1 //===- TargetRegisterInfo.cpp - Target Register Information Implementation ===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the TargetRegisterInfo interface.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Target/TargetMachine.h"
15 #include "llvm/Target/TargetRegisterInfo.h"
16 #include "llvm/ADT/BitVector.h"
17 #include "llvm/Support/raw_ostream.h"
21 TargetRegisterInfo::TargetRegisterInfo(const TargetRegisterInfoDesc *ID,
22 regclass_iterator RCB, regclass_iterator RCE,
23 const char *const *subregindexnames)
24 : InfoDesc(ID), SubRegIndexNames(subregindexnames),
25 RegClassBegin(RCB), RegClassEnd(RCE) {
28 TargetRegisterInfo::~TargetRegisterInfo() {}
30 void PrintReg::print(raw_ostream &OS) const {
33 else if (TargetRegisterInfo::isStackSlot(Reg))
34 OS << "SS#" << TargetRegisterInfo::stackSlot2Index(Reg);
35 else if (TargetRegisterInfo::isVirtualRegister(Reg))
36 OS << "%vreg" << TargetRegisterInfo::virtReg2Index(Reg);
37 else if (TRI && Reg < TRI->getNumRegs())
38 OS << '%' << TRI->getName(Reg);
40 OS << "%physreg" << Reg;
43 OS << ':' << TRI->getSubRegIndexName(SubIdx);
45 OS << ":sub(" << SubIdx << ')';
49 /// getAllocatableClass - Return the maximal subclass of the given register
50 /// class that is alloctable, or NULL.
51 const TargetRegisterClass *
52 TargetRegisterInfo::getAllocatableClass(const TargetRegisterClass *RC) const {
53 if (!RC || RC->isAllocatable())
56 const unsigned *SubClass = RC->getSubClassMask();
57 for (unsigned Base = 0, BaseE = getNumRegClasses();
58 Base < BaseE; Base += 32) {
60 for (unsigned Mask = *SubClass++; Mask; Mask >>= 1) {
61 unsigned Offset = CountTrailingZeros_32(Mask);
62 const TargetRegisterClass *SubRC = getRegClass(Idx + Offset);
63 if (SubRC->isAllocatable())
72 /// getMinimalPhysRegClass - Returns the Register Class of a physical
73 /// register of the given type, picking the most sub register class of
74 /// the right type that contains this physreg.
75 const TargetRegisterClass *
76 TargetRegisterInfo::getMinimalPhysRegClass(unsigned reg, EVT VT) const {
77 assert(isPhysicalRegister(reg) && "reg must be a physical register");
79 // Pick the most sub register class of the right type that contains
81 const TargetRegisterClass* BestRC = 0;
82 for (regclass_iterator I = regclass_begin(), E = regclass_end(); I != E; ++I){
83 const TargetRegisterClass* RC = *I;
84 if ((VT == MVT::Other || RC->hasType(VT)) && RC->contains(reg) &&
85 (!BestRC || BestRC->hasSubClass(RC)))
89 assert(BestRC && "Couldn't find the register class");
93 /// getAllocatableSetForRC - Toggle the bits that represent allocatable
94 /// registers for the specific register class.
95 static void getAllocatableSetForRC(const MachineFunction &MF,
96 const TargetRegisterClass *RC, BitVector &R){
97 assert(RC->isAllocatable() && "invalid for nonallocatable sets");
98 ArrayRef<uint16_t> Order = RC->getRawAllocationOrder(MF);
99 for (unsigned i = 0; i != Order.size(); ++i)
103 BitVector TargetRegisterInfo::getAllocatableSet(const MachineFunction &MF,
104 const TargetRegisterClass *RC) const {
105 BitVector Allocatable(getNumRegs());
107 // A register class with no allocatable subclass returns an empty set.
