1 //===-- TargetLowering.cpp - Implement the TargetLowering class -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This implements the TargetLowering class.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Target/TargetLowering.h"
15 #include "llvm/Target/TargetMachine.h"
16 #include "llvm/Target/MRegisterInfo.h"
17 #include "llvm/CodeGen/SelectionDAG.h"
18 #include "llvm/ADT/StringExtras.h"
19 #include "llvm/Support/MathExtras.h"
22 TargetLowering::TargetLowering(TargetMachine &tm)
23 : TM(tm), TD(TM.getTargetData()) {
24 assert(ISD::BUILTIN_OP_END <= 128 &&
25 "Fixed size array in TargetLowering is not large enough!");
26 // All operations default to being supported.
27 memset(OpActions, 0, sizeof(OpActions));
29 IsLittleEndian = TD.isLittleEndian();
30 ShiftAmountTy = SetCCResultTy = PointerTy = getValueType(TD.getIntPtrType());
31 ShiftAmtHandling = Undefined;
32 memset(RegClassForVT, 0,MVT::LAST_VALUETYPE*sizeof(TargetRegisterClass*));
33 maxStoresPerMemset = maxStoresPerMemcpy = maxStoresPerMemmove = 8;
34 allowUnalignedMemoryAccesses = false;
35 UseUnderscoreSetJmpLongJmp = false;
36 IntDivIsCheap = false;
37 Pow2DivIsCheap = false;
38 StackPointerRegisterToSaveRestore = 0;
39 SchedPreferenceInfo = SchedulingForLatency;
42 TargetLowering::~TargetLowering() {}
44 /// setValueTypeAction - Set the action for a particular value type. This
45 /// assumes an action has not already been set for this value type.
46 static void SetValueTypeAction(MVT::ValueType VT,
47 TargetLowering::LegalizeAction Action,
49 MVT::ValueType *TransformToType,
50 TargetLowering::ValueTypeActionImpl &ValueTypeActions) {
51 ValueTypeActions.setTypeAction(VT, Action);
52 if (Action == TargetLowering::Promote) {
53 MVT::ValueType PromoteTo;
57 unsigned LargerReg = VT+1;
58 while (!TLI.isTypeLegal((MVT::ValueType)LargerReg)) {
60 assert(MVT::isInteger((MVT::ValueType)LargerReg) &&
61 "Nothing to promote to??");
63 PromoteTo = (MVT::ValueType)LargerReg;
66 assert(MVT::isInteger(VT) == MVT::isInteger(PromoteTo) &&
67 MVT::isFloatingPoint(VT) == MVT::isFloatingPoint(PromoteTo) &&
68 "Can only promote from int->int or fp->fp!");
69 assert(VT < PromoteTo && "Must promote to a larger type!");
70 TransformToType[VT] = PromoteTo;
71 } else if (Action == TargetLowering::Expand) {
72 assert((VT == MVT::Vector || MVT::isInteger(VT)) && VT > MVT::i8 &&
73 "Cannot expand this type: target must support SOME integer reg!");
74 // Expand to the next smaller integer type!
75 TransformToType[VT] = (MVT::ValueType)(VT-1);
80 /// computeRegisterProperties - Once all of the register classes are added,
81 /// this allows us to compute derived properties we expose.
82 void TargetLowering::computeRegisterProperties() {
83 assert(MVT::LAST_VALUETYPE <= 32 &&
84 "Too many value types for ValueTypeActions to hold!");
86 // Everything defaults to one.
87 for (unsigned i = 0; i != MVT::LAST_VALUETYPE; ++i)
88 NumElementsForVT[i] = 1;
90 // Find the largest integer register class.
91 unsigned LargestIntReg = MVT::i128;
92 for (; RegClassForVT[LargestIntReg] == 0; --LargestIntReg)
93 assert(LargestIntReg != MVT::i1 && "No integer registers defined!");
95 // Every integer value type larger than this largest register takes twice as
96 // many registers to represent as the previous ValueType.
97 unsigned ExpandedReg = LargestIntReg; ++LargestIntReg;
98 for (++ExpandedReg; MVT::isInteger((MVT::ValueType)ExpandedReg);++ExpandedReg)
99 NumElementsForVT[ExpandedReg] = 2*NumElementsForVT[ExpandedReg-1];
101 // Inspect all of the ValueType's possible, deciding how to process them.
