[IRCE] Fix a regression introduced in r232444.

IRCE should not try to eliminate range checks that check an induction
variable against a loop-varying length.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233101 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/IRCE/bug-loop-varying-upper-limit.ll

@@ -0,0 +1,31 @@
+; RUN: opt -irce-print-changed-loops -S -irce -verify < %s 2>&1 | FileCheck %s
+
+; CHECK-NOT: constrained loop
+
+define void @single_access_no_preloop_no_offset(i32 *%arr, i32 *%a_len_ptr, i32 %n) {
+ entry:
+  %first.itr.check = icmp sgt i32 %n, 0
+  br i1 %first.itr.check, label %loop, label %exit
+
+ loop:
+  %idx = phi i32 [ 0, %entry ] , [ %idx.next, %in.bounds ]
+  %idx.next = add i32 %idx, 1
+  %len = load i32, i32* %a_len_ptr, !range !0
+  %abc = icmp slt i32 %idx, %len
+  br i1 %abc, label %in.bounds, label %out.of.bounds, !prof !1
+
+ in.bounds:
+  %addr = getelementptr i32, i32* %arr, i32 %idx
+  store i32 0, i32* %addr
+  %next = icmp slt i32 %idx.next, %n
+  br i1 %next, label %loop, label %exit
+
+ out.of.bounds:
+  ret void
+
+ exit:
+  ret void
+}
+
+!0 = !{i32 0, i32 2147483647}
+!1 = !{!"branch_weights", i32 64, i32 4}