Add an insertPass API to TargetPassConfig.  <rdar://problem/11498613>

Besides adding the new insertPass function, this patch uses it to
enhance the existing -print-machineinstrs so that the MachineInstrs
after a specific pass can be printed.

Patch by Bin Zeng!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157655 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/Generic/print-machineinstrs.ll b/test/CodeGen/Generic/print-machineinstrs.ll
new file mode 100644
index 0000000..75b4cd1
--- /dev/null
+++ b/test/CodeGen/Generic/print-machineinstrs.ll
@@ -0,0 +1,14 @@
+; RUN: llc < %s -O3 -debug-pass=Structure -print-machineinstrs=branch-folder -o /dev/null |& FileCheck %s
+; RUN: llc < %s -O3 -debug-pass=Structure -print-machineinstrs -o /dev/null |& FileCheck %s
+; RUN: llc < %s -O3 -debug-pass=Structure -print-machineinstrs= -o /dev/null |& FileCheck %s
+
+define i64 @foo(i64 %a, i64 %b) nounwind {
+; CHECK: -branch-folder -print-machineinstrs
+; CHECK: Control Flow Optimizer
+; CHECK-NEXT: MachineFunction Printer
+; CHECK: Machine code for function foo:
+  %c = add i64 %a, %b
+  %d = trunc i64 %c to i32
+  %e = zext i32 %d to i64
+  ret i64 %e
+}