Merge remote-tracking branch 'upstream/release_34' into merge-20140211

Conflicts:
	lib/Linker/LinkModules.cpp
	lib/Support/Unix/Signals.inc

Change-Id: Ia54f291fa5dc828052d2412736e8495c1282aa64

2 files changed, 318 insertions, 117 deletions

diff --git a/utils/FileCheck/CMakeLists.txt b/utils/FileCheck/CMakeLists.txt
index fa56f92..d691ceb 100644
--- a/utils/FileCheck/CMakeLists.txt
+++ b/utils/FileCheck/CMakeLists.txt
@@ -4,7 +4,7 @@ add_llvm_utility(FileCheck
 
 target_link_libraries(FileCheck LLVMSupport)
 if( MINGW )
-  target_link_libraries(FileCheck imagehlp psapi)
+  target_link_libraries(FileCheck imagehlp psapi shell32)
 endif( MINGW )
 if( LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD )
   target_link_libraries(FileCheck pthread)
diff --git a/utils/FileCheck/FileCheck.cpp b/utils/FileCheck/FileCheck.cpp
index 8d5af58..f2510d7 100644
--- a/utils/FileCheck/FileCheck.cpp
+++ b/utils/FileCheck/FileCheck.cpp
@@ -20,6 +20,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringSet.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/PrettyStackTrace.h"
@@ -29,6 +30,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/system_error.h"
 #include <algorithm>
+#include <cctype>
 #include <map>
 #include <string>
 #include <vector>
@@ -41,30 +43,39 @@ static cl::opt<std::string>
 InputFilename("input-file", cl::desc("File to check (defaults to stdin)"),
               cl::init("-"), cl::value_desc("filename"));
 
-static cl::opt<std::string>
-CheckPrefix("check-prefix", cl::init("CHECK"),
-            cl::desc("Prefix to use from check file (defaults to 'CHECK')"));
+static cl::list<std::string>
+CheckPrefixes("check-prefix",
+              cl::desc("Prefix to use from check file (defaults to 'CHECK')"));
 
 static cl::opt<bool>
 NoCanonicalizeWhiteSpace("strict-whitespace",
               cl::desc("Do not treat all horizontal whitespace as equivalent"));
 
+typedef cl::list<std::string>::const_iterator prefix_iterator;
+
 //===----------------------------------------------------------------------===//
 // Pattern Handling Code.
 //===----------------------------------------------------------------------===//
 
+namespace Check {
+  enum CheckType {
+    CheckNone = 0,
+    CheckPlain,
+    CheckNext,
+    CheckNot,
+    CheckDAG,
+    CheckLabel,
+
+    /// MatchEOF - When set, this pattern only matches the end of file. This is
+    /// used for trailing CHECK-NOTs.
+    CheckEOF
+  };
+}
+
 class Pattern {
   SMLoc PatternLoc;
 
-  /// MatchEOF - When set, this pattern only matches the end of file. This is
-  /// used for trailing CHECK-NOTs.
-  bool MatchEOF;
-
-  /// MatchNot
-  bool MatchNot;
-
-  /// MatchDag
-  bool MatchDag;
+  Check::CheckType CheckTy;
 
   /// FixedStr - If non-empty, this pattern is a fixed string match with the
   /// specified fixed string.
@@ -89,17 +100,21 @@ class Pattern {
 
 public:
 
-  Pattern(bool matchEOF = false)
-    : MatchEOF(matchEOF), MatchNot(false), MatchDag(false) { }
+  Pattern(Check::CheckType Ty)
+    : CheckTy(Ty) { }
 
   /// getLoc - Return the location in source code.
   SMLoc getLoc() const { return PatternLoc; }
 
-  /// ParsePattern - Parse the given string into the Pattern.  SM provides the
-  /// SourceMgr used for error reports, and LineNumber is the line number in
-  /// the input file from which the pattern string was read.
-  /// Returns true in case of an error, false otherwise.
-  bool ParsePattern(StringRef PatternStr, SourceMgr &SM, unsigned LineNumber);
+  /// ParsePattern - Parse the given string into the Pattern. Prefix provides
+  /// which prefix is being matched, SM provides the SourceMgr used for error
+  /// reports, and LineNumber is the line number in the input file from which
+  /// the pattern string was read.  Returns true in case of an error, false
+  /// otherwise.
+  bool ParsePattern(StringRef PatternStr,
+                    StringRef Prefix,
+                    SourceMgr &SM,
+                    unsigned LineNumber);
 