102 for (unsigned IntReg = MVT::i1; IntReg <= MVT::i128; ++IntReg)
103 // If we are expanding this type, expand it!
104 if (getNumElements((MVT::ValueType)IntReg) != 1)
105 SetValueTypeAction((MVT::ValueType)IntReg, Expand, *this, TransformToType,
107 else if (!isTypeLegal((MVT::ValueType)IntReg))
108 // Otherwise, if we don't have native support, we must promote to a
110 SetValueTypeAction((MVT::ValueType)IntReg, Promote, *this,
111 TransformToType, ValueTypeActions);
113 TransformToType[(MVT::ValueType)IntReg] = (MVT::ValueType)IntReg;
115 // If the target does not have native support for F32, promote it to F64.
116 if (!isTypeLegal(MVT::f32))
117 SetValueTypeAction(MVT::f32, Promote, *this,
118 TransformToType, ValueTypeActions);
120 TransformToType[MVT::f32] = MVT::f32;
122 // Set MVT::Vector to always be Expanded
123 SetValueTypeAction(MVT::Vector, Expand, *this, TransformToType,
126 assert(isTypeLegal(MVT::f64) && "Target does not support FP?");
127 TransformToType[MVT::f64] = MVT::f64;
130 const char *TargetLowering::getTargetNodeName(unsigned Opcode) const {
134 //===----------------------------------------------------------------------===//
135 // Optimization Methods
136 //===----------------------------------------------------------------------===//
138 /// ShrinkDemandedConstant - Check to see if the specified operand of the
139 /// specified instruction is a constant integer. If so, check to see if there
140 /// are any bits set in the constant that are not demanded. If so, shrink the
141 /// constant and return true.
142 bool TargetLowering::TargetLoweringOpt::ShrinkDemandedConstant(SDOperand Op,
144 // FIXME: ISD::SELECT, ISD::SELECT_CC
145 switch(Op.getOpcode()) {
150 if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1)))
151 if ((~Demanded & C->getValue()) != 0) {
152 MVT::ValueType VT = Op.getValueType();
153 SDOperand New = DAG.getNode(Op.getOpcode(), VT, Op.getOperand(0),
154 DAG.getConstant(Demanded & C->getValue(),
156 return CombineTo(Op, New);
163 /// SimplifyDemandedBits - Look at Op. At this point, we know that only the
164 /// DemandedMask bits of the result of Op are ever used downstream. If we can
165 /// use this information to simplify Op, create a new simplified DAG node and
166 /// return true, returning the original and new nodes in Old and New. Otherwise,
167 /// analyze the expression and return a mask of KnownOne and KnownZero bits for
168 /// the expression (used to simplify the caller). The KnownZero/One bits may
169 /// only be accurate for those bits in the DemandedMask.
170 bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
173 TargetLoweringOpt &TLO,
174 unsigned Depth) const {
175 KnownZero = KnownOne = 0; // Don't know anything.
176 // Other users may use these bits.
177 if (!Op.Val->hasOneUse()) {
179 // If not at the root, Just compute the KnownZero/KnownOne bits to
180 // simplify things downstream.
181 ComputeMaskedBits(Op, DemandedMask, KnownZero, KnownOne, Depth);
184 // If this is the root being simplified, allow it to have multiple uses,
185 // just set the DemandedMask to all bits.
186 DemandedMask = MVT::getIntVTBitMask(Op.getValueType());
187 } else if (DemandedMask == 0) {
188 // Not demanding any bits from Op.
189 if (Op.getOpcode() != ISD::UNDEF)
190 return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::UNDEF, Op.getValueType()));
192 } else if (Depth == 6) { // Limit search depth.
196 uint64_t KnownZero2, KnownOne2, KnownZeroOut, KnownOneOut;
197 switch (Op.getOpcode()) {
199 // We know all of the bits for a constant!
200 KnownOne = cast<ConstantSDNode>(Op)->getValue() & DemandedMask;
201 KnownZero = ~KnownOne & DemandedMask;
202 return false; // Don't fall through, will infinitely loop.
204 // If either the LHS or the RHS are Zero, the result is zero.
205 if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
206 KnownOne, TLO, Depth+1))
208 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
209 if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & ~KnownZero,
210 KnownZero2, KnownOne2, TLO, Depth+1))
212 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
214 // If all of the demanded bits are known one on one side, return the other.
215 // These bits cannot contribute to the result of the 'and'.
