llvm-cov: Implement the preserve-paths flag

Until now, when a path in a gcno file included a directory, we would
emit our .gcov file in that directory, whereas gcov always emits the
file in the current directory. In doing so, this implements gcov's
strange name-mangling -p flag, which is needed to avoid clobbering
files when two with the same name exist in different directories.

The path mangling is a bit ugly and only handles unix-like paths, but
it's simple, and it doesn't make any guesses as to how it should
behave outside of what gcov documents. If we decide this should be
cross platform later, we can consider the compatibility implications
then.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200754 91177308-0d34-0410-b5e6-96231b3b80d8

lib/IR/GCOV.cpp

@@ -16,8 +16,10 @@
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/GCOV.h"
 #include "llvm/Support/MemoryObject.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/system_error.h"
 #include <algorithm>
 using namespace llvm;
@@ -429,6 +431,42 @@ static raw_ostream &operator<<(raw_ostream &OS, const formatBranchInfo &FBI) {
   return OS;
 }
 
+/// Convert a path to a gcov filename. If PreservePaths is true, this
+/// translates "/" to "#", ".." to "^", and drops ".", to match gcov.
+static std::string mangleCoveragePath(StringRef Filename, bool PreservePaths) {
+  if (!PreservePaths)
+    return (sys::path::filename(Filename) + ".gcov").str();
+
+  // This behaviour is defined by gcov in terms of text replacements, so it's
+  // not likely to do anything useful on filesystems with different textual
+  // conventions.
+  llvm::SmallString<256> Result("");
+  StringRef::iterator I, S, E;
+  for (I = S = Filename.begin(), E = Filename.end(); I != E; ++I) {
+    if (*I != '/')
+      continue;
+
+    if (I - S == 1 && *S == '.') {
+      // ".", the current directory, is skipped.
+    } else if (I - S == 2 && *S == '.' && *(S + 1) == '.') {
+      // "..", the parent directory, is replaced with "^".
+      Result.append("^#");
+    } else {
+      if (S < I)
+        // Leave other components intact,
+        Result.append(S, I);
+      // And separate with "#".
+      Result.push_back('#');
+    }
+    S = I + 1;
+  }
+
+  if (S < I)
+    Result.append(S, I);
+  Result.append(".gcov");
+  return Result.str();
+}
+
 /// print -  Print source files with collected line count information.
 void FileInfo::print(StringRef GCNOFile, StringRef GCDAFile) {
   for (StringMap<LineData>::const_iterator I = LineInfo.begin(),
@@ -441,9 +479,10 @@ void FileInfo::print(StringRef GCNOFile, StringRef GCDAFile) {
     }
     StringRef AllLines = Buff->getBuffer();
 
-    std::string CovFilename = Filename.str() + ".gcov";
+    std::string CoveragePath = mangleCoveragePath(Filename,
+                                                  Options.PreservePaths);
     std::string ErrorInfo;
-    raw_fd_ostream OS(CovFilename.c_str(), ErrorInfo);
+    raw_fd_ostream OS(CoveragePath.c_str(), ErrorInfo);
     if (!ErrorInfo.empty())
       errs() << ErrorInfo << "\n";
 
@@ -555,7 +594,7 @@ void FileInfo::print(StringRef GCNOFile, StringRef GCDAFile) {
         }
       }
     }
-    FileCoverages.push_back(FileCoverage);
+    FileCoverages.push_back(std::make_pair(CoveragePath, FileCoverage));
   }
 
   // FIXME: There is no way to detect calls given current instrumentation.
@@ -656,8 +695,8 @@ void FileInfo::printCoverage(const GCOVCoverage &Coverage) const {
 
 // printFuncCoverage - Print per-function coverage info.
 void FileInfo::printFuncCoverage() const {
-  for (MapVector<const GCOVFunction *, GCOVCoverage>::const_iterator I =
-         FuncCoverages.begin(), E = FuncCoverages.end(); I != E; ++I) {
+  for (FuncCoverageMap::const_iterator I = FuncCoverages.begin(),
+                                       E = FuncCoverages.end(); I != E; ++I) {
     const GCOVCoverage &Coverage = I->second;
     outs() << "Function '" << Coverage.Name << "'\n";
     printCoverage(Coverage);
@@ -667,12 +706,12 @@ void FileInfo::printFuncCoverage() const {
 
 // printFileCoverage - Print per-file coverage info.
 void FileInfo::printFileCoverage() const {
-  for (SmallVectorImpl<GCOVCoverage>::const_iterator I =
-         FileCoverages.begin(), E = FileCoverages.end(); I != E; ++I) {
-    const GCOVCoverage &Coverage = *I;
+  for (FileCoverageList::const_iterator I = FileCoverages.begin(),
+                                        E = FileCoverages.end(); I != E; ++I) {
+    const std::string &Filename = I->first;
+    const GCOVCoverage &Coverage = I->second;
     outs() << "File '" << Coverage.Name << "'\n";
     printCoverage(Coverage);
-    outs() << Coverage.Name << ":creating '" << Coverage.Name
-           << ".gcov'\n\n";
+    outs() << Coverage.Name << ":creating '" << Filename << "'\n\n";
   }
 }