diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp
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+++ b/lib/CodeGen/PrologEpilogInserter.cpp
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+//===-- PrologEpilogInserter.cpp - Insert Prolog/Epilog code in function --===//
+//
+// This pass is responsible for finalizing the functions frame layout, saving
+// callee saved registers, and for emitting prolog & epilog code for the
+// function.
+//
+// This pass must be run after register allocation. After this pass is
+// executed, it is illegal to construct MO_FrameIndex operands.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Pass.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/FunctionFrameInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/MRegisterInfo.h"
+#include "llvm/Target/MachineFrameInfo.h"
+#include "llvm/Target/MachineInstrInfo.h"
+
+namespace {
+ struct PEI : public FunctionPass {
+ bool runOnFunction(Function &Fn) {
+ return runOnMachineFunction(MachineFunction::get(&Fn));
+ }
+
+ /// runOnMachineFunction - Insert prolog/epilog code and replace abstract
+ /// frame indexes with appropriate references.
+ ///
+ bool runOnMachineFunction(MachineFunction &Fn) {
+ // Scan the function for modified caller saved registers and insert spill
+ // code for any caller saved registers that are modified. Also calculate
+ // the MaxCallFrameSize and HasCalls variables for the function's frame
+ // information and eliminates call frame pseudo instructions.
+ saveCallerSavedRegisters(Fn);
+
+ // Allow the target machine to make final modifications to the function
+ // before the frame layout is finalized.
+ Fn.getTarget().getRegisterInfo()->processFunctionBeforeFrameFinalized(Fn);
+
+ // Calculate actual frame offsets for all of the abstract stack objects...
+ calculateFrameObjectOffsets(Fn);
+
+ // Replace all MO_FrameIndex operands with physical register references
+ // and actual offsets.
+ //
+ replaceFrameIndices(Fn);
+
+ // Add prolog and epilog code to the function.
+ insertPrologEpilogCode(Fn);
+ return true;
+ }
+
+ private:
+ void saveCallerSavedRegisters(MachineFunction &Fn);
+ void calculateFrameObjectOffsets(MachineFunction &Fn);
+ void replaceFrameIndices(MachineFunction &Fn);
+ void insertPrologEpilogCode(MachineFunction &Fn);
+ };
+}
+
+/// createPrologEpilogCodeInserter - This function returns a pass that inserts
+/// prolog and epilog code, and eliminates abstract frame references.
+///
+Pass *createPrologEpilogCodeInserter() { return new PEI(); }
+
+
+/// saveCallerSavedRegisters - Scan the function for modified caller saved
+/// registers and insert spill code for any caller saved registers that are
+/// modified. Also calculate the MaxCallFrameSize and HasCalls variables for
+/// the function's frame information and eliminates call frame pseudo
+/// instructions.
+///
+void PEI::saveCallerSavedRegisters(MachineFunction &Fn) {
+ const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
+ const TargetFrameInfo &FrameInfo = Fn.getTarget().getFrameInfo();
+
+ // Get the callee saved register list...
+ const unsigned *CSRegs = RegInfo->getCalleeSaveRegs();
+
+ // Get the function call frame set-up and tear-down instruction opcode
+ int FrameSetupOpcode = RegInfo->getCallFrameSetupOpcode();
+ int FrameDestroyOpcode = RegInfo->getCallFrameDestroyOpcode();
+
+ // Early exit for targets which have no callee saved registers and no call
+ // frame setup/destroy pseudo instructions.
+ if ((CSRegs == 0 || CSRegs[0] == 0) &&
+ FrameSetupOpcode == -1 && FrameDestroyOpcode == -1)
+ return;
+
+ // This bitset contains an entry for each physical register for the target...
+ std::vector<bool> ModifiedRegs(MRegisterInfo::FirstVirtualRegister);
+ unsigned MaxCallFrameSize = 0;
+ bool HasCalls = false;
+
+ for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
+ for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); )
+ if ((*I)->getOpcode() == FrameSetupOpcode ||
+ (*I)->getOpcode() == FrameDestroyOpcode) {
+ assert((*I)->getNumOperands() == 1 && "Call Frame Setup/Destroy Pseudo"
+ " instructions should have a single immediate argument!");
+ unsigned Size = (*I)->getOperand(0).getImmedValue();
+ if (Size > MaxCallFrameSize) MaxCallFrameSize = Size;
+ HasCalls = true;
+ RegInfo->eliminateCallFramePseudoInstr(Fn, *BB, I);
+ } else {
+ for (unsigned i = 0, e = (*I)->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = (*I)->getOperand(i);
+ assert(!MO.isVirtualRegister() &&
+ "Register allocation must be performed!");
+ if (MO.isPhysicalRegister() && MO.opIsDef())
+ ModifiedRegs[MO.getReg()] = true; // Register is modified
+ }
+ ++I;
+ }
+
+ FunctionFrameInfo *FFI = Fn.getFrameInfo();
+ FFI->setHasCalls(HasCalls);
+ FFI->setMaxCallFrameSize(MaxCallFrameSize);
+
+ // Now figure out which *callee saved* registers are modified by the current
+ // function, thus needing to be saved and restored in the prolog/epilog.
