Fix SplitCriticalEdge to properly update LCSSA form when splitting a

loop exit edge -- new PHIs may be needed not only for the additional
splits that are made to preserve LoopSimplify form, but also for the
original split. Factor out the code that inserts new PHIs so that it
can be used for both. Remove LoopRotation.cpp's code for manually
updating LCSSA form, as it is now redundant. This fixes PR4934.

llvm-svn: 81363

1 files changed, 34 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopUnswitch/preserve-analyses.ll b/llvm/test/Transforms/LoopUnswitch/preserve-analyses.ll
index 1a0e9e6c879..8d3f1382f3c 100644
--- a/llvm/test/Transforms/LoopUnswitch/preserve-analyses.ll
+++ b/llvm/test/Transforms/LoopUnswitch/preserve-analyses.ll
@@ -93,3 +93,37 @@ bb6:                                              ; preds = %bb2
 return:                                             ; preds = %bb8, %bb
   ret void
 }
+
+; This function requires special handling to preserve LCSSA form.
+; PR4934
+
+define void @pnp_check_irq() nounwind noredzone {
+entry:
+  %conv56 = trunc i64 undef to i32                ; <i32> [#uses=1]
+  br label %while.cond.i
+
+while.cond.i:                                     ; preds = %while.cond.i.backedge, %entry
+  %call.i25 = call i8* @pci_get_device() nounwind noredzone ; <i8*> [#uses=2]
+  br i1 undef, label %if.then65, label %while.body.i
+
+while.body.i:                                     ; preds = %while.cond.i
+  br i1 undef, label %if.then31.i.i, label %while.cond.i.backedge
+
+while.cond.i.backedge:                            ; preds = %if.then31.i.i, %while.body.i
+  br label %while.cond.i
+
+if.then31.i.i:                                    ; preds = %while.body.i
+  switch i32 %conv56, label %while.cond.i.backedge [
+    i32 14, label %if.then42.i.i
+    i32 15, label %if.then42.i.i
+  ]
+
+if.then42.i.i:                                    ; preds = %if.then31.i.i, %if.then31.i.i
+  %call.i25.lcssa48 = phi i8* [ %call.i25, %if.then31.i.i ], [ %call.i25, %if.then31.i.i ] ; <i8*> [#uses=0]
+  unreachable
+
+if.then65:                                        ; preds = %while.cond.i
+  unreachable
+}
+
+declare i8* @pci_get_device() noredzone