llvm-6502/lib/CodeGen/TargetRegisterInfo.cpp
2013-05-24 22:23:49 +00:00

288 lines
10 KiB
C++

//===- TargetRegisterInfo.cpp - Target Register Information Implementation ===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the TargetRegisterInfo interface.
//
//===----------------------------------------------------------------------===//
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
TargetRegisterInfo::TargetRegisterInfo(const TargetRegisterInfoDesc *ID,
regclass_iterator RCB, regclass_iterator RCE,
const char *const *SRINames,
const unsigned *SRILaneMasks,
unsigned SRICoveringLanes)
: InfoDesc(ID), SubRegIndexNames(SRINames),
SubRegIndexLaneMasks(SRILaneMasks),
RegClassBegin(RCB), RegClassEnd(RCE),
CoveringLanes(SRICoveringLanes) {
}
TargetRegisterInfo::~TargetRegisterInfo() {}
void PrintReg::print(raw_ostream &OS) const {
if (!Reg)
OS << "%noreg";
else if (TargetRegisterInfo::isStackSlot(Reg))
OS << "SS#" << TargetRegisterInfo::stackSlot2Index(Reg);
else if (TargetRegisterInfo::isVirtualRegister(Reg))
OS << "%vreg" << TargetRegisterInfo::virtReg2Index(Reg);
else if (TRI && Reg < TRI->getNumRegs())
OS << '%' << TRI->getName(Reg);
else
OS << "%physreg" << Reg;
if (SubIdx) {
if (TRI)
OS << ':' << TRI->getSubRegIndexName(SubIdx);
else
OS << ":sub(" << SubIdx << ')';
}
}
void PrintRegUnit::print(raw_ostream &OS) const {
// Generic printout when TRI is missing.
if (!TRI) {
OS << "Unit~" << Unit;
return;
}
// Check for invalid register units.
if (Unit >= TRI->getNumRegUnits()) {
OS << "BadUnit~" << Unit;
return;
}
// Normal units have at least one root.
MCRegUnitRootIterator Roots(Unit, TRI);
assert(Roots.isValid() && "Unit has no roots.");
OS << TRI->getName(*Roots);
for (++Roots; Roots.isValid(); ++Roots)
OS << '~' << TRI->getName(*Roots);
}
/// getAllocatableClass - Return the maximal subclass of the given register
/// class that is alloctable, or NULL.
const TargetRegisterClass *
TargetRegisterInfo::getAllocatableClass(const TargetRegisterClass *RC) const {
if (!RC || RC->isAllocatable())
return RC;
const unsigned *SubClass = RC->getSubClassMask();
for (unsigned Base = 0, BaseE = getNumRegClasses();
Base < BaseE; Base += 32) {
unsigned Idx = Base;
for (unsigned Mask = *SubClass++; Mask; Mask >>= 1) {
unsigned Offset = countTrailingZeros(Mask);
const TargetRegisterClass *SubRC = getRegClass(Idx + Offset);
if (SubRC->isAllocatable())
return SubRC;
Mask >>= Offset;
Idx += Offset + 1;
}
}
return NULL;
}
/// getMinimalPhysRegClass - Returns the Register Class of a physical
/// register of the given type, picking the most sub register class of
/// the right type that contains this physreg.
const TargetRegisterClass *
TargetRegisterInfo::getMinimalPhysRegClass(unsigned reg, EVT VT) const {
assert(isPhysicalRegister(reg) && "reg must be a physical register");
// Pick the most sub register class of the right type that contains
// this physreg.
const TargetRegisterClass* BestRC = 0;
for (regclass_iterator I = regclass_begin(), E = regclass_end(); I != E; ++I){
const TargetRegisterClass* RC = *I;
if ((VT == MVT::Other || RC->hasType(VT)) && RC->contains(reg) &&
(!BestRC || BestRC->hasSubClass(RC)))
BestRC = RC;
}
assert(BestRC && "Couldn't find the register class");
return BestRC;
}
/// getAllocatableSetForRC - Toggle the bits that represent allocatable
/// registers for the specific register class.
static void getAllocatableSetForRC(const MachineFunction &MF,
const TargetRegisterClass *RC, BitVector &R){
assert(RC->isAllocatable() && "invalid for nonallocatable sets");
ArrayRef<uint16_t> Order = RC->getRawAllocationOrder(MF);
for (unsigned i = 0; i != Order.size(); ++i)
R.set(Order[i]);
}
BitVector TargetRegisterInfo::getAllocatableSet(const MachineFunction &MF,
const TargetRegisterClass *RC) const {
BitVector Allocatable(getNumRegs());
if (RC) {
// A register class with no allocatable subclass returns an empty set.
const TargetRegisterClass *SubClass = getAllocatableClass(RC);
if (SubClass)
getAllocatableSetForRC(MF, SubClass, Allocatable);
} else {
for (TargetRegisterInfo::regclass_iterator I = regclass_begin(),
E = regclass_end(); I != E; ++I)
if ((*I)->isAllocatable())
getAllocatableSetForRC(MF, *I, Allocatable);
}
// Mask out the reserved registers
BitVector Reserved = getReservedRegs(MF);
Allocatable &= Reserved.flip();
return Allocatable;
}
static inline
const TargetRegisterClass *firstCommonClass(const uint32_t *A,
const uint32_t *B,
const TargetRegisterInfo *TRI) {
for (unsigned I = 0, E = TRI->getNumRegClasses(); I < E; I += 32)
if (unsigned Common = *A++ & *B++)
return TRI->getRegClass(I + countTrailingZeros(Common));
return 0;
}
const TargetRegisterClass *
TargetRegisterInfo::getCommonSubClass(const TargetRegisterClass *A,
const TargetRegisterClass *B) const {
// First take care of the trivial cases.
