From b2840fdcd8a98de32e86e70a267b54cf0af35140 Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Tue, 6 Sep 2011 02:43:13 +0000
Subject: [PATCH] Revert r139126 due to selfhost failures reported by
 buildbots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139130 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/ScalarEvolution.cpp              |  8 ++---
 .../ScalarEvolution/max-trip-count.ll         | 31 -------------------
 2 files changed, 2 insertions(+), 37 deletions(-)

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index a2cd38b4bf5..8859c3b22fb 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -5184,12 +5184,8 @@ ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L) {
   // Handle unitary steps, which cannot wraparound.
   // 1*N = -Start; -1*N = Start (mod 2^BW), so:
   //   N = Distance (as unsigned)
-  if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue()) {
-    ConstantRange CR = getUnsignedRange(Start);
-    const SCEV *MaxBECount = getConstant(CountDown ? CR.getUnsignedMax()
-                                                   : ~CR.getUnsignedMin());
-    return ExitLimit(Distance, MaxBECount);
-  }
+  if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue())
+    return Distance;
 
   // If the recurrence is known not to wraparound, unsigned divide computes the
   // back edge count. We know that the value will either become zero (and thus
diff --git a/test/Analysis/ScalarEvolution/max-trip-count.ll b/test/Analysis/ScalarEvolution/max-trip-count.ll
index 596423a4cdc..843fb073087 100644
--- a/test/Analysis/ScalarEvolution/max-trip-count.ll
+++ b/test/Analysis/ScalarEvolution/max-trip-count.ll
@@ -70,34 +70,3 @@ for.end:                                          ; preds = %for.body, %for.cond
 }
 
 declare i32 @printf(i8*, ...)
-
-; Before -indvars ran on this loop, SCEV solved a max loop trip count of
-; 2^31-2.  Afterwards, we can only solve 2^32-1.
-
-define void @test(i8* %a, i32 %n) nounwind {
-entry:
-  %cmp1 = icmp sgt i32 %n, 0
-  br i1 %cmp1, label %for.body.lr.ph, label %for.end
-
-for.body.lr.ph:                                   ; preds = %entry
-  %tmp = zext i32 %n to i64
-  br label %for.body
-
-for.body:                                         ; preds = %for.body, %for.body.lr.ph
-  %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %for.body.lr.ph ]
-  %arrayidx = getelementptr i8* %a, i64 %indvar
-  store i8 0, i8* %arrayidx, align 1
-  %indvar.next = add i64 %indvar, 1
-  %exitcond = icmp ne i64 %indvar.next, %tmp
-  br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge
-
-for.cond.for.end_crit_edge:                       ; preds = %for.body
-  br label %for.end
-
-for.end:                                          ; preds = %for.cond.for.end_crit_edge, %entry
-  ret void
-}
-
-; CHECK: Determining loop execution counts for: @test
-; CHECK-NEXT: backedge-taken count is
-; CHECK-NEXT: max backedge-taken count is -1