216 if ((DemandedMask & ~KnownZero2 & KnownOne)==(DemandedMask & ~KnownZero2))
217 return TLO.CombineTo(Op, Op.getOperand(0));
218 if ((DemandedMask & ~KnownZero & KnownOne2)==(DemandedMask & ~KnownZero))
219 return TLO.CombineTo(Op, Op.getOperand(1));
220 // If all of the demanded bits in the inputs are known zeros, return zero.
221 if ((DemandedMask & (KnownZero|KnownZero2)) == DemandedMask)
222 return TLO.CombineTo(Op, TLO.DAG.getConstant(0, Op.getValueType()));
223 // If the RHS is a constant, see if we can simplify it.
224 if (TLO.ShrinkDemandedConstant(Op, DemandedMask & ~KnownZero2))
227 // If the RHS is a constant, check to see if the LHS would be zero without
228 // using the bits from the RHS. Above, we used knowledge about the RHS to
229 // simplify the LHS, here we're using information from the LHS to simplify
231 if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
232 uint64_t LHSZero, LHSOne;
233 ComputeMaskedBits(Op.getOperand(0), DemandedMask,
234 LHSZero, LHSOne, Depth+1);
235 // If the LHS already has zeros where RHSC does, this and is dead.
236 if ((LHSZero & DemandedMask) == (~RHSC->getValue() & DemandedMask))
237 return TLO.CombineTo(Op, Op.getOperand(0));
238 // If any of the set bits in the RHS are known zero on the LHS, shrink
240 if (TLO.ShrinkDemandedConstant(Op, ~LHSZero & DemandedMask))
244 // Output known-1 bits are only known if set in both the LHS & RHS.
245 KnownOne &= KnownOne2;
246 // Output known-0 are known to be clear if zero in either the LHS | RHS.
247 KnownZero |= KnownZero2;
250 if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
251 KnownOne, TLO, Depth+1))
253 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
254 if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & ~KnownOne,
255 KnownZero2, KnownOne2, TLO, Depth+1))
257 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
259 // If all of the demanded bits are known zero on one side, return the other.
260 // These bits cannot contribute to the result of the 'or'.
261 if ((DemandedMask & ~KnownOne2 & KnownZero) == (DemandedMask & ~KnownOne2))
262 return TLO.CombineTo(Op, Op.getOperand(0));
263 if ((DemandedMask & ~KnownOne & KnownZero2) == (DemandedMask & ~KnownOne))
264 return TLO.CombineTo(Op, Op.getOperand(1));
265 // If all of the potentially set bits on one side are known to be set on
266 // the other side, just use the 'other' side.
267 if ((DemandedMask & (~KnownZero) & KnownOne2) ==
268 (DemandedMask & (~KnownZero)))
269 return TLO.CombineTo(Op, Op.getOperand(0));
270 if ((DemandedMask & (~KnownZero2) & KnownOne) ==
271 (DemandedMask & (~KnownZero2)))
272 return TLO.CombineTo(Op, Op.getOperand(1));
273 // If the RHS is a constant, see if we can simplify it.
274 if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
277 // Output known-0 bits are only known if clear in both the LHS & RHS.
278 KnownZero &= KnownZero2;
279 // Output known-1 are known to be set if set in either the LHS | RHS.
280 KnownOne |= KnownOne2;
283 if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
284 KnownOne, TLO, Depth+1))
286 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
287 if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask, KnownZero2,
288 KnownOne2, TLO, Depth+1))
290 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
292 // If all of the demanded bits are known zero on one side, return the other.
293 // These bits cannot contribute to the result of the 'xor'.
294 if ((DemandedMask & KnownZero) == DemandedMask)
295 return TLO.CombineTo(Op, Op.getOperand(0));
296 if ((DemandedMask & KnownZero2) == DemandedMask)
297 return TLO.CombineTo(Op, Op.getOperand(1));
299 // Output known-0 bits are known if clear or set in both the LHS & RHS.
300 KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
301 // Output known-1 are known to be set if set in only one of the LHS, RHS.
302 KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
304 // If all of the unknown bits are known to be zero on one side or the other
305 // (but not both) turn this into an *inclusive* or.
306 // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
307 if (uint64_t UnknownBits = DemandedMask & ~(KnownZeroOut|KnownOneOut))
308 if ((UnknownBits & (KnownZero|KnownZero2)) == UnknownBits)
309 return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::OR, Op.getValueType(),
312 // If all of the demanded bits on one side are known, and all of the set
313 // bits on that side are also known to be set on the other side, turn this
314 // into an AND, as we know the bits will be cleared.
