[llvm-cov] Add support for creating html reports

Based on a patch by Harlan Haskins!

Differential Revision: http://reviews.llvm.org/D18278

llvm-svn: 274688

docs/CommandGuide/llvm-cov.rst

@@ -238,7 +238,7 @@ OPTIONS
 
 .. option:: -format=<FORMAT>
 
- Use the specified output format. The supported formats are: "text".
+ Use the specified output format. The supported formats are: "text", "html".
 
 .. option:: -output-dir=PATH
 

test/tools/llvm-cov/showLineExecutionCounts.cpp

@@ -38,3 +38,34 @@ int main() {                              // TEXT:   161| [[@LINE]]|int main(
 // Test index creation.
 // RUN: FileCheck -check-prefix=INDEX -input-file %t.dir/index.txt %s
 // INDEX: showLineExecutionCounts.cpp.txt
+//
+// Test html output.
+// RUN: llvm-cov show %S/Inputs/lineExecutionCounts.covmapping -format html -o %t.html.dir -instr-profile %t.profdata -filename-equivalence %s
+// RUN: llvm-cov show %S/Inputs/lineExecutionCounts.covmapping -format html -o %t.html.dir -instr-profile %t.profdata -filename-equivalence -name=main %s
+// RUN: FileCheck -check-prefixes=HTML,HTML-WHOLE-FILE -input-file %t.html.dir/coverage/tmp/showLineExecutionCounts.cpp.html %s
+// RUN: FileCheck -check-prefixes=HTML,HTML-FILTER -input-file %t.html.dir/functions.html %s
+//
+// HTML-WHOLE-FILE: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>// before
+// HTML-FILTER-NOT: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-45]]</pre></td><td class='code'><pre>// before
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>int main() {
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  int x = 0
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>
+// HTML: <td class='uncovered-line'><pre>0</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre><span class='red'>  if (x) {
+// HTML: <td class='uncovered-line'><pre>0</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre><span class='red'>  }</span>
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>    x = 1;
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  }
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>
+// HTML: <td class='covered-line'><pre>16.2k</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  for (int i = 0; i &lt; 100; ++i)
+// HTML: <td class='covered-line'><pre>16.1k</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>    x = 1;
+// HTML: <td class='covered-line'><pre>16.1k</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  }
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  x = x &lt; 10
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  x = x &gt; 10
+// HTML: <td class='uncovered-line'><pre>0</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre><span class='red'>        x - 1:
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>        x + 1;
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  return 0;
+// HTML: <td class='covered-line'><pre>161</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>}
+// HTML-WHOLE-FILE: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>// after
+// HTML-FILTER-NOT: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-45]]</pre></td><td class='code'><pre>// after

