tools/llvm-mca/CodeRegionGenerator.cpp

   1 //===----------------------- CodeRegionGenerator.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 /// \file
   9 ///
  10 /// This file defines classes responsible for generating llvm-mca
  11 /// CodeRegions from various types of input. llvm-mca only analyzes CodeRegions,
  12 /// so the classes here provide the input-to-CodeRegions translation.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "CodeRegionGenerator.h"
  17 #include "llvm/ADT/ArrayRef.h"
  18 #include "llvm/ADT/StringRef.h"
  19 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
  20 #include "llvm/MC/MCStreamer.h"
  21 #include "llvm/MC/MCTargetOptions.h"
  22 #include "llvm/Support/Error.h"
  23 #include "llvm/Support/SMLoc.h"
  24 #include <memory>
  25
  26 namespace llvm {
  27 namespace mca {
  28
  29 // This virtual dtor serves as the anchor for the CodeRegionGenerator class.
  30 CodeRegionGenerator::~CodeRegionGenerator() {}
  31
  32 // A comment consumer that parses strings.  The only valid tokens are strings.
  33 class MCACommentConsumer : public AsmCommentConsumer {
  34 public:
  35   CodeRegions &Regions;
  36
  37   MCACommentConsumer(CodeRegions &R) : Regions(R) {}
  38   void HandleComment(SMLoc Loc, StringRef CommentText) override;
  39 };
  40
  41 // This class provides the callbacks that occur when parsing input assembly.
  42 class MCStreamerWrapper final : public MCStreamer {
  43   CodeRegions &Regions;
  44
  45 public:
  46   MCStreamerWrapper(MCContext &Context, mca::CodeRegions &R)
  47       : MCStreamer(Context), Regions(R) {}
  48
  49   // We only want to intercept the emission of new instructions.
  50   virtual void EmitInstruction(const MCInst &Inst,
  51                                const MCSubtargetInfo &/* unused */) override {
  52     Regions.addInstruction(Inst);
  53   }
  54
  55   bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override {
  56     return true;
  57   }
  58
  59   void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
  60                         unsigned ByteAlignment) override {}
  61   void EmitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,
  62                     uint64_t Size = 0, unsigned ByteAlignment = 0,
  63                     SMLoc Loc = SMLoc()) override {}
  64   void EmitGPRel32Value(const MCExpr *Value) override {}
  65   void BeginCOFFSymbolDef(const MCSymbol *Symbol) override {}
  66   void EmitCOFFSymbolStorageClass(int StorageClass) override {}
  67   void EmitCOFFSymbolType(int Type) override {}
  68   void EndCOFFSymbolDef() override {}
  69
  70   ArrayRef<MCInst> GetInstructionSequence(unsigned Index) const {
  71     return Regions.getInstructionSequence(Index);
  72   }
  73 };
  74
  75 void MCACommentConsumer::HandleComment(SMLoc Loc, StringRef CommentText) {
  76   // Skip empty comments.
  77   StringRef Comment(CommentText);
  78   if (Comment.empty())
  79     return;
  80
  81   // Skip spaces and tabs.
  82   unsigned Position = Comment.find_first_not_of(" \t");
  83   if (Position >= Comment.size())
  84     // We reached the end of the comment. Bail out.
  85     return;
  86
  87   Comment = Comment.drop_front(Position);
  88   if (Comment.consume_front("LLVM-MCA-END")) {
  89     Regions.endRegion(Loc);
  90     return;
  91   }
  92
  93   // Try to parse the LLVM-MCA-BEGIN comment.
  94   if (!Comment.consume_front("LLVM-MCA-BEGIN"))
  95     return;
  96
  97   // Skip spaces and tabs.
  98   Position = Comment.find_first_not_of(" \t");
  99   if (Position < Comment.size())
 100     Comment = Comment.drop_front(Position);
 101   // Use the rest of the string as a descriptor for this code snippet.
 102   Regions.beginRegion(Comment, Loc);
 103 }
 104
 105 Expected<const CodeRegions &> AsmCodeRegionGenerator::parseCodeRegions() {
 106   MCTargetOptions Opts;
 107   Opts.PreserveAsmComments = false;
 108   MCStreamerWrapper Str(Ctx, Regions);
 109
 110   // Create a MCAsmParser and setup the lexer to recognize llvm-mca ASM
 111   // comments.
 112   std::unique_ptr<MCAsmParser> Parser(
 113       createMCAsmParser(Regions.getSourceMgr(), Ctx, Str, MAI));
 114   MCAsmLexer &Lexer = Parser->getLexer();
 115   MCACommentConsumer CC(Regions);
 116   Lexer.setCommentConsumer(&CC);
 117
 118   // Create a target-specific parser and perform the parse.
 119   std::unique_ptr<MCTargetAsmParser> TAP(
 120       TheTarget.createMCAsmParser(STI, *Parser, MCII, Opts));
 121   if (!TAP)
 122     return make_error<StringError>(
 123         "This target does not support assembly parsing.",
 124         inconvertibleErrorCode());
 125   Parser->setTargetParser(*TAP);
 126   Parser->Run(false);
 127
 128   // Get the assembler dialect from the input.  llvm-mca will use this as the
 129   // default dialect when printing reports.
 130   AssemblerDialect = Parser->getAssemblerDialect();
 131   return Regions;
 132 }
 133
 134 } // namespace mca
 135 } // namespace llvm