   /// Match - Match the pattern string against the input buffer Buffer.  This
   /// returns the position that is matched or npos if there is no match.  If
@@ -118,11 +133,7 @@ public:
   bool hasVariable() const { return !(VariableUses.empty() &&
                                       VariableDefs.empty()); }
 
-  void setMatchNot(bool Not) { MatchNot = Not; }
-  bool getMatchNot() const { return MatchNot; }
-
-  void setMatchDag(bool Dag) { MatchDag = Dag; }
-  bool getMatchDag() const { return MatchDag; }
+  Check::CheckType getCheckTy() const { return CheckTy; }
 
 private:
   static void AddFixedStringToRegEx(StringRef FixedStr, std::string &TheStr);
@@ -148,7 +159,9 @@ private:
 };
 
 
-bool Pattern::ParsePattern(StringRef PatternStr, SourceMgr &SM,
+bool Pattern::ParsePattern(StringRef PatternStr,
+                           StringRef Prefix,
+                           SourceMgr &SM,
                            unsigned LineNumber) {
   this->LineNumber = LineNumber;
   PatternLoc = SMLoc::getFromPointer(PatternStr.data());
@@ -162,7 +175,7 @@ bool Pattern::ParsePattern(StringRef PatternStr, SourceMgr &SM,
   if (PatternStr.empty()) {
     SM.PrintMessage(PatternLoc, SourceMgr::DK_Error,
                     "found empty check string with prefix '" +
-                    CheckPrefix+":'");
+                    Prefix + ":'");
     return true;
   }
 
@@ -381,7 +394,7 @@ bool Pattern::EvaluateExpression(StringRef Expr, std::string &Value) const {
 size_t Pattern::Match(StringRef Buffer, size_t &MatchLen,
                       StringMap<StringRef> &VariableTable) const {
   // If this is the EOF pattern, match it immediately.
-  if (MatchEOF) {
+  if (CheckTy == Check::CheckEOF) {
     MatchLen = 0;
     return Buffer.size();
   }
@@ -590,27 +603,30 @@ struct CheckString {
   /// Pat - The pattern to match.
   Pattern Pat;
 
+  /// Prefix - Which prefix name this check matched.
+  StringRef Prefix;
+
   /// Loc - The location in the match file that the check string was specified.
   SMLoc Loc;
 
-  /// IsCheckNext - This is true if this is a CHECK-NEXT: directive (as opposed
-  /// to a CHECK: directive.
-  bool IsCheckNext;
-
-  /// IsCheckLabel - This is true if this is a CHECK-LABEL: directive (as
-  /// opposed to a CHECK: directive.
-  bool IsCheckLabel;
+  /// CheckTy - Specify what kind of check this is. e.g. CHECK-NEXT: directive,
+  /// as opposed to a CHECK: directive.
+  Check::CheckType CheckTy;
 
   /// DagNotStrings - These are all of the strings that are disallowed from
   /// occurring between this match string and the previous one (or start of
   /// file).
   std::vector<Pattern> DagNotStrings;
 
-  CheckString(const Pattern &P, SMLoc L, bool isCheckNext, bool isCheckLabel)
-    : Pat(P), Loc(L), IsCheckNext(isCheckNext), IsCheckLabel(isCheckLabel) {}
+
+  CheckString(const Pattern &P,
+              StringRef S,
+              SMLoc L,
+              Check::CheckType Ty)
+    : Pat(P), Prefix(S), Loc(L), CheckTy(Ty) {}
 
   /// Check - Match check string and its "not strings" and/or "dag strings".
-  size_t Check(const SourceMgr &SM, StringRef Buffer, bool IsLabel,
+  size_t Check(const SourceMgr &SM, StringRef Buffer, bool IsLabelScanMode,
                size_t &MatchLen, StringMap<StringRef> &VariableTable) const;
 
   /// CheckNext - Verify there is a single line in the given buffer.
@@ -666,6 +682,161 @@ static MemoryBuffer *CanonicalizeInputFile(MemoryBuffer *MB,
   return MB2;
 }
 
