1 //===- ConvertFromLLVMIR.cpp - MLIR to LLVM IR conversion -----------------===//
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 file implements a translation between LLVM IR and the MLIR LLVM dialect.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "mlir/Dialect/LLVMIR/LLVMDialect.h"
14 #include "mlir/IR/Builders.h"
15 #include "mlir/IR/BuiltinOps.h"
16 #include "mlir/IR/BuiltinTypes.h"
17 #include "mlir/IR/MLIRContext.h"
18 #include "mlir/Target/LLVMIR/Import.h"
19 #include "mlir/Target/LLVMIR/TypeFromLLVM.h"
20 #include "mlir/Translation.h"
21 
22 #include "llvm/ADT/TypeSwitch.h"
23 #include "llvm/IR/Attributes.h"
24 #include "llvm/IR/Constants.h"
25 #include "llvm/IR/DerivedTypes.h"
26 #include "llvm/IR/Function.h"
27 #include "llvm/IR/InlineAsm.h"
28 #include "llvm/IR/Instructions.h"
29 #include "llvm/IR/Type.h"
30 #include "llvm/IRReader/IRReader.h"
31 #include "llvm/Support/Error.h"
32 #include "llvm/Support/SourceMgr.h"
33 
34 using namespace mlir;
35 using namespace mlir::LLVM;
36 
37 #include "mlir/Dialect/LLVMIR/LLVMConversionEnumsFromLLVM.inc"
38 
39 // Utility to print an LLVM value as a string for passing to emitError().
40 // FIXME: Diagnostic should be able to natively handle types that have
41 // operator << (raw_ostream&) defined.
42 static std::string diag(llvm::Value &v) {
43   std::string s;
44   llvm::raw_string_ostream os(s);
45   os << v;
46   return os.str();
47 }
48 
49 // Handles importing globals and functions from an LLVM module.
50 namespace {
51 class Importer {
52 public:
53   Importer(MLIRContext *context, ModuleOp module)
54       : b(context), context(context), module(module),
55         unknownLoc(FileLineColLoc::get(context, "imported-bitcode", 0, 0)),
56         typeTranslator(*context) {
57     b.setInsertionPointToStart(module.getBody());
58   }
59 
60   /// Imports `f` into the current module.
61   LogicalResult processFunction(llvm::Function *f);
62 
63   /// Imports GV as a GlobalOp, creating it if it doesn't exist.
64   GlobalOp processGlobal(llvm::GlobalVariable *gv);
65 
66 private:
67   /// Returns personality of `f` as a FlatSymbolRefAttr.
68   FlatSymbolRefAttr getPersonalityAsAttr(llvm::Function *f);
69   /// Imports `bb` into `block`, which must be initially empty.
70   LogicalResult processBasicBlock(llvm::BasicBlock *bb, Block *block);
71   /// Imports `inst` and populates instMap[inst] with the imported Value.
72   LogicalResult processInstruction(llvm::Instruction *inst);
73   /// Creates an LLVM-compatible MLIR type for `type`.
74   Type processType(llvm::Type *type);
75   /// `value` is an SSA-use. Return the remapped version of `value` or a
76   /// placeholder that will be remapped later if this is an instruction that
77   /// has not yet been visited.
78   Value processValue(llvm::Value *value);
79   /// Create the most accurate Location possible using a llvm::DebugLoc and
80   /// possibly an llvm::Instruction to narrow the Location if debug information
81   /// is unavailable.
82   Location processDebugLoc(const llvm::DebugLoc &loc,
83                            llvm::Instruction *inst = nullptr);
84   /// `br` branches to `target`. Append the block arguments to attach to the
85   /// generated branch op to `blockArguments`. These should be in the same order
86   /// as the PHIs in `target`.
87   LogicalResult processBranchArgs(llvm::Instruction *br,
88                                   llvm::BasicBlock *target,
89                                   SmallVectorImpl<Value> &blockArguments);
90   /// Returns the builtin type equivalent to be used in attributes for the given
91   /// LLVM IR dialect type.
92   Type getStdTypeForAttr(Type type);
93   /// Return `value` as an attribute to attach to a GlobalOp.
94   Attribute getConstantAsAttr(llvm::Constant *value);
95   /// Return `c` as an MLIR Value. This could either be a ConstantOp, or
96   /// an expanded sequence of ops in the current function's entry block (for
97   /// ConstantExprs or ConstantGEPs).
98   Value processConstant(llvm::Constant *c);
99 
100   /// The current builder, pointing at where the next Instruction should be
101   /// generated.
102   OpBuilder b;
103   /// The current context.
104   MLIRContext *context;
105   /// The current module being created.
106   ModuleOp module;
107   /// The entry block of the current function being processed.
108   Block *currentEntryBlock = nullptr;
109 
110   /// Globals are inserted before the first function, if any.
