-
Notifications
You must be signed in to change notification settings - Fork 10.8k
/
TargetLowering.cpp
10800 lines (9597 loc) · 427 KB
/
TargetLowering.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
//===-- TargetLowering.cpp - Implement the TargetLowering class -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This implements the TargetLowering class.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/CodeGenCommonISel.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/Support/DivisionByConstantInfo.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetMachine.h"
#include <cctype>
using namespace llvm;
/// NOTE: The TargetMachine owns TLOF.
TargetLowering::TargetLowering(const TargetMachine &tm)
: TargetLoweringBase(tm) {}
const char *TargetLowering::getTargetNodeName(unsigned Opcode) const {
return nullptr;
}
bool TargetLowering::isPositionIndependent() const {
return getTargetMachine().isPositionIndependent();
}
/// Check whether a given call node is in tail position within its function. If
/// so, it sets Chain to the input chain of the tail call.
bool TargetLowering::isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,
SDValue &Chain) const {
const Function &F = DAG.getMachineFunction().getFunction();
// First, check if tail calls have been disabled in this function.
if (F.getFnAttribute("disable-tail-calls").getValueAsBool())
return false;
// Conservatively require the attributes of the call to match those of
// the return. Ignore following attributes because they don't affect the
// call sequence.
AttrBuilder CallerAttrs(F.getContext(), F.getAttributes().getRetAttrs());
for (const auto &Attr : {Attribute::Alignment, Attribute::Dereferenceable,
Attribute::DereferenceableOrNull, Attribute::NoAlias,
Attribute::NonNull, Attribute::NoUndef})
CallerAttrs.removeAttribute(Attr);
if (CallerAttrs.hasAttributes())
return false;
// It's not safe to eliminate the sign / zero extension of the return value.
if (CallerAttrs.contains(Attribute::ZExt) ||
CallerAttrs.contains(Attribute::SExt))
return false;
// Check if the only use is a function return node.
return isUsedByReturnOnly(Node, Chain);
}
bool TargetLowering::parametersInCSRMatch(const MachineRegisterInfo &MRI,
const uint32_t *CallerPreservedMask,
const SmallVectorImpl<CCValAssign> &ArgLocs,
const SmallVectorImpl<SDValue> &OutVals) const {
for (unsigned I = 0, E = ArgLocs.size(); I != E; ++I) {
const CCValAssign &ArgLoc = ArgLocs[I];
if (!ArgLoc.isRegLoc())
continue;
MCRegister Reg = ArgLoc.getLocReg();
// Only look at callee saved registers.
if (MachineOperand::clobbersPhysReg(CallerPreservedMask, Reg))
continue;
// Check that we pass the value used for the caller.
// (We look for a CopyFromReg reading a virtual register that is used
// for the function live-in value of register Reg)
SDValue Value = OutVals[I];
if (Value->getOpcode() == ISD::AssertZext)
Value = Value.getOperand(0);
if (Value->getOpcode() != ISD::CopyFromReg)
return false;
Register ArgReg = cast<RegisterSDNode>(Value->getOperand(1))->getReg();
if (MRI.getLiveInPhysReg(ArgReg) != Reg)
return false;
}
return true;
}
/// Set CallLoweringInfo attribute flags based on a call instruction
/// and called function attributes.
void TargetLoweringBase::ArgListEntry::setAttributes(const CallBase *Call,
unsigned ArgIdx) {
IsSExt = Call->paramHasAttr(ArgIdx, Attribute::SExt);
IsZExt = Call->paramHasAttr(ArgIdx, Attribute::ZExt);
IsInReg = Call->paramHasAttr(ArgIdx, Attribute::InReg);
IsSRet = Call->paramHasAttr(ArgIdx, Attribute::StructRet);
IsNest = Call->paramHasAttr(ArgIdx, Attribute::Nest);
IsByVal = Call->paramHasAttr(ArgIdx, Attribute::ByVal);
IsPreallocated = Call->paramHasAttr(ArgIdx, Attribute::Preallocated);
IsInAlloca = Call->paramHasAttr(ArgIdx, Attribute::InAlloca);
IsReturned = Call->paramHasAttr(ArgIdx, Attribute::Returned);
IsSwiftSelf = Call->paramHasAttr(ArgIdx, Attribute::SwiftSelf);
IsSwiftAsync = Call->paramHasAttr(ArgIdx, Attribute::SwiftAsync);
IsSwiftError = Call->paramHasAttr(ArgIdx, Attribute::SwiftError);
Alignment = Call->getParamStackAlign(ArgIdx);
IndirectType = nullptr;
assert(IsByVal + IsPreallocated + IsInAlloca + IsSRet <= 1 &&
"multiple ABI attributes?");
if (IsByVal) {
IndirectType = Call->getParamByValType(ArgIdx);
if (!Alignment)
Alignment = Call->getParamAlign(ArgIdx);
}
if (IsPreallocated)
IndirectType = Call->getParamPreallocatedType(ArgIdx);
if (IsInAlloca)
IndirectType = Call->getParamInAllocaType(ArgIdx);
if (IsSRet)
IndirectType = Call->getParamStructRetType(ArgIdx);
}
/// Generate a libcall taking the given operands as arguments and returning a
/// result of type RetVT.
