llvm-cov: Added file checksum to gcno and gcda files.

Instead of permanently outputting "MVLL" as the file checksum, clang
will create gcno and gcda checksums by hashing the destination block
numbers of every arc. This allows for llvm-cov to check if the two gcov
files are synchronized.

Regenerated the test files so they contain the checksum. Also added
negative test to ensure error when the checksums don't match.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195191 91177308-0d34-0410-b5e6-96231b3b80d8

9 files changed, 101 insertions, 49 deletions

diff --git a/include/llvm/Support/GCOV.h b/include/llvm/Support/GCOV.h
index 0fbe86c3c5..7ba4acb1ae 100644
--- a/include/llvm/Support/GCOV.h
+++ b/include/llvm/Support/GCOV.h
@@ -45,15 +45,15 @@ public:
   
   /// readGCOVFormat - Read GCOV signature at the beginning of buffer.
   GCOV::GCOVFormat readGCOVFormat() {
-    StringRef Magic = Buffer->getBuffer().slice(0, 12);
-    Cursor = 12;
-    if (Magic == "oncg*404MVLL")
+    StringRef Magic = Buffer->getBuffer().slice(0, 8);
+    Cursor = 8;
+    if (Magic == "oncg*404")
       return GCOV::GCNO_404;
-    else if (Magic == "oncg*204MVLL")
+    else if (Magic == "oncg*204")
       return GCOV::GCNO_402;
-    else if (Magic == "adcg*404MVLL")
+    else if (Magic == "adcg*404")
       return GCOV::GCDA_404;
-    else if (Magic == "adcg*204MVLL")
+    else if (Magic == "adcg*204")
       return GCOV::GCDA_402;
     
     Cursor = 0;
@@ -193,12 +193,13 @@ private:
 /// (.gcno and .gcda).
 class GCOVFile {
 public:
-  GCOVFile() : Functions(), RunCount(0), ProgramCount(0) {}
+  GCOVFile() : Checksum(0), Functions(), RunCount(0), ProgramCount(0) {}
   ~GCOVFile();
   bool read(GCOVBuffer &Buffer);
   void dump() const;
   void collectLineCounts(FileInfo &FI);
 private:
+  uint32_t Checksum;
   SmallVector<GCOVFunction *, 16> Functions;
   uint32_t RunCount;
   uint32_t ProgramCount;
diff --git a/lib/IR/GCOV.cpp b/lib/IR/GCOV.cpp
index 25a4ff669d..622c4f7851 100644
--- a/lib/IR/GCOV.cpp
+++ b/lib/IR/GCOV.cpp
@@ -46,6 +46,7 @@ bool GCOVFile::read(GCOVBuffer &Buffer) {
     return false;
 
   if (isGCNOFile(Format)) {
+    if (!Buffer.readInt(Checksum)) return false;
     while (true) {
       if (!Buffer.readFunctionTag()) break;
       GCOVFunction *GFun = new GCOVFunction();
@@ -55,6 +56,12 @@ bool GCOVFile::read(GCOVBuffer &Buffer) {
     }
   }
   else if (isGCDAFile(Format)) {
+    uint32_t Checksum2;
+    if (!Buffer.readInt(Checksum2)) return false;
+    if (Checksum != Checksum2) {
+      errs() << "File checksum does not match.\n";
+      return false;
+    }
     for (size_t i = 0, e = Functions.size(); i < e; ++i) {
       if (!Buffer.readFunctionTag()) {
         errs() << "Unexpected number of functions.\n";
diff --git a/lib/Transforms/Instrumentation/GCOVProfiling.cpp b/lib/Transforms/Instrumentation/GCOVProfiling.cpp
index 206bffbb27..03c63557bc 100644
--- a/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+++ b/lib/Transforms/Instrumentation/GCOVProfiling.cpp
@@ -18,6 +18,7 @@
 