111   Block::iterator getGlobalInsertPt() {
112     auto it = module.getBody()->begin();
113     auto endIt = module.getBody()->end();
114     while (it != endIt && !isa<LLVMFuncOp>(it))
115       ++it;
116     return it;
117   }
118 
119   /// Functions are always inserted before the module terminator.
120   Block::iterator getFuncInsertPt() {
121     return std::prev(module.getBody()->end());
122   }
123 
124   /// Remapped blocks, for the current function.
125   DenseMap<llvm::BasicBlock *, Block *> blocks;
126   /// Remapped values. These are function-local.
127   DenseMap<llvm::Value *, Value> instMap;
128   /// Instructions that had not been defined when first encountered as a use.
129   /// Maps to the dummy Operation that was created in processValue().
130   DenseMap<llvm::Value *, Operation *> unknownInstMap;
131   /// Uniquing map of GlobalVariables.
132   DenseMap<llvm::GlobalVariable *, GlobalOp> globals;
133   /// Cached FileLineColLoc::get("imported-bitcode", 0, 0).
134   Location unknownLoc;
135   /// The stateful type translator (contains named structs).
136   LLVM::TypeFromLLVMIRTranslator typeTranslator;
137 };
138 } // namespace
139 
140 Location Importer::processDebugLoc(const llvm::DebugLoc &loc,
141                                    llvm::Instruction *inst) {
142   if (!loc && inst) {
143     std::string s;
144     llvm::raw_string_ostream os(s);
145     os << "llvm-imported-inst-%";
146     inst->printAsOperand(os, /*PrintType=*/false);
147     return FileLineColLoc::get(context, os.str(), 0, 0);
148   }
149   if (!loc) {
150     return unknownLoc;
151   }
152   // FIXME: Obtain the filename from DILocationInfo.
153   return FileLineColLoc::get(context, "imported-bitcode", loc.getLine(),
154                              loc.getCol());
155 }
156 
157 Type Importer::processType(llvm::Type *type) {
158   if (Type result = typeTranslator.translateType(type))
159     return result;
160 
161   // FIXME: Diagnostic should be able to natively handle types that have
162   // operator<<(raw_ostream&) defined.
163   std::string s;
164   llvm::raw_string_ostream os(s);
165   os << *type;
166   emitError(unknownLoc) << "unhandled type: " << os.str();
167   return nullptr;
168 }
169 
170 // We only need integers, floats, doubles, and vectors and tensors thereof for
171 // attributes. Scalar and vector types are converted to the standard
172 // equivalents. Array types are converted to ranked tensors; nested array types
173 // are converted to multi-dimensional tensors or vectors, depending on the
174 // innermost type being a scalar or a vector.
175 Type Importer::getStdTypeForAttr(Type type) {
176   if (!type)
177     return nullptr;
178 
179   if (type.isa<IntegerType, FloatType>())
180     return type;
181 
182   // LLVM vectors can only contain scalars.
183   if (LLVM::isCompatibleVectorType(type)) {
184     auto numElements = LLVM::getVectorNumElements(type);
185     if (numElements.isScalable()) {
186       emitError(unknownLoc) << "scalable vectors not supported";
187       return nullptr;
188     }
189     Type elementType = getStdTypeForAttr(LLVM::getVectorElementType(type));
190     if (!elementType)
191       return nullptr;
192     return VectorType::get(numElements.getKnownMinValue(), elementType);
193   }
194 
195   // LLVM arrays can contain other arrays or vectors.
196   if (auto arrayType = type.dyn_cast<LLVMArrayType>()) {
197     // Recover the nested array shape.
198     SmallVector<int64_t, 4> shape;
199     shape.push_back(arrayType.getNumElements());
200     while (arrayType.getElementType().isa<LLVMArrayType>()) {
201       arrayType = arrayType.getElementType().cast<LLVMArrayType>();
202       shape.push_back(arrayType.getNumElements());
203     }
204 
205     // If the innermost type is a vector, use the multi-dimensional vector as
206     // attribute type.
207     if (LLVM::isCompatibleVectorType(arrayType.getElementType())) {
208       auto numElements = LLVM::getVectorNumElements(arrayType.getElementType());
209       if (numElements.isScalable()) {
210         emitError(unknownLoc) << "scalable vectors not supported";
211         return nullptr;
212       }
213       shape.push_back(numElements.getKnownMinValue());
214 
215       Type elementType = getStdTypeForAttr(
216           LLVM::getVectorElementType(arrayType.getElementType()));
217       if (!elementType)
218         return nullptr;
219       return VectorType::get(shape, elementType);
220     }
221 
222     // Otherwise use a tensor.
223     Type elementType = getStdTypeForAttr(arrayType.getElementType());
224     if (!elementType)
225       return nullptr;
226     return RankedTensorType::get(shape, elementType);
227   }
228 
229   return nullptr;
230 }
231 
232 // Get the given constant as an attribute. Not all constants can be represented
233 // as attributes.