std::pair<SDValue, SDValue>
TargetLowering::makeLibCall(SelectionDAG &DAG, RTLIB::Libcall LC, EVT RetVT,
ArrayRef<SDValue> Ops,
MakeLibCallOptions CallOptions,
const SDLoc &dl,
SDValue InChain) const {
if (!InChain)
InChain = DAG.getEntryNode();
TargetLowering::ArgListTy Args;
Args.reserve(Ops.size());
TargetLowering::ArgListEntry Entry;
for (unsigned i = 0; i < Ops.size(); ++i) {
SDValue NewOp = Ops[i];
Entry.Node = NewOp;
Entry.Ty = Entry.Node.getValueType().getTypeForEVT(*DAG.getContext());
Entry.IsSExt = shouldSignExtendTypeInLibCall(NewOp.getValueType(),
CallOptions.IsSExt);
Entry.IsZExt = !Entry.IsSExt;
if (CallOptions.IsSoften &&
!shouldExtendTypeInLibCall(CallOptions.OpsVTBeforeSoften[i])) {
Entry.IsSExt = Entry.IsZExt = false;
}
Args.push_back(Entry);
}
if (LC == RTLIB::UNKNOWN_LIBCALL)
report_fatal_error("Unsupported library call operation!");
SDValue Callee = DAG.getExternalSymbol(getLibcallName(LC),
getPointerTy(DAG.getDataLayout()));
Type *RetTy = RetVT.getTypeForEVT(*DAG.getContext());
TargetLowering::CallLoweringInfo CLI(DAG);
bool signExtend = shouldSignExtendTypeInLibCall(RetVT, CallOptions.IsSExt);
bool zeroExtend = !signExtend;
if (CallOptions.IsSoften &&
!shouldExtendTypeInLibCall(CallOptions.RetVTBeforeSoften)) {
signExtend = zeroExtend = false;
}
CLI.setDebugLoc(dl)
.setChain(InChain)
.setLibCallee(getLibcallCallingConv(LC), RetTy, Callee, std::move(Args))
.setNoReturn(CallOptions.DoesNotReturn)
.setDiscardResult(!CallOptions.IsReturnValueUsed)
.setIsPostTypeLegalization(CallOptions.IsPostTypeLegalization)
.setSExtResult(signExtend)
.setZExtResult(zeroExtend);
return LowerCallTo(CLI);
}
bool TargetLowering::findOptimalMemOpLowering(
std::vector<EVT> &MemOps, unsigned Limit, const MemOp &Op, unsigned DstAS,
unsigned SrcAS, const AttributeList &FuncAttributes) const {
if (Limit != ~unsigned(0) && Op.isMemcpyWithFixedDstAlign() &&
Op.getSrcAlign() < Op.getDstAlign())
return false;
EVT VT = getOptimalMemOpType(Op, FuncAttributes);
if (VT == MVT::Other) {
// Use the largest integer type whose alignment constraints are satisfied.
// We only need to check DstAlign here as SrcAlign is always greater or
// equal to DstAlign (or zero).
VT = MVT::i64;
if (Op.isFixedDstAlign())
while (Op.getDstAlign() < (VT.getSizeInBits() / 8) &&
!allowsMisalignedMemoryAccesses(VT, DstAS, Op.getDstAlign()))
VT = (MVT::SimpleValueType)(VT.getSimpleVT().SimpleTy - 1);
assert(VT.isInteger());
// Find the largest legal integer type.
MVT LVT = MVT::i64;
while (!isTypeLegal(LVT))
LVT = (MVT::SimpleValueType)(LVT.SimpleTy - 1);
assert(LVT.isInteger());
// If the type we've chosen is larger than the largest legal integer type
// then use that instead.
if (VT.bitsGT(LVT))
VT = LVT;
}
unsigned NumMemOps = 0;
uint64_t Size = Op.size();
while (Size) {
unsigned VTSize = VT.getSizeInBits() / 8;
while (VTSize > Size) {
// For now, only use non-vector load / store's for the left-over pieces.
EVT NewVT = VT;
unsigned NewVTSize;
bool Found = false;
if (VT.isVector() || VT.isFloatingPoint()) {
NewVT = (VT.getSizeInBits() > 64) ? MVT::i64 : MVT::i32;
if (isOperationLegalOrCustom(ISD::STORE, NewVT) &&
isSafeMemOpType(NewVT.getSimpleVT()))
Found = true;
else if (NewVT == MVT::i64 &&
isOperationLegalOrCustom(ISD::STORE, MVT::f64) &&
isSafeMemOpType(MVT::f64)) {
// i64 is usually not legal on 32-bit targets, but f64 may be.