 #include "llvm/Transforms/Instrumentation.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringExtras.h"
@@ -62,20 +63,28 @@ GCOVOptions GCOVOptions::getDefault() {
 }
 
 namespace {
+  class GCOVFunction;
+
   class GCOVProfiler : public ModulePass {
   public:
     static char ID;
     GCOVProfiler() : ModulePass(ID), Options(GCOVOptions::getDefault()) {
-      ReversedVersion[0] = Options.Version[3];
-      ReversedVersion[1] = Options.Version[2];
-      ReversedVersion[2] = Options.Version[1];
-      ReversedVersion[3] = Options.Version[0];
-      ReversedVersion[4] = '\0';
-      initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
+      init();
     }
     GCOVProfiler(const GCOVOptions &Options) : ModulePass(ID), Options(Options){
       assert((Options.EmitNotes || Options.EmitData) &&
              "GCOVProfiler asked to do nothing?");
+      init();
+    }
+    ~GCOVProfiler() {
+      DeleteContainerPointers(Funcs);
+    }
+    virtual const char *getPassName() const {
+      return "GCOV Profiler";
+    }
+
+  private:
+    void init() {
       ReversedVersion[0] = Options.Version[3];
       ReversedVersion[1] = Options.Version[2];
       ReversedVersion[2] = Options.Version[1];
@@ -83,11 +92,6 @@ namespace {
       ReversedVersion[4] = '\0';
       initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
     }
-    virtual const char *getPassName() const {
-      return "GCOV Profiler";
-    }
-
-  private:
     bool runOnModule(Module &M);
 
     // Create the .gcno files for the Module based on DebugInfo.
@@ -131,9 +135,12 @@ namespace {
 
     // Reversed, NUL-terminated copy of Options.Version.
     char ReversedVersion[5];  
+    // Checksum, produced by hash of EdgeDestinations
+    uint32_t FileChecksum;
 
     Module *M;
     LLVMContext *Ctx;
+    SmallVector<GCOVFunction *, 16> Funcs;
   };
 }
 
@@ -145,7 +152,7 @@ ModulePass *llvm::createGCOVProfilerPass(const GCOVOptions &Options) {
   return new GCOVProfiler(Options);
 }
 
-static std::string getFunctionName(DISubprogram SP) {
+static StringRef getFunctionName(DISubprogram SP) {
   if (!SP.getLinkageName().empty())
     return SP.getLinkageName();
   return SP.getName();
@@ -302,7 +309,8 @@ namespace {
   class GCOVFunction : public GCOVRecord {
    public:
     GCOVFunction(DISubprogram SP, raw_ostream *os, uint32_t Ident,
-                 bool UseCfgChecksum) {
+                 bool UseCfgChecksum) :
+        SP(SP), Ident(Ident), UseCfgChecksum(UseCfgChecksum), CfgChecksum(0) {
       this->os = os;
 
       Function *F = SP.getFunction();
@@ -312,20 +320,6 @@ namespace {
         Blocks[BB] = new GCOVBlock(i++, os);
       }
       ReturnBlock = new GCOVBlock(i++, os);
-
-      writeBytes(FunctionTag, 4);
-      uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(getFunctionName(SP)) +
-          1 + lengthOfGCOVString(SP.getFilename()) + 1;
-      if (UseCfgChecksum)
-        ++BlockLen;
-      write(BlockLen);
-      write(Ident);
-      write(0);  // lineno checksum
-      if (UseCfgChecksum)
-        write(0);  // cfg checksum
-      writeGCOVString(getFunctionName(SP));
-      writeGCOVString(SP.getFilename());
-      write(SP.getLineNumber());
     }
 
     ~GCOVFunction() {
@@ -341,7 +335,37 @@ namespace {
       return *ReturnBlock;
     }
 
+    std::string getEdgeDestinations() {
+      std::string EdgeDestinations;
+      raw_string_ostream EDOS(EdgeDestinations);
+      Function *F = Blocks.begin()->first->getParent();
+      for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
+        GCOVBlock &Block = *Blocks[I];
+        for (int i = 0, e = Block.OutEdges.size(); i != e; ++i)
+          EDOS << Block.OutEdges[i]->Number;
+      }
+      return EdgeDestinations;
+    }
+
+    void setCfgChecksum(uint32_t Checksum) {
+      CfgChecksum = Checksum;
+    }
+
     void writeOut() {
+      writeBytes(FunctionTag, 4);
+      uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(getFunctionName(SP)) +
+          1 + lengthOfGCOVString(SP.getFilename()) + 1;
+      if (UseCfgChecksum)
+        ++BlockLen;
+      write(BlockLen);
+      write(Ident);
+      write(0);  // lineno checksum
+      if (UseCfgChecksum)
+        write(CfgChecksum);
+      writeGCOVString(getFunctionName(SP));
+      writeGCOVString(SP.getFilename());
+      write(SP.getLineNumber());
+
       // Emit count of blocks.
       writeBytes(BlockTag, 4);
       write(Blocks.size() + 1);
@@ -375,6 +399,10 @@ namespace {
     }
 