315 // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
316 if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask) { // all known
317 if ((KnownOne & KnownOne2) == KnownOne) {
318 MVT::ValueType VT = Op.getValueType();
319 SDOperand ANDC = TLO.DAG.getConstant(~KnownOne & DemandedMask, VT);
320 return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::AND, VT, Op.getOperand(0),
325 // If the RHS is a constant, see if we can simplify it.
326 // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
327 if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
330 KnownZero = KnownZeroOut;
331 KnownOne = KnownOneOut;
334 // If we know the result of a setcc has the top bits zero, use this info.
335 if (getSetCCResultContents() == TargetLowering::ZeroOrOneSetCCResult)
336 KnownZero |= (MVT::getIntVTBitMask(Op.getValueType()) ^ 1ULL);
339 if (SimplifyDemandedBits(Op.getOperand(2), DemandedMask, KnownZero,
340 KnownOne, TLO, Depth+1))
342 if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero2,
343 KnownOne2, TLO, Depth+1))
345 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
346 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
348 // If the operands are constants, see if we can simplify them.
349 if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
352 // Only known if known in both the LHS and RHS.
353 KnownOne &= KnownOne2;
354 KnownZero &= KnownZero2;
357 if (SimplifyDemandedBits(Op.getOperand(3), DemandedMask, KnownZero,
358 KnownOne, TLO, Depth+1))
360 if (SimplifyDemandedBits(Op.getOperand(2), DemandedMask, KnownZero2,
361 KnownOne2, TLO, Depth+1))
363 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
364 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
366 // If the operands are constants, see if we can simplify them.
367 if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
370 // Only known if known in both the LHS and RHS.
371 KnownOne &= KnownOne2;
372 KnownZero &= KnownZero2;
375 if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
376 if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask >> SA->getValue(),
377 KnownZero, KnownOne, TLO, Depth+1))
379 KnownZero <<= SA->getValue();
380 KnownOne <<= SA->getValue();
381 KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
385 if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
386 MVT::ValueType VT = Op.getValueType();
387 unsigned ShAmt = SA->getValue();
389 // Compute the new bits that are at the top now.
390 uint64_t HighBits = (1ULL << ShAmt)-1;
391 HighBits <<= MVT::getSizeInBits(VT) - ShAmt;
392 uint64_t TypeMask = MVT::getIntVTBitMask(VT);
394 if (SimplifyDemandedBits(Op.getOperand(0),
395 (DemandedMask << ShAmt) & TypeMask,
396 KnownZero, KnownOne, TLO, Depth+1))
398 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
399 KnownZero &= TypeMask;
400 KnownOne &= TypeMask;
403 KnownZero |= HighBits; // high bits known zero.
407 if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
408 MVT::ValueType VT = Op.getValueType();
409 unsigned ShAmt = SA->getValue();
411 // Compute the new bits that are at the top now.
412 uint64_t HighBits = (1ULL << ShAmt)-1;
413 HighBits <<= MVT::getSizeInBits(VT) - ShAmt;
414 uint64_t TypeMask = MVT::getIntVTBitMask(VT);
416 if (SimplifyDemandedBits(Op.getOperand(0),
417 (DemandedMask << ShAmt) & TypeMask,
418 KnownZero, KnownOne, TLO, Depth+1))
420 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
421 KnownZero &= TypeMask;
422 KnownOne &= TypeMask;
423 KnownZero >>= SA->getValue();
424 KnownOne >>= SA->getValue();
426 // Handle the sign bits.
427 uint64_t SignBit = MVT::getIntVTSignBit(VT);
428 SignBit >>= SA->getValue(); // Adjust to where it is now in the mask.
430 // If the input sign bit is known to be zero, or if none of the top bits
431 // are demanded, turn this into an unsigned shift right.
432 if ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) {
433 return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, VT, Op.getOperand(0),
435 } else if (KnownOne & SignBit) { // New bits are known one.
436 KnownOne |= HighBits;
440 case ISD::SIGN_EXTEND_INREG: {
441 MVT::ValueType VT = Op.getValueType();
442 MVT::ValueType EVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
444 // Sign extension. Compute the demanded bits in the result that are not
445 // present in the input.