test/tools/llvm-cov/showTemplateInstantiations.cpp

@@ -38,3 +38,48 @@ int main() {         // ALL:         1| [[@LINE]]|int main() {
 }                    // ALL-NEXT:    1| [[@LINE]]|}
 // after coverage    // ALL-NEXT:     | [[@LINE]]|// after
                      // FILTER-NOT:   | [[@LINE-1]]|// after
+
+// Test html output.
+// RUN: llvm-cov show %S/Inputs/templateInstantiations.covmapping -instr-profile %S/Inputs/templateInstantiations.profdata -filename-equivalence %s -format html -o %t.html.dir
+// RUN: llvm-cov show %S/Inputs/templateInstantiations.covmapping -instr-profile %S/Inputs/templateInstantiations.profdata -filename-equivalence -name=_Z4funcIbEiT_ %s -format html -o %t.html.dir
+// RUN: FileCheck -check-prefixes=HTML-SHARED,HTML-ALL -input-file=%t.html.dir/coverage/tmp/showTemplateInstantiations.cpp.html %s
+// RUN: FileCheck -check-prefixes=HTML-SHARED,HTML-FILTER -input-file=%t.html.dir/functions.html %s
+
+// HTML-ALL: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>// before
+// HTML-FILTER-NOT: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-45]]</pre></td><td class='code'><pre>// before
+// HTML-ALL: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>template&lt;typename T&gt;
+// HTML-ALL: <td class='covered-line'><pre>2</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>int func(T x) {
+// HTML-ALL: <td class='covered-line'><pre>2</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  if(x)
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>    ret
+// HTML-ALL: <td class='covered-line'><pre>2</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  else
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>    ret
+// HTML-ALL: <td class='uncovered-line'><pre>0</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>
+// HTML-ALL: <td class='covered-line'><pre>2</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>}
+
+// HTML-SHARED: <div class='source-name-title'><pre>_Z4funcIbEiT_</pre></div><table>
+// HTML-SHARED: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-53]]</pre></td><td class='code'><pre>int func(T x) {
+// HTML-SHARED: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-53]]</pre></td><td class='code'><pre>  if(x)
+// HTML-SHARED: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-53]]</pre></td><td class='code'><pre>    ret
+// HTML-SHARED: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-53]]</pre></td><td class='code'><pre>  else
+// HTML-SHARED: <td class='uncovered-line'><pre>0</pre></td><td class='line-number'><pre>[[@LINE-53]]</pre></td><td class='code'><pre>
+// HTML-SHARED: <td class='uncovered-line'><pre>0</pre></td><td class='line-number'><pre>[[@LINE-53]]</pre></td><td class='code'><pre>
+// HTML-SHARED: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-53]]</pre></td><td class='code'><pre>}
+
+// HTML-ALL: <div class='source-name-title'><pre>_Z4funcIiEiT_</pre></div><table>
+// HTML-FILTER-NOT: <div class='source-name-title'><pre>_Z4funcIiEiT_</pre></div><table>
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-63]]</pre></td><td class='code'><pre>int func(T x) {
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-63]]</pre></td><td class='code'><pre>  if(x)
+// HTML-ALL: <td class='uncovered-line'><pre>0</pre></td><td class='line-number'><pre>[[@LINE-63]]</pre></td><td class='code'><pre>
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-63]]</pre></td><td class='code'><pre>  else
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-63]]</pre></td><td class='code'><pre>    ret
+// HTML-ALL: <td class='uncovered-line'><pre>0</pre></td><td class='line-number'><pre>[[@LINE-63]]</pre></td><td class='code'><pre>
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-63]]</pre></td><td class='code'><pre>}
+
+// HTML-ALL: td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>int main() {
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  func&lt;int&gt;(0);
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  func&lt;bool&gt;(true);
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>  return 0;
+// HTML-ALL: <td class='covered-line'><pre>1</pre></td><td class='line-number'><pre>[[@LINE-44]]</pre></td><td class='code'><pre>}
+
+// HTML-ALL: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-45]]</pre></td><td class='code'><pre>// after
+// HTML-FILTER-NOT: <td class='uncovered-line'></td><td class='line-number'><pre>[[@LINE-46]]</pre></td><td class='code'><pre>// after

tools/llvm-cov/CMakeLists.txt

@@ -8,6 +8,7 @@ add_llvm_tool(llvm-cov
   CoverageReport.cpp
   CoverageSummaryInfo.cpp
   SourceCoverageView.cpp
+  SourceCoverageViewHTML.cpp
   SourceCoverageViewText.cpp
   TestingSupport.cpp
   )

tools/llvm-cov/CodeCoverage.cpp

@@ -272,6 +272,8 @@ int CodeCoverageTool::run(Command Cmd, int argc, const char **argv) {
       "format", cl::desc("Output format for line-based coverage reports"),
       cl::values(clEnumValN(CoverageViewOptions::OutputFormat::Text, "text",
                             "Text output"),
+                 clEnumValN(CoverageViewOptions::OutputFormat::HTML, "html",
+                            "HTML output"),
                  clEnumValEnd),
       cl::init(CoverageViewOptions::OutputFormat::Text));
 
