0025-Xtensa-Reserve-an-emergency-spill-slot-for.patch

From 7b5a9f0abbe35627c7e72aaff0b358fcd183425b Mon Sep 17 00:00:00 2001
From: Andrei Safronov <safronov@espressif.com>
Date: Wed, 5 Apr 2023 00:58:47 +0300
Subject: [PATCH 025/158] [Xtensa] Reserve an emergency spill slot for

 scavenger.

Reserve an emergency spill slot for the register scavenger
when Windowed Call ABI is used.
---
 llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp | 16 ++++++++++++++++
 llvm/lib/Target/Xtensa/XtensaFrameLowering.h   |  3 +++
 2 files changed, 19 insertions(+)

diff --git a/llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp b/llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp
index 82cc9584a31b..53b6b7e1b018 100644
--- a/llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp
+++ b/llvm/lib/Target/Xtensa/XtensaFrameLowering.cpp
@@ -360,3 +360,19 @@ void XtensaFrameLowering::determineCalleeSaves(MachineFunction &MF,
   int FI = MF.getFrameInfo().CreateStackObject(Size, Alignment, false);
   RS->addScavengingFrameIndex(FI);
 }
+
+void XtensaFrameLowering::processFunctionBeforeFrameFinalized(
+    MachineFunction &MF, RegScavenger *RS) const {
+  const XtensaSubtarget &STI = MF.getSubtarget<XtensaSubtarget>();
+
+  // In WinABI mode add register scavenging slot
+  // FIXME: It may be posssible to add spill slot by more optimal way
+  if (STI.isWinABI() && (MF.getFrameInfo().estimateStackSize(MF) > 256)) {
+    MachineFrameInfo &MFI = MF.getFrameInfo();
+    const TargetRegisterClass &RC = Xtensa::ARRegClass;
+    const TargetRegisterInfo &TRI = *MF.getSubtarget().getRegisterInfo();
+    unsigned Size = TRI.getSpillSize(RC);
+    Align Alignment = TRI.getSpillAlign(RC);
+    RS->addScavengingFrameIndex(MFI.CreateStackObject(Size, Alignment, false));
+  }
+}
diff --git a/llvm/lib/Target/Xtensa/XtensaFrameLowering.h b/llvm/lib/Target/Xtensa/XtensaFrameLowering.h
index b112f069cd61..8eb44c493266 100644
--- a/llvm/lib/Target/Xtensa/XtensaFrameLowering.h
+++ b/llvm/lib/Target/Xtensa/XtensaFrameLowering.h
@@ -44,6 +44,9 @@ public:
 
   void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
                             RegScavenger *RS) const override;
+
+  void processFunctionBeforeFrameFinalized(MachineFunction &MF,
+                                           RegScavenger *RS) const override;
 };
 
 } // namespace llvm
-- 
2.40.1