446 uint64_t NewBits = ~MVT::getIntVTBitMask(EVT) & DemandedMask;
448 // If none of the extended bits are demanded, eliminate the sextinreg.
450 return TLO.CombineTo(Op, Op.getOperand(0));
452 uint64_t InSignBit = MVT::getIntVTSignBit(EVT);
453 int64_t InputDemandedBits = DemandedMask & MVT::getIntVTBitMask(EVT);
455 // Since the sign extended bits are demanded, we know that the sign
457 InputDemandedBits |= InSignBit;
459 if (SimplifyDemandedBits(Op.getOperand(0), InputDemandedBits,
460 KnownZero, KnownOne, TLO, Depth+1))
462 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
464 // If the sign bit of the input is known set or clear, then we know the
465 // top bits of the result.
467 // If the input sign bit is known zero, convert this into a zero extension.
468 if (KnownZero & InSignBit)
469 return TLO.CombineTo(Op,
470 TLO.DAG.getZeroExtendInReg(Op.getOperand(0), EVT));
472 if (KnownOne & InSignBit) { // Input sign bit known set
474 KnownZero &= ~NewBits;
475 } else { // Input sign bit unknown
476 KnownZero &= ~NewBits;
477 KnownOne &= ~NewBits;
484 MVT::ValueType VT = Op.getValueType();
485 unsigned LowBits = Log2_32(MVT::getSizeInBits(VT))+1;
486 KnownZero = ~((1ULL << LowBits)-1) & MVT::getIntVTBitMask(VT);
490 case ISD::ZEXTLOAD: {
491 MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(3))->getVT();
492 KnownZero |= ~MVT::getIntVTBitMask(VT) & DemandedMask;
495 case ISD::ZERO_EXTEND: {
496 uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
498 // If none of the top bits are demanded, convert this into an any_extend.
499 uint64_t NewBits = (~InMask) & DemandedMask;
501 return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ANY_EXTEND,
505 if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
506 KnownZero, KnownOne, TLO, Depth+1))
508 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
509 KnownZero |= NewBits;
512 case ISD::SIGN_EXTEND: {
513 MVT::ValueType InVT = Op.getOperand(0).getValueType();
514 uint64_t InMask = MVT::getIntVTBitMask(InVT);
515 uint64_t InSignBit = MVT::getIntVTSignBit(InVT);
516 uint64_t NewBits = (~InMask) & DemandedMask;
518 // If none of the top bits are demanded, convert this into an any_extend.
520 return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ANY_EXTEND,Op.getValueType(),
523 // Since some of the sign extended bits are demanded, we know that the sign
525 uint64_t InDemandedBits = DemandedMask & InMask;
526 InDemandedBits |= InSignBit;
528 if (SimplifyDemandedBits(Op.getOperand(0), InDemandedBits, KnownZero,
529 KnownOne, TLO, Depth+1))
532 // If the sign bit is known zero, convert this to a zero extend.
533 if (KnownZero & InSignBit)
534 return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ZERO_EXTEND,
538 // If the sign bit is known one, the top bits match.
539 if (KnownOne & InSignBit) {
541 KnownZero &= ~NewBits;
542 } else { // Otherwise, top bits aren't known.
543 KnownOne &= ~NewBits;
544 KnownZero &= ~NewBits;
548 case ISD::ANY_EXTEND: {
549 uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
550 if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
551 KnownZero, KnownOne, TLO, Depth+1))
553 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
556 case ISD::AssertZext: {
557 MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
558 uint64_t InMask = MVT::getIntVTBitMask(VT);
559 if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
560 KnownZero, KnownOne, TLO, Depth+1))
562 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
563 KnownZero |= ~InMask & DemandedMask;
567 if (ConstantSDNode *AA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
568 if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask, KnownZero,
569 KnownOne, TLO, Depth+1))
571 // Compute the KnownOne/KnownZero masks for the constant, so we can set
572 // KnownZero appropriately if we're adding a constant that has all low
574 ComputeMaskedBits(Op.getOperand(1),
575 MVT::getIntVTBitMask(Op.getValueType()),
576 KnownZero2, KnownOne2, Depth+1);
578 uint64_t KnownZeroOut = std::min(CountTrailingZeros_64(~KnownZero),
579 CountTrailingZeros_64(~KnownZero2));
580 KnownZero = (1ULL << KnownZeroOut) - 1;
583 SDOperand SH = Op.getOperand(0);
584 // fold (add (shl x, c1), (shl c2, c1)) -> (shl (add x, c2), c1)
585 if (KnownZero && SH.getOpcode() == ISD::SHL && SH.Val->hasOneUse() &&
586 Op.Val->hasOneUse()) {
587 if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(SH.getOperand(1))) {
588 MVT::ValueType VT = Op.getValueType();
589 unsigned ShiftAmt = SA->getValue();
590 uint64_t AddAmt = AA->getValue();
591 uint64_t AddShr = AddAmt >> ShiftAmt;
592 if (AddAmt == (AddShr << ShiftAmt)) {
593 SDOperand ADD = TLO.DAG.getNode(ISD::ADD, VT, SH.getOperand(0),
594 TLO.DAG.getConstant(AddShr, VT));
595 SDOperand SHL = TLO.DAG.getNode(ISD::SHL, VT, ADD,SH.getOperand(1));
596 return TLO.CombineTo(Op, SHL);
604 // If we know the value of all of the demanded bits, return this as a
606 if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask)
607 return TLO.CombineTo(Op, TLO.DAG.getConstant(KnownOne, Op.getValueType()));
612 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
613 /// this predicate to simplify operations downstream. Mask is known to be zero
614 /// for bits that V cannot have.
