PGO branch weight: update edge weights in SelectionDAGBuilder.

When converting from "or + br" to two branches, or converting from
"and + br" to two branches, we correctly update the edge weights of
the two branches.

The previous attempt at r200431 was reverted at r200434 because of
two testing case failures. I modified my patch a little, but forgot
to re-run "make check-all".

Testing case CodeGen/ARM/lsr-unfolded-offset.ll is updated because of
the patch's impact on branch probability which causes changes in
spill placement.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200502 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/X86/MachineBranchProb.ll

@@ -0,0 +1,34 @@
+; RUN: llc < %s -mtriple=x86_64-apple-darwin -print-machineinstrs=expand-isel-pseudos -o /dev/null 2>&1 | FileCheck %s
+
+;; Make sure a transformation in SelectionDAGBuilder that converts "or + br" to
+;; two branches correctly updates the branch probability.
+
+@max_regno = common global i32 0, align 4
+
+define void @test(i32* %old, i32 %final) {
+for.cond:
+  br label %for.cond2
+
+for.cond2:                                        ; preds = %for.inc, %for.cond
+  %i.1 = phi i32 [ %inc19, %for.inc ], [ 0, %for.cond ]
+  %bit.0 = phi i32 [ %shl, %for.inc ], [ 1, %for.cond ]
+  %tobool = icmp eq i32 %bit.0, 0
+  %v3 = load i32* @max_regno, align 4
+  %cmp4 = icmp eq i32 %i.1, %v3
+  %or.cond = or i1 %tobool, %cmp4
+  br i1 %or.cond, label %for.inc20, label %for.inc, !prof !0
+; CHECK: BB#1: derived from LLVM BB %for.cond2
+; CHECK: Successors according to CFG: BB#3(56008718) BB#4(2203492365)
+; CHECK: BB#4: derived from LLVM BB %for.cond2
+; CHECK: Successors according to CFG: BB#3(112017436) BB#2(4294967294)
+
+for.inc:                                          ; preds = %for.cond2
+  %shl = shl i32 %bit.0, 1
+  %inc19 = add nsw i32 %i.1, 1
+  br label %for.cond2
+
+for.inc20:                                        ; preds = %for.cond2
+  ret void
+}
+
+!0 = metadata !{metadata !"branch_weights", i32 112017436, i32 -735157296}