@@ -333,6 +335,11 @@ int CodeCoverageTool::run(Command Cmd, int argc, const char **argv) {
                             ? sys::Process::StandardOutHasColors()
                             : UseColor == cl::BOU_TRUE;
       break;
+    case CoverageViewOptions::OutputFormat::HTML:
+      if (UseColor == cl::BOU_FALSE)
+        error("Color output cannot be disabled when generating html.");
+      ViewOpts.Colors = true;
+      break;
     }
 
     // Create the function filters
@@ -527,6 +534,9 @@ int CodeCoverageTool::report(int argc, const char **argv,
   if (Err)
     return Err;
 
+  if (ViewOpts.Format == CoverageViewOptions::OutputFormat::HTML)
+    error("HTML output for summary reports is not yet supported.");
+
   auto Coverage = load();
   if (!Coverage)
     return 1;

tools/llvm-cov/CoverageViewOptions.h

@@ -17,7 +17,8 @@ namespace llvm {
 /// \brief The options for displaying the code coverage information.
 struct CoverageViewOptions {
   enum class OutputFormat {
-    Text
+    Text,
+    HTML
   };
 
   bool Debug;

tools/llvm-cov/SourceCoverageView.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "SourceCoverageView.h"
+#include "SourceCoverageViewHTML.h"
 #include "SourceCoverageViewText.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
@@ -74,6 +75,8 @@ CoveragePrinter::create(const CoverageViewOptions &Opts) {
   switch (Opts.Format) {
   case CoverageViewOptions::OutputFormat::Text:
     return llvm::make_unique<CoveragePrinterText>(Opts);
+  case CoverageViewOptions::OutputFormat::HTML:
+    return llvm::make_unique<CoveragePrinterHTML>(Opts);
   }
   llvm_unreachable("Unknown coverage output format!");
 }
@@ -111,6 +114,9 @@ SourceCoverageView::create(StringRef SourceName, const MemoryBuffer &File,
   case CoverageViewOptions::OutputFormat::Text:
     return llvm::make_unique<SourceCoverageViewText>(SourceName, File, Options,
                                                      std::move(CoverageInfo));
+  case CoverageViewOptions::OutputFormat::HTML:
+    return llvm::make_unique<SourceCoverageViewHTML>(SourceName, File, Options,
+                                                     std::move(CoverageInfo));
   }
   llvm_unreachable("Unknown coverage output format!");
 }

