mirror of
https://github.com/c64scene-ar/llvm-6502.git
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a844bdeab3
Added ISD::DECLARE node type to represent llvm.dbg.declare intrinsic. Now the intrinsic calls are lowered into a SDNode and lives on through out the codegen passes. For now, since all the debugging information recording is done at isel time, when a ISD::DECLARE node is selected, it has the side effect of also recording the variable. This is a short term solution that should be fixed in time. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46659 91177308-0d34-0410-b5e6-96231b3b80d8
553 lines
21 KiB
C++
553 lines
21 KiB
C++
//===-- PrologEpilogInserter.cpp - Insert Prolog/Epilog code in function --===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass is responsible for finalizing the functions frame layout, saving
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// callee saved registers, and for emitting prolog & epilog code for the
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// function.
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//
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// This pass must be run after register allocation. After this pass is
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// executed, it is illegal to construct MO_FrameIndex operands.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/RegisterScavenging.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/MRegisterInfo.h"
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#include "llvm/Target/TargetFrameInfo.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/ADT/STLExtras.h"
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#include <climits>
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using namespace llvm;
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namespace {
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struct VISIBILITY_HIDDEN PEI : public MachineFunctionPass {
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static char ID;
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PEI() : MachineFunctionPass((intptr_t)&ID) {}
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const char *getPassName() const {
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return "Prolog/Epilog Insertion & Frame Finalization";
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}
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/// runOnMachineFunction - Insert prolog/epilog code and replace abstract
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/// frame indexes with appropriate references.
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///
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bool runOnMachineFunction(MachineFunction &Fn) {
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const MRegisterInfo *MRI = Fn.getTarget().getRegisterInfo();
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RS = MRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : NULL;
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// Get MachineModuleInfo so that we can track the construction of the
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// frame.
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if (MachineModuleInfo *MMI = getAnalysisToUpdate<MachineModuleInfo>())
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Fn.getFrameInfo()->setMachineModuleInfo(MMI);
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// Allow the target machine to make some adjustments to the function
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// e.g. UsedPhysRegs before calculateCalleeSavedRegisters.
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MRI->processFunctionBeforeCalleeSavedScan(Fn, RS);
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// Scan the function for modified callee saved registers and insert spill
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// code for any callee saved registers that are modified. Also calculate
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// the MaxCallFrameSize and HasCalls variables for the function's frame
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// information and eliminates call frame pseudo instructions.
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calculateCalleeSavedRegisters(Fn);
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// Add the code to save and restore the callee saved registers
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saveCalleeSavedRegisters(Fn);
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// Allow the target machine to make final modifications to the function
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// before the frame layout is finalized.
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Fn.getTarget().getRegisterInfo()->processFunctionBeforeFrameFinalized(Fn);
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// Calculate actual frame offsets for all of the abstract stack objects...
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calculateFrameObjectOffsets(Fn);
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// Add prolog and epilog code to the function. This function is required
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// to align the stack frame as necessary for any stack variables or
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// called functions. Because of this, calculateCalleeSavedRegisters
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// must be called before this function in order to set the HasCalls
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// and MaxCallFrameSize variables.
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insertPrologEpilogCode(Fn);
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// Replace all MO_FrameIndex operands with physical register references
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// and actual offsets.
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//
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replaceFrameIndices(Fn);
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delete RS;
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return true;
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}
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private:
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RegScavenger *RS;
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// MinCSFrameIndex, MaxCSFrameIndex - Keeps the range of callee saved
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// stack frame indexes.
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unsigned MinCSFrameIndex, MaxCSFrameIndex;
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void calculateCalleeSavedRegisters(MachineFunction &Fn);
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void saveCalleeSavedRegisters(MachineFunction &Fn);
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void calculateFrameObjectOffsets(MachineFunction &Fn);
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void replaceFrameIndices(MachineFunction &Fn);
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void insertPrologEpilogCode(MachineFunction &Fn);
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};
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char PEI::ID = 0;
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}
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/// createPrologEpilogCodeInserter - This function returns a pass that inserts
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/// prolog and epilog code, and eliminates abstract frame references.