NewVT = MVT::f64;
Found = true;
}
}
if (!Found) {
do {
NewVT = (MVT::SimpleValueType)(NewVT.getSimpleVT().SimpleTy - 1);
if (NewVT == MVT::i8)
break;
} while (!isSafeMemOpType(NewVT.getSimpleVT()));
}
NewVTSize = NewVT.getSizeInBits() / 8;
// If the new VT cannot cover all of the remaining bits, then consider
// issuing a (or a pair of) unaligned and overlapping load / store.
unsigned Fast;
if (NumMemOps && Op.allowOverlap() && NewVTSize < Size &&
allowsMisalignedMemoryAccesses(
VT, DstAS, Op.isFixedDstAlign() ? Op.getDstAlign() : Align(1),
MachineMemOperand::MONone, &Fast) &&
Fast)
VTSize = Size;
else {
VT = NewVT;
VTSize = NewVTSize;
}
}
if (++NumMemOps > Limit)
return false;
MemOps.push_back(VT);
Size -= VTSize;
}
return true;
}
/// Soften the operands of a comparison. This code is shared among BR_CC,
/// SELECT_CC, and SETCC handlers.
void TargetLowering::softenSetCCOperands(SelectionDAG &DAG, EVT VT,
SDValue &NewLHS, SDValue &NewRHS,
ISD::CondCode &CCCode,
const SDLoc &dl, const SDValue OldLHS,
const SDValue OldRHS) const {
SDValue Chain;
return softenSetCCOperands(DAG, VT, NewLHS, NewRHS, CCCode, dl, OldLHS,
OldRHS, Chain);
}
void TargetLowering::softenSetCCOperands(SelectionDAG &DAG, EVT VT,
SDValue &NewLHS, SDValue &NewRHS,
ISD::CondCode &CCCode,
const SDLoc &dl, const SDValue OldLHS,
const SDValue OldRHS,
SDValue &Chain,
bool IsSignaling) const {
// FIXME: Currently we cannot really respect all IEEE predicates due to libgcc
// not supporting it. We can update this code when libgcc provides such
// functions.
assert((VT == MVT::f32 || VT == MVT::f64 || VT == MVT::f128 || VT == MVT::ppcf128)
&& "Unsupported setcc type!");
// Expand into one or more soft-fp libcall(s).
RTLIB::Libcall LC1 = RTLIB::UNKNOWN_LIBCALL, LC2 = RTLIB::UNKNOWN_LIBCALL;
bool ShouldInvertCC = false;
switch (CCCode) {
case ISD::SETEQ:
case ISD::SETOEQ:
LC1 = (VT == MVT::f32) ? RTLIB::OEQ_F32 :
(VT == MVT::f64) ? RTLIB::OEQ_F64 :
(VT == MVT::f128) ? RTLIB::OEQ_F128 : RTLIB::OEQ_PPCF128;
break;
case ISD::SETNE:
case ISD::SETUNE:
LC1 = (VT == MVT::f32) ? RTLIB::UNE_F32 :
(VT == MVT::f64) ? RTLIB::UNE_F64 :
(VT == MVT::f128) ? RTLIB::UNE_F128 : RTLIB::UNE_PPCF128;
break;
case ISD::SETGE:
case ISD::SETOGE:
LC1 = (VT == MVT::f32) ? RTLIB::OGE_F32 :
(VT == MVT::f64) ? RTLIB::OGE_F64 :
(VT == MVT::f128) ? RTLIB::OGE_F128 : RTLIB::OGE_PPCF128;
break;
case ISD::SETLT:
case ISD::SETOLT:
LC1 = (VT == MVT::f32) ? RTLIB::OLT_F32 :
(VT == MVT::f64) ? RTLIB::OLT_F64 :
(VT == MVT::f128) ? RTLIB::OLT_F128 : RTLIB::OLT_PPCF128;
break;
case ISD::SETLE:
case ISD::SETOLE:
LC1 = (VT == MVT::f32) ? RTLIB::OLE_F32 :
(VT == MVT::f64) ? RTLIB::OLE_F64 :
(VT == MVT::f128) ? RTLIB::OLE_F128 : RTLIB::OLE_PPCF128;
break;
case ISD::SETGT:
case ISD::SETOGT:
LC1 = (VT == MVT::f32) ? RTLIB::OGT_F32 :
(VT == MVT::f64) ? RTLIB::OGT_F64 :
(VT == MVT::f128) ? RTLIB::OGT_F128 : RTLIB::OGT_PPCF128;
break;
case ISD::SETO:
ShouldInvertCC = true;
[[fallthrough]];
case ISD::SETUO:
LC1 = (VT == MVT::f32) ? RTLIB::UO_F32 :
(VT == MVT::f64) ? RTLIB::UO_F64 :
(VT == MVT::f128) ? RTLIB::UO_F128 : RTLIB::UO_PPCF128;
break;
case ISD::SETONE:
// SETONE = O && UNE
ShouldInvertCC = true;
[[fallthrough]];
case ISD::SETUEQ:
LC1 = (VT == MVT::f32) ? RTLIB::UO_F32 :
(VT == MVT::f64) ? RTLIB::UO_F64 :
(VT == MVT::f128) ? RTLIB::UO_F128 : RTLIB::UO_PPCF128;
LC2 = (VT == MVT::f32) ? RTLIB::OEQ_F32 :
(VT == MVT::f64) ? RTLIB::OEQ_F64 :
(VT == MVT::f128) ? RTLIB::OEQ_F128 : RTLIB::OEQ_PPCF128;
break;
default:
// Invert CC for unordered comparisons
ShouldInvertCC = true;
switch (CCCode) {
case ISD::SETULT:
LC1 = (VT == MVT::f32) ? RTLIB::OGE_F32 :
(VT == MVT::f64) ? RTLIB::OGE_F64 :
(VT == MVT::f128) ? RTLIB::OGE_F128 : RTLIB::OGE_PPCF128;
break;
case ISD::SETULE:
LC1 = (VT == MVT::f32) ? RTLIB::OGT_F32 :
(VT == MVT::f64) ? RTLIB::OGT_F64 :
(VT == MVT::f128) ? RTLIB::OGT_F128 : RTLIB::OGT_PPCF128;
break;
case ISD::SETUGT:
LC1 = (VT == MVT::f32) ? RTLIB::OLE_F32 :
(VT == MVT::f64) ? RTLIB::OLE_F64 :
(VT == MVT::f128) ? RTLIB::OLE_F128 : RTLIB::OLE_PPCF128;
break;
case ISD::SETUGE:
LC1 = (VT == MVT::f32) ? RTLIB::OLT_F32 :
(VT == MVT::f64) ? RTLIB::OLT_F64 :
(VT == MVT::f128) ? RTLIB::OLT_F128 : RTLIB::OLT_PPCF128;
break;
default: llvm_unreachable("Do not know how to soften this setcc!");
}
}
// Use the target specific return value for comparison lib calls.