tools/llvm-cov/SourceCoverageViewHTML.cpp

@@ -0,0 +1,436 @@
+//===- SourceCoverageViewHTML.cpp - A html code coverage view -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file This file implements the html coverage renderer.
+///
+//===----------------------------------------------------------------------===//
+
+#include "SourceCoverageViewHTML.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Path.h"
+
+using namespace llvm;
+
+namespace {
+
+const char *BeginHeader =
+  "<head>"
+    "<meta name='viewport' content='width=device-width,initial-scale=1'>"
+    "<meta charset='UTF-8'>";
+
+const char *CSSForCoverage =
+  "<style>"
+R"(
+
+.red {
+  background-color: #FFD0D0;
+}
+.cyan {
+  background-color: cyan;
+}
+.black {
+  background-color: black;
+  color: white;
+}
+.green {
+  background-color: #98FFA6;
+  color: white;
+}
+.magenta {
+  background-color: #F998FF;
+  color: white;
+}
+body {
+  font-family: -apple-system, sans-serif;
+}
+pre {
+  margin-top: 0px !important;
+  margin-bottom: 0px !important;
+}
+.source-name-title {
+  padding: 5px 10px;
+  border-bottom: 1px solid #dbdbdb;
+  background-color: #eee;
+}
+.centered {
+  display: table;
+  margin-left: auto;
+  margin-right: auto;
+  border: 1px solid #dbdbdb;
+  border-radius: 3px;
+}
+.expansion-view {
+  background-color: rgba(0, 0, 0, 0);
+  margin-left: 0px;
+  margin-top: 5px;
+  margin-right: 5px;
+  margin-bottom: 5px;
+  border: 1px solid #dbdbdb;
+  border-radius: 3px;
+}
+table {
+  border-collapse: collapse;
+}
+.line-number {
+  text-align: right;
+  color: #aaa;
+}
+.covered-line {
+  text-align: right;
+  color: #0080ff;
+}
+.uncovered-line {
+  text-align: right;
+  color: #ff3300;
+}
+.tooltip {
+  position: relative;
+  display: inline;
+  background-color: #b3e6ff;
+  text-decoration: none;
+}
+.tooltip span.tooltip-content {
+  position: absolute;
+  width: 100px;
+  margin-left: -50px;
+  color: #FFFFFF;
+  background: #000000;
+  height: 30px;
+  line-height: 30px;
+  text-align: center;
+  visibility: hidden;
+  border-radius: 6px;
+}
+.tooltip span.tooltip-content:after {
+  content: '';
+  position: absolute;
+  top: 100%;
+  left: 50%;
+  margin-left: -8px;
+  width: 0; height: 0;
+  border-top: 8px solid #000000;
+  border-right: 8px solid transparent;
+  border-left: 8px solid transparent;
+}
+:hover.tooltip span.tooltip-content {
+  visibility: visible;
+  opacity: 0.8;
+  bottom: 30px;
+  left: 50%;
+  z-index: 999;
+}
+th, td {
+  vertical-align: top;
+  padding: 2px 5px;
+  border-collapse: collapse;
+  border-right: solid 1px #eee;
+  border-left: solid 1px #eee;
+}
+td:first-child {
+  border-left: none;
+}
+td:last-child {
+  border-right: none;
+}
+
+)"
+  "</style>";
+
+const char *EndHeader = "</head>";
+
+const char *BeginCenteredDiv = "<div class='centered'>";
+
+const char *EndCenteredDiv = "</div>";
+
+const char *BeginSourceNameDiv = "<div class='source-name-title'>";
+
+const char *EndSourceNameDiv = "</div>";
+
+const char *BeginCodeTD = "<td class='code'>";
+
+const char *EndCodeTD = "</td>";
+
+const char *BeginPre = "<pre>";
+
+const char *EndPre = "</pre>";
+
+const char *BeginExpansionDiv = "<div class='expansion-view'>";
+
+const char *EndExpansionDiv = "</div>";
+
+const char *BeginTable = "<table>";
+
+const char *EndTable = "</table>";
+
+void emitPrelude(raw_ostream &OS) {
+  OS << "<!doctype html>"
+        "<html>"
+     << BeginHeader << CSSForCoverage << EndHeader << "<body>"
+     << BeginCenteredDiv;
+}
+
+void emitEpilog(raw_ostream &OS) {
+  OS << EndCenteredDiv << "</body>"
+                          "</html>";
+}
+
+// Return a string with the special characters in \p Str escaped.
+std::string escape(StringRef Str) {
+  std::string Result;
+  for (char C : Str) {
+    if (C == '&')
+      Result += "&amp;";
+    else if (C == '<')
+      Result += "&lt;";
+    else if (C == '>')
+      Result += "&gt;";
+    else if (C == '\"')
+      Result += "&quot;";
+    else
+      Result += C;
+  }
+  return Result;
+}
+
+// Create a \p Name tag around \p Str, and optionally set its \p ClassName.
