354546&r2=354547&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp Wed Feb 20 21:51:29 2019
@@ -355,6 +355,8 @@ private:
     BasicBlock *NewPreheader = Preheader->splitBasicBlock(
         Preheader->getTerminator(),
         Twine(Preheader->getName()).concat("-split"));
+    if (MSSAU)
+      MSSAU->removeEdge(Preheader, L.getHeader());
     DTUpdates.push_back({DominatorTree::Delete, Preheader, L.getHeader()});
     DTUpdates.push_back({DominatorTree::Insert, NewPreheader, L.getHeader()});
     DTUpdates.push_back({DominatorTree::Insert, Preheader, NewPreheader});

Modified: llvm/trunk/test/Transforms/LoopSimplifyCFG/lcssa.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopSimplifyCFG/lcssa.ll?rev=354547&r1=354546&r2=354547&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopSimplifyCFG/lcssa.ll (original)
+++ llvm/trunk/test/Transforms/LoopSimplifyCFG/lcssa.ll Wed Feb 20 21:51:29 2019
@@ -154,3 +154,41 @@ bb8:
 bb10:                                             ; preds = %bb2
   ret void
 }
+
+define void @memlcssa() {
+; CHECK-LABEL: @memlcssa(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i32 0, label [[ENTRY_SPLIT:%.*]] [
+; CHECK-NEXT:    i32 1, label [[DEFAULT_BB:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       entry-split:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[FOR_BODY]]
+; CHECK:       default.bb:
+; CHECK-NEXT:    unreachable
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %exit, %entry
+  br label %switch.bb
+
+switch.bb:                                        ; preds = %for.body
+  switch i2 1, label %default.bb [
+  i2 1, label %case.bb
+  ]
+
+case.bb:                                          ; preds = %switch
+  br label %exit
+
+default.bb:                                       ; preds = %switch
+  unreachable
+
+exit:                                             ; preds = %case.bb
+  call void @foo()
+  br label %for.body
+}
+
+declare void @foo()