EVT RetVT = getCmpLibcallReturnType();
SDValue Ops[2] = {NewLHS, NewRHS};
TargetLowering::MakeLibCallOptions CallOptions;
EVT OpsVT[2] = { OldLHS.getValueType(),
OldRHS.getValueType() };
CallOptions.setTypeListBeforeSoften(OpsVT, RetVT, true);
auto Call = makeLibCall(DAG, LC1, RetVT, Ops, CallOptions, dl, Chain);
NewLHS = Call.first;
NewRHS = DAG.getConstant(0, dl, RetVT);
CCCode = getCmpLibcallCC(LC1);
if (ShouldInvertCC) {
assert(RetVT.isInteger());
CCCode = getSetCCInverse(CCCode, RetVT);
}
if (LC2 == RTLIB::UNKNOWN_LIBCALL) {
// Update Chain.
Chain = Call.second;
} else {
EVT SetCCVT =
getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(), RetVT);
SDValue Tmp = DAG.getSetCC(dl, SetCCVT, NewLHS, NewRHS, CCCode);
auto Call2 = makeLibCall(DAG, LC2, RetVT, Ops, CallOptions, dl, Chain);
CCCode = getCmpLibcallCC(LC2);
if (ShouldInvertCC)
CCCode = getSetCCInverse(CCCode, RetVT);
NewLHS = DAG.getSetCC(dl, SetCCVT, Call2.first, NewRHS, CCCode);
if (Chain)
Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Call.second,
Call2.second);
NewLHS = DAG.getNode(ShouldInvertCC ? ISD::AND : ISD::OR, dl,
Tmp.getValueType(), Tmp, NewLHS);
NewRHS = SDValue();
}
}
/// Return the entry encoding for a jump table in the current function. The
/// returned value is a member of the MachineJumpTableInfo::JTEntryKind enum.
unsigned TargetLowering::getJumpTableEncoding() const {
// In non-pic modes, just use the address of a block.
if (!isPositionIndependent())
return MachineJumpTableInfo::EK_BlockAddress;
// In PIC mode, if the target supports a GPRel32 directive, use it.
if (getTargetMachine().getMCAsmInfo()->getGPRel32Directive() != nullptr)
return MachineJumpTableInfo::EK_GPRel32BlockAddress;
// Otherwise, use a label difference.
return MachineJumpTableInfo::EK_LabelDifference32;
}
SDValue TargetLowering::getPICJumpTableRelocBase(SDValue Table,
SelectionDAG &DAG) const {
// If our PIC model is GP relative, use the global offset table as the base.
unsigned JTEncoding = getJumpTableEncoding();
if ((JTEncoding == MachineJumpTableInfo::EK_GPRel64BlockAddress) ||
(JTEncoding == MachineJumpTableInfo::EK_GPRel32BlockAddress))
return DAG.getGLOBAL_OFFSET_TABLE(getPointerTy(DAG.getDataLayout()));
return Table;
}
/// This returns the relocation base for the given PIC jumptable, the same as
/// getPICJumpTableRelocBase, but as an MCExpr.
const MCExpr *
TargetLowering::getPICJumpTableRelocBaseExpr(const MachineFunction *MF,
unsigned JTI,MCContext &Ctx) const{
// The normal PIC reloc base is the label at the start of the jump table.
return MCSymbolRefExpr::create(MF->getJTISymbol(JTI, Ctx), Ctx);
}
bool
TargetLowering::isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const {
const TargetMachine &TM = getTargetMachine();
const GlobalValue *GV = GA->getGlobal();
// If the address is not even local to this DSO we will have to load it from
// a got and then add the offset.
if (!TM.shouldAssumeDSOLocal(*GV->getParent(), GV))
return false;
// If the code is position independent we will have to add a base register.
if (isPositionIndependent())
return false;
// Otherwise we can do it.
return true;
}
//===----------------------------------------------------------------------===//
// Optimization Methods
//===----------------------------------------------------------------------===//
/// If the specified instruction has a constant integer operand and there are
/// bits set in that constant that are not demanded, then clear those bits and
/// return true.