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///
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FunctionPass *llvm::createPrologEpilogCodeInserter() { return new PEI(); }
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/// calculateCalleeSavedRegisters - Scan the function for modified callee saved
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/// registers. Also calculate the MaxCallFrameSize and HasCalls variables for
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/// the function's frame information and eliminates call frame pseudo
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/// instructions.
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///
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void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
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const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
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const TargetFrameInfo *TFI = Fn.getTarget().getFrameInfo();
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// Get the callee saved register list...
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const unsigned *CSRegs = RegInfo->getCalleeSavedRegs(&Fn);
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// Get the function call frame set-up and tear-down instruction opcode
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int FrameSetupOpcode = RegInfo->getCallFrameSetupOpcode();
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int FrameDestroyOpcode = RegInfo->getCallFrameDestroyOpcode();
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// These are used to keep track the callee-save area. Initialize them.
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MinCSFrameIndex = INT_MAX;
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MaxCSFrameIndex = 0;
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// Early exit for targets which have no callee saved registers and no call
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// frame setup/destroy pseudo instructions.
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if ((CSRegs == 0 || CSRegs[0] == 0) &&
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FrameSetupOpcode == -1 && FrameDestroyOpcode == -1)
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return;
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unsigned MaxCallFrameSize = 0;
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bool HasCalls = false;
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std::vector<MachineBasicBlock::iterator> FrameSDOps;
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for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
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for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
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if (I->getOpcode() == FrameSetupOpcode ||
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I->getOpcode() == FrameDestroyOpcode) {
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assert(I->getNumOperands() >= 1 && "Call Frame Setup/Destroy Pseudo"
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" instructions should have a single immediate argument!");
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unsigned Size = I->getOperand(0).getImm();
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if (Size > MaxCallFrameSize) MaxCallFrameSize = Size;
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HasCalls = true;
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FrameSDOps.push_back(I);
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}
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MachineFrameInfo *FFI = Fn.getFrameInfo();
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FFI->setHasCalls(HasCalls);
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FFI->setMaxCallFrameSize(MaxCallFrameSize);
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for (unsigned i = 0, e = FrameSDOps.size(); i != e; ++i) {
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MachineBasicBlock::iterator I = FrameSDOps[i];
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// If call frames are not being included as part of the stack frame,
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// and there is no dynamic allocation (therefore referencing frame slots
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// off sp), leave the pseudo ops alone. We'll eliminate them later.
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if (RegInfo->hasReservedCallFrame(Fn) || RegInfo->hasFP(Fn))
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RegInfo->eliminateCallFramePseudoInstr(Fn, *I->getParent(), I);
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}
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// Now figure out which *callee saved* registers are modified by the current
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// function, thus needing to be saved and restored in the prolog/epilog.
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//
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const TargetRegisterClass* const *CSRegClasses =
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RegInfo->getCalleeSavedRegClasses(&Fn);
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std::vector<CalleeSavedInfo> CSI;
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for (unsigned i = 0; CSRegs[i]; ++i) {
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unsigned Reg = CSRegs[i];
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if (Fn.getRegInfo().isPhysRegUsed(Reg)) {
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// If the reg is modified, save it!
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CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
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} else {
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for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
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*AliasSet; ++AliasSet) { // Check alias registers too.
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if (Fn.getRegInfo().isPhysRegUsed(*AliasSet)) {
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CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
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break;
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}
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}
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}
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}
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if (CSI.empty())
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return; // Early exit if no callee saved registers are modified!
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unsigned NumFixedSpillSlots;
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const std::pair<unsigned,int> *FixedSpillSlots =
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TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
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// Now that we know which registers need to be saved and restored, allocate
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// stack slots for them.
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for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
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unsigned Reg = CSI[i].getReg();
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const TargetRegisterClass *RC = CSI[i].getRegClass();
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// Check to see if this physreg must be spilled to a particular stack slot
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// on this target.
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const std::pair<unsigned,int> *FixedSlot = FixedSpillSlots;
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while (FixedSlot != FixedSpillSlots+NumFixedSpillSlots &&
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FixedSlot->first != Reg)
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++FixedSlot;
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int FrameIdx;
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if (FixedSlot == FixedSpillSlots+NumFixedSpillSlots) {
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// Nope, just spill it anywhere convenient.