+ //
+ std::vector<unsigned> RegsToSave;
+ for (unsigned i = 0; CSRegs[i]; ++i) {
+ unsigned Reg = CSRegs[i];
+ if (ModifiedRegs[Reg]) {
+ RegsToSave.push_back(Reg); // If modified register...
+ } else if (const unsigned *AliasSet = RegInfo->getAliasSet(Reg))
+ for (unsigned j = 0; AliasSet[j]; ++j) // Check alias registers too...
+ if (ModifiedRegs[AliasSet[j]]) {
+ RegsToSave.push_back(Reg);
+ break;
+ }
+ }
+
+ if (RegsToSave.empty())
+ return; // Early exit if no caller saved registers are modified!
+
+ // Now that we know which registers need to be saved and restored, allocate
+ // stack slots for them.
+ std::vector<int> StackSlots;
+ for (unsigned i = 0, e = RegsToSave.size(); i != e; ++i) {
+ const TargetRegisterClass *RC = RegInfo->getRegClass(RegsToSave[i]);
+ int FrameIdx = FFI->CreateStackObject(RC->getSize(), RC->getAlignment());
+ StackSlots.push_back(FrameIdx);
+ }
+
+ // Now that we have a stack slot for each register to be saved, insert spill
+ // code into the entry block...
+ MachineBasicBlock *MBB = Fn.begin();
+ MachineBasicBlock::iterator I = MBB->begin();
+ for (unsigned i = 0, e = RegsToSave.size(); i != e; ++i) {
+ const TargetRegisterClass *RC = RegInfo->getRegClass(RegsToSave[i]);
+
+ // Insert the spill to the stack frame...
+ RegInfo->storeRegToStackSlot(*MBB, I, RegsToSave[i], StackSlots[i], RC);
+ }
+
+ // Add code to restore the callee-save registers in each exiting block.
+ const MachineInstrInfo &MII = Fn.getTarget().getInstrInfo();
+ for (MachineFunction::iterator FI = Fn.begin(), E = Fn.end(); FI != E; ++FI) {
+ // If last instruction is a return instruction, add an epilogue
+ if (MII.isReturn(FI->back()->getOpcode())) {
+ MBB = FI; I = MBB->end()-1;
+
+ for (unsigned i = 0, e = RegsToSave.size(); i != e; ++i) {
+ const TargetRegisterClass *RC = RegInfo->getRegClass(RegsToSave[i]);
+ RegInfo->loadRegFromStackSlot(*MBB, I, RegsToSave[i],StackSlots[i], RC);
+ --I; // Insert in reverse order
+ }
+ }
+ }
+}
+
+
+/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
+/// abstract stack objects...
+///
+void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
+ const TargetFrameInfo &TFI = Fn.getTarget().getFrameInfo();
+
+ bool StackGrowsDown =
+ TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
+ assert(StackGrowsDown && "Only tested on stack down growing targets!");
+
+ // Loop over all of the stack objects, assigning sequential addresses...
+ FunctionFrameInfo *FFI = Fn.getFrameInfo();
+
+ // Start at the beginning of the local area...
+ int Offset = -TFI.getOffsetOfLocalArea();
+ for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) {
+ Offset += FFI->getObjectSize(i); // Allocate Size bytes...
+
+ unsigned Align = FFI->getObjectAlignment(i);
+ Offset = (Offset+Align-1)/Align*Align; // Adjust to Alignment boundary...
+
+ FFI->setObjectOffset(i, -Offset); // Set the computed offset
+ }
+
+ // Align the final stack pointer offset...
+ unsigned StackAlign = TFI.getStackAlignment();
+ Offset = (Offset+StackAlign-1)/StackAlign*StackAlign;
+
+ // Set the final value of the stack pointer...
+ FFI->setStackSize(Offset);
+}
+
+
+/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
+/// register references and actual offsets.
+///
+void PEI::replaceFrameIndices(MachineFunction &Fn) {
+ if (!Fn.getFrameInfo()->hasStackObjects()) return; // Nothing to do?
+
+ const TargetMachine &TM = Fn.getTarget();
+ assert(TM.getRegisterInfo() && "TM::getRegisterInfo() must be implemented!");
+ const MRegisterInfo &MRI = *TM.getRegisterInfo();
+
+ for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
+ for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
+ for (unsigned i = 0, e = (*I)->getNumOperands(); i != e; ++i)
+ if ((*I)->getOperand(i).isFrameIndex()) {
+ // If this instruction has a FrameIndex operand, we need to use that
+ // target machine register info object to eliminate it.
+ MRI.eliminateFrameIndex(Fn, I);
+ break;
+ }
+}
+
+
+/// insertPrologEpilogCode - Scan the function for modified caller saved
+/// registers, insert spill code for these caller saved registers, then add
+/// prolog and epilog code to the function.
+///
+void PEI::insertPrologEpilogCode(MachineFunction &Fn) {
+ // Add prologue to the function...
+ Fn.getTarget().getRegisterInfo()->emitPrologue(Fn);
+
+ // Add epilogue to restore the callee-save registers in each exiting block
+ const MachineInstrInfo &MII = Fn.getTarget().getInstrInfo();
+ for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
+ // If last instruction is a return instruction, add an epilogue
+ if (MII.isReturn(I->back()->getOpcode()))
+ Fn.getTarget().getRegisterInfo()->emitEpilogue(Fn, *I);
+ }
+}