bool TargetLowering::ShrinkDemandedConstant(SDValue Op,
const APInt &DemandedBits,
const APInt &DemandedElts,
TargetLoweringOpt &TLO) const {
SDLoc DL(Op);
unsigned Opcode = Op.getOpcode();
// Early-out if we've ended up calling an undemanded node, leave this to
// constant folding.
if (DemandedBits.isZero() || DemandedElts.isZero())
return false;
// Do target-specific constant optimization.
if (targetShrinkDemandedConstant(Op, DemandedBits, DemandedElts, TLO))
return TLO.New.getNode();
// FIXME: ISD::SELECT, ISD::SELECT_CC
switch (Opcode) {
default:
break;
case ISD::XOR:
case ISD::AND:
case ISD::OR: {
auto *Op1C = dyn_cast<ConstantSDNode>(Op.getOperand(1));
if (!Op1C || Op1C->isOpaque())
return false;
// If this is a 'not' op, don't touch it because that's a canonical form.
const APInt &C = Op1C->getAPIntValue();
if (Opcode == ISD::XOR && DemandedBits.isSubsetOf(C))
return false;
if (!C.isSubsetOf(DemandedBits)) {
EVT VT = Op.getValueType();
SDValue NewC = TLO.DAG.getConstant(DemandedBits & C, DL, VT);
SDValue NewOp = TLO.DAG.getNode(Opcode, DL, VT, Op.getOperand(0), NewC);
return TLO.CombineTo(Op, NewOp);
}
break;
}
}
return false;
}
bool TargetLowering::ShrinkDemandedConstant(SDValue Op,
const APInt &DemandedBits,
TargetLoweringOpt &TLO) const {
EVT VT = Op.getValueType();
APInt DemandedElts = VT.isVector()
? APInt::getAllOnes(VT.getVectorNumElements())
: APInt(1, 1);
return ShrinkDemandedConstant(Op, DemandedBits, DemandedElts, TLO);
}
/// Convert x+y to (VT)((SmallVT)x+(SmallVT)y) if the casts are free.
/// This uses isZExtFree and ZERO_EXTEND for the widening cast, but it could be
/// generalized for targets with other types of implicit widening casts.
bool TargetLowering::ShrinkDemandedOp(SDValue Op, unsigned BitWidth,
const APInt &DemandedBits,
TargetLoweringOpt &TLO) const {
assert(Op.getNumOperands() == 2 &&
"ShrinkDemandedOp only supports binary operators!");
assert(Op.getNode()->getNumValues() == 1 &&
"ShrinkDemandedOp only supports nodes with one result!");
EVT VT = Op.getValueType();
SelectionDAG &DAG = TLO.DAG;
SDLoc dl(Op);
// Early return, as this function cannot handle vector types.
if (VT.isVector())
return false;
// Don't do this if the node has another user, which may require the
// full value.
if (!Op.getNode()->hasOneUse())
return false;
// Search for the smallest integer type with free casts to and from
// Op's type. For expedience, just check power-of-2 integer types.
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
unsigned DemandedSize = DemandedBits.getActiveBits();
for (unsigned SmallVTBits = llvm::bit_ceil(DemandedSize);
SmallVTBits < BitWidth; SmallVTBits = NextPowerOf2(SmallVTBits)) {
EVT SmallVT = EVT::getIntegerVT(*DAG.getContext(), SmallVTBits);
if (TLI.isTruncateFree(VT, SmallVT) && TLI.isZExtFree(SmallVT, VT)) {
// We found a type with free casts.
SDValue X = DAG.getNode(
Op.getOpcode(), dl, SmallVT,
DAG.getNode(ISD::TRUNCATE, dl, SmallVT, Op.getOperand(0)),
DAG.getNode(ISD::TRUNCATE, dl, SmallVT, Op.getOperand(1)));
assert(DemandedSize <= SmallVTBits && "Narrowed below demanded bits?");
SDValue Z = DAG.getNode(ISD::ANY_EXTEND, dl, VT, X);
return TLO.CombineTo(Op, Z);
}
}
return false;
}
bool TargetLowering::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
DAGCombinerInfo &DCI) const {
SelectionDAG &DAG = DCI.DAG;
TargetLoweringOpt TLO(DAG, !DCI.isBeforeLegalize(),
!DCI.isBeforeLegalizeOps());
KnownBits Known;
bool Simplified = SimplifyDemandedBits(Op, DemandedBits, Known, TLO);
if (Simplified) {
DCI.AddToWorklist(Op.getNode());
DCI.CommitTargetLoweringOpt(TLO);
}
return Simplified;
}
bool TargetLowering::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
const APInt &DemandedElts,
DAGCombinerInfo &DCI) const {
SelectionDAG &DAG = DCI.DAG;
TargetLoweringOpt TLO(DAG, !DCI.isBeforeLegalize(),
!DCI.isBeforeLegalizeOps());
KnownBits Known;
bool Simplified =
SimplifyDemandedBits(Op, DemandedBits, DemandedElts, Known, TLO);
if (Simplified) {
DCI.AddToWorklist(Op.getNode());
DCI.CommitTargetLoweringOpt(TLO);
}
return Simplified;
}
bool TargetLowering::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
KnownBits &Known,
TargetLoweringOpt &TLO,
unsigned Depth,
bool AssumeSingleUse) const {
EVT VT = Op.getValueType();
// Since the number of lanes in a scalable vector is unknown at compile time,
// we track one bit which is implicitly broadcast to all lanes. This means
// that all lanes in a scalable vector are considered demanded.