+static bool IsPartOfWord(char c) {
+  return (isalnum(c) || c == '-' || c == '_');
+}
+
+// Get the size of the prefix extension.
+static size_t CheckTypeSize(Check::CheckType Ty) {
+  switch (Ty) {
+  case Check::CheckNone:
+    return 0;
+
+  case Check::CheckPlain:
+    return sizeof(":") - 1;
+
+  case Check::CheckNext:
+    return sizeof("-NEXT:") - 1;
+
+  case Check::CheckNot:
+    return sizeof("-NOT:") - 1;
+
+  case Check::CheckDAG:
+    return sizeof("-DAG:") - 1;
+
+  case Check::CheckLabel:
+    return sizeof("-LABEL:") - 1;
+
+  case Check::CheckEOF:
+    llvm_unreachable("Should not be using EOF size");
+  }
+
+  llvm_unreachable("Bad check type");
+}
+
+static Check::CheckType FindCheckType(StringRef Buffer, StringRef Prefix) {
+  char NextChar = Buffer[Prefix.size()];
+
+  // Verify that the : is present after the prefix.
+  if (NextChar == ':')
+    return Check::CheckPlain;
+
+  if (NextChar != '-')
+    return Check::CheckNone;
+
+  StringRef Rest = Buffer.drop_front(Prefix.size() + 1);
+  if (Rest.startswith("NEXT:"))
+    return Check::CheckNext;
+
+  if (Rest.startswith("NOT:"))
+    return Check::CheckNot;
+
+  if (Rest.startswith("DAG:"))
+    return Check::CheckDAG;
+
+  if (Rest.startswith("LABEL:"))
+    return Check::CheckLabel;
+
+  return Check::CheckNone;
+}
+
+// From the given position, find the next character after the word.
+static size_t SkipWord(StringRef Str, size_t Loc) {
+  while (Loc < Str.size() && IsPartOfWord(Str[Loc]))
+    ++Loc;
+  return Loc;
+}
+
+// Try to find the first match in buffer for any prefix. If a valid match is
+// found, return that prefix and set its type and location.  If there are almost
+// matches (e.g. the actual prefix string is found, but is not an actual check
+// string), but no valid match, return an empty string and set the position to
+// resume searching from. If no partial matches are found, return an empty
+// string and the location will be StringRef::npos. If one prefix is a substring
+// of another, the maximal match should be found. e.g. if "A" and "AA" are
+// prefixes then AA-CHECK: should match the second one.
+static StringRef FindFirstCandidateMatch(StringRef &Buffer,
+                                         Check::CheckType &CheckTy,
+                                         size_t &CheckLoc) {
+  StringRef FirstPrefix;
+  size_t FirstLoc = StringRef::npos;
+  size_t SearchLoc = StringRef::npos;
+  Check::CheckType FirstTy = Check::CheckNone;
+
+  CheckTy = Check::CheckNone;
+  CheckLoc = StringRef::npos;
+
+  for (prefix_iterator I = CheckPrefixes.begin(), E = CheckPrefixes.end();
+       I != E; ++I) {
+    StringRef Prefix(*I);
+    size_t PrefixLoc = Buffer.find(Prefix);
+
+    if (PrefixLoc == StringRef::npos)
+      continue;
+
+    // Track where we are searching for invalid prefixes that look almost right.
+    // We need to only advance to the first partial match on the next attempt
+    // since a partial match could be a substring of a later, valid prefix.
+    // Need to skip to the end of the word, otherwise we could end up
+    // matching a prefix in a substring later.
+    if (PrefixLoc < SearchLoc)
+      SearchLoc = SkipWord(Buffer, PrefixLoc);
+
+    // We only want to find the first match to avoid skipping some.
+    if (PrefixLoc > FirstLoc)
+      continue;
+    // If one matching check-prefix is a prefix of another, choose the
+    // longer one.
+    if (PrefixLoc == FirstLoc && Prefix.size() < FirstPrefix.size())
+      continue;
+
+    StringRef Rest = Buffer.drop_front(PrefixLoc);
+    // Make sure we have actually found the prefix, and not a word containing
+    // it. This should also prevent matching the wrong prefix when one is a
+    // substring of another.
+    if (PrefixLoc != 0 && IsPartOfWord(Buffer[PrefixLoc - 1]))
+      continue;
+
+    FirstLoc = PrefixLoc;
+    FirstTy = FindCheckType(Rest, Prefix);
+    FirstPrefix = Prefix;
+  }
+
+  // If the first prefix is invalid, we should continue the search after it.
+  if (FirstTy == Check::CheckNone) {
+    CheckLoc = SearchLoc;
+    return "";
+  }
+
+  CheckTy = FirstTy;
+  CheckLoc = FirstLoc;
+  return FirstPrefix;
+}
+
+static StringRef FindFirstMatchingPrefix(StringRef &Buffer,
+                                         unsigned &LineNumber,
+                                         Check::CheckType &CheckTy,
+                                         size_t &CheckLoc) {
+  while (!Buffer.empty()) {
+    StringRef Prefix = FindFirstCandidateMatch(Buffer, CheckTy, CheckLoc);
+    // If we found a real match, we are done.
+    if (!Prefix.empty()) {
+      LineNumber += Buffer.substr(0, CheckLoc).count('\n');
+      return Prefix;
+    }
+
+    // We didn't find any almost matches either, we are also done.
+    if (CheckLoc == StringRef::npos)
+      return StringRef();
+
+    LineNumber += Buffer.substr(0, CheckLoc + 1).count('\n');
+
+    // Advance to the last possible match we found and try again.
+    Buffer = Buffer.drop_front(CheckLoc + 1);
+  }
+
+  return StringRef();
+}
 