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unsigned Align = RC->getAlignment();
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unsigned StackAlign = TFI->getStackAlignment();
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// We may not be able to sastify the desired alignment specification of
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// the TargetRegisterClass if the stack alignment is smaller. Use the min.
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Align = std::min(Align, StackAlign);
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FrameIdx = FFI->CreateStackObject(RC->getSize(), Align);
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if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx;
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if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx;
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} else {
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// Spill it to the stack where we must.
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FrameIdx = FFI->CreateFixedObject(RC->getSize(), FixedSlot->second);
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}
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CSI[i].setFrameIdx(FrameIdx);
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}
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FFI->setCalleeSavedInfo(CSI);
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}
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/// saveCalleeSavedRegisters - Insert spill code for any callee saved registers
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/// that are modified in the function.
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///
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void PEI::saveCalleeSavedRegisters(MachineFunction &Fn) {
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// Get callee saved register information.
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MachineFrameInfo *FFI = Fn.getFrameInfo();
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const std::vector<CalleeSavedInfo> &CSI = FFI->getCalleeSavedInfo();
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// Early exit if no callee saved registers are modified!
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if (CSI.empty())
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return;
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const TargetInstrInfo &TII = *Fn.getTarget().getInstrInfo();
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// Now that we have a stack slot for each register to be saved, insert spill
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// code into the entry block.
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MachineBasicBlock *MBB = Fn.begin();
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MachineBasicBlock::iterator I = MBB->begin();
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if (!TII.spillCalleeSavedRegisters(*MBB, I, CSI)) {
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for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
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// Add the callee-saved register as live-in. It's killed at the spill.
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MBB->addLiveIn(CSI[i].getReg());
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// Insert the spill to the stack frame.
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TII.storeRegToStackSlot(*MBB, I, CSI[i].getReg(), true,
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CSI[i].getFrameIdx(), CSI[i].getRegClass());
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}
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}
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// Add code to restore the callee-save registers in each exiting block.
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for (MachineFunction::iterator FI = Fn.begin(), E = Fn.end(); FI != E; ++FI)
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// If last instruction is a return instruction, add an epilogue.
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if (!FI->empty() && FI->back().getDesc().isReturn()) {
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MBB = FI;
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I = MBB->end(); --I;
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// Skip over all terminator instructions, which are part of the return
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// sequence.
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MachineBasicBlock::iterator I2 = I;
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while (I2 != MBB->begin() && (--I2)->getDesc().isTerminator())
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I = I2;
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bool AtStart = I == MBB->begin();
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MachineBasicBlock::iterator BeforeI = I;
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if (!AtStart)
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--BeforeI;
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// Restore all registers immediately before the return and any terminators
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// that preceed it.
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if (!TII.restoreCalleeSavedRegisters(*MBB, I, CSI)) {
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for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
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TII.loadRegFromStackSlot(*MBB, I, CSI[i].getReg(),
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CSI[i].getFrameIdx(),
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CSI[i].getRegClass());
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assert(I != MBB->begin() &&
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"loadRegFromStackSlot didn't insert any code!");
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// Insert in reverse order. loadRegFromStackSlot can insert multiple
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// instructions.
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if (AtStart)
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I = MBB->begin();
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else {
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I = BeforeI;
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++I;
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}
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}
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}
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}
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}
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/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
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/// abstract stack objects.
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///
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void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
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const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo();
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bool StackGrowsDown =
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TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
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// Loop over all of the stack objects, assigning sequential addresses...
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MachineFrameInfo *FFI = Fn.getFrameInfo();
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unsigned MaxAlign = 0;
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// Start at the beginning of the local area.
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// The Offset is the distance from the stack top in the direction
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// of stack growth -- so it's always positive.
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int64_t Offset = TFI.getOffsetOfLocalArea();
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if (StackGrowsDown)
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Offset = -Offset;
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assert(Offset >= 0
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&& "Local area offset should be in direction of stack growth");
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// If there are fixed sized objects that are preallocated in the local area,
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// non-fixed objects can't be allocated right at the start of local area.