234 Attribute Importer::getConstantAsAttr(llvm::Constant *value) {
235   if (auto *ci = dyn_cast<llvm::ConstantInt>(value))
236     return b.getIntegerAttr(
237         IntegerType::get(context, ci->getType()->getBitWidth()),
238         ci->getValue());
239   if (auto *c = dyn_cast<llvm::ConstantDataArray>(value))
240     if (c->isString())
241       return b.getStringAttr(c->getAsString());
242   if (auto *c = dyn_cast<llvm::ConstantFP>(value)) {
243     if (c->getType()->isDoubleTy())
244       return b.getFloatAttr(FloatType::getF64(context), c->getValueAPF());
245     if (c->getType()->isFloatingPointTy())
246       return b.getFloatAttr(FloatType::getF32(context), c->getValueAPF());
247   }
248   if (auto *f = dyn_cast<llvm::Function>(value))
249     return SymbolRefAttr::get(b.getContext(), f->getName());
250 
251   // Convert constant data to a dense elements attribute.
252   if (auto *cd = dyn_cast<llvm::ConstantDataSequential>(value)) {
253     Type type = processType(cd->getElementType());
254     if (!type)
255       return nullptr;
256 
257     auto attrType = getStdTypeForAttr(processType(cd->getType()))
258                         .dyn_cast_or_null<ShapedType>();
259     if (!attrType)
260       return nullptr;
261 
262     if (type.isa<IntegerType>()) {
263       SmallVector<APInt, 8> values;
264       values.reserve(cd->getNumElements());
265       for (unsigned i = 0, e = cd->getNumElements(); i < e; ++i)
266         values.push_back(cd->getElementAsAPInt(i));
267       return DenseElementsAttr::get(attrType, values);
268     }
269 
270     if (type.isa<Float32Type, Float64Type>()) {
271       SmallVector<APFloat, 8> values;
272       values.reserve(cd->getNumElements());
273       for (unsigned i = 0, e = cd->getNumElements(); i < e; ++i)
274         values.push_back(cd->getElementAsAPFloat(i));
275       return DenseElementsAttr::get(attrType, values);
276     }
277 
278     return nullptr;
279   }
280 
281   // Unpack constant aggregates to create dense elements attribute whenever
282   // possible. Return nullptr (failure) otherwise.
283   if (isa<llvm::ConstantAggregate>(value)) {
284     auto outerType = getStdTypeForAttr(processType(value->getType()))
285                          .dyn_cast_or_null<ShapedType>();
286     if (!outerType)
287       return nullptr;
288 
289     SmallVector<Attribute, 8> values;
290     SmallVector<int64_t, 8> shape;
291 
292     for (unsigned i = 0, e = value->getNumOperands(); i < e; ++i) {
293       auto nested = getConstantAsAttr(value->getAggregateElement(i))
294                         .dyn_cast_or_null<DenseElementsAttr>();
295       if (!nested)
296         return nullptr;
297 
298       values.append(nested.value_begin<Attribute>(),
299                     nested.value_end<Attribute>());
300     }
301 
302     return DenseElementsAttr::get(outerType, values);
303   }
304 
305   return nullptr;
306 }
307 
308 GlobalOp Importer::processGlobal(llvm::GlobalVariable *gv) {
309   auto it = globals.find(gv);
310   if (it != globals.end())
311     return it->second;
312 
313   OpBuilder b(module.getBody(), getGlobalInsertPt());
314   Attribute valueAttr;
315   if (gv->hasInitializer())
316     valueAttr = getConstantAsAttr(gv->getInitializer());
317   Type type = processType(gv->getValueType());
318   if (!type)
319     return nullptr;
320 
321   uint64_t alignment = 0;
322   llvm::MaybeAlign maybeAlign = gv->getAlign();
323   if (maybeAlign.hasValue()) {
324     llvm::Align align = maybeAlign.getValue();
325     alignment = align.value();
326   }
327 
328   GlobalOp op =
329       b.create<GlobalOp>(UnknownLoc::get(context), type, gv->isConstant(),
330                          convertLinkageFromLLVM(gv->getLinkage()),
331                          gv->getName(), valueAttr, alignment);
332 
333   if (gv->hasInitializer() && !valueAttr) {
334     Region &r = op.getInitializerRegion();
335     currentEntryBlock = b.createBlock(&r);
336     b.setInsertionPoint(currentEntryBlock, currentEntryBlock->begin());
337     Value v = processConstant(gv->getInitializer());
338     if (!v)
339       return nullptr;
340     b.create<ReturnOp>(op.getLoc(), ArrayRef<Value>({v}));
341   }
342   if (gv->hasAtLeastLocalUnnamedAddr())
343     op.setUnnamedAddrAttr(UnnamedAddrAttr::get(
344         context, convertUnnamedAddrFromLLVM(gv->getUnnamedAddr())));
345   if (gv->hasSection())
346     op.setSectionAttr(b.getStringAttr(gv->getSection()));
347 
348   return globals[gv] = op;
349 }
350 
351 Value Importer::processConstant(llvm::Constant *c) {
352   OpBuilder bEntry(currentEntryBlock, currentEntryBlock->begin());
353   if (Attribute attr = getConstantAsAttr(c)) {
354     // These constants can be represented as attributes.