 /// ReadCheckFile - Read the check file, which specifies the sequence of
 /// expected strings.  The strings are added to the CheckStrings vector.
@@ -696,49 +867,27 @@ static bool ReadCheckFile(SourceMgr &SM,
   unsigned LineNumber = 1;
 
   while (1) {
-    // See if Prefix occurs in the memory buffer.
-    size_t PrefixLoc = Buffer.find(CheckPrefix);
-    // If we didn't find a match, we're done.
-    if (PrefixLoc == StringRef::npos)
+    Check::CheckType CheckTy;
+    size_t PrefixLoc;
+
+    // See if a prefix occurs in the memory buffer.
+    StringRef UsedPrefix = FindFirstMatchingPrefix(Buffer,
+                                                   LineNumber,
+                                                   CheckTy,
+                                                   PrefixLoc);
+    if (UsedPrefix.empty())
       break;
 
-    LineNumber += Buffer.substr(0, PrefixLoc).count('\n');
-
-    Buffer = Buffer.substr(PrefixLoc);
-
-    const char *CheckPrefixStart = Buffer.data();
-
-    // When we find a check prefix, keep track of whether we find CHECK: or
-    // CHECK-NEXT:
-    bool IsCheckNext = false, IsCheckNot = false, IsCheckDag = false,
-         IsCheckLabel = false;
-
-    // Verify that the : is present after the prefix.
-    if (Buffer[CheckPrefix.size()] == ':') {
-      Buffer = Buffer.substr(CheckPrefix.size()+1);
-    } else if (Buffer.size() > CheckPrefix.size()+6 &&
-               memcmp(Buffer.data()+CheckPrefix.size(), "-NEXT:", 6) == 0) {
-      Buffer = Buffer.substr(CheckPrefix.size()+6);
-      IsCheckNext = true;
-    } else if (Buffer.size() > CheckPrefix.size()+5 &&
-               memcmp(Buffer.data()+CheckPrefix.size(), "-NOT:", 5) == 0) {
-      Buffer = Buffer.substr(CheckPrefix.size()+5);
-      IsCheckNot = true;
-    } else if (Buffer.size() > CheckPrefix.size()+5 &&
-               memcmp(Buffer.data()+CheckPrefix.size(), "-DAG:", 5) == 0) {
-      Buffer = Buffer.substr(CheckPrefix.size()+5);
-      IsCheckDag = true;
-    } else if (Buffer.size() > CheckPrefix.size()+7 &&
-               memcmp(Buffer.data()+CheckPrefix.size(), "-LABEL:", 7) == 0) {
-      Buffer = Buffer.substr(CheckPrefix.size()+7);
-      IsCheckLabel = true;
-    } else {
-      Buffer = Buffer.substr(1);
-      continue;
-    }
+    Buffer = Buffer.drop_front(PrefixLoc);
+
+    // Location to use for error messages.
+    const char *UsedPrefixStart = Buffer.data() + (PrefixLoc == 0 ? 0 : 1);
 
