1 files changed, 38 insertions, 15 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index 1a84cdd49f1..651ad9ad4c8 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -211,6 +211,24 @@ AArch64FrameLowering::getStackIDForScalableVectors() const {
   return TargetStackID::SVEVector;
 }
 
+/// Returns the size of the fixed object area (allocated next to sp on entry)
+/// On Win64 this may include a var args area and an UnwindHelp object for EH.
+static unsigned getFixedObjectSize(const MachineFunction &MF,
+                                   const AArch64FunctionInfo *AFI, bool IsWin64,
+                                   bool IsFunclet) {
+  if (!IsWin64 || IsFunclet) {
+    // Only Win64 uses fixed objects, and then only for the function (not
+    // funclets)
+    return 0;
+  } else {
+    // Var args are stored here in the primary function.
+    const unsigned VarArgsArea = AFI->getVarArgsGPRSize();
+    // To support EH funclets we allocate an UnwindHelp object
+    const unsigned UnwindHelpObject = (MF.hasEHFunclets() ? 8 : 0);
+    return alignTo(VarArgsArea + UnwindHelpObject, 16);
+  }
+}
+
 /// Returns the size of the entire SVE stackframe (calleesaves + spills).
 static StackOffset getSVEStackSize(const MachineFunction &MF) {
   const AArch64FunctionInfo *AFI = MF.getInfo<AArch64FunctionInfo>();
@@ -959,10 +977,7 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
 
   bool IsWin64 =
       Subtarget.isCallingConvWin64(MF.getFunction().getCallingConv());
-  // Var args are accounted for in the containing function, so don't
-  // include them for funclets.
-  unsigned FixedObject = (IsWin64 && !IsFunclet) ?
-                         alignTo(AFI->getVarArgsGPRSize(), 16) : 0;
+  unsigned FixedObject = getFixedObjectSize(MF, AFI, IsWin64, IsFunclet);
 
   auto PrologueSaveSize = AFI->getCalleeSavedStackSize() + FixedObject;
   // All of the remaining stack allocations are for locals.
@@ -1442,10 +1457,7 @@ void AArch64FrameLowering::emitEpilogue(MachineFunction &MF,
 
   bool IsWin64 =
       Subtarget.isCallingConvWin64(MF.getFunction().getCallingConv());
-  // Var args are accounted for in the containing function, so don't
-  // include them for funclets.
-  unsigned FixedObject =
-      (IsWin64 && !IsFunclet) ? alignTo(AFI->getVarArgsGPRSize(), 16) : 0;
+  unsigned FixedObject = getFixedObjectSize(MF, AFI, IsWin64, IsFunclet);
 
   uint64_t AfterCSRPopSize = ArgumentPopSize;
   auto PrologueSaveSize = AFI->getCalleeSavedStackSize() + FixedObject;
@@ -1671,7 +1683,9 @@ static StackOffset getFPOffset(const MachineFunction &MF, int64_t ObjectOffset)
   const auto &Subtarget = MF.getSubtarget<AArch64Subtarget>();
   bool IsWin64 =
       Subtarget.isCallingConvWin64(MF.getFunction().getCallingConv());
-  unsigned FixedObject = IsWin64 ? alignTo(AFI->getVarArgsGPRSize(), 16) : 0;
+
+  unsigned FixedObject =
+      getFixedObjectSize(MF, AFI, IsWin64, /*IsFunclet=*/false);
   unsigned FPAdjust = isTargetDarwin(MF)
                         ? 16 : AFI->getCalleeSavedStackSize(MF.getFrameInfo());
   return {ObjectOffset + FixedObject + FPAdjust, MVT::i8};
@@ -2624,9 +2638,14 @@ void AArch64FrameLowering::processFunctionBeforeFrameFinalized(
     ++MBBI;
 
   // Create an UnwindHelp object.
-  int UnwindHelpFI =
-      MFI.CreateStackObject(/*size*/8, /*alignment*/16, false);
+  // The UnwindHelp object is allocated at the start of the fixed object area
+  int64_t FixedObject =
+      getFixedObjectSize(MF, AFI, /*IsWin64*/ true, /*IsFunclet*/ false);
+  int UnwindHelpFI = MFI.CreateFixedObject(/*Size*/ 8,
+                                           /*SPOffset*/ -FixedObject,
+                                           /*IsImmutable=*/false);
   EHInfo.UnwindHelpFrameIdx = UnwindHelpFI;
+
   // We need to store -2 into the UnwindHelp object at the start of the
   // function.
   DebugLoc DL;
@@ -2648,10 +2667,14 @@ int AArch64FrameLowering::getFrameIndexReferencePreferSP(
     const MachineFunction &MF, int FI, unsigned &FrameReg,
     bool IgnoreSPUpdates) const {
   const MachineFrameInfo &MFI = MF.getFrameInfo();
-  LLVM_DEBUG(dbgs() << "Offset from the SP for " << FI << " is "
-                    << MFI.getObjectOffset(FI) << "\n");
-  FrameReg = AArch64::SP;
-  return MFI.getObjectOffset(FI);
+  if (IgnoreSPUpdates) {
+    LLVM_DEBUG(dbgs() << "Offset from the SP for " << FI << " is "
+                      << MFI.getObjectOffset(FI) << "\n");
+    FrameReg = AArch64::SP;
+    return MFI.getObjectOffset(FI);
+  }
+
+  return getFrameIndexReference(MF, FI, FrameReg);
 }
 
 /// The parent frame offset (aka dispFrame) is only used on X86_64 to retrieve