path: root/utils/TableGen/CodeGenRegisters.cpp

//===- CodeGenRegisters.cpp - Register and RegisterClass Info -------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines structures to encapsulate information gleaned from the
// target register and register class definitions.
//
//===----------------------------------------------------------------------===//

#include "CodeGenRegisters.h"
#include "CodeGenTarget.h"
#include "Error.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"

using namespace llvm;

//===----------------------------------------------------------------------===//
//                              CodeGenRegister
//===----------------------------------------------------------------------===//

CodeGenRegister::CodeGenRegister(Record *R, unsigned Enum)
  : TheDef(R),
    EnumValue(Enum),
    CostPerUse(R->getValueAsInt("CostPerUse")),
    SubRegsComplete(false)
{}

const std::string &CodeGenRegister::getName() const {
  return TheDef->getName();
}

namespace {
  struct Orphan {
    CodeGenRegister *SubReg;
    Record *First, *Second;
    Orphan(CodeGenRegister *r, Record *a, Record *b)
      : SubReg(r), First(a), Second(b) {}
  };
}

const CodeGenRegister::SubRegMap &
CodeGenRegister::getSubRegs(CodeGenRegBank &RegBank) {
  // Only compute this map once.
  if (SubRegsComplete)
    return SubRegs;
  SubRegsComplete = true;

  std::vector<Record*> SubList = TheDef->getValueAsListOfDefs("SubRegs");
  std::vector<Record*> Indices = TheDef->getValueAsListOfDefs("SubRegIndices");
  if (SubList.size() != Indices.size())
    throw TGError(TheDef->getLoc(), "Register " + getName() +
                  " SubRegIndices doesn't match SubRegs");

  // First insert the direct subregs and make sure they are fully indexed.
  for (unsigned i = 0, e = SubList.size(); i != e; ++i) {
    CodeGenRegister *SR = RegBank.getReg(SubList[i]);
    if (!SubRegs.insert(std::make_pair(Indices[i], SR)).second)
      throw TGError(TheDef->getLoc(), "SubRegIndex " + Indices[i]->getName() +
                    " appears twice in Register " + getName());
  }

  // Keep track of inherited subregs and how they can be reached.
  SmallVector<Orphan, 8> Orphans;

  // Clone inherited subregs and place duplicate entries on Orphans.
  // Here the order is important - earlier subregs take precedence.
  for (unsigned i = 0, e = SubList.size(); i != e; ++i) {
    CodeGenRegister *SR = RegBank.getReg(SubList[i]);
    const SubRegMap &Map = SR->getSubRegs(RegBank);

    // Add this as a super-register of SR now all sub-registers are in the list.
    // This creates a topological ordering, the exact order depends on the
    // order getSubRegs is called on all registers.
    SR->SuperRegs.push_back(this);

    for (SubRegMap::const_iterator SI = Map.begin(), SE = Map.end(); SI != SE;
         ++SI) {
      if (!SubRegs.insert(*SI).second)
        Orphans.push_back(Orphan(SI->second, Indices[i], SI->first));

      // Noop sub-register indexes are possible, so avoid duplicates.
      if (SI->second != SR)
        SI->second->SuperRegs.push_back(this);
    }
  }

  // Process the composites.
  ListInit *Comps = TheDef->getValueAsListInit("CompositeIndices");
  for (unsigned i = 0, e = Comps->size(); i != e; ++i) {
    DagInit *Pat = dynamic_cast<DagInit*>(Comps->getElement(i));
    if (!Pat)
      throw TGError(TheDef->getLoc(), "Invalid dag '" +
                    Comps->getElement(i)->getAsString() +
                    "' in CompositeIndices");
    DefInit *BaseIdxInit = dynamic_cast<DefInit*>(Pat->getOperator());
    if (!BaseIdxInit || !BaseIdxInit->getDef()->isSubClassOf("SubRegIndex"))
      throw TGError(TheDef->getLoc(), "Invalid SubClassIndex in " +
                    Pat->getAsString());

    // Resolve list of subreg indices into R2.
    CodeGenRegister *R2 = this;
    for (DagInit::const_arg_iterator di = Pat->arg_begin(),
         de = Pat->arg_end(); di != de; ++di) {
      DefInit *IdxInit = dynamic_cast<DefInit*>(*di);
      if (!IdxInit || !IdxInit->getDef()->isSubClassOf("SubRegIndex"))
        throw TGError(TheDef->getLoc(), "Invalid SubClassIndex in " +
                      Pat->getAsString());
      const SubRegMap &R2Subs = R2->getSubRegs(RegBank);
      SubRegMap::const_iterator ni = R2Subs.find(IdxInit->getDef());
      if (ni == R2Subs.end())
        throw TGError(TheDef->getLoc(), "Composite " + Pat->getAsString() +
                      " refers to bad index in " + R2->getName());
      R2 = ni->second;
    }

    // Insert composite index. Allow overriding inherited indices etc.
    SubRegs[BaseIdxInit->getDef()] = R2;

    // R2 is no longer an orphan.
    for (unsigned j = 0, je = Orphans.size(); j != je; ++j)
      if (Orphans[j].SubReg == R2)
          Orphans[j].SubReg = 0;
  }

  // Now Orphans contains the inherited subregisters without a direct index.
  // Create inferred indexes for all missing entries.
  for (unsigned i = 0, e = Orphans.size(); i != e; ++i) {
    Orphan &O = Orphans[i];
    if (!O.SubReg)
      continue;
    SubRegs[RegBank.getCompositeSubRegIndex(O.First, O.Second, true)] =
      O.SubReg;
  }
  return SubRegs;
}

void
CodeGenRegister::addSubRegsPreOrder(SetVector<CodeGenRegister*> &OSet) const {
  assert(SubRegsComplete && "Must precompute sub-registers");
  std::vector<Record*> Indices = TheDef->getValueAsListOfDefs("SubRegIndices");
  for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
    CodeGenRegister *SR = SubRegs.find(Indices[i])->second;
    if (OSet.insert(SR))
      SR->addSubRegsPreOrder(OSet);
  }
}

//===----------------------------------------------------------------------===//
//                               RegisterTuples
//===----------------------------------------------------------------------===//

// A RegisterTuples def is used to generate pseudo-registers from lists of
// sub-registers. We provide a SetTheory expander class that returns the new
// registers.
namespace {
struct TupleExpander : SetTheory::Expander {
  void expand(SetTheory &ST, Record *Def, SetTheory::RecSet &Elts) {