APInt DemandedElts = VT.isFixedLengthVector()
? APInt::getAllOnes(VT.getVectorNumElements())
: APInt(1, 1);
return SimplifyDemandedBits(Op, DemandedBits, DemandedElts, Known, TLO, Depth,
AssumeSingleUse);
}
// TODO: Under what circumstances can we create nodes? Constant folding?
SDValue TargetLowering::SimplifyMultipleUseDemandedBits(
SDValue Op, const APInt &DemandedBits, const APInt &DemandedElts,
SelectionDAG &DAG, unsigned Depth) const {
EVT VT = Op.getValueType();
// Limit search depth.
if (Depth >= SelectionDAG::MaxRecursionDepth)
return SDValue();
// Ignore UNDEFs.
if (Op.isUndef())
return SDValue();
// Not demanding any bits/elts from Op.
if (DemandedBits == 0 || DemandedElts == 0)
return DAG.getUNDEF(VT);
bool IsLE = DAG.getDataLayout().isLittleEndian();
unsigned NumElts = DemandedElts.getBitWidth();
unsigned BitWidth = DemandedBits.getBitWidth();
KnownBits LHSKnown, RHSKnown;
switch (Op.getOpcode()) {
case ISD::BITCAST: {
if (VT.isScalableVector())
return SDValue();
SDValue Src = peekThroughBitcasts(Op.getOperand(0));
EVT SrcVT = Src.getValueType();
EVT DstVT = Op.getValueType();
if (SrcVT == DstVT)
return Src;
unsigned NumSrcEltBits = SrcVT.getScalarSizeInBits();
unsigned NumDstEltBits = DstVT.getScalarSizeInBits();
if (NumSrcEltBits == NumDstEltBits)
if (SDValue V = SimplifyMultipleUseDemandedBits(
Src, DemandedBits, DemandedElts, DAG, Depth + 1))
return DAG.getBitcast(DstVT, V);
if (SrcVT.isVector() && (NumDstEltBits % NumSrcEltBits) == 0) {
unsigned Scale = NumDstEltBits / NumSrcEltBits;
unsigned NumSrcElts = SrcVT.getVectorNumElements();
APInt DemandedSrcBits = APInt::getZero(NumSrcEltBits);
APInt DemandedSrcElts = APInt::getZero(NumSrcElts);
for (unsigned i = 0; i != Scale; ++i) {
unsigned EltOffset = IsLE ? i : (Scale - 1 - i);
unsigned BitOffset = EltOffset * NumSrcEltBits;
APInt Sub = DemandedBits.extractBits(NumSrcEltBits, BitOffset);
if (!Sub.isZero()) {
DemandedSrcBits |= Sub;
for (unsigned j = 0; j != NumElts; ++j)
if (DemandedElts[j])
DemandedSrcElts.setBit((j * Scale) + i);
}
}
if (SDValue V = SimplifyMultipleUseDemandedBits(
Src, DemandedSrcBits, DemandedSrcElts, DAG, Depth + 1))
return DAG.getBitcast(DstVT, V);
}
// TODO - bigendian once we have test coverage.
if (IsLE && (NumSrcEltBits % NumDstEltBits) == 0) {
unsigned Scale = NumSrcEltBits / NumDstEltBits;
unsigned NumSrcElts = SrcVT.isVector() ? SrcVT.getVectorNumElements() : 1;
APInt DemandedSrcBits = APInt::getZero(NumSrcEltBits);
APInt DemandedSrcElts = APInt::getZero(NumSrcElts);
for (unsigned i = 0; i != NumElts; ++i)
if (DemandedElts[i]) {
unsigned Offset = (i % Scale) * NumDstEltBits;
DemandedSrcBits.insertBits(DemandedBits, Offset);
DemandedSrcElts.setBit(i / Scale);
}
if (SDValue V = SimplifyMultipleUseDemandedBits(
Src, DemandedSrcBits, DemandedSrcElts, DAG, Depth + 1))
return DAG.getBitcast(DstVT, V);
}
break;
}
case ISD::AND: {
LHSKnown = DAG.computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
RHSKnown = DAG.computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
// If all of the demanded bits are known 1 on one side, return the other.
