[gcov] Display the hit counter for the line of a function definition

[calixte]

Summary

Right now there is no hit counter on the line of function.
So the idea is add the line of the function to all the lines covered by the entry block.
Tests in compiler-rt/profile will be fixed in another patch: https://reviews.llvm.org/D49854

[marco-c]

I hope this won't have any side effects we are not expecting. The updated tests in compiler-rt all look good, so I'm reasonably confident.

lib/Transforms/Instrumentation/GCOVProfiling.cpp

588 ↗

(On Diff #157480)

Nit: you might try to use EntryBlock, if it still usable after the split. Not so important though.

The formatting seems to be off.

[calixte]

Fix formatting.

[calixte]

lib/Transforms/Instrumentation/GCOVProfiling.cpp

588 ↗

(On Diff #157480)

It seems that EntryBlock::splitBasicBlock (http://llvm.org/doxygen/BasicBlock_8cpp_source.html#l00401) is creating a new BasicBlock so we must get it from F.

[calixte]

lib/Transforms/Instrumentation/GCOVProfiling.cpp

588 ↗

(On Diff #157480)

In fact the entry block is not changed by splitBasicBlock.

[calixte]

Don't get EntryBlock again

llvm/trunk/lib/Transforms/Instrumentation/GCOVProfiling.cpp

for (auto &F : M->functions()) {
         ++It;
       EntryBlock.splitBasicBlock(It);
 
       Funcs.push_back(make_unique<GCOVFunction>(SP, &F, &out, FunctionIdent++,
                                                 Options.UseCfgChecksum,
                                                 Options.ExitBlockBeforeBody));
       GCOVFunction &Func = *Funcs.back();
 
+      // Add the function line number to the lines of the entry block
+      // to have a counter for the function definition.
+      Func.getBlock(&EntryBlock)
+          .getFile(SP->getFilename())
+          .addLine(SP->getLine());
+
       for (auto &BB : F) {
         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)));
           }
         } else if (isa<ReturnInst>(TI)) {