+std::string tag(const std::string &Name, const std::string &Str,
+                const std::string &ClassName = "") {
+  std::string Tag = "<" + Name;
+  if (ClassName != "")
+    Tag += " class='" + ClassName + "'";
+  return Tag + ">" + Str + "</" + Name + ">";
+}
+
+// Create an anchor to \p Link with the label \p Str.
+std::string a(const std::string &Link, const std::string &Str) {
+  return "<a href='" + Link + "'>" + Str + "</a>";
+}
+
+} // anonymous namespace
+
+Expected<CoveragePrinter::OwnedStream>
+CoveragePrinterHTML::createViewFile(StringRef Path, bool InToplevel) {
+  auto OSOrErr = createOutputStream(Path, "html", InToplevel);
+  if (!OSOrErr)
+    return OSOrErr;
+
+  OwnedStream OS = std::move(OSOrErr.get());
+  emitPrelude(*OS.get());
+  return std::move(OS);
+}
+
+void CoveragePrinterHTML::closeViewFile(OwnedStream OS) {
+  emitEpilog(*OS.get());
+}
+
+Error CoveragePrinterHTML::createIndexFile(ArrayRef<StringRef> SourceFiles) {
+  auto OSOrErr = createOutputStream("index", "html", /*InToplevel=*/true);
+  if (Error E = OSOrErr.takeError())
+    return E;
+  auto OS = std::move(OSOrErr.get());
+  raw_ostream &OSRef = *OS.get();
+
+  // Emit a table containing links to reports for each file in the covmapping.
+  emitPrelude(OSRef);
+  OSRef << BeginSourceNameDiv << "Index" << EndSourceNameDiv;
+  OSRef << BeginTable;
+  for (StringRef SF : SourceFiles) {
+    std::string LinkText = escape(sys::path::relative_path(SF));
+    std::string LinkTarget =
+        escape(getOutputPath(SF, "html", /*InToplevel=*/false));
+    OSRef << tag("tr", tag("td", tag("pre", a(LinkTarget, LinkText), "code")));
+  }
+  OSRef << EndTable;
+  emitEpilog(OSRef);
+
+  return Error::success();
+}
+
+void SourceCoverageViewHTML::renderViewHeader(raw_ostream &OS) {
+  OS << BeginTable;
+}
+
+void SourceCoverageViewHTML::renderViewFooter(raw_ostream &OS) {
+  OS << EndTable;
+}
+
+void SourceCoverageViewHTML::renderSourceName(raw_ostream &OS) {
+  OS << BeginSourceNameDiv << tag("pre", escape(getSourceName()))
+     << EndSourceNameDiv;
+}
+
+void SourceCoverageViewHTML::renderLinePrefix(raw_ostream &OS, unsigned) {
+  OS << "<tr>";
+}
+
+void SourceCoverageViewHTML::renderLineSuffix(raw_ostream &OS, unsigned) {
+  // If this view has sub-views, renderLine() cannot close the view's cell.
+  // Take care of it here, after all sub-views have been rendered.
+  if (hasSubViews())
+    OS << EndCodeTD;
+  OS << "</tr>";
+}
+
+void SourceCoverageViewHTML::renderViewDivider(raw_ostream &, unsigned) {
+  // The table-based output makes view dividers unnecessary.
+}
+
+void SourceCoverageViewHTML::renderLine(
+    raw_ostream &OS, LineRef L, const coverage::CoverageSegment *WrappedSegment,
+    CoverageSegmentArray Segments, unsigned ExpansionCol, unsigned) {
+  StringRef Line = L.Line;
+
+  // Steps for handling text-escaping, highlighting, and tooltip creation:
+  //
+  // 1. Split the line into N+1 snippets, where N = |Segments|. The first
+  //    snippet starts from Col=1 and ends at the start of the first segment.
+  //    The last snippet starts at the last mapped column in the line and ends
+  //    at the end of the line. Both are required but may be empty.
+
+  SmallVector<std::string, 8> Snippets;
+
+  unsigned LCol = 1;
+  auto Snip = [&](unsigned Start, unsigned Len) {
+    assert(Start + Len <= Line.size() && "Snippet extends past the EOL");
+    Snippets.push_back(Line.substr(Start, Len));
+    LCol += Len;
+  };
+
+  Snip(LCol - 1, Segments.empty() ? 0 : (Segments.front()->Col - 1));
+
+  for (unsigned I = 1, E = Segments.size(); I < E; ++I) {
+    assert(LCol == Segments[I - 1]->Col && "Snippet start position is wrong");
+    Snip(LCol - 1, Segments[I]->Col - LCol);
+  }
+
+  // |Line| + 1 is needed to avoid underflow when, e.g |Line| = 0 and LCol = 1.
+  Snip(LCol - 1, Line.size() + 1 - LCol);
+  assert(LCol == Line.size() + 1 && "Final snippet doesn't reach the EOL");
+
+  // 2. Escape all of the snippets.
+
+  for (unsigned I = 0, E = Snippets.size(); I < E; ++I)
+    Snippets[I] = escape(Snippets[I]);
+