355     OpBuilder b(currentEntryBlock, currentEntryBlock->begin());
356     Type type = processType(c->getType());
357     if (!type)
358       return nullptr;
359     if (auto symbolRef = attr.dyn_cast<FlatSymbolRefAttr>())
360       return instMap[c] = bEntry.create<AddressOfOp>(unknownLoc, type,
361                                                      symbolRef.getValue());
362     return instMap[c] = bEntry.create<ConstantOp>(unknownLoc, type, attr);
363   }
364   if (auto *cn = dyn_cast<llvm::ConstantPointerNull>(c)) {
365     Type type = processType(cn->getType());
366     if (!type)
367       return nullptr;
368     return instMap[c] = bEntry.create<NullOp>(unknownLoc, type);
369   }
370   if (auto *gv = dyn_cast<llvm::GlobalVariable>(c))
371     return bEntry.create<AddressOfOp>(UnknownLoc::get(context),
372                                       processGlobal(gv));
373 
374   if (auto *ce = dyn_cast<llvm::ConstantExpr>(c)) {
375     llvm::Instruction *i = ce->getAsInstruction();
376     OpBuilder::InsertionGuard guard(b);
377     b.setInsertionPoint(currentEntryBlock, currentEntryBlock->begin());
378     if (failed(processInstruction(i)))
379       return nullptr;
380     assert(instMap.count(i));
381 
382     // Remove this zombie LLVM instruction now, leaving us only with the MLIR
383     // op.
384     i->deleteValue();
385     return instMap[c] = instMap[i];
386   }
387   if (auto *ue = dyn_cast<llvm::UndefValue>(c)) {
388     Type type = processType(ue->getType());
389     if (!type)
390       return nullptr;
391     return instMap[c] = bEntry.create<UndefOp>(UnknownLoc::get(context), type);
392   }
393   emitError(unknownLoc) << "unhandled constant: " << diag(*c);
394   return nullptr;
395 }
396 
397 Value Importer::processValue(llvm::Value *value) {
398   auto it = instMap.find(value);
399   if (it != instMap.end())
400     return it->second;
401 
402   // We don't expect to see instructions in dominator order. If we haven't seen
403   // this instruction yet, create an unknown op and remap it later.
404   if (isa<llvm::Instruction>(value)) {
405     OperationState state(UnknownLoc::get(context), "llvm.unknown");
406     Type type = processType(value->getType());
407     if (!type)
408       return nullptr;
409     state.addTypes(type);
410     unknownInstMap[value] = b.createOperation(state);
411     return unknownInstMap[value]->getResult(0);
412   }
413 
414   if (auto *c = dyn_cast<llvm::Constant>(value))
415     return processConstant(c);
416 
417   emitError(unknownLoc) << "unhandled value: " << diag(*value);
418   return nullptr;
419 }
420 
421 /// Return the MLIR OperationName for the given LLVM opcode.
422 static StringRef lookupOperationNameFromOpcode(unsigned opcode) {
423 // Maps from LLVM opcode to MLIR OperationName. This is deliberately ordered
424 // as in llvm/IR/Instructions.def to aid comprehension and spot missing
425 // instructions.
426 #define INST(llvm_n, mlir_n)                                                   \
427   { llvm::Instruction::llvm_n, LLVM::mlir_n##Op::getOperationName() }
428   static const DenseMap<unsigned, StringRef> opcMap = {
429       // Ret is handled specially.
430       // Br is handled specially.
431       // FIXME: switch
432       // FIXME: indirectbr
433       // FIXME: invoke
434       INST(Resume, Resume),
435       // FIXME: unreachable
436       // FIXME: cleanupret
437       // FIXME: catchret
438       // FIXME: catchswitch
439       // FIXME: callbr
440       // FIXME: fneg
441       INST(Add, Add), INST(FAdd, FAdd), INST(Sub, Sub), INST(FSub, FSub),
442       INST(Mul, Mul), INST(FMul, FMul), INST(UDiv, UDiv), INST(SDiv, SDiv),
443       INST(FDiv, FDiv), INST(URem, URem), INST(SRem, SRem), INST(FRem, FRem),
444       INST(Shl, Shl), INST(LShr, LShr), INST(AShr, AShr), INST(And, And),
445       INST(Or, Or), INST(Xor, XOr), INST(Alloca, Alloca), INST(Load, Load),
446       INST(Store, Store),
447       // Getelementptr is handled specially.
