The BLX instruction is encoded differently than the BL, because why not? In

[oota-llvm.git] / lib / Target / ARM / Thumb1FrameInfo.cpp

diff --git a/lib/Target/ARM/Thumb1FrameInfo.cpp b/lib/Target/ARM/Thumb1FrameInfo.cpp
index 6a3c1e15eafb131ebad4a8c33e5fb57d90ff0b6a..d92d83c4e46e30085e3b22200f39ffadff6e6fa3 100644 (file)
--- a/lib/Target/ARM/Thumb1FrameInfo.cpp
+++ b/lib/Target/ARM/Thumb1FrameInfo.cpp
@@ -17,6 +17,7 @@
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
 
 using namespace llvm;
 
@@ -117,13 +118,6 @@ void Thumb1FrameInfo::emitPrologue(MachineFunction &MF) const {
       dl = MBBI->getDebugLoc();
   }
 
-  // Adjust FP so it point to the stack slot that contains the previous FP.
-  if (hasFP(MF)) {
-    BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
-      .addFrameIndex(FramePtrSpillFI).addImm(0);
-    AFI->setShouldRestoreSPFromFP(true);
-  }
-
   // Determine starting offsets of spill areas.
   unsigned DPRCSOffset  = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
   unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
@@ -132,12 +126,21 @@ void Thumb1FrameInfo::emitPrologue(MachineFunction &MF) const {
   AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
   AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
   AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
-
   NumBytes = DPRCSOffset;
-  if (NumBytes) {
+
+  // Adjust FP so it point to the stack slot that contains the previous FP.
+  if (hasFP(MF)) {
+    BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
+      .addFrameIndex(FramePtrSpillFI).addImm(0);
+    if (NumBytes > 7)
+      // If offset is > 7 then sp cannot be adjusted in a single instruction,
+      // try restoring from fp instead.
+      AFI->setShouldRestoreSPFromFP(true);
+  }
+
+  if (NumBytes)
     // Insert it after all the callee-save spills.
     emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -NumBytes);
-  }
 
   if (STI.isTargetELF() && hasFP(MF))
     MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
@@ -219,10 +222,14 @@ void Thumb1FrameInfo::emitEpilogue(MachineFunction &MF,
       NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
       // Reset SP based on frame pointer only if the stack frame extends beyond
       // frame pointer stack slot or target is ELF and the function has FP.
-      if (NumBytes)
-        emitThumbRegPlusImmediate(MBB, MBBI, ARM::SP, FramePtr, -NumBytes,
+      if (NumBytes) {
+        assert(MF.getRegInfo().isPhysRegUsed(ARM::R4) &&
+               "No scratch register to restore SP from FP!");
+        emitThumbRegPlusImmediate(MBB, MBBI, ARM::R4, FramePtr, -NumBytes,
                                   TII, *RegInfo, dl);
-      else
+        BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVtgpr2gpr), ARM::SP)
+          .addReg(ARM::R4);
+      } else
         BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVtgpr2gpr), ARM::SP)
           .addReg(FramePtr);
     } else {
@@ -257,3 +264,82 @@ void Thumb1FrameInfo::emitEpilogue(MachineFunction &MF,
     MBB.erase(MBBI);
   }
 }
+
+bool Thumb1FrameInfo::
+spillCalleeSavedRegisters(MachineBasicBlock &MBB,
+                          MachineBasicBlock::iterator MI,
+                          const std::vector<CalleeSavedInfo> &CSI,
+                          const TargetRegisterInfo *TRI) const {
+  if (CSI.empty())
+    return false;
+
+  DebugLoc DL;
+  MachineFunction &MF = *MBB.getParent();
+  const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+
+  if (MI != MBB.end()) DL = MI->getDebugLoc();
+
+  MachineInstrBuilder MIB = BuildMI(MBB, MI, DL, TII.get(ARM::tPUSH));
+  AddDefaultPred(MIB);
+  for (unsigned i = CSI.size(); i != 0; --i) {
+    unsigned Reg = CSI[i-1].getReg();
+    bool isKill = true;
+
+    // Add the callee-saved register as live-in unless it's LR and
+    // @llvm.returnaddress is called. If LR is returned for @llvm.returnaddress
+    // then it's already added to the function and entry block live-in sets.
+    if (Reg == ARM::LR) {
+      MachineFunction &MF = *MBB.getParent();
+      if (MF.getFrameInfo()->isReturnAddressTaken() &&
+          MF.getRegInfo().isLiveIn(Reg))
+        isKill = false;
+    }
+
+    if (isKill)
+      MBB.addLiveIn(Reg);
+
+    MIB.addReg(Reg, getKillRegState(isKill));
+  }
+  return true;
+}
+
+bool Thumb1FrameInfo::
+restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                            MachineBasicBlock::iterator MI,
+                            const std::vector<CalleeSavedInfo> &CSI,
+                            const TargetRegisterInfo *TRI) const {
+  if (CSI.empty())
+    return false;
+
+  MachineFunction &MF = *MBB.getParent();
+  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+  const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+
+  bool isVarArg = AFI->getVarArgsRegSaveSize() > 0;
+  DebugLoc DL = MI->getDebugLoc();
+  MachineInstrBuilder MIB = BuildMI(MF, DL, TII.get(ARM::tPOP));
+  AddDefaultPred(MIB);
+
+  bool NumRegs = false;
+  for (unsigned i = CSI.size(); i != 0; --i) {
+    unsigned Reg = CSI[i-1].getReg();
+    if (Reg == ARM::LR) {
+      // Special epilogue for vararg functions. See emitEpilogue
+      if (isVarArg)
+        continue;
+      Reg = ARM::PC;
+      (*MIB).setDesc(TII.get(ARM::tPOP_RET));
+      MI = MBB.erase(MI);
+    }
+    MIB.addReg(Reg, getDefRegState(true));
+    NumRegs = true;
+  }
+
+  // It's illegal to emit pop instruction without operands.
+  if (NumRegs)
+    MBB.insert(MI, &*MIB);
+  else
+    MF.DeleteMachineInstr(MIB);
+
+  return true;
+}