1 files changed, 143 insertions, 0 deletions
diff --git a/lib/Target/Alpha/AlphaFrameLowering.cpp b/lib/Target/Alpha/AlphaFrameLowering.cpp
new file mode 100644
index 0000000000..949bd4fb2c
--- /dev/null
+++ b/lib/Target/Alpha/AlphaFrameLowering.cpp
@@ -0,0 +1,143 @@
+//=====- AlphaFrameLowering.cpp - Alpha Frame Information ------*- C++ -*-====//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the Alpha implementation of TargetFrameLowering class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AlphaFrameLowering.h"
+#include "AlphaInstrInfo.h"
+#include "AlphaMachineFunctionInfo.h"
+#include "llvm/Function.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/ADT/Twine.h"
+
+using namespace llvm;
+
+static long getUpper16(long l) {
+  long y = l / Alpha::IMM_MULT;
+  if (l % Alpha::IMM_MULT > Alpha::IMM_HIGH)
+    ++y;
+  return y;
+}
+
+static long getLower16(long l) {
+  long h = getUpper16(l);
+  return l - h * Alpha::IMM_MULT;
+}
+
+// hasFP - Return true if the specified function should have a dedicated frame
+// pointer register.  This is true if the function has variable sized allocas or
+// if frame pointer elimination is disabled.
+//
+bool AlphaFrameLowering::hasFP(const MachineFunction &MF) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  return MFI->hasVarSizedObjects();
+}
+
+void AlphaFrameLowering::emitPrologue(MachineFunction &MF) const {
+  MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
+  MachineBasicBlock::iterator MBBI = MBB.begin();
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+
+  DebugLoc dl = (MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc());
+  bool FP = hasFP(MF);
+
+  // Handle GOP offset
+  BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDAHg), Alpha::R29)
+    .addGlobalAddress(MF.getFunction()).addReg(Alpha::R27).addImm(++curgpdist);
+  BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDAg), Alpha::R29)
+    .addGlobalAddress(MF.getFunction()).addReg(Alpha::R29).addImm(curgpdist);
+
+  BuildMI(MBB, MBBI, dl, TII.get(Alpha::ALTENT))
+    .addGlobalAddress(MF.getFunction());
+
+  // Get the number of bytes to allocate from the FrameInfo
+  long NumBytes = MFI->getStackSize();
+
+  if (FP)
+    NumBytes += 8; //reserve space for the old FP
+
+  // Do we need to allocate space on the stack?
+  if (NumBytes == 0) return;
+
+  unsigned Align = getStackAlignment();
+  NumBytes = (NumBytes+Align-1)/Align*Align;
+
+  // Update frame info to pretend that this is part of the stack...
+  MFI->setStackSize(NumBytes);
+
+  // adjust stack pointer: r30 -= numbytes
+  NumBytes = -NumBytes;
+  if (NumBytes >= Alpha::IMM_LOW) {
+    BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDA), Alpha::R30).addImm(NumBytes)
+      .addReg(Alpha::R30);
+  } else if (getUpper16(NumBytes) >= Alpha::IMM_LOW) {
+    BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDAH), Alpha::R30)
+      .addImm(getUpper16(NumBytes)).addReg(Alpha::R30);
+    BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDA), Alpha::R30)
+      .addImm(getLower16(NumBytes)).addReg(Alpha::R30);
+  } else {
+    report_fatal_error("Too big a stack frame at " + Twine(NumBytes));
+  }
+
+  // Now if we need to, save the old FP and set the new
+  if (FP) {
+    BuildMI(MBB, MBBI, dl, TII.get(Alpha::STQ))
+      .addReg(Alpha::R15).addImm(0).addReg(Alpha::R30);
+    // This must be the last instr in the prolog
+    BuildMI(MBB, MBBI, dl, TII.get(Alpha::BISr), Alpha::R15)
+      .addReg(Alpha::R30).addReg(Alpha::R30);
+  }
+
+}
+
+void AlphaFrameLowering::emitEpilogue(MachineFunction &MF,
+                                  MachineBasicBlock &MBB) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  MachineBasicBlock::iterator MBBI = prior(MBB.end());
+  const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+
+  assert((MBBI->getOpcode() == Alpha::RETDAG ||
+          MBBI->getOpcode() == Alpha::RETDAGp)
+         && "Can only insert epilog into returning blocks");
+  DebugLoc dl = MBBI->getDebugLoc();
+
+  bool FP = hasFP(MF);
+
+  // Get the number of bytes allocated from the FrameInfo...
+  long NumBytes = MFI->getStackSize();
+
+  //now if we need to, restore the old FP
+  if (FP) {
+    //copy the FP into the SP (discards allocas)
+    BuildMI(MBB, MBBI, dl, TII.get(Alpha::BISr), Alpha::R30).addReg(Alpha::R15)
+      .addReg(Alpha::R15);
+    //restore the FP
+    BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDQ), Alpha::R15)
+      .addImm(0).addReg(Alpha::R15);
+  }
+
+  if (NumBytes != 0) {
+    if (NumBytes <= Alpha::IMM_HIGH) {
+      BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDA), Alpha::R30).addImm(NumBytes)
+        .addReg(Alpha::R30);
+    } else if (getUpper16(NumBytes) <= Alpha::IMM_HIGH) {
+      BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDAH), Alpha::R30)
+        .addImm(getUpper16(NumBytes)).addReg(Alpha::R30);
+      BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDA), Alpha::R30)
+        .addImm(getLower16(NumBytes)).addReg(Alpha::R30);
+    } else {
+      report_fatal_error("Too big a stack frame at " + Twine(NumBytes));
+    }
+  }
+}