108 const TargetRegisterClass *SubClass = getAllocatableClass(RC);
110 getAllocatableSetForRC(MF, SubClass, Allocatable);
112 for (TargetRegisterInfo::regclass_iterator I = regclass_begin(),
113 E = regclass_end(); I != E; ++I)
114 if ((*I)->isAllocatable())
115 getAllocatableSetForRC(MF, *I, Allocatable);
118 // Mask out the reserved registers
119 BitVector Reserved = getReservedRegs(MF);
120 Allocatable &= Reserved.flip();
126 const TargetRegisterClass *firstCommonClass(const uint32_t *A,
128 const TargetRegisterInfo *TRI) {
129 for (unsigned I = 0, E = TRI->getNumRegClasses(); I < E; I += 32)
130 if (unsigned Common = *A++ & *B++)
131 return TRI->getRegClass(I + CountTrailingZeros_32(Common));
135 const TargetRegisterClass *
136 TargetRegisterInfo::getCommonSubClass(const TargetRegisterClass *A,
137 const TargetRegisterClass *B) const {
138 // First take care of the trivial cases.
144 // Register classes are ordered topologically, so the largest common
145 // sub-class it the common sub-class with the smallest ID.
146 return firstCommonClass(A->getSubClassMask(), B->getSubClassMask(), this);
149 const TargetRegisterClass *
150 TargetRegisterInfo::getMatchingSuperRegClass(const TargetRegisterClass *A,
151 const TargetRegisterClass *B,
152 unsigned Idx) const {
153 assert(A && B && "Missing register class");
154 assert(Idx && "Bad sub-register index");
156 // Find Idx in the list of super-register indices.
157 for (SuperRegClassIterator RCI(B, this); RCI.isValid(); ++RCI)
158 if (RCI.getSubReg() == Idx)
159 // The bit mask contains all register classes that are projected into B
160 // by Idx. Find a class that is also a sub-class of A.
161 return firstCommonClass(RCI.getMask(), A->getSubClassMask(), this);
165 const TargetRegisterClass *TargetRegisterInfo::
166 getCommonSuperRegClass(const TargetRegisterClass *RCA, unsigned SubA,
167 const TargetRegisterClass *RCB, unsigned SubB,
168 unsigned &PreA, unsigned &PreB) const {
169 assert(RCA && SubA && RCB && SubB && "Invalid arguments");
171 // Search all pairs of sub-register indices that project into RCA and RCB
172 // respectively. This is quadratic, but usually the sets are very small. On
173 // most targets like X86, there will only be a single sub-register index
174 // (e.g., sub_16bit projecting into GR16).
176 // The worst case is a register class like DPR on ARM.
177 // We have indices dsub_0..dsub_7 projecting into that class.
179 // It is very common that one register class is a sub-register of the other.
180 // Arrange for RCA to be the larger register so the answer will be found in
181 // the first iteration. This makes the search linear for the most common
183 const TargetRegisterClass *BestRC = 0;
184 unsigned *BestPreA = &PreA;
185 unsigned *BestPreB = &PreB;
186 if (RCA->getSize() < RCB->getSize()) {
188 std::swap(SubA, SubB);
189 std::swap(BestPreA, BestPreB);
192 // Also terminate the search one we have found a register class as small as
194 unsigned MinSize = RCA->getSize();
196 for (SuperRegClassIterator IA(RCA, this, true); IA.isValid(); ++IA) {
197 unsigned FinalA = composeSubRegIndices(IA.getSubReg(), SubA);
198 for (SuperRegClassIterator IB(RCB, this, true); IB.isValid(); ++IB) {
199 // Check if a common super-register class exists for this index pair.
200 const TargetRegisterClass *RC =
201 firstCommonClass(IA.getMask(), IB.getMask(), this);
202 if (!RC || RC->getSize() < MinSize)
205 // The indexes must compose identically: PreA+SubA == PreB+SubB.
206 unsigned FinalB = composeSubRegIndices(IB.getSubReg(), SubB);
207 if (FinalA != FinalB)
210 // Is RC a better candidate than BestRC?
211 if (BestRC && RC->getSize() >= BestRC->getSize())
214 // Yes, RC is the smallest super-register seen so far.
216 *BestPreA = IA.getSubReg();
217 *BestPreB = IB.getSubReg();
219 // Bail early if we reached MinSize. We won't find a better candidate.
220 if (BestRC->getSize() == MinSize)