    private:
+    DISubprogram SP;
+    uint32_t Ident;
+    bool UseCfgChecksum;
+    uint32_t CfgChecksum;
     DenseMap<BasicBlock *, GCOVBlock *> Blocks;
     GCOVBlock *ReturnBlock;
   };
@@ -427,9 +455,7 @@ void GCOVProfiler::emitProfileNotes() {
     std::string ErrorInfo;
     raw_fd_ostream out(mangleName(CU, "gcno").c_str(), ErrorInfo,
                        sys::fs::F_Binary);
-    out.write("oncg", 4);
-    out.write(ReversedVersion, 4);
-    out.write("MVLL", 4);
+    std::string EdgeDestinations;
 
     DIArray SPs = CU.getSubprograms();
     for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
@@ -441,17 +467,19 @@ void GCOVProfiler::emitProfileNotes() {
 
       Function *F = SP.getFunction();
       if (!F) continue;
-      GCOVFunction Func(SP, &out, i, Options.UseCfgChecksum);
+      GCOVFunction *Func =
+        new GCOVFunction(SP, &out, i, Options.UseCfgChecksum);
+      Funcs.push_back(Func);
 
       for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
-        GCOVBlock &Block = Func.getBlock(BB);
+        GCOVBlock &Block = Func->getBlock(BB);
         TerminatorInst *TI = BB->getTerminator();
         if (int successors = TI->getNumSuccessors()) {
           for (int i = 0; i != successors; ++i) {
-            Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
+            Block.addEdge(Func->getBlock(TI->getSuccessor(i)));
           }
         } else if (isa<ReturnInst>(TI)) {
-          Block.addEdge(Func.getReturnBlock());
+          Block.addEdge(Func->getReturnBlock());
         }
 
         uint32_t Line = 0;
@@ -467,8 +495,18 @@ void GCOVProfiler::emitProfileNotes() {
           Lines.addLine(Loc.getLine());
         }
       }
-      Func.writeOut();
+      EdgeDestinations += Func->getEdgeDestinations();
     }
+
+    FileChecksum = hash_value(EdgeDestinations);
+    out.write("oncg", 4);
+    out.write(ReversedVersion, 4);
+    out.write(reinterpret_cast<char*>(&FileChecksum), 4);
+
+    for (SmallVectorImpl<GCOVFunction *>::iterator I = Funcs.begin(),
+           E = Funcs.end(); I != E; ++I)
+      (*I)->writeOut();
+
     out.write("\0\0\0\0\0\0\0\0", 8);  // EOF
     out.close();
   }
@@ -666,6 +704,7 @@ Constant *GCOVProfiler::getStartFileFunc() {
   Type *Args[] = {
     Type::getInt8PtrTy(*Ctx),  // const char *orig_filename
     Type::getInt8PtrTy(*Ctx),  // const char version[4]
+    Type::getInt32Ty(*Ctx),    // uint32_t checksum
   };
   FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
   return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
@@ -683,10 +722,11 @@ Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
 }
 