-    // Okay, we found the prefix, yay.  Remember the rest of the line, but
-    // ignore leading and trailing whitespace.
+    // PrefixLoc is to the start of the prefix. Skip to the end.
+    Buffer = Buffer.drop_front(UsedPrefix.size() + CheckTypeSize(CheckTy));
+
+    // Okay, we found the prefix, yay. Remember the rest of the line, but ignore
+    // leading and trailing whitespace.
     Buffer = Buffer.substr(Buffer.find_first_not_of(" \t"));
 
     // Scan ahead to the end of line.
@@ -748,59 +897,65 @@ static bool ReadCheckFile(SourceMgr &SM,
     SMLoc PatternLoc = SMLoc::getFromPointer(Buffer.data());
 
     // Parse the pattern.
-    Pattern P;
-    if (P.ParsePattern(Buffer.substr(0, EOL), SM, LineNumber))
+    Pattern P(CheckTy);
+    if (P.ParsePattern(Buffer.substr(0, EOL), UsedPrefix, SM, LineNumber))
       return true;
 
     // Verify that CHECK-LABEL lines do not define or use variables
-    if (IsCheckLabel && P.hasVariable()) {
-      SM.PrintMessage(SMLoc::getFromPointer(CheckPrefixStart),
+    if ((CheckTy == Check::CheckLabel) && P.hasVariable()) {
+      SM.PrintMessage(SMLoc::getFromPointer(UsedPrefixStart),
                       SourceMgr::DK_Error,
-                      "found '"+CheckPrefix+"-LABEL:' with variable definition"
-                      " or use'");
+                      "found '" + UsedPrefix + "-LABEL:'"
+                      " with variable definition or use");
       return true;
     }
 
-    P.setMatchNot(IsCheckNot);
-    P.setMatchDag(IsCheckDag);
-
     Buffer = Buffer.substr(EOL);
 
     // Verify that CHECK-NEXT lines have at least one CHECK line before them.
-    if (IsCheckNext && CheckStrings.empty()) {
-      SM.PrintMessage(SMLoc::getFromPointer(CheckPrefixStart),
+    if ((CheckTy == Check::CheckNext) && CheckStrings.empty()) {
+      SM.PrintMessage(SMLoc::getFromPointer(UsedPrefixStart),
                       SourceMgr::DK_Error,
-                      "found '"+CheckPrefix+"-NEXT:' without previous '"+
-                      CheckPrefix+ ": line");
+                      "found '" + UsedPrefix + "-NEXT:' without previous '"
+                      + UsedPrefix + ": line");
       return true;
     }
 
     // Handle CHECK-DAG/-NOT.
-    if (IsCheckDag || IsCheckNot) {
+    if (CheckTy == Check::CheckDAG || CheckTy == Check::CheckNot) {
       DagNotMatches.push_back(P);
       continue;
     }
 
     // Okay, add the string we captured to the output vector and move on.
     CheckStrings.push_back(CheckString(P,
+                                       UsedPrefix,
                                        PatternLoc,
-                                       IsCheckNext,
-                                       IsCheckLabel));
+                                       CheckTy));
     std::swap(DagNotMatches, CheckStrings.back().DagNotStrings);
   }
 
-  // Add an EOF pattern for any trailing CHECK-DAG/-NOTs.
+  // Add an EOF pattern for any trailing CHECK-DAG/-NOTs, and use the first
+  // prefix as a filler for the error message.
   if (!DagNotMatches.empty()) {
-    CheckStrings.push_back(CheckString(Pattern(true),
+    CheckStrings.push_back(CheckString(Pattern(Check::CheckEOF),
+                                       CheckPrefixes[0],
                                        SMLoc::getFromPointer(Buffer.data()),
-                                       false,
-                                       false));
+                                       Check::CheckEOF));
     std::swap(DagNotMatches, CheckStrings.back().DagNotStrings);
   }
 
   if (CheckStrings.empty()) {
-    errs() << "error: no check strings found with prefix '" << CheckPrefix
-           << ":'\n";
+    errs() << "error: no check strings found with prefix"
+           << (CheckPrefixes.size() > 1 ? "es " : " ");
+    for (size_t I = 0, N = CheckPrefixes.size(); I != N; ++I) {
+      StringRef Prefix(CheckPrefixes[I]);
+      errs() << '\'' << Prefix << ":'";
+      if (I != N - 1)
+        errs() << ", ";
+    }
+
+    errs() << '\n';
     return true;
   }
 
