Reland [AArch64][DebugInfo] Do not recompute CalleeSavedStackSize (Take 2)

llvm/test/DebugInfo/MIR/X86/live-debug-values-reg-copy.mir failed with
EXPENSIVE_CHECKS enabled, causing the patch to be reverted in
rG2c496bb5309c972d59b11f05aee4782ddc087e71.

This patch relands the patch with a proper fix to the
live-debug-values-reg-copy.mir tests, by ensuring the MIR encodes the
callee-saves correctly so that the CalleeSaved info is taken from MIR
directly, rather than letting it be recalculated by the PEI pass. I've
done this by running `llc -stop-before=prologepilog` on the LLVM
IR as captured in the test files, adding the extra MOV instructions
that were manually added in the original test file, then running `llc
-run-pass=prologepilog` and finally re-added the comments for the MOV
instructions.

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp b/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
index 9eeacc2584c..bc59be890c9 100644
--- a/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
+++ b/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
@@ -60,6 +60,19 @@ bool TargetFrameLowering::needsFrameIndexResolution(
   return MF.getFrameInfo().hasStackObjects();
 }
 
+void TargetFrameLowering::getCalleeSaves(const MachineFunction &MF,
+                                         BitVector &CalleeSaves) const {
+  const TargetRegisterInfo &TRI = *MF.getSubtarget().getRegisterInfo();
+  CalleeSaves.resize(TRI.getNumRegs());
+
+  const MachineFrameInfo &MFI = MF.getFrameInfo();
+  if (!MFI.isCalleeSavedInfoValid())
+    return;
+
+  for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
+    CalleeSaves.set(Info.getReg());
+}
+
 void TargetFrameLowering::determineCalleeSaves(MachineFunction &MF,
                                                BitVector &SavedRegs,
                                                RegScavenger *RS) const {