Merging r325085:

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r325085 | rnk | 2018-02-13 16:24:29 -0800 (Tue, 13 Feb 2018) | 3 lines

[X86] Remove dead code from retpoline thunk generation

Follow-up to r325049
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_50@325091 91177308-0d34-0410-b5e6-96231b3b80d8

Author: rnk

lib/Target/X86/X86RetpolineThunks.cpp

@@ -74,7 +74,6 @@ class X86RetpolineThunks : public MachineFunctionPass {
 
   void createThunkFunction(Module &M, StringRef Name);
   void insertRegReturnAddrClobber(MachineBasicBlock &MBB, unsigned Reg);
-  void insert32BitPushReturnAddrClobber(MachineBasicBlock &MBB);
   void populateThunk(MachineFunction &MF, Optional<unsigned> Reg = None);
 };
 
@@ -225,31 +224,6 @@ void X86RetpolineThunks::insertRegReturnAddrClobber(MachineBasicBlock &MBB,
       .addReg(Reg);
 }
 
-void X86RetpolineThunks::insert32BitPushReturnAddrClobber(
-    MachineBasicBlock &MBB) {
-  // The instruction sequence we use to replace the return address without
-  // a scratch register is somewhat complicated:
-  //   # Clear capture_spec from return address.
-  //   addl $4, %esp
-  //   # Top of stack words are: Callee, RA. Exchange Callee and RA.
-  //   pushl 4(%esp)  # Push callee
-  //   pushl 4(%esp)  # Push RA
-  //   popl 8(%esp)   # Pop RA to final RA
-  //   popl (%esp)    # Pop callee to next top of stack
-  //   retl           # Ret to callee
-  BuildMI(&MBB, DebugLoc(), TII->get(X86::ADD32ri), X86::ESP)
-      .addReg(X86::ESP)
-      .addImm(4);
-  addRegOffset(BuildMI(&MBB, DebugLoc(), TII->get(X86::PUSH32rmm)), X86::ESP,
-               false, 4);
-  addRegOffset(BuildMI(&MBB, DebugLoc(), TII->get(X86::PUSH32rmm)), X86::ESP,
-               false, 4);
-  addRegOffset(BuildMI(&MBB, DebugLoc(), TII->get(X86::POP32rmm)), X86::ESP,
-               false, 8);
-  addRegOffset(BuildMI(&MBB, DebugLoc(), TII->get(X86::POP32rmm)), X86::ESP,
-               false, 0);
-}
-
 void X86RetpolineThunks::populateThunk(MachineFunction &MF,
                                        Optional<unsigned> Reg) {
   // Set MF properties. We never use vregs...