@@ -852,12 +1007,16 @@ static unsigned CountNumNewlinesBetween(StringRef Range) {
 }
 
 size_t CheckString::Check(const SourceMgr &SM, StringRef Buffer,
-                          bool IsLabel, size_t &MatchLen,
+                          bool IsLabelScanMode, size_t &MatchLen,
                           StringMap<StringRef> &VariableTable) const {
   size_t LastPos = 0;
   std::vector<const Pattern *> NotStrings;
 
-  if (!IsLabel) {
+  // IsLabelScanMode is true when we are scanning forward to find CHECK-LABEL
+  // bounds; we have not processed variable definitions within the bounded block
+  // yet so cannot handle any final CHECK-DAG yet; this is handled when going
+  // over the block again (including the last CHECK-LABEL) in normal mode.
+  if (!IsLabelScanMode) {
     // Match "dag strings" (with mixed "not strings" if any).
     LastPos = CheckDag(SM, Buffer, NotStrings, VariableTable);
     if (LastPos == StringRef::npos)
@@ -873,7 +1032,9 @@ size_t CheckString::Check(const SourceMgr &SM, StringRef Buffer,
   }
   MatchPos += LastPos;
 
-  if (!IsLabel) {
+  // Similar to the above, in "label-scan mode" we can't yet handle CHECK-NEXT
+  // or CHECK-NOT
+  if (!IsLabelScanMode) {
     StringRef SkippedRegion = Buffer.substr(LastPos, MatchPos);
 
     // If this check is a "CHECK-NEXT", verify that the previous match was on
@@ -891,7 +1052,7 @@ size_t CheckString::Check(const SourceMgr &SM, StringRef Buffer,
 }
 
 bool CheckString::CheckNext(const SourceMgr &SM, StringRef Buffer) const {
-  if (!IsCheckNext)
+  if (CheckTy != Check::CheckNext)
     return false;
 
   // Count the number of newlines between the previous match and this one.
@@ -904,7 +1065,7 @@ bool CheckString::CheckNext(const SourceMgr &SM, StringRef Buffer) const {
   unsigned NumNewLines = CountNumNewlinesBetween(Buffer);
 
   if (NumNewLines == 0) {
-    SM.PrintMessage(Loc, SourceMgr::DK_Error, CheckPrefix+
+    SM.PrintMessage(Loc, SourceMgr::DK_Error, Prefix +
                     "-NEXT: is on the same line as previous match");
     SM.PrintMessage(SMLoc::getFromPointer(Buffer.end()),
                     SourceMgr::DK_Note, "'next' match was here");
@@ -914,7 +1075,7 @@ bool CheckString::CheckNext(const SourceMgr &SM, StringRef Buffer) const {
   }
 
   if (NumNewLines != 1) {
-    SM.PrintMessage(Loc, SourceMgr::DK_Error, CheckPrefix+
+    SM.PrintMessage(Loc, SourceMgr::DK_Error, Prefix +
                     "-NEXT: is not on the line after the previous match");
     SM.PrintMessage(SMLoc::getFromPointer(Buffer.end()),
                     SourceMgr::DK_Note, "'next' match was here");
@@ -932,7 +1093,7 @@ bool CheckString::CheckNot(const SourceMgr &SM, StringRef Buffer,
   for (unsigned ChunkNo = 0, e = NotStrings.size();
        ChunkNo != e; ++ChunkNo) {
     const Pattern *Pat = NotStrings[ChunkNo];
-    assert(Pat->getMatchNot() && "Expect CHECK-NOT!");
+    assert((Pat->getCheckTy() == Check::CheckNot) && "Expect CHECK-NOT!");
 
     size_t MatchLen = 0;
     size_t Pos = Pat->Match(Buffer, MatchLen, VariableTable);
@@ -941,9 +1102,9 @@ bool CheckString::CheckNot(const SourceMgr &SM, StringRef Buffer,
 
     SM.PrintMessage(SMLoc::getFromPointer(Buffer.data()+Pos),
                     SourceMgr::DK_Error,
-                    CheckPrefix+"-NOT: string occurred!");
+                    Prefix + "-NOT: string occurred!");
     SM.PrintMessage(Pat->getLoc(), SourceMgr::DK_Note,
-                    CheckPrefix+"-NOT: pattern specified here");
+                    Prefix + "-NOT: pattern specified here");
     return true;
   }
 