615 bool TargetLowering::MaskedValueIsZero(SDOperand Op, uint64_t Mask,
616 unsigned Depth) const {
617 uint64_t KnownZero, KnownOne;
618 ComputeMaskedBits(Op, Mask, KnownZero, KnownOne, Depth);
619 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
620 return (KnownZero & Mask) == Mask;
623 /// ComputeMaskedBits - Determine which of the bits specified in Mask are
624 /// known to be either zero or one and return them in the KnownZero/KnownOne
625 /// bitsets. This code only analyzes bits in Mask, in order to short-circuit
627 void TargetLowering::ComputeMaskedBits(SDOperand Op, uint64_t Mask,
628 uint64_t &KnownZero, uint64_t &KnownOne,
629 unsigned Depth) const {
630 KnownZero = KnownOne = 0; // Don't know anything.
631 if (Depth == 6 || Mask == 0)
632 return; // Limit search depth.
634 uint64_t KnownZero2, KnownOne2;
636 switch (Op.getOpcode()) {
638 // We know all of the bits for a constant!
639 KnownOne = cast<ConstantSDNode>(Op)->getValue() & Mask;
640 KnownZero = ~KnownOne & Mask;
643 // If either the LHS or the RHS are Zero, the result is zero.
644 ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
646 ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
647 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
648 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
650 // Output known-1 bits are only known if set in both the LHS & RHS.
651 KnownOne &= KnownOne2;
652 // Output known-0 are known to be clear if zero in either the LHS | RHS.
653 KnownZero |= KnownZero2;
656 ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
658 ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
659 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
660 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
662 // Output known-0 bits are only known if clear in both the LHS & RHS.
663 KnownZero &= KnownZero2;
664 // Output known-1 are known to be set if set in either the LHS | RHS.
665 KnownOne |= KnownOne2;
668 ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
669 ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
670 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
671 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
673 // Output known-0 bits are known if clear or set in both the LHS & RHS.
674 uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
675 // Output known-1 are known to be set if set in only one of the LHS, RHS.
676 KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
677 KnownZero = KnownZeroOut;
681 ComputeMaskedBits(Op.getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
682 ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
683 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
684 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
686 // Only known if known in both the LHS and RHS.
687 KnownOne &= KnownOne2;
688 KnownZero &= KnownZero2;
691 ComputeMaskedBits(Op.getOperand(3), Mask, KnownZero, KnownOne, Depth+1);
692 ComputeMaskedBits(Op.getOperand(2), Mask, KnownZero2, KnownOne2, Depth+1);
693 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
694 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
696 // Only known if known in both the LHS and RHS.
697 KnownOne &= KnownOne2;
698 KnownZero &= KnownZero2;
701 // If we know the result of a setcc has the top bits zero, use this info.