+  // 3. Use \p WrappedSegment to set the highlight for snippets 0 and 1. Use
+  //    segment 1 to set the highlight for snippet 2, segment 2 to set the
+  //    highlight for snippet 3, and so on.
+
+  Optional<std::string> Color;
+  auto Highlight = [&](const std::string &Snippet) {
+    return tag("span", Snippet, Color.getValue());
+  };
+
+  auto CheckIfUncovered = [](const coverage::CoverageSegment *S) {
+    return S && S->HasCount && S->Count == 0;
+  };
+
+  if (CheckIfUncovered(WrappedSegment) ||
+      CheckIfUncovered(Segments.empty() ? nullptr : Segments.front())) {
+    Color = "red";
+    Snippets[0] = Highlight(Snippets[0]);
+    Snippets[1] = Highlight(Snippets[1]);
+  }
+
+  for (unsigned I = 1, E = Segments.size(); I < E; ++I) {
+    const auto *CurSeg = Segments[I];
+    if (CurSeg->Col == ExpansionCol)
+      Color = "cyan";
+    else if (CheckIfUncovered(CurSeg))
+      Color = "red";
+    else
+      Color = None;
+
+    if (Color.hasValue())
+      Snippets[I + 1] = Highlight(Snippets[I + 1]);
+  }
+
+  // 4. Snippets[1:N+1] correspond to \p Segments[0:N]: use these to generate
+  //    sub-line region count tooltips if needed.
+
+  bool HasMultipleRegions = [&] {
+    unsigned RegionCount = 0;
+    for (const auto *S : Segments)
+      if (S->HasCount && S->IsRegionEntry)
+        if (++RegionCount > 1)
+          return true;
+    return false;
+  }();
+
+  if (shouldRenderRegionMarkers(HasMultipleRegions)) {
+    for (unsigned I = 0, E = Segments.size(); I < E; ++I) {
+      const auto *CurSeg = Segments[I];
+      if (!CurSeg->IsRegionEntry || !CurSeg->HasCount)
+        continue;
+
+      Snippets[I + 1] =
+          tag("div", Snippets[I + 1] + tag("span", formatCount(CurSeg->Count),
+                                          "tooltip-content"),
+              "tooltip");
+    }
+  }
+
+  OS << BeginCodeTD;
+  OS << BeginPre;
+  for (const auto &Snippet : Snippets)
+    OS << Snippet;
+  OS << EndPre;
+
+  // If there are no sub-views left to attach to this cell, end the cell.
+  // Otherwise, end it after the sub-views are rendered (renderLineSuffix()).
+  if (!hasSubViews())
+    OS << EndCodeTD;
+}
+
+void SourceCoverageViewHTML::renderLineCoverageColumn(
+    raw_ostream &OS, const LineCoverageStats &Line) {
+  std::string Count = "";
+  if (Line.isMapped())
+    Count = tag("pre", formatCount(Line.ExecutionCount));
+  std::string CoverageClass =
+      (Line.ExecutionCount > 0) ? "covered-line" : "uncovered-line";
+  OS << tag("td", Count, CoverageClass);
+}
+
+void SourceCoverageViewHTML::renderLineNumberColumn(raw_ostream &OS,
+                                                    unsigned LineNo) {
+  OS << tag("td", tag("pre", utostr(uint64_t(LineNo))), "line-number");
+}
+
+void SourceCoverageViewHTML::renderRegionMarkers(raw_ostream &,
+                                                 CoverageSegmentArray,
+                                                 unsigned) {
+  // Region markers are rendered in-line using tooltips.
+}
+
+void SourceCoverageViewHTML::renderExpansionSite(
+    raw_ostream &OS, LineRef L, const coverage::CoverageSegment *WrappedSegment,
+    CoverageSegmentArray Segments, unsigned ExpansionCol, unsigned ViewDepth) {
+  // Render the line containing the expansion site. No extra formatting needed.
+  renderLine(OS, L, WrappedSegment, Segments, ExpansionCol, ViewDepth);
+}
+
+void SourceCoverageViewHTML::renderExpansionView(raw_ostream &OS,
+                                                 ExpansionView &ESV,
+                                                 unsigned ViewDepth) {
+  OS << BeginExpansionDiv;
+  ESV.View->print(OS, /*WholeFile=*/false, /*ShowSourceName=*/false,
+                  ViewDepth + 1);
+  OS << EndExpansionDiv;
+}
+
+void SourceCoverageViewHTML::renderInstantiationView(raw_ostream &OS,
+                                                     InstantiationView &ISV,
+                                                     unsigned ViewDepth) {
+  OS << BeginExpansionDiv;
+  ISV.View->print(OS, /*WholeFile=*/false, /*ShowSourceName=*/true, ViewDepth);
+  OS << EndExpansionDiv;
+}