@@ -963,15 +1124,16 @@ size_t CheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
        ChunkNo != e; ++ChunkNo) {
     const Pattern &Pat = DagNotStrings[ChunkNo];
 
-    assert((Pat.getMatchDag() ^ Pat.getMatchNot()) &&
+    assert((Pat.getCheckTy() == Check::CheckDAG ||
+            Pat.getCheckTy() == Check::CheckNot) &&
            "Invalid CHECK-DAG or CHECK-NOT!");
 
-    if (Pat.getMatchNot()) {
+    if (Pat.getCheckTy() == Check::CheckNot) {
       NotStrings.push_back(&Pat);
       continue;
     }
 
-    assert(Pat.getMatchDag() && "Expect CHECK-DAG!");
+    assert((Pat.getCheckTy() == Check::CheckDAG) && "Expect CHECK-DAG!");
 
     size_t MatchLen = 0, MatchPos;
 
@@ -992,17 +1154,17 @@ size_t CheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
         // Reordered?
         SM.PrintMessage(SMLoc::getFromPointer(Buffer.data() + MatchPos),
                         SourceMgr::DK_Error,
-                        CheckPrefix+"-DAG: found a match of CHECK-DAG"
+                        Prefix + "-DAG: found a match of CHECK-DAG"
                         " reordering across a CHECK-NOT");
         SM.PrintMessage(SMLoc::getFromPointer(Buffer.data() + LastPos),
                         SourceMgr::DK_Note,
-                        CheckPrefix+"-DAG: the farthest match of CHECK-DAG"
+                        Prefix + "-DAG: the farthest match of CHECK-DAG"
                         " is found here");
         SM.PrintMessage(NotStrings[0]->getLoc(), SourceMgr::DK_Note,
-                        CheckPrefix+"-NOT: the crossed pattern specified"
+                        Prefix + "-NOT: the crossed pattern specified"
                         " here");
         SM.PrintMessage(Pat.getLoc(), SourceMgr::DK_Note,
-                        CheckPrefix+"-DAG: the reordered pattern specified"
+                        Prefix + "-DAG: the reordered pattern specified"
                         " here");
         return StringRef::npos;
       }
@@ -1026,11 +1188,50 @@ size_t CheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
   return LastPos;
 }
 
+// A check prefix must contain only alphanumeric, hyphens and underscores.
+static bool ValidateCheckPrefix(StringRef CheckPrefix) {
+  Regex Validator("^[a-zA-Z0-9_-]*$");
+  return Validator.match(CheckPrefix);
+}
+
+static bool ValidateCheckPrefixes() {
+  StringSet<> PrefixSet;
+
+  for (prefix_iterator I = CheckPrefixes.begin(), E = CheckPrefixes.end();
+       I != E; ++I) {
+    StringRef Prefix(*I);
+
+    if (!PrefixSet.insert(Prefix))
+      return false;
+
+    if (!ValidateCheckPrefix(Prefix))
+      return false;
+  }
+
+  return true;
+}
+
+// I don't think there's a way to specify an initial value for cl::list,
+// so if nothing was specified, add the default
+static void AddCheckPrefixIfNeeded() {
+  if (CheckPrefixes.empty())
+    CheckPrefixes.push_back("CHECK");
+}
+
 int main(int argc, char **argv) {
   sys::PrintStackTraceOnErrorSignal();
   PrettyStackTraceProgram X(argc, argv);
   cl::ParseCommandLineOptions(argc, argv);
 
+  if (!ValidateCheckPrefixes()) {
+    errs() << "Supplied check-prefix is invalid! Prefixes must be unique and "
+              "start with a letter and contain only alphanumeric characters, "
+              "hyphens and underscores\n";
+    return 2;
+  }
+
+  AddCheckPrefixIfNeeded();
+
   SourceMgr SM;
 
   // Read the expected strings from the check file.
@@ -1076,7 +1277,7 @@ int main(int argc, char **argv) {
       CheckRegion = Buffer;
     } else {
       const CheckString &CheckLabelStr = CheckStrings[j];
-      if (!CheckLabelStr.IsCheckLabel) {
+      if (CheckLabelStr.CheckTy != Check::CheckLabel) {
         ++j;
         continue;
       }