448       INST(Ret, Return), INST(Fence, Fence),
449       // FIXME: atomiccmpxchg
450       // FIXME: atomicrmw
451       INST(Trunc, Trunc), INST(ZExt, ZExt), INST(SExt, SExt),
452       INST(FPToUI, FPToUI), INST(FPToSI, FPToSI), INST(UIToFP, UIToFP),
453       INST(SIToFP, SIToFP), INST(FPTrunc, FPTrunc), INST(FPExt, FPExt),
454       INST(PtrToInt, PtrToInt), INST(IntToPtr, IntToPtr),
455       INST(BitCast, Bitcast), INST(AddrSpaceCast, AddrSpaceCast),
456       // FIXME: cleanuppad
457       // FIXME: catchpad
458       // ICmp is handled specially.
459       // FIXME: fcmp
460       // PHI is handled specially.
461       INST(Freeze, Freeze), INST(Call, Call),
462       // FIXME: select
463       // FIXME: vaarg
464       // FIXME: extractelement
465       // FIXME: insertelement
466       // FIXME: shufflevector
467       // FIXME: extractvalue
468       // FIXME: insertvalue
469       // FIXME: landingpad
470   };
471 #undef INST
472 
473   return opcMap.lookup(opcode);
474 }
475 
476 static ICmpPredicate getICmpPredicate(llvm::CmpInst::Predicate p) {
477   switch (p) {
478   default:
479     llvm_unreachable("incorrect comparison predicate");
480   case llvm::CmpInst::Predicate::ICMP_EQ:
481     return LLVM::ICmpPredicate::eq;
482   case llvm::CmpInst::Predicate::ICMP_NE:
483     return LLVM::ICmpPredicate::ne;
484   case llvm::CmpInst::Predicate::ICMP_SLT:
485     return LLVM::ICmpPredicate::slt;
486   case llvm::CmpInst::Predicate::ICMP_SLE:
487     return LLVM::ICmpPredicate::sle;
488   case llvm::CmpInst::Predicate::ICMP_SGT:
489     return LLVM::ICmpPredicate::sgt;
490   case llvm::CmpInst::Predicate::ICMP_SGE:
491     return LLVM::ICmpPredicate::sge;
492   case llvm::CmpInst::Predicate::ICMP_ULT:
493     return LLVM::ICmpPredicate::ult;
494   case llvm::CmpInst::Predicate::ICMP_ULE:
495     return LLVM::ICmpPredicate::ule;
496   case llvm::CmpInst::Predicate::ICMP_UGT:
497     return LLVM::ICmpPredicate::ugt;
498   case llvm::CmpInst::Predicate::ICMP_UGE:
499     return LLVM::ICmpPredicate::uge;
500   }
501   llvm_unreachable("incorrect comparison predicate");
502 }
503 
504 static AtomicOrdering getLLVMAtomicOrdering(llvm::AtomicOrdering ordering) {
505   switch (ordering) {
506   case llvm::AtomicOrdering::NotAtomic:
507     return LLVM::AtomicOrdering::not_atomic;
508   case llvm::AtomicOrdering::Unordered:
509     return LLVM::AtomicOrdering::unordered;
510   case llvm::AtomicOrdering::Monotonic:
511     return LLVM::AtomicOrdering::monotonic;
512   case llvm::AtomicOrdering::Acquire:
513     return LLVM::AtomicOrdering::acquire;
514   case llvm::AtomicOrdering::Release:
515     return LLVM::AtomicOrdering::release;
516   case llvm::AtomicOrdering::AcquireRelease:
517     return LLVM::AtomicOrdering::acq_rel;
518   case llvm::AtomicOrdering::SequentiallyConsistent:
519     return LLVM::AtomicOrdering::seq_cst;
520   }
521   llvm_unreachable("incorrect atomic ordering");
522 }
523 
524 // `br` branches to `target`. Return the branch arguments to `br`, in the
525 // same order of the PHIs in `target`.
526 LogicalResult
527 Importer::processBranchArgs(llvm::Instruction *br, llvm::BasicBlock *target,
528                             SmallVectorImpl<Value> &blockArguments) {
529   for (auto inst = target->begin(); isa<llvm::PHINode>(inst); ++inst) {
530     auto *pn = cast<llvm::PHINode>(&*inst);
531     Value value = processValue(pn->getIncomingValueForBlock(br->getParent()));
532     if (!value)
533       return failure();
534     blockArguments.push_back(value);
535   }
536   return success();
537 }
538 
539 LogicalResult Importer::processInstruction(llvm::Instruction *inst) {
540   // FIXME: Support uses of SubtargetData. Currently inbounds GEPs, fast-math
541   // flags and call / operand attributes are not supported.
542   Location loc = processDebugLoc(inst->getDebugLoc(), inst);
543   Value &v = instMap[inst];
544   assert(!v && "processInstruction must be called only once per instruction!");
545   switch (inst->getOpcode()) {
546   default:
547     return emitError(loc) << "unknown instruction: " << diag(*inst);
548   case llvm::Instruction::Add:
549   case llvm::Instruction::FAdd:
550   case llvm::Instruction::Sub:
551   case llvm::Instruction::FSub:
552   case llvm::Instruction::Mul:
553   case llvm::Instruction::FMul:
554   case llvm::Instruction::UDiv:
555   case llvm::Instruction::SDiv:
556   case llvm::Instruction::FDiv:
557   case llvm::Instruction::URem:
558   case llvm::Instruction::SRem:
559   case llvm::Instruction::FRem:
560   case llvm::Instruction::Shl:
561   case llvm::Instruction::LShr:
562   case llvm::Instruction::AShr:
563   case llvm::Instruction::And:
564   case llvm::Instruction::Or:
565   case llvm::Instruction::Xor:
566   case llvm::Instruction::Alloca:
567   case llvm::Instruction::Load:
568   case llvm::Instruction::Store:
569   case llvm::Instruction::Ret:
570   case llvm::Instruction::Resume:
571   case llvm::Instruction::Trunc:
572   case llvm::Instruction::ZExt:
573   case llvm::Instruction::SExt:
574   case llvm::Instruction::FPToUI:
575   case llvm::Instruction::FPToSI:
576   case llvm::Instruction::UIToFP:
577   case llvm::Instruction::SIToFP:
578   case llvm::Instruction::FPTrunc:
579   case llvm::Instruction::FPExt:
580   case llvm::Instruction::PtrToInt:
581   case llvm::Instruction::IntToPtr:
582   case llvm::Instruction::AddrSpaceCast:
583   case llvm::Instruction::Freeze:
584   case llvm::Instruction::BitCast: {
585     OperationState state(loc, lookupOperationNameFromOpcode(inst->getOpcode()));
586     SmallVector<Value, 4> ops;
587     ops.reserve(inst->getNumOperands());
588     for (auto *op : inst->operand_values()) {
589       Value value = processValue(op);
590       if (!value)
591         return failure();
592       ops.push_back(value);
593     }
594     state.addOperands(ops);
595     if (!inst->getType()->isVoidTy()) {
596       Type type = processType(inst->getType());
597       if (!type)
598         return failure();
599       state.addTypes(type);
600     }
601     Operation *op = b.createOperation(state);
602     if (!inst->getType()->isVoidTy())
603       v = op->getResult(0);
604     return success();
605   }
606   case llvm::Instruction::ICmp: {
607     Value lhs = processValue(inst->getOperand(0));
608     Value rhs = processValue(inst->getOperand(1));
609     if (!lhs || !rhs)
610       return failure();
611     v = b.create<ICmpOp>(
612         loc, getICmpPredicate(cast<llvm::ICmpInst>(inst)->getPredicate()), lhs,
613         rhs);
614     return success();
615   }
616   case llvm::Instruction::Br: {
617     auto *brInst = cast<llvm::BranchInst>(inst);
618     OperationState state(loc,
619                          brInst->isConditional() ? "llvm.cond_br" : "llvm.br");
620     if (brInst->isConditional()) {
621       Value condition = processValue(brInst->getCondition());
622       if (!condition)
623         return failure();
624       state.addOperands(condition);
625     }
626 
627     std::array<int32_t, 3> operandSegmentSizes = {1, 0, 0};
628     for (int i : llvm::seq<int>(0, brInst->getNumSuccessors())) {
629       auto *succ = brInst->getSuccessor(i);
630       SmallVector<Value, 4> blockArguments;
631       if (failed(processBranchArgs(brInst, succ, blockArguments)))
632         return failure();
633       state.addSuccessors(blocks[succ]);
634       state.addOperands(blockArguments);
635       operandSegmentSizes[i + 1] = blockArguments.size();
636     }
637 
638     if (brInst->isConditional()) {
639       state.addAttribute(LLVM::CondBrOp::getOperandSegmentSizeAttr(),
640                          b.getI32VectorAttr(operandSegmentSizes));
641     }
642 
643     b.createOperation(state);
644     return success();
645   }
646   case llvm::Instruction::PHI: {
647     Type type = processType(inst->getType());
648     if (!type)
649       return failure();
650     v = b.getInsertionBlock()->addArgument(type);
651     return success();
652   }
653   case llvm::Instruction::Call: {
654     llvm::CallInst *ci = cast<llvm::CallInst>(inst);
655     SmallVector<Value, 4> ops;
656     ops.reserve(inst->getNumOperands());
657     for (auto &op : ci->args()) {
658       Value arg = processValue(op.get());
659       if (!arg)