 Constant *GCOVProfiler::getEmitFunctionFunc() {
-  Type *Args[3] = {
+  Type *Args[] = {
     Type::getInt32Ty(*Ctx),    // uint32_t ident
     Type::getInt8PtrTy(*Ctx),  // const char *function_name
     Type::getInt8Ty(*Ctx),     // uint8_t use_extra_checksum
+    Type::getInt32Ty(*Ctx),    // uint32_t cfg_checksum
   };
   FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
   return M->getOrInsertFunction("llvm_gcda_emit_function", FTy);
@@ -760,17 +800,19 @@ Function *GCOVProfiler::insertCounterWriteout(
     for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
       DICompileUnit CU(CU_Nodes->getOperand(i));
       std::string FilenameGcda = mangleName(CU, "gcda");
-      Builder.CreateCall2(StartFile,
+      Builder.CreateCall3(StartFile,
                           Builder.CreateGlobalStringPtr(FilenameGcda),
-                          Builder.CreateGlobalStringPtr(ReversedVersion));
+                          Builder.CreateGlobalStringPtr(ReversedVersion),
+                          Builder.getInt32(FileChecksum));
       for (unsigned j = 0, e = CountersBySP.size(); j != e; ++j) {
         DISubprogram SP(CountersBySP[j].second);
-        Builder.CreateCall3(
+        Builder.CreateCall4(
             EmitFunction, Builder.getInt32(j),
             Options.FunctionNamesInData ?
               Builder.CreateGlobalStringPtr(getFunctionName(SP)) :
               Constant::getNullValue(Builder.getInt8PtrTy()),
-            Builder.getInt8(Options.UseCfgChecksum));
+            Builder.getInt8(Options.UseCfgChecksum),
+            Builder.getInt32(FileChecksum));
 
         GlobalVariable *GV = CountersBySP[j].first;
         unsigned Arcs =
diff --git a/test/Transforms/GCOVProfiling/version.ll b/test/Transforms/GCOVProfiling/version.ll
index 15bcb052ac..409954c0d9 100644
--- a/test/Transforms/GCOVProfiling/version.ll
+++ b/test/Transforms/GCOVProfiling/version.ll
@@ -1,11 +1,11 @@
 ; RUN: echo '!9 = metadata !{metadata !"%T/version.ll", metadata !0}' > %t1
 ; RUN: cat %s %t1 > %t2
 ; RUN: opt -insert-gcov-profiling -disable-output < %t2
-; RUN: head -c12 %T/version.gcno | grep '^oncg\*204MVLL$'
+; RUN: head -c8 %T/version.gcno | grep '^oncg\*204'
 ; RUN: rm %T/version.gcno
 ; RUN: not opt -insert-gcov-profiling -default-gcov-version=asdfasdf -disable-output < %t2
 ; RUN: opt -insert-gcov-profiling -default-gcov-version=407* -disable-output < %t2
-; RUN: head -c12 %T/version.gcno | grep '^oncg\*704MVLL$'
+; RUN: head -c8 %T/version.gcno | grep '^oncg\*704'
 ; RUN: rm %T/version.gcno
 
 define void @test() {
diff --git a/test/tools/llvm-cov/Inputs/test.gcda b/test/tools/llvm-cov/Inputs/test.gcda
index 23d03bdd1f..a62c069c9a 100644
--- a/test/tools/llvm-cov/Inputs/test.gcda
+++ b/test/tools/llvm-cov/Inputs/test.gcda
diff --git a/test/tools/llvm-cov/Inputs/test.gcno b/test/tools/llvm-cov/Inputs/test.gcno
index 6162604e74..218398548e 100644
--- a/test/tools/llvm-cov/Inputs/test.gcno
+++ b/test/tools/llvm-cov/Inputs/test.gcno
diff --git a/test/tools/llvm-cov/Inputs/test_checksum_mismatch.gcda b/test/tools/llvm-cov/Inputs/test_checksum_mismatch.gcda
new file mode 100644
index 0000000000..2fcf33dd21
--- /dev/null
+++ b/test/tools/llvm-cov/Inputs/test_checksum_mismatch.gcda
diff --git a/test/tools/llvm-cov/Inputs/test_read_fail.gcno b/test/tools/llvm-cov/Inputs/test_read_fail.gcno
index 63b5d71e69..bcc20a65ee 100644
--- a/test/tools/llvm-cov/Inputs/test_read_fail.gcno
+++ b/test/tools/llvm-cov/Inputs/test_read_fail.gcno
diff --git a/test/tools/llvm-cov/llvm-cov.test b/test/tools/llvm-cov/llvm-cov.test
index 28738a78d1..d95af9b40f 100644
--- a/test/tools/llvm-cov/llvm-cov.test
+++ b/test/tools/llvm-cov/llvm-cov.test
@@ -7,4 +7,6 @@ RUN:   | diff -aub test.cpp.gcov -
 
 RUN: not llvm-cov -gcno=test_read_fail.gcno -gcda=test.gcda
 
+RUN: not llvm-cov -gcno=test.gcno -gcda=test_checksum_mismatch.gcda
+
 XFAIL: powerpc64, s390x