if (A == B)
return A;
if (!A || !B)
return 0;
// Register classes are ordered topologically, so the largest common
// sub-class it the common sub-class with the smallest ID.
return firstCommonClass(A->getSubClassMask(), B->getSubClassMask(), this);
}
const TargetRegisterClass *
TargetRegisterInfo::getMatchingSuperRegClass(const TargetRegisterClass *A,
const TargetRegisterClass *B,
unsigned Idx) const {
assert(A && B && "Missing register class");
assert(Idx && "Bad sub-register index");
// Find Idx in the list of super-register indices.
for (SuperRegClassIterator RCI(B, this); RCI.isValid(); ++RCI)
if (RCI.getSubReg() == Idx)
// The bit mask contains all register classes that are projected into B
// by Idx. Find a class that is also a sub-class of A.
return firstCommonClass(RCI.getMask(), A->getSubClassMask(), this);
return 0;
}
const TargetRegisterClass *TargetRegisterInfo::
getCommonSuperRegClass(const TargetRegisterClass *RCA, unsigned SubA,
const TargetRegisterClass *RCB, unsigned SubB,
unsigned &PreA, unsigned &PreB) const {
assert(RCA && SubA && RCB && SubB && "Invalid arguments");
// Search all pairs of sub-register indices that project into RCA and RCB
// respectively. This is quadratic, but usually the sets are very small. On
// most targets like X86, there will only be a single sub-register index
// (e.g., sub_16bit projecting into GR16).
//
// The worst case is a register class like DPR on ARM.
// We have indices dsub_0..dsub_7 projecting into that class.
//
// It is very common that one register class is a sub-register of the other.
// Arrange for RCA to be the larger register so the answer will be found in
// the first iteration. This makes the search linear for the most common
// case.
const TargetRegisterClass *BestRC = 0;
unsigned *BestPreA = &PreA;
unsigned *BestPreB = &PreB;
if (RCA->getSize() < RCB->getSize()) {
std::swap(RCA, RCB);
std::swap(SubA, SubB);
std::swap(BestPreA, BestPreB);
}
// Also terminate the search one we have found a register class as small as
// RCA.
unsigned MinSize = RCA->getSize();
for (SuperRegClassIterator IA(RCA, this, true); IA.isValid(); ++IA) {
unsigned FinalA = composeSubRegIndices(IA.getSubReg(), SubA);
for (SuperRegClassIterator IB(RCB, this, true); IB.isValid(); ++IB) {
// Check if a common super-register class exists for this index pair.
const TargetRegisterClass *RC =
firstCommonClass(IA.getMask(), IB.getMask(), this);
if (!RC || RC->getSize() < MinSize)
continue;
// The indexes must compose identically: PreA+SubA == PreB+SubB.
unsigned FinalB = composeSubRegIndices(IB.getSubReg(), SubB);
if (FinalA != FinalB)
continue;
// Is RC a better candidate than BestRC?
if (BestRC && RC->getSize() >= BestRC->getSize())
continue;
// Yes, RC is the smallest super-register seen so far.
BestRC = RC;
*BestPreA = IA.getSubReg();
*BestPreB = IB.getSubReg();
// Bail early if we reached MinSize. We won't find a better candidate.
if (BestRC->getSize() == MinSize)
return BestRC;
}
}
return BestRC;
}
// Compute target-independent register allocator hints to help eliminate copies.
void
TargetRegisterInfo::getRegAllocationHints(unsigned VirtReg,
ArrayRef<MCPhysReg> Order,
SmallVectorImpl<MCPhysReg> &Hints,
const MachineFunction &MF,
const VirtRegMap *VRM) const {
const MachineRegisterInfo &MRI = MF.getRegInfo();
std::pair<unsigned, unsigned> Hint = MRI.getRegAllocationHint(VirtReg);
// Hints with HintType != 0 were set by target-dependent code.
// Such targets must provide their own implementation of
// TRI::getRegAllocationHints to interpret those hint types.
assert(Hint.first == 0 && "Target must implement TRI::getRegAllocationHints");
// Target-independent hints are either a physical or a virtual register.
unsigned Phys = Hint.second;
if (VRM && isVirtualRegister(Phys))
Phys = VRM->getPhys(Phys);
// Check that Phys is a valid hint in VirtReg's register class.
if (!isPhysicalRegister(Phys))
return;
if (MRI.isReserved(Phys))
return;
// Check that Phys is in the allocation order. We shouldn't heed hints
// from VirtReg's register class if they aren't in the allocation order. The
// target probably has a reason for removing the register.
if (std::find(Order.begin(), Order.end(), Phys) == Order.end())
return;
// All clear, tell the register allocator to prefer this register.
Hints.push_back(Phys);
}