660         return failure();
661       ops.push_back(arg);
662     }
663 
664     SmallVector<Type, 2> tys;
665     if (!ci->getType()->isVoidTy()) {
666       Type type = processType(inst->getType());
667       if (!type)
668         return failure();
669       tys.push_back(type);
670     }
671     Operation *op;
672     if (llvm::Function *callee = ci->getCalledFunction()) {
673       op = b.create<CallOp>(
674           loc, tys, SymbolRefAttr::get(b.getContext(), callee->getName()), ops);
675     } else {
676       Value calledValue = processValue(ci->getCalledOperand());
677       if (!calledValue)
678         return failure();
679       ops.insert(ops.begin(), calledValue);
680       op = b.create<CallOp>(loc, tys, ops);
681     }
682     if (!ci->getType()->isVoidTy())
683       v = op->getResult(0);
684     return success();
685   }
686   case llvm::Instruction::LandingPad: {
687     llvm::LandingPadInst *lpi = cast<llvm::LandingPadInst>(inst);
688     SmallVector<Value, 4> ops;
689 
690     for (unsigned i = 0, ie = lpi->getNumClauses(); i < ie; i++)
691       ops.push_back(processConstant(lpi->getClause(i)));
692 
693     Type ty = processType(lpi->getType());
694     if (!ty)
695       return failure();
696 
697     v = b.create<LandingpadOp>(loc, ty, lpi->isCleanup(), ops);
698     return success();
699   }
700   case llvm::Instruction::Invoke: {
701     llvm::InvokeInst *ii = cast<llvm::InvokeInst>(inst);
702 
703     SmallVector<Type, 2> tys;
704     if (!ii->getType()->isVoidTy())
705       tys.push_back(processType(inst->getType()));
706 
707     SmallVector<Value, 4> ops;
708     ops.reserve(inst->getNumOperands() + 1);
709     for (auto &op : ii->args())
710       ops.push_back(processValue(op.get()));
711 
712     SmallVector<Value, 4> normalArgs, unwindArgs;
713     (void)processBranchArgs(ii, ii->getNormalDest(), normalArgs);
714     (void)processBranchArgs(ii, ii->getUnwindDest(), unwindArgs);
715 
716     Operation *op;
717     if (llvm::Function *callee = ii->getCalledFunction()) {
718       op = b.create<InvokeOp>(
719           loc, tys, SymbolRefAttr::get(b.getContext(), callee->getName()), ops,
720           blocks[ii->getNormalDest()], normalArgs, blocks[ii->getUnwindDest()],
721           unwindArgs);
722     } else {
723       ops.insert(ops.begin(), processValue(ii->getCalledOperand()));
724       op = b.create<InvokeOp>(loc, tys, ops, blocks[ii->getNormalDest()],
725                               normalArgs, blocks[ii->getUnwindDest()],
726                               unwindArgs);
727     }
728 
729     if (!ii->getType()->isVoidTy())
730       v = op->getResult(0);
731     return success();
732   }
733   case llvm::Instruction::Fence: {
734     StringRef syncscope;
735     SmallVector<StringRef, 4> ssNs;
736     llvm::LLVMContext &llvmContext = inst->getContext();
737     llvm::FenceInst *fence = cast<llvm::FenceInst>(inst);
738     llvmContext.getSyncScopeNames(ssNs);
739     int fenceSyncScopeID = fence->getSyncScopeID();
740     for (unsigned i = 0, e = ssNs.size(); i != e; i++) {
741       if (fenceSyncScopeID == llvmContext.getOrInsertSyncScopeID(ssNs[i])) {
742         syncscope = ssNs[i];
743         break;
744       }
745     }
746     b.create<FenceOp>(loc, getLLVMAtomicOrdering(fence->getOrdering()),
747                       syncscope);
748     return success();
749   }
750   case llvm::Instruction::GetElementPtr: {
751     // FIXME: Support inbounds GEPs.
752     llvm::GetElementPtrInst *gep = cast<llvm::GetElementPtrInst>(inst);
753     SmallVector<Value, 4> ops;
754     for (auto *op : gep->operand_values()) {
755       Value value = processValue(op);
756       if (!value)
757         return failure();
758       ops.push_back(value);
759     }
760     Type type = processType(inst->getType());
761     if (!type)
762       return failure();
763     v = b.create<GEPOp>(loc, type, ops[0],
764                         llvm::makeArrayRef(ops).drop_front());
765     return success();
766   }
767   }
768 }
769 
770 FlatSymbolRefAttr Importer::getPersonalityAsAttr(llvm::Function *f) {
771   if (!f->hasPersonalityFn())
772     return nullptr;
773 
774   llvm::Constant *pf = f->getPersonalityFn();
775 
776   // If it directly has a name, we can use it.
777   if (pf->hasName())
778     return SymbolRefAttr::get(b.getContext(), pf->getName());
779 
780   // If it doesn't have a name, currently, only function pointers that are
781   // bitcast to i8* are parsed.