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// We currently don't support filling in holes in between fixed sized objects,
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// so we adjust 'Offset' to point to the end of last fixed sized
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// preallocated object.
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for (int i = FFI->getObjectIndexBegin(); i != 0; ++i) {
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int64_t FixedOff;
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if (StackGrowsDown) {
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// The maximum distance from the stack pointer is at lower address of
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// the object -- which is given by offset. For down growing stack
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// the offset is negative, so we negate the offset to get the distance.
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FixedOff = -FFI->getObjectOffset(i);
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} else {
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// The maximum distance from the start pointer is at the upper
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// address of the object.
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FixedOff = FFI->getObjectOffset(i) + FFI->getObjectSize(i);
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}
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if (FixedOff > Offset) Offset = FixedOff;
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}
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// First assign frame offsets to stack objects that are used to spill
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// callee saved registers.
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if (StackGrowsDown) {
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for (unsigned i = MinCSFrameIndex; i <= MaxCSFrameIndex; ++i) {
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// If stack grows down, we need to add size of find the lowest
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// address of the object.
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Offset += FFI->getObjectSize(i);
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unsigned Align = FFI->getObjectAlignment(i);
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// If the alignment of this object is greater than that of the stack, then
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// increase the stack alignment to match.
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MaxAlign = std::max(MaxAlign, Align);
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// Adjust to alignment boundary
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Offset = (Offset+Align-1)/Align*Align;
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FFI->setObjectOffset(i, -Offset); // Set the computed offset
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}
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} else {
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for (unsigned i = MaxCSFrameIndex; i >= MinCSFrameIndex; --i) {
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unsigned Align = FFI->getObjectAlignment(i);
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// If the alignment of this object is greater than that of the stack, then
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// increase the stack alignment to match.
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MaxAlign = std::max(MaxAlign, Align);
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// Adjust to alignment boundary
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Offset = (Offset+Align-1)/Align*Align;
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FFI->setObjectOffset(i, Offset);
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Offset += FFI->getObjectSize(i);
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}
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}
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// Make sure the special register scavenging spill slot is closest to the
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// frame pointer if a frame pointer is required.
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const MRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
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if (RS && RegInfo->hasFP(Fn)) {
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int SFI = RS->getScavengingFrameIndex();
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if (SFI >= 0) {
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// If stack grows down, we need to add size of the lowest
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// address of the object.
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if (StackGrowsDown)
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Offset += FFI->getObjectSize(SFI);
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unsigned Align = FFI->getObjectAlignment(SFI);
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// Adjust to alignment boundary
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Offset = (Offset+Align-1)/Align*Align;
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if (StackGrowsDown) {
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FFI->setObjectOffset(SFI, -Offset); // Set the computed offset
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} else {
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FFI->setObjectOffset(SFI, Offset);
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Offset += FFI->getObjectSize(SFI);
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}
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}
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}
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// Then assign frame offsets to stack objects that are not used to spill
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// callee saved registers.
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for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) {
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if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
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continue;
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if (RS && (int)i == RS->getScavengingFrameIndex())
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continue;
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// If stack grows down, we need to add size of find the lowest
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// address of the object.
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if (StackGrowsDown)
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Offset += FFI->getObjectSize(i);
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unsigned Align = FFI->getObjectAlignment(i);
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// If the alignment of this object is greater than that of the stack, then
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// increase the stack alignment to match.
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MaxAlign = std::max(MaxAlign, Align);
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// Adjust to alignment boundary
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Offset = (Offset+Align-1)/Align*Align;
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if (StackGrowsDown) {
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FFI->setObjectOffset(i, -Offset); // Set the computed offset
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} else {
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FFI->setObjectOffset(i, Offset);
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Offset += FFI->getObjectSize(i);
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}
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}
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// Make sure the special register scavenging spill slot is closest to the
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// stack pointer.
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if (RS && !RegInfo->hasFP(Fn)) {
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int SFI = RS->getScavengingFrameIndex();
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if (SFI >= 0) {
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// If stack grows down, we need to add size of find the lowest
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// address of the object.