// These bits cannot contribute to the result of the 'and' in this
// context.
if (DemandedBits.isSubsetOf(LHSKnown.Zero | RHSKnown.One))
return Op.getOperand(0);
if (DemandedBits.isSubsetOf(RHSKnown.Zero | LHSKnown.One))
return Op.getOperand(1);
break;
}
case ISD::OR: {
LHSKnown = DAG.computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
RHSKnown = DAG.computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
// If all of the demanded bits are known zero on one side, return the
// other. These bits cannot contribute to the result of the 'or' in this
// context.
if (DemandedBits.isSubsetOf(LHSKnown.One | RHSKnown.Zero))
return Op.getOperand(0);
if (DemandedBits.isSubsetOf(RHSKnown.One | LHSKnown.Zero))
return Op.getOperand(1);
break;
}
case ISD::XOR: {
LHSKnown = DAG.computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
RHSKnown = DAG.computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
// If all of the demanded bits are known zero on one side, return the
// other.
if (DemandedBits.isSubsetOf(RHSKnown.Zero))
return Op.getOperand(0);
if (DemandedBits.isSubsetOf(LHSKnown.Zero))
return Op.getOperand(1);
break;
}
case ISD::SHL: {
// If we are only demanding sign bits then we can use the shift source
// directly.
if (const APInt *MaxSA =
DAG.getValidMaximumShiftAmountConstant(Op, DemandedElts)) {
SDValue Op0 = Op.getOperand(0);
unsigned ShAmt = MaxSA->getZExtValue();
unsigned NumSignBits =
DAG.ComputeNumSignBits(Op0, DemandedElts, Depth + 1);
unsigned UpperDemandedBits = BitWidth - DemandedBits.countr_zero();
if (NumSignBits > ShAmt && (NumSignBits - ShAmt) >= (UpperDemandedBits))
return Op0;
}
break;
}
case ISD::SETCC: {
SDValue Op0 = Op.getOperand(0);
SDValue Op1 = Op.getOperand(1);
ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(2))->get();
// If (1) we only need the sign-bit, (2) the setcc operands are the same
// width as the setcc result, and (3) the result of a setcc conforms to 0 or
// -1, we may be able to bypass the setcc.
if (DemandedBits.isSignMask() &&
Op0.getScalarValueSizeInBits() == BitWidth &&
getBooleanContents(Op0.getValueType()) ==
BooleanContent::ZeroOrNegativeOneBooleanContent) {
// If we're testing X < 0, then this compare isn't needed - just use X!
// FIXME: We're limiting to integer types here, but this should also work
// if we don't care about FP signed-zero. The use of SETLT with FP means
// that we don't care about NaNs.
if (CC == ISD::SETLT && Op1.getValueType().isInteger() &&
(isNullConstant(Op1) || ISD::isBuildVectorAllZeros(Op1.getNode())))
return Op0;
}
break;
}
case ISD::SIGN_EXTEND_INREG: {
// If none of the extended bits are demanded, eliminate the sextinreg.
SDValue Op0 = Op.getOperand(0);
EVT ExVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
unsigned ExBits = ExVT.getScalarSizeInBits();
if (DemandedBits.getActiveBits() <= ExBits &&
shouldRemoveRedundantExtend(Op))
return Op0;
// If the input is already sign extended, just drop the extension.
unsigned NumSignBits = DAG.ComputeNumSignBits(Op0, DemandedElts, Depth + 1);
if (NumSignBits >= (BitWidth - ExBits + 1))
return Op0;
break;
}
case ISD::ANY_EXTEND_VECTOR_INREG:
case ISD::SIGN_EXTEND_VECTOR_INREG:
case ISD::ZERO_EXTEND_VECTOR_INREG: {
if (VT.isScalableVector())
return SDValue();
// If we only want the lowest element and none of extended bits, then we can
// return the bitcasted source vector.
SDValue Src = Op.getOperand(0);
EVT SrcVT = Src.getValueType();
EVT DstVT = Op.getValueType();
if (IsLE && DemandedElts == 1 &&
DstVT.getSizeInBits() == SrcVT.getSizeInBits() &&
DemandedBits.getActiveBits() <= SrcVT.getScalarSizeInBits()) {
return DAG.getBitcast(DstVT, Src);
}
break;
}
case ISD::INSERT_VECTOR_ELT: {
if (VT.isScalableVector())
return SDValue();
// If we don't demand the inserted element, return the base vector.
SDValue Vec = Op.getOperand(0);
auto *CIdx = dyn_cast<ConstantSDNode>(Op.getOperand(2));
EVT VecVT = Vec.getValueType();
if (CIdx && CIdx->getAPIntValue().ult(VecVT.getVectorNumElements()) &&
!DemandedElts[CIdx->getZExtValue()])
return Vec;
break;
}
case ISD::INSERT_SUBVECTOR: {
if (VT.isScalableVector())
return SDValue();
SDValue Vec = Op.getOperand(0);
SDValue Sub = Op.getOperand(1);
uint64_t Idx = Op.getConstantOperandVal(2);
unsigned NumSubElts = Sub.getValueType().getVectorNumElements();
APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);
// If we don't demand the inserted subvector, return the base vector.
if (DemandedSubElts == 0)
return Vec;
break;
}
case ISD::VECTOR_SHUFFLE: {
assert(!VT.isScalableVector());
ArrayRef<int> ShuffleMask = cast<ShuffleVectorSDNode>(Op)->getMask();
// If all the demanded elts are from one operand and are inline,
// then we can use the operand directly.
bool AllUndef = true, IdentityLHS = true, IdentityRHS = true;
for (unsigned i = 0; i != NumElts; ++i) {
int M = ShuffleMask[i];
if (M < 0 || !DemandedElts[i])
continue;
AllUndef = false;
IdentityLHS &= (M == (int)i);
IdentityRHS &= ((M - NumElts) == i);
}
if (AllUndef)
return DAG.getUNDEF(Op.getValueType());
if (IdentityLHS)
return Op.getOperand(0);
if (IdentityRHS)
return Op.getOperand(1);
break;
}
default:
// TODO: Probably okay to remove after audit; here to reduce change size
// in initial enablement patch for scalable vectors
if (VT.isScalableVector())
return SDValue();
if (Op.getOpcode() >= ISD::BUILTIN_OP_END)
if (SDValue V = SimplifyMultipleUseDemandedBitsForTargetNode(
Op, DemandedBits, DemandedElts, DAG, Depth))
return V;
break;
}
return SDValue();
}
SDValue TargetLowering::SimplifyMultipleUseDemandedBits(
SDValue Op, const APInt &DemandedBits, SelectionDAG &DAG,
unsigned Depth) const {
EVT VT = Op.getValueType();
// Since the number of lanes in a scalable vector is unknown at compile time,
// we track one bit which is implicitly broadcast to all lanes. This means
// that all lanes in a scalable vector are considered demanded.
APInt DemandedElts = VT.isFixedLengthVector()
? APInt::getAllOnes(VT.getVectorNumElements())
: APInt(1, 1);
return SimplifyMultipleUseDemandedBits(Op, DemandedBits, DemandedElts, DAG,
Depth);
}
SDValue TargetLowering::SimplifyMultipleUseDemandedVectorElts(
SDValue Op, const APInt &DemandedElts, SelectionDAG &DAG,
unsigned Depth) const {
APInt DemandedBits = APInt::getAllOnes(Op.getScalarValueSizeInBits());
return SimplifyMultipleUseDemandedBits(Op, DemandedBits, DemandedElts, DAG,
Depth);
}
// Attempt to form ext(avgfloor(A, B)) from shr(add(ext(A), ext(B)), 1).
// or to form ext(avgceil(A, B)) from shr(add(ext(A), ext(B), 1), 1).
static SDValue combineShiftToAVG(SDValue Op, SelectionDAG &DAG,
const TargetLowering &TLI,
const APInt &DemandedBits,
const APInt &DemandedElts,
unsigned Depth) {
assert((Op.getOpcode() == ISD::SRL || Op.getOpcode() == ISD::SRA) &&
"SRL or SRA node is required here!");
// Is the right shift using an immediate value of 1?
ConstantSDNode *N1C = isConstOrConstSplat(Op.getOperand(1), DemandedElts);
if (!N1C || !N1C->isOne())
return SDValue();
// We are looking for an avgfloor
// add(ext, ext)
// or one of these as a avgceil
// add(add(ext, ext), 1)
// add(add(ext, 1), ext)
// add(ext, add(ext, 1))
SDValue Add = Op.getOperand(0);
if (Add.getOpcode() != ISD::ADD)
return SDValue();
SDValue ExtOpA = Add.getOperand(0);
SDValue ExtOpB = Add.getOperand(1);
SDValue Add2;
auto MatchOperands = [&](SDValue Op1, SDValue Op2, SDValue Op3, SDValue A) {
ConstantSDNode *ConstOp;
if ((ConstOp = isConstOrConstSplat(Op2, DemandedElts)) &&
ConstOp->isOne()) {
ExtOpA = Op1;
ExtOpB = Op3;
Add2 = A;
return true;
}
if ((ConstOp = isConstOrConstSplat(Op3, DemandedElts)) &&
ConstOp->isOne()) {
ExtOpA = Op1;
ExtOpB = Op2;
Add2 = A;
return true;
}
return false;
};
bool IsCeil =
(ExtOpA.getOpcode() == ISD::ADD &&
MatchOperands(ExtOpA.getOperand(0), ExtOpA.getOperand(1), ExtOpB, ExtOpA)) ||
(ExtOpB.getOpcode() == ISD::ADD &&
MatchOperands(ExtOpB.getOperand(0), ExtOpB.getOperand(1), ExtOpA, ExtOpB));
// If the shift is signed (sra):
// - Needs >= 2 sign bit for both operands.
// - Needs >= 2 zero bits.
// If the shift is unsigned (srl):
// - Needs >= 1 zero bit for both operands.
// - Needs 1 demanded bit zero and >= 2 sign bits.
unsigned ShiftOpc = Op.getOpcode();
bool IsSigned = false;
unsigned KnownBits;
unsigned NumSignedA = DAG.ComputeNumSignBits(ExtOpA, DemandedElts, Depth);
unsigned NumSignedB = DAG.ComputeNumSignBits(ExtOpB, DemandedElts, Depth);
unsigned NumSigned = std::min(NumSignedA, NumSignedB) - 1;
unsigned NumZeroA =
DAG.computeKnownBits(ExtOpA, DemandedElts, Depth).countMinLeadingZeros();
unsigned NumZeroB =
DAG.computeKnownBits(ExtOpB, DemandedElts, Depth).countMinLeadingZeros();
unsigned NumZero = std::min(NumZeroA, NumZeroB);
switch (ShiftOpc) {
default:
llvm_unreachable("Unexpected ShiftOpc in combineShiftToAVG");
case ISD::SRA: {
if (NumZero >= 2 && NumSigned < NumZero) {
IsSigned = false;