From f19c6f576367a368cf729cd0019d16d691163d72 Mon Sep 17 00:00:00 2001
From: Robert Lytton <robert@xmos.com>
Date: Mon, 2 Dec 2013 11:05:28 +0000
Subject: XCore target: Make handling of large frames not dependent upon an FP.

eliminateFrameIndex() has been reworked to handle both small & large frames
with either a FP or SP.
An additional Slot is required for Scavenging spills when not using FP for large frames.
Reworked the handling of Register Scavenging.

Whether we are using an FP or not, whether it is a large frame or not,
and whether we are using a large code model or not are now independent.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196091 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/XCore/XCoreFrameLowering.cpp | 62 +++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 23 deletions(-)

(limited to 'lib/Target/XCore/XCoreFrameLowering.cpp')

diff --git a/lib/Target/XCore/XCoreFrameLowering.cpp b/lib/Target/XCore/XCoreFrameLowering.cpp
index 06eab7a4ce..ea25e71961 100644
--- a/lib/Target/XCore/XCoreFrameLowering.cpp
+++ b/lib/Target/XCore/XCoreFrameLowering.cpp
@@ -302,10 +302,11 @@ void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
   } // else Don't erase the return instruction.
 }
 
-bool XCoreFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
-                                               MachineBasicBlock::iterator MI,
-                                        const std::vector<CalleeSavedInfo> &CSI,
-                                          const TargetRegisterInfo *TRI) const {
+bool XCoreFrameLowering::
+spillCalleeSavedRegisters(MachineBasicBlock &MBB,
+                          MachineBasicBlock::iterator MI,
+                          const std::vector<CalleeSavedInfo> &CSI,
+                          const TargetRegisterInfo *TRI) const {
   if (CSI.empty())
     return true;
 
@@ -337,10 +338,11 @@ bool XCoreFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
   return true;
 }
 
-bool XCoreFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
-                                                 MachineBasicBlock::iterator MI,
-                                        const std::vector<CalleeSavedInfo> &CSI,
-                                            const TargetRegisterInfo *TRI) const{
+bool XCoreFrameLowering::
+restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                            MachineBasicBlock::iterator MI,
+                            const std::vector<CalleeSavedInfo> &CSI,
+                            const TargetRegisterInfo *TRI) const{
   MachineFunction *MF = MBB.getParent();
   const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
 
@@ -420,11 +422,10 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
   MBB.erase(I);
 }
 
-void
-XCoreFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
-                                                     RegScavenger *RS) const {
+void XCoreFrameLowering::
+processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
+                                     RegScavenger *RS) const {
   MachineFrameInfo *MFI = MF.getFrameInfo();
-  const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
   bool LRUsed = MF.getRegInfo().isPhysRegUsed(XCore::LR);
   const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
   XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
@@ -434,7 +435,7 @@ XCoreFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
     bool isVarArg = MF.getFunction()->isVarArg();
     int FrameIdx;
     if (! isVarArg) {
-      // A fixed offset of 0 allows us to save / restore LR using entsp / retsp.
+      // A fixed offset of 0 allows us to save/restore LR using entsp/retsp.
       FrameIdx = MFI->CreateFixedObject(RC->getSize(), 0, true);
     } else {
       FrameIdx = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(),
@@ -443,17 +444,32 @@ XCoreFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
     XFI->setUsesLR(FrameIdx);
     XFI->setLRSpillSlot(FrameIdx);
   }
-  if (RegInfo->requiresRegisterScavenging(MF)) {
-    // Reserve a slot close to SP or frame pointer.
-    RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
-                                                       RC->getAlignment(),
-                                                       false));
-  }
-  if (hasFP(MF)) {
-    // A callee save register is used to hold the FP.
-    // This needs saving / restoring in the epilogue / prologue.
+
+  // A callee save register is used to hold the FP.
+  // This needs saving / restoring in the epilogue / prologue.
+  if (hasFP(MF))
     XFI->setFPSpillSlot(MFI->CreateStackObject(RC->getSize(),
                                                RC->getAlignment(),
                                                false));
-  }
+}
+
+void XCoreFrameLowering::
+processFunctionBeforeFrameFinalized(MachineFunction &MF,
+                                    RegScavenger *RS) const {
+  assert(RS && "requiresRegisterScavenging failed");
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
+  XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
+  // Reserve slots close to SP or frame pointer for Scavenging spills.
+  // When using SP for small frames, we don't need any scratch registers.
+  // When using SP for large frames, we may need 2 scratch registers.
+  // When using FP, for large or small frames, we may need 1 scratch register.
+  if (XFI->isLargeFrame(MF) || hasFP(MF))
+    RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
+                                                       RC->getAlignment(),
+                                                       false));
+  if (XFI->isLargeFrame(MF) && !hasFP(MF))
+    RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
+                                                       RC->getAlignment(),
+                                                       false));
 }
-- 
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