[llvm] r277502 - [LoopUnroll] Ensure we create prolog loops in simplified form.

[Michael Zolotukhin via llvm-commits]

Author: mzolotukhin
Date: Tue Aug  2 14:19:31 2016
New Revision: 277502

URL: http://llvm.org/viewvc/llvm-project?rev=277502&view=rev
Log:
[LoopUnroll] Ensure we create prolog loops in simplified form.

Modified:
    llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
    llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll

Modified: llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp?rev=277502&r1=277501&r2=277502&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp Tue Aug  2 14:19:31 2016
@@ -112,6 +112,18 @@ static void ConnectProlog(Loop *L, Value
     }
   }
 
+  // Make sure that created prolog loop is in simplified form
+  SmallVector<BasicBlock *, 4> PrologExitPreds;
+  Loop *PrologLoop = LI->getLoopFor(PrologLatch);
+  if (PrologLoop) {
+    for (BasicBlock *PredBB : predecessors(PrologExit))
+      if (PrologLoop->contains(PredBB))
+        PrologExitPreds.push_back(PredBB);
+
+    SplitBlockPredecessors(PrologExit, PrologExitPreds, ".unr-lcssa", DT, LI,
+                           PreserveLCSSA);
+  }
+
   // Create a branch around the original loop, which is taken if there are no
   // iterations remaining to be executed after running the prologue.
   Instruction *InsertPt = PrologExit->getTerminator();

Modified: llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll?rev=277502&r1=277501&r2=277502&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll (original)
+++ llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll Tue Aug  2 14:19:31 2016
@@ -23,7 +23,7 @@ target datalayout = "e-p:64:64:64-i1:8:8
 ; PROLOG: %indvars.iv.prol = phi i64 [ %indvars.iv.next.prol, %for.body.prol ], [ 0, %for.body.prol.preheader ]
 ; PROLOG:  %prol.iter.sub = sub i32 %prol.iter, 1
 ; PROLOG:  %prol.iter.cmp = icmp ne i32 %prol.iter.sub, 0
-; PROLOG:  br i1 %prol.iter.cmp, label %for.body.prol, label %for.body.prol.loopexit, !llvm.loop !0
+; PROLOG:  br i1 %prol.iter.cmp, label %for.body.prol, label %for.body.prol.loopexit.unr-lcssa, !llvm.loop !0
 
 
 define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {