1//===----- CodeGen/ExpandVectorPredication.cpp - Expand VP intrinsics -----===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This pass implements IR expansion for vector predication intrinsics, allowing
10// targets to enable vector predication until just before codegen.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/CodeGen/ExpandVectorPredication.h"
15#include "llvm/ADT/Statistic.h"
16#include "llvm/Analysis/TargetTransformInfo.h"
17#include "llvm/Analysis/ValueTracking.h"
18#include "llvm/Analysis/VectorUtils.h"
19#include "llvm/CodeGen/Passes.h"
20#include "llvm/IR/Constants.h"
21#include "llvm/IR/Function.h"
22#include "llvm/IR/IRBuilder.h"
23#include "llvm/IR/InstIterator.h"
24#include "llvm/IR/Instructions.h"
25#include "llvm/IR/IntrinsicInst.h"
26#include "llvm/IR/Intrinsics.h"
27#include "llvm/InitializePasses.h"
28#include "llvm/Pass.h"
29#include "llvm/Support/CommandLine.h"
30#include "llvm/Support/Compiler.h"
31#include "llvm/Support/Debug.h"
32#include <optional>
33
34using namespace llvm;
35
36using VPLegalization = TargetTransformInfo::VPLegalization;
37using VPTransform = TargetTransformInfo::VPLegalization::VPTransform;
38
39// Keep this in sync with TargetTransformInfo::VPLegalization.
40#define VPINTERNAL_VPLEGAL_CASES \
41 VPINTERNAL_CASE(Legal) \
42 VPINTERNAL_CASE(Discard) \
43 VPINTERNAL_CASE(Convert)
44
45#define VPINTERNAL_CASE(X) "|" #X
46
47// Override options.
48static cl::opt<std::string> EVLTransformOverride(
49 "expandvp-override-evl-transform", cl::init(Val: ""), cl::Hidden,
50 cl::desc("Options: <empty>" VPINTERNAL_VPLEGAL_CASES
51 ". If non-empty, ignore "
52 "TargetTransformInfo and "
53 "always use this transformation for the %evl parameter (Used in "
54 "testing)."));
55
56static cl::opt<std::string> MaskTransformOverride(
57 "expandvp-override-mask-transform", cl::init(Val: ""), cl::Hidden,
58 cl::desc("Options: <empty>" VPINTERNAL_VPLEGAL_CASES
59 ". If non-empty, Ignore "
60 "TargetTransformInfo and "
61 "always use this transformation for the %mask parameter (Used in "
62 "testing)."));
63
64#undef VPINTERNAL_CASE
65#define VPINTERNAL_CASE(X) .Case(#X, VPLegalization::X)
66
67static VPTransform parseOverrideOption(const std::string &TextOpt) {
68 return StringSwitch<VPTransform>(TextOpt) VPINTERNAL_VPLEGAL_CASES;
69}
70
71#undef VPINTERNAL_VPLEGAL_CASES
72
73// Whether any override options are set.
74static bool anyExpandVPOverridesSet() {
75 return !EVLTransformOverride.empty() || !MaskTransformOverride.empty();
76}
77
78#define DEBUG_TYPE "expandvp"
79
80STATISTIC(NumFoldedVL, "Number of folded vector length params");
81STATISTIC(NumLoweredVPOps, "Number of folded vector predication operations");
82
83///// Helpers {
84
85/// \returns Whether the vector mask \p MaskVal has all lane bits set.
86static bool isAllTrueMask(Value *MaskVal) {
87 if (Value *SplattedVal = getSplatValue(V: MaskVal))
88 if (auto *ConstValue = dyn_cast<Constant>(Val: SplattedVal))
89 return ConstValue->isAllOnesValue();
90
91 return false;
92}
93
94/// \returns A non-excepting divisor constant for this type.
95static Constant *getSafeDivisor(Type *DivTy) {
96 assert(DivTy->isIntOrIntVectorTy() && "Unsupported divisor type");
97 return ConstantInt::get(Ty: DivTy, V: 1u, IsSigned: false);
98}
99
100/// Transfer operation properties from \p OldVPI to \p NewVal.
101static void transferDecorations(Value &NewVal, VPIntrinsic &VPI) {
102 auto *NewInst = dyn_cast<Instruction>(Val: &NewVal);
103 if (!NewInst || !isa<FPMathOperator>(Val: NewVal))
104 return;
105
106 auto *OldFMOp = dyn_cast<FPMathOperator>(Val: &VPI);
107 if (!OldFMOp)
108 return;
109
110 NewInst->setFastMathFlags(OldFMOp->getFastMathFlags());
111}
112
113/// Transfer all properties from \p OldOp to \p NewOp and replace all uses.
114/// OldVP gets erased.
115static void replaceOperation(Value &NewOp, VPIntrinsic &OldOp) {
116 transferDecorations(NewVal&: NewOp, VPI&: OldOp);
117 OldOp.replaceAllUsesWith(V: &NewOp);
118 OldOp.eraseFromParent();
119}
120
121static bool maySpeculateLanes(VPIntrinsic &VPI) {
122 // The result of VP reductions depends on the mask and evl.
123 if (isa<VPReductionIntrinsic>(Val: VPI))
124 return false;
125 // Fallback to whether the intrinsic is speculatable.
126 if (auto IntrID = VPI.getFunctionalIntrinsicID())
127 return Intrinsic::getAttributes(C&: VPI.getContext(), id: *IntrID)
128 .hasFnAttr(Attribute::AttrKind::Speculatable);
129 if (auto Opc = VPI.getFunctionalOpcode())
130 return isSafeToSpeculativelyExecuteWithOpcode(Opcode: *Opc, Inst: &VPI);
131 return false;
132}
133
134//// } Helpers
135
136namespace {
137
138// Expansion pass state at function scope.
139struct CachingVPExpander {
140 Function &F;
141 const TargetTransformInfo &TTI;
142
143 /// \returns A (fixed length) vector with ascending integer indices
144 /// (<0, 1, ..., NumElems-1>).
145 /// \p Builder
146 /// Used for instruction creation.
147 /// \p LaneTy
148 /// Integer element type of the result vector.
149 /// \p NumElems
150 /// Number of vector elements.
151 Value *createStepVector(IRBuilder<> &Builder, Type *LaneTy,
152 unsigned NumElems);
153
154 /// \returns A bitmask that is true where the lane position is less-than \p
155 /// EVLParam
156 ///
157 /// \p Builder
158 /// Used for instruction creation.
159 /// \p VLParam
160 /// The explicit vector length parameter to test against the lane
161 /// positions.
162 /// \p ElemCount
163 /// Static (potentially scalable) number of vector elements.
164 Value *convertEVLToMask(IRBuilder<> &Builder, Value *EVLParam,
165 ElementCount ElemCount);
166
167 Value *foldEVLIntoMask(VPIntrinsic &VPI);
168
169 /// "Remove" the %evl parameter of \p PI by setting it to the static vector
170 /// length of the operation.
171 void discardEVLParameter(VPIntrinsic &PI);
172
173 /// Lower this VP binary operator to a unpredicated binary operator.
174 Value *expandPredicationInBinaryOperator(IRBuilder<> &Builder,
175 VPIntrinsic &PI);
176
177 /// Lower this VP int call to a unpredicated int call.
178 Value *expandPredicationToIntCall(IRBuilder<> &Builder, VPIntrinsic &PI,
179 unsigned UnpredicatedIntrinsicID);
180
181 /// Lower this VP fp call to a unpredicated fp call.
182 Value *expandPredicationToFPCall(IRBuilder<> &Builder, VPIntrinsic &PI,
183 unsigned UnpredicatedIntrinsicID);
184
185 /// Lower this VP reduction to a call to an unpredicated reduction intrinsic.
186 Value *expandPredicationInReduction(IRBuilder<> &Builder,
187 VPReductionIntrinsic &PI);
188
189 /// Lower this VP cast operation to a non-VP intrinsic.
190 Value *expandPredicationToCastIntrinsic(IRBuilder<> &Builder,
191 VPIntrinsic &VPI);
192
193 /// Lower this VP memory operation to a non-VP intrinsic.
194 Value *expandPredicationInMemoryIntrinsic(IRBuilder<> &Builder,
195 VPIntrinsic &VPI);
196
197 /// Lower this VP comparison to a call to an unpredicated comparison.
198 Value *expandPredicationInComparison(IRBuilder<> &Builder,
199 VPCmpIntrinsic &PI);
200
201 /// Query TTI and expand the vector predication in \p P accordingly.
202 Value *expandPredication(VPIntrinsic &PI);
203
204 /// Determine how and whether the VPIntrinsic \p VPI shall be expanded. This
205 /// overrides TTI with the cl::opts listed at the top of this file.
206 VPLegalization getVPLegalizationStrategy(const VPIntrinsic &VPI) const;
207 bool UsingTTIOverrides;
208
209public:
210 CachingVPExpander(Function &F, const TargetTransformInfo &TTI)
211 : F(F), TTI(TTI), UsingTTIOverrides(anyExpandVPOverridesSet()) {}
212
213 bool expandVectorPredication();
214};
215
216//// CachingVPExpander {
217
218Value *CachingVPExpander::createStepVector(IRBuilder<> &Builder, Type *LaneTy,
219 unsigned NumElems) {
220 // TODO add caching
221 SmallVector<Constant *, 16> ConstElems;
222
223 for (unsigned Idx = 0; Idx < NumElems; ++Idx)
224 ConstElems.push_back(Elt: ConstantInt::get(Ty: LaneTy, V: Idx, IsSigned: false));
225
226 return ConstantVector::get(V: ConstElems);
227}
228
229Value *CachingVPExpander::convertEVLToMask(IRBuilder<> &Builder,
230 Value *EVLParam,
231 ElementCount ElemCount) {
232 // TODO add caching
233 // Scalable vector %evl conversion.
234 if (ElemCount.isScalable()) {
235 auto *M = Builder.GetInsertBlock()->getModule();
236 Type *BoolVecTy = VectorType::get(ElementType: Builder.getInt1Ty(), EC: ElemCount);
237 Function *ActiveMaskFunc = Intrinsic::getDeclaration(
238 M, Intrinsic::id: get_active_lane_mask, Tys: {BoolVecTy, EVLParam->getType()});
239 // `get_active_lane_mask` performs an implicit less-than comparison.
240 Value *ConstZero = Builder.getInt32(C: 0);
241 return Builder.CreateCall(Callee: ActiveMaskFunc, Args: {ConstZero, EVLParam});
242 }
243
244 // Fixed vector %evl conversion.
245 Type *LaneTy = EVLParam->getType();
246 unsigned NumElems = ElemCount.getFixedValue();
247 Value *VLSplat = Builder.CreateVectorSplat(NumElts: NumElems, V: EVLParam);
248 Value *IdxVec = createStepVector(Builder, LaneTy, NumElems);
249 return Builder.CreateICmp(P: CmpInst::ICMP_ULT, LHS: IdxVec, RHS: VLSplat);
250}
251
252Value *
253CachingVPExpander::expandPredicationInBinaryOperator(IRBuilder<> &Builder,
254 VPIntrinsic &VPI) {
255 assert((maySpeculateLanes(VPI) || VPI.canIgnoreVectorLengthParam()) &&
256 "Implicitly dropping %evl in non-speculatable operator!");
257
258 auto OC = static_cast<Instruction::BinaryOps>(*VPI.getFunctionalOpcode());
259 assert(Instruction::isBinaryOp(OC));
260
261 Value *Op0 = VPI.getOperand(i_nocapture: 0);
262 Value *Op1 = VPI.getOperand(i_nocapture: 1);
263 Value *Mask = VPI.getMaskParam();
264
265 // Blend in safe operands.
266 if (Mask && !isAllTrueMask(MaskVal: Mask)) {
267 switch (OC) {
268 default:
269 // Can safely ignore the predicate.
270 break;
271
272 // Division operators need a safe divisor on masked-off lanes (1).
273 case Instruction::UDiv:
274 case Instruction::SDiv:
275 case Instruction::URem:
276 case Instruction::SRem:
277 // 2nd operand must not be zero.
278 Value *SafeDivisor = getSafeDivisor(DivTy: VPI.getType());
279 Op1 = Builder.CreateSelect(C: Mask, True: Op1, False: SafeDivisor);
280 }
281 }
282
283 Value *NewBinOp = Builder.CreateBinOp(Opc: OC, LHS: Op0, RHS: Op1, Name: VPI.getName());
284
285 replaceOperation(NewOp&: *NewBinOp, OldOp&: VPI);
286 return NewBinOp;
287}
288
289Value *CachingVPExpander::expandPredicationToIntCall(
290 IRBuilder<> &Builder, VPIntrinsic &VPI, unsigned UnpredicatedIntrinsicID) {
291 switch (UnpredicatedIntrinsicID) {
292 case Intrinsic::abs:
293 case Intrinsic::smax:
294 case Intrinsic::smin:
295 case Intrinsic::umax:
296 case Intrinsic::umin: {
297 Value *Op0 = VPI.getOperand(i_nocapture: 0);
298 Value *Op1 = VPI.getOperand(i_nocapture: 1);
299 Function *Fn = Intrinsic::getDeclaration(
300 M: VPI.getModule(), id: UnpredicatedIntrinsicID, Tys: {VPI.getType()});
301 Value *NewOp = Builder.CreateCall(Callee: Fn, Args: {Op0, Op1}, Name: VPI.getName());
302 replaceOperation(NewOp&: *NewOp, OldOp&: VPI);
303 return NewOp;
304 }
305 case Intrinsic::bswap:
306 case Intrinsic::bitreverse: {
307 Value *Op = VPI.getOperand(i_nocapture: 0);
308 Function *Fn = Intrinsic::getDeclaration(
309 M: VPI.getModule(), id: UnpredicatedIntrinsicID, Tys: {VPI.getType()});
310 Value *NewOp = Builder.CreateCall(Callee: Fn, Args: {Op}, Name: VPI.getName());
311 replaceOperation(NewOp&: *NewOp, OldOp&: VPI);
312 return NewOp;
313 }
314 }
315 return nullptr;
316}
317
318Value *CachingVPExpander::expandPredicationToFPCall(
319 IRBuilder<> &Builder, VPIntrinsic &VPI, unsigned UnpredicatedIntrinsicID) {
320 assert((maySpeculateLanes(VPI) || VPI.canIgnoreVectorLengthParam()) &&
321 "Implicitly dropping %evl in non-speculatable operator!");
322
323 switch (UnpredicatedIntrinsicID) {
324 case Intrinsic::fabs:
325 case Intrinsic::sqrt: {
326 Value *Op0 = VPI.getOperand(i_nocapture: 0);
327 Function *Fn = Intrinsic::getDeclaration(
328 M: VPI.getModule(), id: UnpredicatedIntrinsicID, Tys: {VPI.getType()});
329 Value *NewOp = Builder.CreateCall(Callee: Fn, Args: {Op0}, Name: VPI.getName());
330 replaceOperation(NewOp&: *NewOp, OldOp&: VPI);
331 return NewOp;
332 }
333 case Intrinsic::maxnum:
334 case Intrinsic::minnum: {
335 Value *Op0 = VPI.getOperand(i_nocapture: 0);
336 Value *Op1 = VPI.getOperand(i_nocapture: 1);
337 Function *Fn = Intrinsic::getDeclaration(
338 M: VPI.getModule(), id: UnpredicatedIntrinsicID, Tys: {VPI.getType()});
339 Value *NewOp = Builder.CreateCall(Callee: Fn, Args: {Op0, Op1}, Name: VPI.getName());
340 replaceOperation(NewOp&: *NewOp, OldOp&: VPI);
341 return NewOp;
342 }
343 case Intrinsic::experimental_constrained_fma:
344 case Intrinsic::experimental_constrained_fmuladd: {
345 Value *Op0 = VPI.getOperand(i_nocapture: 0);
346 Value *Op1 = VPI.getOperand(i_nocapture: 1);
347 Value *Op2 = VPI.getOperand(i_nocapture: 2);
348 Function *Fn = Intrinsic::getDeclaration(
349 M: VPI.getModule(), id: UnpredicatedIntrinsicID, Tys: {VPI.getType()});
350 Value *NewOp =
351 Builder.CreateConstrainedFPCall(Callee: Fn, Args: {Op0, Op1, Op2}, Name: VPI.getName());
352 replaceOperation(NewOp&: *NewOp, OldOp&: VPI);
353 return NewOp;
354 }
355 }
356
357 return nullptr;
358}
359
360static Value *getNeutralReductionElement(const VPReductionIntrinsic &VPI,
361 Type *EltTy) {
362 bool Negative = false;
363 unsigned EltBits = EltTy->getScalarSizeInBits();
364 switch (VPI.getIntrinsicID()) {
365 default:
366 llvm_unreachable("Expecting a VP reduction intrinsic");
367 case Intrinsic::vp_reduce_add:
368 case Intrinsic::vp_reduce_or:
369 case Intrinsic::vp_reduce_xor:
370 case Intrinsic::vp_reduce_umax:
371 return Constant::getNullValue(Ty: EltTy);
372 case Intrinsic::vp_reduce_mul:
373 return ConstantInt::get(Ty: EltTy, V: 1, /*IsSigned*/ false);
374 case Intrinsic::vp_reduce_and:
375 case Intrinsic::vp_reduce_umin:
376 return ConstantInt::getAllOnesValue(Ty: EltTy);
377 case Intrinsic::vp_reduce_smin:
378 return ConstantInt::get(Context&: EltTy->getContext(),
379 V: APInt::getSignedMaxValue(numBits: EltBits));
380 case Intrinsic::vp_reduce_smax:
381 return ConstantInt::get(Context&: EltTy->getContext(),
382 V: APInt::getSignedMinValue(numBits: EltBits));
383 case Intrinsic::vp_reduce_fmax:
384 Negative = true;
385 [[fallthrough]];
386 case Intrinsic::vp_reduce_fmin: {
387 FastMathFlags Flags = VPI.getFastMathFlags();
388 const fltSemantics &Semantics = EltTy->getFltSemantics();
389 return !Flags.noNaNs() ? ConstantFP::getQNaN(Ty: EltTy, Negative)
390 : !Flags.noInfs()
391 ? ConstantFP::getInfinity(Ty: EltTy, Negative)
392 : ConstantFP::get(Ty: EltTy,
393 V: APFloat::getLargest(Sem: Semantics, Negative));
394 }
395 case Intrinsic::vp_reduce_fadd:
396 return ConstantFP::getNegativeZero(Ty: EltTy);
397 case Intrinsic::vp_reduce_fmul:
398 return ConstantFP::get(Ty: EltTy, V: 1.0);
399 }
400}
401
402Value *
403CachingVPExpander::expandPredicationInReduction(IRBuilder<> &Builder,
404 VPReductionIntrinsic &VPI) {
405 assert((maySpeculateLanes(VPI) || VPI.canIgnoreVectorLengthParam()) &&
406 "Implicitly dropping %evl in non-speculatable operator!");
407
408 Value *Mask = VPI.getMaskParam();
409 Value *RedOp = VPI.getOperand(i_nocapture: VPI.getVectorParamPos());
410
411 // Insert neutral element in masked-out positions
412 if (Mask && !isAllTrueMask(MaskVal: Mask)) {
413 auto *NeutralElt = getNeutralReductionElement(VPI, EltTy: VPI.getType());
414 auto *NeutralVector = Builder.CreateVectorSplat(
415 EC: cast<VectorType>(Val: RedOp->getType())->getElementCount(), V: NeutralElt);
416 RedOp = Builder.CreateSelect(C: Mask, True: RedOp, False: NeutralVector);
417 }
418
419 Value *Reduction;
420 Value *Start = VPI.getOperand(i_nocapture: VPI.getStartParamPos());
421
422 switch (VPI.getIntrinsicID()) {
423 default:
424 llvm_unreachable("Impossible reduction kind");
425 case Intrinsic::vp_reduce_add:
426 Reduction = Builder.CreateAddReduce(Src: RedOp);
427 Reduction = Builder.CreateAdd(LHS: Reduction, RHS: Start);
428 break;
429 case Intrinsic::vp_reduce_mul:
430 Reduction = Builder.CreateMulReduce(Src: RedOp);
431 Reduction = Builder.CreateMul(LHS: Reduction, RHS: Start);
432 break;
433 case Intrinsic::vp_reduce_and:
434 Reduction = Builder.CreateAndReduce(Src: RedOp);
435 Reduction = Builder.CreateAnd(LHS: Reduction, RHS: Start);
436 break;
437 case Intrinsic::vp_reduce_or:
438 Reduction = Builder.CreateOrReduce(Src: RedOp);
439 Reduction = Builder.CreateOr(LHS: Reduction, RHS: Start);
440 break;
441 case Intrinsic::vp_reduce_xor:
442 Reduction = Builder.CreateXorReduce(Src: RedOp);
443 Reduction = Builder.CreateXor(LHS: Reduction, RHS: Start);
444 break;
445 case Intrinsic::vp_reduce_smax:
446 Reduction = Builder.CreateIntMaxReduce(Src: RedOp, /*IsSigned*/ true);
447 Reduction =
448 Builder.CreateBinaryIntrinsic(Intrinsic::ID: smax, LHS: Reduction, RHS: Start);
449 break;
450 case Intrinsic::vp_reduce_smin:
451 Reduction = Builder.CreateIntMinReduce(Src: RedOp, /*IsSigned*/ true);
452 Reduction =
453 Builder.CreateBinaryIntrinsic(Intrinsic::ID: smin, LHS: Reduction, RHS: Start);
454 break;
455 case Intrinsic::vp_reduce_umax:
456 Reduction = Builder.CreateIntMaxReduce(Src: RedOp, /*IsSigned*/ false);
457 Reduction =
458 Builder.CreateBinaryIntrinsic(Intrinsic::ID: umax, LHS: Reduction, RHS: Start);
459 break;
460 case Intrinsic::vp_reduce_umin:
461 Reduction = Builder.CreateIntMinReduce(Src: RedOp, /*IsSigned*/ false);
462 Reduction =
463 Builder.CreateBinaryIntrinsic(Intrinsic::ID: umin, LHS: Reduction, RHS: Start);
464 break;
465 case Intrinsic::vp_reduce_fmax:
466 Reduction = Builder.CreateFPMaxReduce(Src: RedOp);
467 transferDecorations(NewVal&: *Reduction, VPI);
468 Reduction =
469 Builder.CreateBinaryIntrinsic(Intrinsic::ID: maxnum, LHS: Reduction, RHS: Start);
470 break;
471 case Intrinsic::vp_reduce_fmin:
472 Reduction = Builder.CreateFPMinReduce(Src: RedOp);
473 transferDecorations(NewVal&: *Reduction, VPI);
474 Reduction =
475 Builder.CreateBinaryIntrinsic(Intrinsic::ID: minnum, LHS: Reduction, RHS: Start);
476 break;
477 case Intrinsic::vp_reduce_fadd:
478 Reduction = Builder.CreateFAddReduce(Acc: Start, Src: RedOp);
479 break;
480 case Intrinsic::vp_reduce_fmul:
481 Reduction = Builder.CreateFMulReduce(Acc: Start, Src: RedOp);
482 break;
483 }
484
485 replaceOperation(NewOp&: *Reduction, OldOp&: VPI);
486 return Reduction;
487}
488
489Value *CachingVPExpander::expandPredicationToCastIntrinsic(IRBuilder<> &Builder,
490 VPIntrinsic &VPI) {
491 Value *CastOp = nullptr;
492 switch (VPI.getIntrinsicID()) {
493 default:
494 llvm_unreachable("Not a VP cast intrinsic");
495 case Intrinsic::vp_sext:
496 CastOp =
497 Builder.CreateSExt(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
498 break;
499 case Intrinsic::vp_zext:
500 CastOp =
501 Builder.CreateZExt(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
502 break;
503 case Intrinsic::vp_trunc:
504 CastOp =
505 Builder.CreateTrunc(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
506 break;
507 case Intrinsic::vp_inttoptr:
508 CastOp =
509 Builder.CreateIntToPtr(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
510 break;
511 case Intrinsic::vp_ptrtoint:
512 CastOp =
513 Builder.CreatePtrToInt(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
514 break;
515 case Intrinsic::vp_fptosi:
516 CastOp =
517 Builder.CreateFPToSI(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
518 break;
519
520 case Intrinsic::vp_fptoui:
521 CastOp =
522 Builder.CreateFPToUI(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
523 break;
524 case Intrinsic::vp_sitofp:
525 CastOp =
526 Builder.CreateSIToFP(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
527 break;
528 case Intrinsic::vp_uitofp:
529 CastOp =
530 Builder.CreateUIToFP(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
531 break;
532 case Intrinsic::vp_fptrunc:
533 CastOp =
534 Builder.CreateFPTrunc(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
535 break;
536 case Intrinsic::vp_fpext:
537 CastOp =
538 Builder.CreateFPExt(V: VPI.getOperand(i_nocapture: 0), DestTy: VPI.getType(), Name: VPI.getName());
539 break;
540 }
541 replaceOperation(NewOp&: *CastOp, OldOp&: VPI);
542 return CastOp;
543}
544
545Value *
546CachingVPExpander::expandPredicationInMemoryIntrinsic(IRBuilder<> &Builder,
547 VPIntrinsic &VPI) {
548 assert(VPI.canIgnoreVectorLengthParam());
549
550 const auto &DL = F.getParent()->getDataLayout();
551
552 Value *MaskParam = VPI.getMaskParam();
553 Value *PtrParam = VPI.getMemoryPointerParam();
554 Value *DataParam = VPI.getMemoryDataParam();
555 bool IsUnmasked = isAllTrueMask(MaskVal: MaskParam);
556
557 MaybeAlign AlignOpt = VPI.getPointerAlignment();
558
559 Value *NewMemoryInst = nullptr;
560 switch (VPI.getIntrinsicID()) {
561 default:
562 llvm_unreachable("Not a VP memory intrinsic");
563 case Intrinsic::vp_store:
564 if (IsUnmasked) {
565 StoreInst *NewStore =
566 Builder.CreateStore(Val: DataParam, Ptr: PtrParam, /*IsVolatile*/ isVolatile: false);
567 if (AlignOpt.has_value())
568 NewStore->setAlignment(*AlignOpt);
569 NewMemoryInst = NewStore;
570 } else
571 NewMemoryInst = Builder.CreateMaskedStore(
572 Val: DataParam, Ptr: PtrParam, Alignment: AlignOpt.valueOrOne(), Mask: MaskParam);
573
574 break;
575 case Intrinsic::vp_load:
576 if (IsUnmasked) {
577 LoadInst *NewLoad =
578 Builder.CreateLoad(Ty: VPI.getType(), Ptr: PtrParam, /*IsVolatile*/ isVolatile: false);
579 if (AlignOpt.has_value())
580 NewLoad->setAlignment(*AlignOpt);
581 NewMemoryInst = NewLoad;
582 } else
583 NewMemoryInst = Builder.CreateMaskedLoad(
584 Ty: VPI.getType(), Ptr: PtrParam, Alignment: AlignOpt.valueOrOne(), Mask: MaskParam);
585
586 break;
587 case Intrinsic::vp_scatter: {
588 auto *ElementType =
589 cast<VectorType>(Val: DataParam->getType())->getElementType();
590 NewMemoryInst = Builder.CreateMaskedScatter(
591 Val: DataParam, Ptrs: PtrParam,
592 Alignment: AlignOpt.value_or(u: DL.getPrefTypeAlign(Ty: ElementType)), Mask: MaskParam);
593 break;
594 }
595 case Intrinsic::vp_gather: {
596 auto *ElementType = cast<VectorType>(Val: VPI.getType())->getElementType();
597 NewMemoryInst = Builder.CreateMaskedGather(
598 Ty: VPI.getType(), Ptrs: PtrParam,
599 Alignment: AlignOpt.value_or(u: DL.getPrefTypeAlign(Ty: ElementType)), Mask: MaskParam, PassThru: nullptr,
600 Name: VPI.getName());
601 break;
602 }
603 }
604
605 assert(NewMemoryInst);
606 replaceOperation(NewOp&: *NewMemoryInst, OldOp&: VPI);
607 return NewMemoryInst;
608}
609
610Value *CachingVPExpander::expandPredicationInComparison(IRBuilder<> &Builder,
611 VPCmpIntrinsic &VPI) {
612 assert((maySpeculateLanes(VPI) || VPI.canIgnoreVectorLengthParam()) &&
613 "Implicitly dropping %evl in non-speculatable operator!");
614
615 assert(*VPI.getFunctionalOpcode() == Instruction::ICmp ||
616 *VPI.getFunctionalOpcode() == Instruction::FCmp);
617
618 Value *Op0 = VPI.getOperand(i_nocapture: 0);
619 Value *Op1 = VPI.getOperand(i_nocapture: 1);
620 auto Pred = VPI.getPredicate();
621
622 auto *NewCmp = Builder.CreateCmp(Pred, LHS: Op0, RHS: Op1);
623
624 replaceOperation(NewOp&: *NewCmp, OldOp&: VPI);
625 return NewCmp;
626}
627
628void CachingVPExpander::discardEVLParameter(VPIntrinsic &VPI) {
629 LLVM_DEBUG(dbgs() << "Discard EVL parameter in " << VPI << "\n");
630
631 if (VPI.canIgnoreVectorLengthParam())
632 return;
633
634 Value *EVLParam = VPI.getVectorLengthParam();
635 if (!EVLParam)
636 return;
637
638 ElementCount StaticElemCount = VPI.getStaticVectorLength();
639 Value *MaxEVL = nullptr;
640 Type *Int32Ty = Type::getInt32Ty(C&: VPI.getContext());
641 if (StaticElemCount.isScalable()) {
642 // TODO add caching
643 auto *M = VPI.getModule();
644 Function *VScaleFunc =
645 Intrinsic::getDeclaration(M, Intrinsic::vscale, Int32Ty);
646 IRBuilder<> Builder(VPI.getParent(), VPI.getIterator());
647 Value *FactorConst = Builder.getInt32(C: StaticElemCount.getKnownMinValue());
648 Value *VScale = Builder.CreateCall(Callee: VScaleFunc, Args: {}, Name: "vscale");
649 MaxEVL = Builder.CreateMul(LHS: VScale, RHS: FactorConst, Name: "scalable_size",
650 /*NUW*/ HasNUW: true, /*NSW*/ HasNSW: false);
651 } else {
652 MaxEVL = ConstantInt::get(Ty: Int32Ty, V: StaticElemCount.getFixedValue(), IsSigned: false);
653 }
654 VPI.setVectorLengthParam(MaxEVL);
655}
656
657Value *CachingVPExpander::foldEVLIntoMask(VPIntrinsic &VPI) {
658 LLVM_DEBUG(dbgs() << "Folding vlen for " << VPI << '\n');
659
660 IRBuilder<> Builder(&VPI);
661
662 // Ineffective %evl parameter and so nothing to do here.
663 if (VPI.canIgnoreVectorLengthParam())
664 return &VPI;
665
666 // Only VP intrinsics can have an %evl parameter.
667 Value *OldMaskParam = VPI.getMaskParam();
668 Value *OldEVLParam = VPI.getVectorLengthParam();
669 assert(OldMaskParam && "no mask param to fold the vl param into");
670 assert(OldEVLParam && "no EVL param to fold away");
671
672 LLVM_DEBUG(dbgs() << "OLD evl: " << *OldEVLParam << '\n');
673 LLVM_DEBUG(dbgs() << "OLD mask: " << *OldMaskParam << '\n');
674
675 // Convert the %evl predication into vector mask predication.
676 ElementCount ElemCount = VPI.getStaticVectorLength();
677 Value *VLMask = convertEVLToMask(Builder, EVLParam: OldEVLParam, ElemCount);
678 Value *NewMaskParam = Builder.CreateAnd(LHS: VLMask, RHS: OldMaskParam);
679 VPI.setMaskParam(NewMaskParam);
680
681 // Drop the %evl parameter.
682 discardEVLParameter(VPI);
683 assert(VPI.canIgnoreVectorLengthParam() &&
684 "transformation did not render the evl param ineffective!");
685
686 // Reassess the modified instruction.
687 return &VPI;
688}
689
690Value *CachingVPExpander::expandPredication(VPIntrinsic &VPI) {
691 LLVM_DEBUG(dbgs() << "Lowering to unpredicated op: " << VPI << '\n');
692
693 IRBuilder<> Builder(&VPI);
694
695 // Try lowering to a LLVM instruction first.
696 auto OC = VPI.getFunctionalOpcode();
697
698 if (OC && Instruction::isBinaryOp(Opcode: *OC))
699 return expandPredicationInBinaryOperator(Builder, VPI);
700
701 if (auto *VPRI = dyn_cast<VPReductionIntrinsic>(Val: &VPI))
702 return expandPredicationInReduction(Builder, VPI&: *VPRI);
703
704 if (auto *VPCmp = dyn_cast<VPCmpIntrinsic>(Val: &VPI))
705 return expandPredicationInComparison(Builder, VPI&: *VPCmp);
706
707 if (VPCastIntrinsic::isVPCast(ID: VPI.getIntrinsicID())) {
708 return expandPredicationToCastIntrinsic(Builder, VPI);
709 }
710
711 switch (VPI.getIntrinsicID()) {
712 default:
713 break;
714 case Intrinsic::vp_fneg: {
715 Value *NewNegOp = Builder.CreateFNeg(V: VPI.getOperand(i_nocapture: 0), Name: VPI.getName());
716 replaceOperation(NewOp&: *NewNegOp, OldOp&: VPI);
717 return NewNegOp;
718 }
719 case Intrinsic::vp_abs:
720 case Intrinsic::vp_smax:
721 case Intrinsic::vp_smin:
722 case Intrinsic::vp_umax:
723 case Intrinsic::vp_umin:
724 case Intrinsic::vp_bswap:
725 case Intrinsic::vp_bitreverse:
726 return expandPredicationToIntCall(Builder, VPI,
727 UnpredicatedIntrinsicID: VPI.getFunctionalIntrinsicID().value());
728 case Intrinsic::vp_fabs:
729 case Intrinsic::vp_sqrt:
730 case Intrinsic::vp_maxnum:
731 case Intrinsic::vp_minnum:
732 case Intrinsic::vp_maximum:
733 case Intrinsic::vp_minimum:
734 return expandPredicationToFPCall(Builder, VPI,
735 UnpredicatedIntrinsicID: VPI.getFunctionalIntrinsicID().value());
736 case Intrinsic::vp_load:
737 case Intrinsic::vp_store:
738 case Intrinsic::vp_gather:
739 case Intrinsic::vp_scatter:
740 return expandPredicationInMemoryIntrinsic(Builder, VPI);
741 }
742
743 if (auto CID = VPI.getConstrainedIntrinsicID())
744 if (Value *Call = expandPredicationToFPCall(Builder, VPI, UnpredicatedIntrinsicID: *CID))
745 return Call;
746
747 return &VPI;
748}
749
750//// } CachingVPExpander
751
752struct TransformJob {
753 VPIntrinsic *PI;
754 TargetTransformInfo::VPLegalization Strategy;
755 TransformJob(VPIntrinsic *PI, TargetTransformInfo::VPLegalization InitStrat)
756 : PI(PI), Strategy(InitStrat) {}
757
758 bool isDone() const { return Strategy.shouldDoNothing(); }
759};
760
761void sanitizeStrategy(VPIntrinsic &VPI, VPLegalization &LegalizeStrat) {
762 // Operations with speculatable lanes do not strictly need predication.
763 if (maySpeculateLanes(VPI)) {
764 // Converting a speculatable VP intrinsic means dropping %mask and %evl.
765 // No need to expand %evl into the %mask only to ignore that code.
766 if (LegalizeStrat.OpStrategy == VPLegalization::Convert)
767 LegalizeStrat.EVLParamStrategy = VPLegalization::Discard;
768 return;
769 }
770
771 // We have to preserve the predicating effect of %evl for this
772 // non-speculatable VP intrinsic.
773 // 1) Never discard %evl.
774 // 2) If this VP intrinsic will be expanded to non-VP code, make sure that
775 // %evl gets folded into %mask.
776 if ((LegalizeStrat.EVLParamStrategy == VPLegalization::Discard) ||
777 (LegalizeStrat.OpStrategy == VPLegalization::Convert)) {
778 LegalizeStrat.EVLParamStrategy = VPLegalization::Convert;
779 }
780}
781
782VPLegalization
783CachingVPExpander::getVPLegalizationStrategy(const VPIntrinsic &VPI) const {
784 auto VPStrat = TTI.getVPLegalizationStrategy(PI: VPI);
785 if (LLVM_LIKELY(!UsingTTIOverrides)) {
786 // No overrides - we are in production.
787 return VPStrat;
788 }
789
790 // Overrides set - we are in testing, the following does not need to be
791 // efficient.
792 VPStrat.EVLParamStrategy = parseOverrideOption(TextOpt: EVLTransformOverride);
793 VPStrat.OpStrategy = parseOverrideOption(TextOpt: MaskTransformOverride);
794 return VPStrat;
795}
796
797/// Expand llvm.vp.* intrinsics as requested by \p TTI.
798bool CachingVPExpander::expandVectorPredication() {
799 SmallVector<TransformJob, 16> Worklist;
800
801 // Collect all VPIntrinsics that need expansion and determine their expansion
802 // strategy.
803 for (auto &I : instructions(F)) {
804 auto *VPI = dyn_cast<VPIntrinsic>(Val: &I);
805 if (!VPI)
806 continue;
807 auto VPStrat = getVPLegalizationStrategy(VPI: *VPI);
808 sanitizeStrategy(VPI&: *VPI, LegalizeStrat&: VPStrat);
809 if (!VPStrat.shouldDoNothing())
810 Worklist.emplace_back(Args&: VPI, Args&: VPStrat);
811 }
812 if (Worklist.empty())
813 return false;
814
815 // Transform all VPIntrinsics on the worklist.
816 LLVM_DEBUG(dbgs() << "\n:::: Transforming " << Worklist.size()
817 << " instructions ::::\n");
818 for (TransformJob Job : Worklist) {
819 // Transform the EVL parameter.
820 switch (Job.Strategy.EVLParamStrategy) {
821 case VPLegalization::Legal:
822 break;
823 case VPLegalization::Discard:
824 discardEVLParameter(VPI&: *Job.PI);
825 break;
826 case VPLegalization::Convert:
827 if (foldEVLIntoMask(VPI&: *Job.PI))
828 ++NumFoldedVL;
829 break;
830 }
831 Job.Strategy.EVLParamStrategy = VPLegalization::Legal;
832
833 // Replace with a non-predicated operation.
834 switch (Job.Strategy.OpStrategy) {
835 case VPLegalization::Legal:
836 break;
837 case VPLegalization::Discard:
838 llvm_unreachable("Invalid strategy for operators.");
839 case VPLegalization::Convert:
840 expandPredication(VPI&: *Job.PI);
841 ++NumLoweredVPOps;
842 break;
843 }
844 Job.Strategy.OpStrategy = VPLegalization::Legal;
845
846 assert(Job.isDone() && "incomplete transformation");
847 }
848
849 return true;
850}
851class ExpandVectorPredication : public FunctionPass {
852public:
853 static char ID;
854 ExpandVectorPredication() : FunctionPass(ID) {
855 initializeExpandVectorPredicationPass(*PassRegistry::getPassRegistry());
856 }
857
858 bool runOnFunction(Function &F) override {
859 const auto *TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
860 CachingVPExpander VPExpander(F, *TTI);
861 return VPExpander.expandVectorPredication();
862 }
863
864 void getAnalysisUsage(AnalysisUsage &AU) const override {
865 AU.addRequired<TargetTransformInfoWrapperPass>();
866 AU.setPreservesCFG();
867 }
868};
869} // namespace
870
871char ExpandVectorPredication::ID;
872INITIALIZE_PASS_BEGIN(ExpandVectorPredication, "expandvp",
873 "Expand vector predication intrinsics", false, false)
874INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
875INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
876INITIALIZE_PASS_END(ExpandVectorPredication, "expandvp",
877 "Expand vector predication intrinsics", false, false)
878
879FunctionPass *llvm::createExpandVectorPredicationPass() {
880 return new ExpandVectorPredication();
881}
882
883PreservedAnalyses
884ExpandVectorPredicationPass::run(Function &F, FunctionAnalysisManager &AM) {
885 const auto &TTI = AM.getResult<TargetIRAnalysis>(IR&: F);
886 CachingVPExpander VPExpander(F, TTI);
887 if (!VPExpander.expandVectorPredication())
888 return PreservedAnalyses::all();
889 PreservedAnalyses PA;
890 PA.preserveSet<CFGAnalyses>();
891 return PA;
892}
893

source code of llvm/lib/CodeGen/ExpandVectorPredication.cpp