2 files changed, 13 insertions, 0 deletions
diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
index d0986a73b70..a83170a1131 100644
--- a/llvm/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -87,6 +87,17 @@ bool ARMFrameLowering::noFramePointerElim(const MachineFunction &MF) const {
          MF.getSubtarget<ARMSubtarget>().useFastISel();
 }
 
+/// Returns true if the target can safely skip saving callee-saved registers
+/// for noreturn nounwind functions.
+bool ARMFrameLowering::enableCalleeSaveSkip(const MachineFunction &MF) const {
+  assert(MF.getFunction().hasFnAttribute(Attribute::NoReturn) &&
+      MF.getFunction().hasFnAttribute(Attribute::NoUnwind));
+
+  // Frame pointer and link register are not treated as normal CSR, thus we
+  // can always skip CSR saves for nonreturning functions.
+  return true;
+}
+
 /// hasFP - Return true if the specified function should have a dedicated frame
 /// pointer register.  This is true if the function has variable sized allocas
 /// or if frame pointer elimination is disabled.
diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.h b/llvm/lib/Target/ARM/ARMFrameLowering.h
index 1f18e2bf80c..e994cab28fe 100644
--- a/llvm/lib/Target/ARM/ARMFrameLowering.h
+++ b/llvm/lib/Target/ARM/ARMFrameLowering.h
@@ -44,6 +44,8 @@ public:
 
   bool noFramePointerElim(const MachineFunction &MF) const override;
 
+  bool enableCalleeSaveSkip(const MachineFunction &MF) const override;
+
   bool hasFP(const MachineFunction &MF) const override;
   bool hasReservedCallFrame(const MachineFunction &MF) const override;
   bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override;