1 //===-- SnippetFile.cpp -----------------------------------------*- C++ -*-===//
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 #include "SnippetFile.h"
10 #include "Error.h"
11 #include "llvm/MC/MCContext.h"
12 #include "llvm/MC/MCInstPrinter.h"
13 #include "llvm/MC/MCObjectFileInfo.h"
14 #include "llvm/MC/MCParser/MCAsmLexer.h"
15 #include "llvm/MC/MCParser/MCAsmParser.h"
16 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
17 #include "llvm/MC/MCRegisterInfo.h"
18 #include "llvm/MC/MCStreamer.h"
19 #include "llvm/MC/TargetRegistry.h"
20 #include "llvm/Support/Format.h"
21 #include "llvm/Support/Path.h"
22 #include "llvm/Support/SourceMgr.h"
23 #include <string>
24 
25 namespace llvm {
26 namespace exegesis {
27 namespace {
28 
29 // An MCStreamer that reads a BenchmarkCode definition from a file.
30 class BenchmarkCodeStreamer : public MCStreamer, public AsmCommentConsumer {
31 public:
BenchmarkCodeStreamer(MCContext * Context,const MCRegisterInfo * TheRegInfo,BenchmarkCode * Result)32   explicit BenchmarkCodeStreamer(MCContext *Context,
33                                  const MCRegisterInfo *TheRegInfo,
34                                  BenchmarkCode *Result)
35       : MCStreamer(*Context), RegInfo(TheRegInfo), Result(Result) {}
36 
37   // Implementation of the MCStreamer interface. We only care about
38   // instructions.
emitInstruction(const MCInst & Instruction,const MCSubtargetInfo & STI)39   void emitInstruction(const MCInst &Instruction,
40                        const MCSubtargetInfo &STI) override {
41     Result->Key.Instructions.push_back(Instruction);
42   }
43 
44   // Implementation of the AsmCommentConsumer.
HandleComment(SMLoc Loc,StringRef CommentText)45   void HandleComment(SMLoc Loc, StringRef CommentText) override {
46     CommentText = CommentText.trim();
47     if (!CommentText.consume_front("LLVM-EXEGESIS-"))
48       return;
49     if (CommentText.consume_front("DEFREG")) {
50       // LLVM-EXEGESIS-DEFREF <reg> <hex_value>
51       RegisterValue RegVal;
52       SmallVector<StringRef, 2> Parts;
53       CommentText.split(Parts, ' ', /*unlimited splits*/ -1,
54                         /*do not keep empty strings*/ false);
55       if (Parts.size() != 2) {
56         errs() << "invalid comment 'LLVM-EXEGESIS-DEFREG " << CommentText
57                << "', expected two parameters <REG> <HEX_VALUE>\n";
58         ++InvalidComments;
59         return;
60       }
61       if (!(RegVal.Register = findRegisterByName(Parts[0].trim()))) {
62         errs() << "unknown register '" << Parts[0]
63                << "' in 'LLVM-EXEGESIS-DEFREG " << CommentText << "'\n";
64         ++InvalidComments;
65         return;
66       }
67       const StringRef HexValue = Parts[1].trim();
68       RegVal.Value = APInt(
69           /* each hex digit is 4 bits */ HexValue.size() * 4, HexValue, 16);
70       Result->Key.RegisterInitialValues.push_back(std::move(RegVal));
71       return;
72     }
73     if (CommentText.consume_front("LIVEIN")) {
74       // LLVM-EXEGESIS-LIVEIN <reg>
75       const auto RegName = CommentText.ltrim();
76       if (unsigned Reg = findRegisterByName(RegName))
77         Result->LiveIns.push_back(Reg);
78       else {
79         errs() << "unknown register '" << RegName
80                << "' in 'LLVM-EXEGESIS-LIVEIN " << CommentText << "'\n";
81         ++InvalidComments;
82       }
83       return;
84     }
85   }
86 
numInvalidComments() const87   unsigned numInvalidComments() const { return InvalidComments; }
88 
89 private:
90   // We only care about instructions, we don't implement this part of the API.
emitCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)91   void emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
92                         unsigned ByteAlignment) override {}
emitSymbolAttribute(MCSymbol * Symbol,MCSymbolAttr Attribute)93   bool emitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override {
94     return false;
95   }
emitValueToAlignment(unsigned ByteAlignment,int64_t Value,unsigned ValueSize,unsigned MaxBytesToEmit)96   void emitValueToAlignment(unsigned ByteAlignment, int64_t Value,
97                             unsigned ValueSize,
98                             unsigned MaxBytesToEmit) override {}
emitZerofill(MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment,SMLoc Loc)99   void emitZerofill(MCSection *Section, MCSymbol *Symbol, uint64_t Size,
100                     unsigned ByteAlignment, SMLoc Loc) override {}
101 
findRegisterByName(const StringRef RegName) const102   unsigned findRegisterByName(const StringRef RegName) const {
103     // FIXME: Can we do better than this ?
