Revert "Use R0/R1 instead of R4/R5 for ARM eh_return return values"

lib/Target/ARM/ARMFrameLowering.cpp

Index: lib/Target/ARM/ARMFrameLowering.cpp
diff --git a/lib/Target/ARM/ARMFrameLowering.cpp b/lib/Target/ARM/ARMFrameLowering.cpp
index 4f537cc9a2161d2650752e558a7dff98c53cfbe5..8895dfa5c8e0b6ca1a503f5671c966ba5b4810b7 100644
--- a/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/lib/Target/ARM/ARMFrameLowering.cpp
@@ -966,15 +966,6 @@ void ARMFrameLowering::emitPushInst(MachineBasicBlock &MBB,
           isKill = false;
       }
 
-      // @LOCALMOD-START
-      // Functions which call EHReturn spill all CSRs plus R0/R1
-      if ((Reg == ARM::R0 || Reg == ARM::R1) &&
-          MF.getRegInfo().isLiveIn(Reg)) {
-        assert(MF.getMMI().callsEHReturn());
-        isKill = false;
-      }
-      // @LOCALMOD-END
-
       if (isKill)
         MBB.addLiveIn(Reg);
 
@@ -1034,7 +1025,6 @@ void ARMFrameLowering::emitPopInst(MachineBasicBlock &MBB,
   while (i != 0) {
     unsigned LastReg = 0;
     bool DeleteRet = false;
-    unsigned SkippedPop = 0; // @LOCALMOD
     for (; i != 0; --i) {
       unsigned Reg = CSI[i-1].getReg();
       if (!(Func)(Reg, STI.isTargetDarwin())) continue;
@@ -1043,19 +1033,6 @@ void ARMFrameLowering::emitPopInst(MachineBasicBlock &MBB,
       if (Reg >= ARM::D8 && Reg < ARM::D8 + NumAlignedDPRCS2Regs)
         continue;
 
-      // @LOCALMOD-START
-      // Functions which call EHReturn spill all of their CSRs plus R0 and R1,
-      // (the EHReturn return value registers). Epilogs which return via
-      // EHreturn pop all of them, but epilogs which return via normal return
-      // must not restore R0 and R1, as that would clobber the return value.
-      if (MF.getMMI().callsEHReturn() &&
-          RetOpcode != ARM::ARMeh_return &&
-          (Reg == ARM::R0 || Reg == ARM::R1)) {
-        SkippedPop++;
-        continue;
-      }
-      // @LOCALMOD-END
-
       if (Reg == ARM::LR && !isTailCall && !isVarArg && !isInterrupt &&
           STI.hasV5TOps() &&
           !STI.isTargetNaCl() /* @LOCALMOD */) {
@@ -1075,21 +1052,6 @@ void ARMFrameLowering::emitPopInst(MachineBasicBlock &MBB,
       Regs.push_back(Reg);
     }
 
-    // @LOCALMOD-START
-    if (SkippedPop) {
-      // We need to increment the stack pointer to compensate for the skipped
-      // pops. However we cannot directly increment it because the epilog
-      // insertion code places the stack pointer restore before the CSR
-      // restores; it does this by finding the first instruction that's not a
-      // pop.  If we put an add here, the restore would go in between the
-      // restore of the FP registers and the GPRs, instead of before the FP
-      // restore. So use a pop into R12 to adjust SP.
-      while(SkippedPop--)
-         AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(LdmOpc), ARM::SP)
-                         .addReg(ARM::SP)).addReg(ARM::R12);
-    }
-    // @LOCALMOD-END
-
     if (Regs.empty())
       continue;
     if (Regs.size() > 1 || LdrOpc == 0) {