702 if (getSetCCResultContents() == TargetLowering::ZeroOrOneSetCCResult)
703 KnownZero |= (MVT::getIntVTBitMask(Op.getValueType()) ^ 1ULL);
706 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
707 if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
708 Mask >>= SA->getValue();
709 ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
710 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
711 KnownZero <<= SA->getValue();
712 KnownOne <<= SA->getValue();
713 KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
717 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
718 if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
719 uint64_t HighBits = (1ULL << SA->getValue())-1;
720 HighBits <<= MVT::getSizeInBits(Op.getValueType())-SA->getValue();
721 Mask <<= SA->getValue();
722 ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
723 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
724 KnownZero >>= SA->getValue();
725 KnownOne >>= SA->getValue();
726 KnownZero |= HighBits; // high bits known zero.
730 if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
731 uint64_t HighBits = (1ULL << SA->getValue())-1;
732 HighBits <<= MVT::getSizeInBits(Op.getValueType())-SA->getValue();
733 Mask <<= SA->getValue();
734 ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
735 assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
736 KnownZero >>= SA->getValue();
737 KnownOne >>= SA->getValue();
739 // Handle the sign bits.
740 uint64_t SignBit = 1ULL << (MVT::getSizeInBits(Op.getValueType())-1);
741 SignBit >>= SA->getValue(); // Adjust to where it is now in the mask.
743 if (KnownZero & SignBit) { // New bits are known zero.
744 KnownZero |= HighBits;
745 } else if (KnownOne & SignBit) { // New bits are known one.
746 KnownOne |= HighBits;
750 case ISD::SIGN_EXTEND_INREG: {
751 MVT::ValueType VT = Op.getValueType();
752 MVT::ValueType EVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
754 // Sign extension. Compute the demanded bits in the result that are not
755 // present in the input.
756 uint64_t NewBits = ~MVT::getIntVTBitMask(EVT) & Mask;
758 uint64_t InSignBit = MVT::getIntVTSignBit(EVT);
759 int64_t InputDemandedBits = Mask & MVT::getIntVTBitMask(EVT);
761 // If the sign extended bits are demanded, we know that the sign
764 InputDemandedBits |= InSignBit;
766 ComputeMaskedBits(Op.getOperand(0), InputDemandedBits,
767 KnownZero, KnownOne, Depth+1);
768 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
770 // If the sign bit of the input is known set or clear, then we know the
771 // top bits of the result.
772 if (KnownZero & InSignBit) { // Input sign bit known clear
773 KnownZero |= NewBits;
774 KnownOne &= ~NewBits;
775 } else if (KnownOne & InSignBit) { // Input sign bit known set
777 KnownZero &= ~NewBits;
778 } else { // Input sign bit unknown
779 KnownZero &= ~NewBits;
780 KnownOne &= ~NewBits;
787 MVT::ValueType VT = Op.getValueType();
788 unsigned LowBits = Log2_32(MVT::getSizeInBits(VT))+1;
789 KnownZero = ~((1ULL << LowBits)-1) & MVT::getIntVTBitMask(VT);
793 case ISD::ZEXTLOAD: {
794 MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(3))->getVT();
795 KnownZero |= ~MVT::getIntVTBitMask(VT) & Mask;
798 case ISD::ZERO_EXTEND: {
799 uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
800 uint64_t NewBits = (~InMask) & Mask;
801 ComputeMaskedBits(Op.getOperand(0), Mask & InMask, KnownZero,
803 KnownZero |= NewBits & Mask;
804 KnownOne &= ~NewBits;
807 case ISD::SIGN_EXTEND: {
808 MVT::ValueType InVT = Op.getOperand(0).getValueType();
809 unsigned InBits = MVT::getSizeInBits(InVT);
810 uint64_t InMask = MVT::getIntVTBitMask(InVT);
811 uint64_t InSignBit = 1ULL << (InBits-1);
812 uint64_t NewBits = (~InMask) & Mask;
813 uint64_t InDemandedBits = Mask & InMask;
815 // If any of the sign extended bits are demanded, we know that the sign
818 InDemandedBits |= InSignBit;
820 ComputeMaskedBits(Op.getOperand(0), InDemandedBits, KnownZero,
822 // If the sign bit is known zero or one, the top bits match.
823 if (KnownZero & InSignBit) {
824 KnownZero |= NewBits;
825 KnownOne &= ~NewBits;
826 } else if (KnownOne & InSignBit) {
828 KnownZero &= ~NewBits;
829 } else { // Otherwise, top bits aren't known.