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if (StackGrowsDown)
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Offset += FFI->getObjectSize(SFI);
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unsigned Align = FFI->getObjectAlignment(SFI);
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// Adjust to alignment boundary
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Offset = (Offset+Align-1)/Align*Align;
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if (StackGrowsDown) {
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FFI->setObjectOffset(SFI, -Offset); // Set the computed offset
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} else {
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FFI->setObjectOffset(SFI, Offset);
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Offset += FFI->getObjectSize(SFI);
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}
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}
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}
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// Round up the size to a multiple of the alignment, but only if there are
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// calls or alloca's in the function. This ensures that any calls to
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// subroutines have their stack frames suitable aligned.
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if (!RegInfo->targetHandlesStackFrameRounding() &&
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(FFI->hasCalls() || FFI->hasVarSizedObjects())) {
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// If we have reserved argument space for call sites in the function
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// immediately on entry to the current function, count it as part of the
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// overall stack size.
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if (RegInfo->hasReservedCallFrame(Fn))
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Offset += FFI->getMaxCallFrameSize();
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unsigned AlignMask = TFI.getStackAlignment() - 1;
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Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
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|
}
|
|
|
|
// Update frame info to pretend that this is part of the stack...
|
|
FFI->setStackSize(Offset+TFI.getOffsetOfLocalArea());
|
|
|
|
// Remember the required stack alignment in case targets need it to perform
|
|
// dynamic stack alignment.
|
|
assert(FFI->getMaxAlignment() == MaxAlign &&
|
|
"Stack alignment calculation broken!");
|
|
}
|
|
|
|
|
|
/// insertPrologEpilogCode - Scan the function for modified callee saved
|
|
/// registers, insert spill code for these callee 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
|
|
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
|
|
// If last instruction is a return instruction, add an epilogue
|
|
if (!I->empty() && I->back().getDesc().isReturn())
|
|
Fn.getTarget().getRegisterInfo()->emitEpilogue(Fn, *I);
|
|
}
|
|
}
|
|
|
|
|
|
/// 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();
|
|
const TargetFrameInfo *TFI = TM.getFrameInfo();
|
|
bool StackGrowsDown =
|
|
TFI->getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
|
|
int FrameSetupOpcode = MRI.getCallFrameSetupOpcode();
|
|
int FrameDestroyOpcode = MRI.getCallFrameDestroyOpcode();
|
|
|
|
for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
|
|
int SPAdj = 0; // SP offset due to call frame setup / destroy.
|
|
if (RS) RS->enterBasicBlock(BB);
|
|
for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
|
|
MachineInstr *MI = I;
|
|
|
|
if (I->getOpcode() == FrameSetupOpcode ||
|
|
I->getOpcode() == FrameDestroyOpcode) {
|
|
// Remember how much SP has been adjustment to create the call frame.
|
|
int Size = I->getOperand(0).getImm();
|
|
if ((!StackGrowsDown && I->getOpcode() == FrameSetupOpcode) ||
|
|
(StackGrowsDown && I->getOpcode() == FrameDestroyOpcode))
|
|
Size = -Size;
|
|
SPAdj += Size;
|
|
MachineBasicBlock::iterator PrevI = prior(I);
|
|
MRI.eliminateCallFramePseudoInstr(Fn, *BB, I);
|
|
// Visit the instructions created by eliminateCallFramePseudoInstr().
|
|
I = next(PrevI);
|
|
MI = NULL;
|
|
} else if (I->getOpcode() == TargetInstrInfo::DECLARE)
|
|
// Ignore it.
|
|
I++;
|
|
else {
|
|
I++;
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
|
|
if (MI->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(MI, SPAdj, RS);
|
|
|
|
// Revisit the instruction in full. Some instructions (e.g. inline
|
|
// asm instructions) can have multiple frame indices.
|
|
--I;
|
|
MI = 0;
|
|
break;
|
|
}
|
|
}
|
|
// Update register states.
|
|
if (RS && MI) RS->forward(MI);
|
|
}
|
|
assert(SPAdj == 0 && "Unbalanced call frame setup / destroy pairs?");
|
|
}
|
|
}
|