Revert "blockfreq: Rewrite BlockFrequencyInfoImpl" (#2)

This reverts commit r206666, as planned.

Still stumped on why the bots are failing.  Sanitizer bots haven't
turned anything up.  If anyone can help me debug either of the failures
(referenced in r206666) I'll owe them a beer.  (In the meantime, I'll be
auditing my patch for undefined behaviour.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206677 91177308-0d34-0410-b5e6-96231b3b80d8

test/Analysis/BlockFrequencyInfo/loop_with_branch.ll

@@ -1,44 +0,0 @@
-; RUN: opt < %s -analyze -block-freq | FileCheck %s
-
-; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_with_branch':
-; CHECK-NEXT: block-frequency-info: loop_with_branch
-define void @loop_with_branch(i32 %a) {
-; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]]
-entry:
-  %skip_loop = call i1 @foo0(i32 %a)
-  br i1 %skip_loop, label %skip, label %header, !prof !0
-
-; CHECK-NEXT: skip: float = 0.25,
-skip:
-  br label %exit
-
-; CHECK-NEXT: header: float = 4.5,
-header:
-  %i = phi i32 [ 0, %entry ], [ %i.next, %back ]
-  %i.next = add i32 %i, 1
-  %choose = call i2 @foo1(i32 %i)
-  switch i2 %choose, label %exit [ i2 0, label %left
-                                   i2 1, label %right ], !prof !1
-
-; CHECK-NEXT: left: float = 1.5,
-left:
-  br label %back
-
-; CHECK-NEXT: right: float = 2.25,
-right:
-  br label %back
-
-; CHECK-NEXT: back: float = 3.75,
-back:
-  br label %header
-
-; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]]
-exit:
-  ret void
-}
-
-declare i1 @foo0(i32)
-declare i2 @foo1(i32)
-
-!0 = metadata !{metadata !"branch_weights", i32 1, i32 3}
-!1 = metadata !{metadata !"branch_weights", i32 1, i32 2, i32 3}