830 KnownOne &= ~NewBits;
831 KnownZero &= ~NewBits;
835 case ISD::ANY_EXTEND: {
836 MVT::ValueType VT = Op.getOperand(0).getValueType();
837 ComputeMaskedBits(Op.getOperand(0), Mask & MVT::getIntVTBitMask(VT),
838 KnownZero, KnownOne, Depth+1);
841 case ISD::AssertZext: {
842 MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
843 uint64_t InMask = MVT::getIntVTBitMask(VT);
844 ComputeMaskedBits(Op.getOperand(0), Mask & InMask, KnownZero,
846 KnownZero |= (~InMask) & Mask;
850 // If either the LHS or the RHS are Zero, the result is zero.
851 ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
852 ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
853 assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
854 assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
856 // Output known-0 bits are known if clear or set in both the low clear bits
857 // common to both LHS & RHS;
858 uint64_t KnownZeroOut = std::min(CountTrailingZeros_64(~KnownZero),
859 CountTrailingZeros_64(~KnownZero2));
861 KnownZero = (1ULL << KnownZeroOut) - 1;
866 // We know that the top bits of C-X are clear if X contains less bits
867 // than C (i.e. no wrap-around can happen). For example, 20-X is
868 // positive if we can prove that X is >= 0 and < 16. Remember to update
869 // SimplifyDemandedBits if/when this is implemented.
872 // Allow the target to implement this method for its nodes.
873 if (Op.getOpcode() >= ISD::BUILTIN_OP_END)
874 computeMaskedBitsForTargetNode(Op, Mask, KnownZero, KnownOne);
879 /// computeMaskedBitsForTargetNode - Determine which of the bits specified
880 /// in Mask are known to be either zero or one and return them in the
881 /// KnownZero/KnownOne bitsets.
882 void TargetLowering::computeMaskedBitsForTargetNode(const SDOperand Op,
886 unsigned Depth) const {
887 assert(Op.getOpcode() >= ISD::BUILTIN_OP_END &&
888 "Should use MaskedValueIsZero if you don't know whether Op"
889 " is a target node!");
894 //===----------------------------------------------------------------------===//
895 // Inline Assembler Implementation Methods
896 //===----------------------------------------------------------------------===//
898 TargetLowering::ConstraintType
899 TargetLowering::getConstraintType(char ConstraintLetter) const {
900 // FIXME: lots more standard ones to handle.
901 switch (ConstraintLetter) {
902 default: return C_Unknown;
903 case 'r': return C_RegisterClass;
905 case 'o': // offsetable
906 case 'V': // not offsetable
908 case 'i': // Simple Integer or Relocatable Constant
909 case 'n': // Simple Integer
910 case 's': // Relocatable Constant
911 case 'I': // Target registers.
923 bool TargetLowering::isOperandValidForConstraint(SDOperand Op,
924 char ConstraintLetter) {
925 switch (ConstraintLetter) {
926 default: return false;
927 case 'i': // Simple Integer or Relocatable Constant
928 case 'n': // Simple Integer
929 case 's': // Relocatable Constant
930 return true; // FIXME: not right.
935 std::vector<unsigned> TargetLowering::
936 getRegClassForInlineAsmConstraint(const std::string &Constraint,
937 MVT::ValueType VT) const {
938 return std::vector<unsigned>();
942 std::pair<unsigned, const TargetRegisterClass*> TargetLowering::
943 getRegForInlineAsmConstraint(const std::string &Constraint,
944 MVT::ValueType VT) const {
945 if (Constraint[0] != '{')
946 return std::pair<unsigned, const TargetRegisterClass*>(0, 0);
947 assert(*(Constraint.end()-1) == '}' && "Not a brace enclosed constraint?");
949 // Remove the braces from around the name.
950 std::string RegName(Constraint.begin()+1, Constraint.end()-1);
952 // Figure out which register class contains this reg.
953 const MRegisterInfo *RI = TM.getRegisterInfo();
954 for (MRegisterInfo::regclass_iterator RCI = RI->regclass_begin(),
955 E = RI->regclass_end(); RCI != E; ++RCI) {
956 const TargetRegisterClass *RC = *RCI;
958 // If none of the the value types for this register class are valid, we
959 // can't use it. For example, 64-bit reg classes on 32-bit targets.
960 bool isLegal = false;
961 for (TargetRegisterClass::vt_iterator I = RC->vt_begin(), E = RC->vt_end();
963 if (isTypeLegal(*I)) {
969 if (!isLegal) continue;
971 for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
973 if (StringsEqualNoCase(RegName, RI->get(*I).Name))
974 return std::make_pair(*I, RC);
978 return std::pair<unsigned, const TargetRegisterClass*>(0, 0);