tools/llvm-cov/SourceCoverageViewHTML.h

@@ -0,0 +1,83 @@
+//===- SourceCoverageViewHTML.h - A html code coverage view ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file This file defines the interface to the html coverage renderer.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_COV_SOURCECOVERAGEVIEWHTML_H
+#define LLVM_COV_SOURCECOVERAGEVIEWHTML_H
+
+#include "SourceCoverageView.h"
+
+namespace llvm {
+
+/// \brief A coverage printer for html output.
+class CoveragePrinterHTML : public CoveragePrinter {
+public:
+  Expected<OwnedStream> createViewFile(StringRef Path,
+                                       bool InToplevel) override;
+
+  void closeViewFile(OwnedStream OS) override;
+
+  Error createIndexFile(ArrayRef<StringRef> SourceFiles) override;
+
+  CoveragePrinterHTML(const CoverageViewOptions &Opts)
+      : CoveragePrinter(Opts) {}
+};
+
+/// \brief A code coverage view which supports html-based rendering.
+class SourceCoverageViewHTML : public SourceCoverageView {
+  void renderViewHeader(raw_ostream &OS) override;
+
+  void renderViewFooter(raw_ostream &OS) override;
+
+  void renderSourceName(raw_ostream &OS) override;
+
+  void renderLinePrefix(raw_ostream &OS, unsigned ViewDepth) override;
+
+  void renderLineSuffix(raw_ostream &OS, unsigned ViewDepth) override;
+
+  void renderViewDivider(raw_ostream &OS, unsigned ViewDepth) override;
+
+  void renderLine(raw_ostream &OS, LineRef L,
+                  const coverage::CoverageSegment *WrappedSegment,
+                  CoverageSegmentArray Segments, unsigned ExpansionCol,
+                  unsigned ViewDepth) override;
+
+  void renderExpansionSite(raw_ostream &OS, LineRef L,
+                           const coverage::CoverageSegment *WrappedSegment,
+                           CoverageSegmentArray Segments, unsigned ExpansionCol,
+                           unsigned ViewDepth) override;
+
+  void renderExpansionView(raw_ostream &OS, ExpansionView &ESV,
+                           unsigned ViewDepth) override;
+
+  void renderInstantiationView(raw_ostream &OS, InstantiationView &ISV,
+                               unsigned ViewDepth) override;
+
+  void renderLineCoverageColumn(raw_ostream &OS,
+                                const LineCoverageStats &Line) override;
+
+  void renderLineNumberColumn(raw_ostream &OS, unsigned LineNo) override;
+
+  void renderRegionMarkers(raw_ostream &OS, CoverageSegmentArray Segments,
+                           unsigned ViewDepth) override;
+
+public:
+  SourceCoverageViewHTML(StringRef SourceName, const MemoryBuffer &File,
+                         const CoverageViewOptions &Options,
+                         coverage::CoverageData &&CoverageInfo)
+      : SourceCoverageView(SourceName, File, Options, std::move(CoverageInfo)) {
+  }
+};
+
+} // namespace llvm
+
+#endif // LLVM_COV_SOURCECOVERAGEVIEWHTML_H