Spill R4 if it's going to be used to restore SP from FP.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123567 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMFrameLowering.cpp b/lib/Target/ARM/ARMFrameLowering.cpp
index b8cbf5d..0b514da 100644
--- a/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/lib/Target/ARM/ARMFrameLowering.cpp
@@ -801,15 +801,23 @@
// Spill R4 if Thumb2 function requires stack realignment - it will be used as
// scratch register. Also spill R4 if Thumb2 function has varsized objects,
- // since it's always posible to restore sp from fp in a single instruction.
+ // since it's not always possible to restore sp from fp in a single
+ // instruction.
// FIXME: It will be better just to find spare register here.
if (AFI->isThumb2Function() &&
(MFI->hasVarSizedObjects() || RegInfo->needsStackRealignment(MF)))
MF.getRegInfo().setPhysRegUsed(ARM::R4);
- // Spill LR if Thumb1 function uses variable length argument lists.
- if (AFI->isThumb1OnlyFunction() && AFI->getVarArgsRegSaveSize() > 0)
- MF.getRegInfo().setPhysRegUsed(ARM::LR);
+ if (AFI->isThumb1OnlyFunction()) {
+ // Spill LR if Thumb1 function uses variable length argument lists.
+ if (AFI->getVarArgsRegSaveSize() > 0)
+ MF.getRegInfo().setPhysRegUsed(ARM::LR);
+
+ // Spill R4 if Thumb1 epilogue has to restore SP from FP since
+ // FIXME: It will be better just to find spare register here.
+ if (MFI->hasVarSizedObjects())
+ MF.getRegInfo().setPhysRegUsed(ARM::R4);
+ }
// Spill the BasePtr if it's used.
if (RegInfo->hasBasePointer(MF))