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/MCTargetOptions.h"
21 #include "llvm/Support/Error.h"
22 #include "llvm/Support/SMLoc.h"
23 #include <memory>
24 
25 namespace llvm {
26 namespace mca {
27 
28 // This virtual dtor serves as the anchor for the CodeRegionGenerator class.
29 CodeRegionGenerator::~CodeRegionGenerator() {}
30 
31 Expected<const CodeRegions &> AsmCodeRegionGenerator::parseCodeRegions(
32     const std::unique_ptr<MCInstPrinter> &IP) {
33   MCTargetOptions Opts;
34   Opts.PreserveAsmComments = false;
35   CodeRegions &Regions = getRegions();
36   MCStreamerWrapper *Str = getMCStreamer();
37 
38   // Need to initialize an MCTargetStreamer otherwise
39   // certain asm directives will cause a segfault.
40   // Using nulls() so that anything emitted by the MCTargetStreamer
41   // doesn't show up in the llvm-mca output.
42   raw_ostream &OSRef = nulls();
43   formatted_raw_ostream FOSRef(OSRef);
44   TheTarget.createAsmTargetStreamer(*Str, FOSRef, IP.get(),
45                                     /*IsVerboseAsm=*/true);
46 
47   // Create a MCAsmParser and setup the lexer to recognize llvm-mca ASM
48   // comments.
49   std::unique_ptr<MCAsmParser> Parser(
50       createMCAsmParser(Regions.getSourceMgr(), Ctx, *Str, MAI));
51   MCAsmLexer &Lexer = Parser->getLexer();
52   MCACommentConsumer *CCP = getCommentConsumer();
53   Lexer.setCommentConsumer(CCP);
54   // Enable support for MASM literal numbers (example: 05h, 101b).
55   Lexer.setLexMasmIntegers(true);
56 
57   std::unique_ptr<MCTargetAsmParser> TAP(
58       TheTarget.createMCAsmParser(STI, *Parser, MCII, Opts));
59   if (!TAP)
60     return make_error<StringError>(
61         "This target does not support assembly parsing.",
62         inconvertibleErrorCode());
63   Parser->setTargetParser(*TAP);
64   Parser->Run(false);
65 
66   if (CCP->hadErr())
67     return make_error<StringError>("There was an error parsing comments.",
68                                    inconvertibleErrorCode());
69 
70   // Set the assembler dialect from the input. llvm-mca will use this as the
71   // default dialect when printing reports.
72   AssemblerDialect = Parser->getAssemblerDialect();
73   return Regions;
74 }
75 
76 void AnalysisRegionCommentConsumer::HandleComment(SMLoc Loc,
77                                                   StringRef CommentText) {
78   // Skip empty comments.
79   StringRef Comment(CommentText);
80   if (Comment.empty())
81     return;
82 
83   // Skip spaces and tabs.
84   unsigned Position = Comment.find_first_not_of(" \t");
85   if (Position >= Comment.size())
86     // We reached the end of the comment. Bail out.
87     return;
88 
89   Comment = Comment.drop_front(Position);
90   if (Comment.consume_front("LLVM-MCA-END")) {
91     // Skip spaces and tabs.
92     Position = Comment.find_first_not_of(" \t");
93     if (Position < Comment.size())
94       Comment = Comment.drop_front(Position);
95     Regions.endRegion(Comment, Loc);
96     return;
97   }
98 
99   // Try to parse the LLVM-MCA-BEGIN comment.
100   if (!Comment.consume_front("LLVM-MCA-BEGIN"))
101     return;
102 
103   // Skip spaces and tabs.
104   Position = Comment.find_first_not_of(" \t");
105   if (Position < Comment.size())
106     Comment = Comment.drop_front(Position);
107   // Use the rest of the string as a descriptor for this code snippet.
108   Regions.beginRegion(Comment, Loc);
109 }
110 
111 void InstrumentRegionCommentConsumer::HandleComment(SMLoc Loc,
112                                                     StringRef CommentText) {
113   // Skip empty comments.
114   StringRef Comment(CommentText);
115   if (Comment.empty())
116     return;
117 
118   // Skip spaces and tabs.
119   unsigned Position = Comment.find_first_not_of(" \t");
120   if (Position >= Comment.size())
121     // We reached the end of the comment. Bail out.
122     return;
123   Comment = Comment.drop_front(Position);
124 
125   // Bail out if not an MCA style comment
126   if (!Comment.consume_front("LLVM-MCA-"))
127     return;
128 
129   // Skip AnalysisRegion comments
130   if (Comment.consume_front("BEGIN") || Comment.consume_front("END"))
131     return;
132 
133   if (IM.shouldIgnoreInstruments())
134     return;
135 
136   auto [InstrumentKind, Data] = Comment.split(" ");
137 
138   // An error if not of the form LLVM-MCA-TARGET-KIND
139   if (!IM.supportsInstrumentType(InstrumentKind)) {
140     if (InstrumentKind.empty())
141       SM.PrintMessage(
142           Loc, llvm::SourceMgr::DK_Error,
143           "No instrumentation kind was provided in LLVM-MCA comment");
144     else
145       SM.PrintMessage(Loc, llvm::SourceMgr::DK_Error,
146                       "Unknown instrumentation type in LLVM-MCA comment: " +
147                           InstrumentKind);
148     FoundError = true;
149     return;
150   }
151 
152   UniqueInstrument I = IM.createInstrument(InstrumentKind, Data);
153   if (!I) {
154     if (Data.empty())
155       SM.PrintMessage(Loc, llvm::SourceMgr::DK_Error,
156                       "Failed to create " + InstrumentKind +
157                           " instrument with no data");
158     else
159       SM.PrintMessage(Loc, llvm::SourceMgr::DK_Error,
160                       "Failed to create " + InstrumentKind +
161                           " instrument with data: " + Data);
162     FoundError = true;
163     return;
164   }
165 
166   // End InstrumentType region if one is open
167   if (Regions.isRegionActive(InstrumentKind))
168     Regions.endRegion(InstrumentKind, Loc);
169   // Start new instrumentation region
170   Regions.beginRegion(InstrumentKind, Loc, std::move(I));
171 }
172 
173 } // namespace mca
174 } // namespace llvm
175