Re-enable "[SCEV] Make isLoopEntryGuardedByCond a bit smarter"

The failures happened because of assert which was overconfident about
SCEV's proving capabilities and is generally not valid.

Differential Revision: https://reviews.llvm.org/D42835

llvm-svn: 324473

1 files changed, 30 insertions, 0 deletions

diff --git a/llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll b/llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll
index 70cf714ba9f..30249828107 100644
--- a/llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll
+++ b/llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll
@@ -325,6 +325,36 @@ exit:
   ret void
 }
 
+; check that we can figure out that iv.next > 1 from the facts that iv >= 0 and
+; iv.start != 0.
+define void @test11(i64* %inc_ptr) {
+; CHECK-LABEL: @test11
+entry:
+  %inc = load i64, i64* %inc_ptr, !range !0
+  %ne.cond = icmp ne i64 %inc, 0
+  br i1 %ne.cond, label %loop, label %exit
+
+loop:
+  %iv = phi i64 [ %inc, %entry ], [ %iv.next, %backedge ]
+  %iv.next = add i64 %iv, 1
+  %brcond = icmp sgt i64 %iv.next, 1
+  ; CHECK: br i1 true, label %if.true, label %if.false
+  br i1 %brcond, label %if.true, label %if.false
+
+if.true:
+  br label %backedge
+
+if.false:
+  br label %backedge
+
+backedge:
+  %loopcond = icmp slt i64 %iv, 200
+  br i1 %loopcond, label %loop, label %exit
+
+exit:
+  ret void
+}
+
 !1 = !{i64 -1, i64 100}