[X86] Refactor the prologue emission to prepare for shrink-wrapping.

- Add a late pass to expand pseudo instructions (tail call and EH returns).
  Instead of doing it in the prologue emission.
- Factor some static methods in X86FrameLowering to ease code sharing.

NFC.

Related to <rdar://problem/20821487>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237977 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86TargetMachine.cpp

@@ -187,6 +187,7 @@ public:
   void addPreRegAlloc() override;
   void addPostRegAlloc() override;
   void addPreEmitPass() override;
+  void addPreSched2() override;
 };
 } // namespace
 
@@ -235,6 +236,8 @@ void X86PassConfig::addPostRegAlloc() {
   addPass(createX86FloatingPointStackifierPass());
 }
 
+void X86PassConfig::addPreSched2() { addPass(createX86ExpandPseudoPass()); }
+
 void X86PassConfig::addPreEmitPass() {
   if (getOptLevel() != CodeGenOpt::None)
     addPass(createExecutionDependencyFixPass(&X86::VR128RegClass));