104     for (unsigned I = 0, E = RegInfo->getNumRegs(); I < E; ++I) {
105       if (RegName == RegInfo->getName(I))
106         return I;
107     }
108     errs() << "'" << RegName
109            << "' is not a valid register name for the target\n";
110     return 0;
111   }
112 
113   const MCRegisterInfo *const RegInfo;
114   BenchmarkCode *const Result;
115   unsigned InvalidComments = 0;
116 };
117 
118 } // namespace
119 
120 // Reads code snippets from file `Filename`.
readSnippets(const LLVMState & State,StringRef Filename)121 Expected<std::vector<BenchmarkCode>> readSnippets(const LLVMState &State,
122                                                   StringRef Filename) {
123   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferPtr =
124       MemoryBuffer::getFileOrSTDIN(Filename);
125   if (std::error_code EC = BufferPtr.getError()) {
126     return make_error<Failure>("cannot read snippet: " + Filename + ": " +
127                                EC.message());
128   }
129   SourceMgr SM;
130   SM.AddNewSourceBuffer(std::move(BufferPtr.get()), SMLoc());
131 
132   BenchmarkCode Result;
133 
134   const TargetMachine &TM = State.getTargetMachine();
135   MCContext Context(TM.getTargetTriple(), TM.getMCAsmInfo(),
136                     TM.getMCRegisterInfo(), TM.getMCSubtargetInfo());
137   std::unique_ptr<MCObjectFileInfo> ObjectFileInfo(
138       TM.getTarget().createMCObjectFileInfo(Context, /*PIC=*/false));
139   Context.setObjectFileInfo(ObjectFileInfo.get());
140   Context.initInlineSourceManager();
141   BenchmarkCodeStreamer Streamer(&Context, TM.getMCRegisterInfo(), &Result);
142 
143   std::string Error;
144   raw_string_ostream ErrorStream(Error);
145   formatted_raw_ostream InstPrinterOStream(ErrorStream);
146   const std::unique_ptr<MCInstPrinter> InstPrinter(
147       TM.getTarget().createMCInstPrinter(
148           TM.getTargetTriple(), TM.getMCAsmInfo()->getAssemblerDialect(),
149           *TM.getMCAsmInfo(), *TM.getMCInstrInfo(), *TM.getMCRegisterInfo()));
150   // The following call will take care of calling Streamer.setTargetStreamer.
151   TM.getTarget().createAsmTargetStreamer(Streamer, InstPrinterOStream,
152                                          InstPrinter.get(),
153                                          TM.Options.MCOptions.AsmVerbose);
154   if (!Streamer.getTargetStreamer())
155     return make_error<Failure>("cannot create target asm streamer");
156 
157   const std::unique_ptr<MCAsmParser> AsmParser(
158       createMCAsmParser(SM, Context, Streamer, *TM.getMCAsmInfo()));
159   if (!AsmParser)
160     return make_error<Failure>("cannot create asm parser");
161   AsmParser->getLexer().setCommentConsumer(&Streamer);
162 
163   const std::unique_ptr<MCTargetAsmParser> TargetAsmParser(
164       TM.getTarget().createMCAsmParser(*TM.getMCSubtargetInfo(), *AsmParser,
165                                        *TM.getMCInstrInfo(),
166                                        MCTargetOptions()));
167 
168   if (!TargetAsmParser)
169     return make_error<Failure>("cannot create target asm parser");
170   AsmParser->setTargetParser(*TargetAsmParser);
171 
172   if (AsmParser->Run(false))
173     return make_error<Failure>("cannot parse asm file");
174   if (Streamer.numInvalidComments())
175     return make_error<Failure>(Twine("found ")
176                                    .concat(Twine(Streamer.numInvalidComments()))
177                                    .concat(" invalid LLVM-EXEGESIS comments"));
178   return std::vector<BenchmarkCode>{std::move(Result)};
179 }
180 
181 } // namespace exegesis
182 } // namespace llvm
183