782   if (auto *ce = dyn_cast<llvm::ConstantExpr>(pf)) {
783     if (ce->getOpcode() == llvm::Instruction::BitCast &&
784         ce->getType() == llvm::Type::getInt8PtrTy(f->getContext())) {
785       if (auto *func = dyn_cast<llvm::Function>(ce->getOperand(0)))
786         return SymbolRefAttr::get(b.getContext(), func->getName());
787     }
788   }
789   return FlatSymbolRefAttr();
790 }
791 
792 LogicalResult Importer::processFunction(llvm::Function *f) {
793   blocks.clear();
794   instMap.clear();
795   unknownInstMap.clear();
796 
797   auto functionType =
798       processType(f->getFunctionType()).dyn_cast<LLVMFunctionType>();
799   if (!functionType)
800     return failure();
801 
802   b.setInsertionPoint(module.getBody(), getFuncInsertPt());
803   LLVMFuncOp fop =
804       b.create<LLVMFuncOp>(UnknownLoc::get(context), f->getName(), functionType,
805                            convertLinkageFromLLVM(f->getLinkage()));
806 
807   if (FlatSymbolRefAttr personality = getPersonalityAsAttr(f))
808     fop->setAttr(b.getStringAttr("personality"), personality);
809   else if (f->hasPersonalityFn())
810     emitWarning(UnknownLoc::get(context),
811                 "could not deduce personality, skipping it");
812 
813   if (f->isDeclaration())
814     return success();
815 
816   // Eagerly create all blocks.
817   SmallVector<Block *, 4> blockList;
818   for (llvm::BasicBlock &bb : *f) {
819     blockList.push_back(b.createBlock(&fop.getBody(), fop.getBody().end()));
820     blocks[&bb] = blockList.back();
821   }
822   currentEntryBlock = blockList[0];
823 
824   // Add function arguments to the entry block.
825   for (const auto &kv : llvm::enumerate(f->args()))
826     instMap[&kv.value()] =
827         blockList[0]->addArgument(functionType.getParamType(kv.index()));
828 
829   for (auto bbs : llvm::zip(*f, blockList)) {
830     if (failed(processBasicBlock(&std::get<0>(bbs), std::get<1>(bbs))))
831       return failure();
832   }
833 
834   // Now that all instructions are guaranteed to have been visited, ensure
835   // any unknown uses we encountered are remapped.
836   for (auto &llvmAndUnknown : unknownInstMap) {
837     assert(instMap.count(llvmAndUnknown.first));
838     Value newValue = instMap[llvmAndUnknown.first];
839     Value oldValue = llvmAndUnknown.second->getResult(0);
840     oldValue.replaceAllUsesWith(newValue);
841     llvmAndUnknown.second->erase();
842   }
843   return success();
844 }
845 
846 LogicalResult Importer::processBasicBlock(llvm::BasicBlock *bb, Block *block) {
847   b.setInsertionPointToStart(block);
848   for (llvm::Instruction &inst : *bb) {
849     if (failed(processInstruction(&inst)))
850       return failure();
851   }
852   return success();
853 }
854 
855 OwningModuleRef
856 mlir::translateLLVMIRToModule(std::unique_ptr<llvm::Module> llvmModule,
857                               MLIRContext *context) {
858   context->loadDialect<LLVMDialect>();
859   OwningModuleRef module(ModuleOp::create(
860       FileLineColLoc::get(context, "", /*line=*/0, /*column=*/0)));
861 
862   Importer deserializer(context, module.get());
863   for (llvm::GlobalVariable &gv : llvmModule->globals()) {
864     if (!deserializer.processGlobal(&gv))
865       return {};
866   }
867   for (llvm::Function &f : llvmModule->functions()) {
868     if (failed(deserializer.processFunction(&f)))
869       return {};
870   }
871 
872   return module;
873 }
874 
875 // Deserializes the LLVM bitcode stored in `input` into an MLIR module in the
876 // LLVM dialect.
877 OwningModuleRef translateLLVMIRToModule(llvm::SourceMgr &sourceMgr,
878                                         MLIRContext *context) {
879   llvm::SMDiagnostic err;
880   llvm::LLVMContext llvmContext;
881   std::unique_ptr<llvm::Module> llvmModule = llvm::parseIR(
882       *sourceMgr.getMemoryBuffer(sourceMgr.getMainFileID()), err, llvmContext);
883   if (!llvmModule) {
884     std::string errStr;
885     llvm::raw_string_ostream errStream(errStr);
886     err.print(/*ProgName=*/"", errStream);
887     emitError(UnknownLoc::get(context)) << errStream.str();
888     return {};
889   }
890   return translateLLVMIRToModule(std::move(llvmModule), context);
891 }
892 
893 namespace mlir {
894 void registerFromLLVMIRTranslation() {
895   TranslateToMLIRRegistration fromLLVM(
896       "import-llvm", [](llvm::SourceMgr &sourceMgr, MLIRContext *context) {
897         return ::translateLLVMIRToModule(sourceMgr, context);
898       });
899 }
900 } // namespace mlir
901