1 files changed, 15 insertions, 16 deletions
diff --git a/contrib/llvm-project/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp b/contrib/llvm-project/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
index c2962c4857c3..0f4ece64bff5 100644
--- a/contrib/llvm-project/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
+++ b/contrib/llvm-project/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
@@ -40,7 +40,6 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
-#include <bitset>
 #include <cassert>
 #include <iterator>
 #include <vector>
@@ -538,18 +537,30 @@ void Thumb1FrameLowering::emitEpilogue(MachineFunction &MF,
                  AFI->getDPRCalleeSavedAreaSize() +
                  ArgRegsSaveSize);
 
+    // We are likely to need a scratch register and we know all callee-save
+    // registers are free at this point in the epilogue, so pick one.
+    unsigned ScratchRegister = ARM::NoRegister;
+    bool HasFP = hasFP(MF);
+    for (auto &I : MFI.getCalleeSavedInfo()) {
+      Register Reg = I.getReg();
+      if (isARMLowRegister(Reg) && !(HasFP && Reg == FramePtr)) {
+        ScratchRegister = Reg;
+        break;
+      }
+    }
+
     if (AFI->shouldRestoreSPFromFP()) {
       NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
       // Reset SP based on frame pointer only if the stack frame extends beyond
       // frame pointer stack slot, the target is ELF and the function has FP, or
       // the target uses var sized objects.
       if (NumBytes) {
-        assert(!MFI.getPristineRegs(MF).test(ARM::R4) &&
+        assert(ScratchRegister != ARM::NoRegister &&
                "No scratch register to restore SP from FP!");
-        emitThumbRegPlusImmediate(MBB, MBBI, dl, ARM::R4, FramePtr, -NumBytes,
+        emitThumbRegPlusImmediate(MBB, MBBI, dl, ScratchRegister, FramePtr, -NumBytes,
                                   TII, *RegInfo, MachineInstr::FrameDestroy);
         BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), ARM::SP)
-            .addReg(ARM::R4)
+            .addReg(ScratchRegister)
             .add(predOps(ARMCC::AL))
             .setMIFlag(MachineInstr::FrameDestroy);
       } else
@@ -558,18 +569,6 @@ void Thumb1FrameLowering::emitEpilogue(MachineFunction &MF,
             .add(predOps(ARMCC::AL))
             .setMIFlag(MachineInstr::FrameDestroy);
     } else {
-      // For a large stack frame, we might need a scratch register to store
-      // the size of the frame.  We know all callee-save registers are free
-      // at this point in the epilogue, so pick one.
-      unsigned ScratchRegister = ARM::NoRegister;
-      bool HasFP = hasFP(MF);
-      for (auto &I : MFI.getCalleeSavedInfo()) {
-        Register Reg = I.getReg();
-        if (isARMLowRegister(Reg) && !(HasFP && Reg == FramePtr)) {
-          ScratchRegister = Reg;
-          break;
-        }
-      }
       if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tBX_RET &&
           &MBB.front() != &*MBBI && std::prev(MBBI)->getOpcode() == ARM::tPOP) {
         MachineBasicBlock::iterator PMBBI = std::prev(MBBI);