[IR] Add a boolean field in DILocation to know if a line must covered or not

Summary:
Some lines have a hit counter where they should not have one.
For example, in C++, some cleanup is adding at the end of a scope represented by a '}'.
So such a line has a hit counter where a user expects to not have one.
The goal of the patch is to add this information in DILocation which is used to get the covered lines in GCOVProfiling.cpp.
A following patch in clang will add this information when generating IR (https://reviews.llvm.org/D49916).

Reviewers: marco-c, davidxl, vsk, javed.absar, rnk

Reviewed By: rnk

Subscribers: eraman, xur, danielcdh, aprantl, rnk, dblaikie, #debug-info, vsk, llvm-commits, sylvestre.ledru

Tags: #debug-info

Differential Revision: https://reviews.llvm.org/D49915

llvm-svn: 342631

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/docs/SourceLevelDebugging.rst b/llvm/docs/SourceLevelDebugging.rst
index 24e70f82d52..4cccfb40bd4 100644
--- a/llvm/docs/SourceLevelDebugging.rst
+++ b/llvm/docs/SourceLevelDebugging.rst
@@ -429,8 +429,23 @@ instruction.  One can extract line number information encoded in LLVM IR using
     unsigned Line = Loc->getLine();
     StringRef File = Loc->getFilename();
     StringRef Dir = Loc->getDirectory();
+    bool ImplicitCode = Loc->isImplicitCode();
   }
 
+When the flag ImplicitCode is true then it means that the Instruction has been
+added by the front-end but doesn't correspond to source code written by the user. For example
+
+.. code-block:: c++
+
+  if (MyBoolean) {
+    MyObject MO;
+    ...
+  }
+
+At the end of the scope the MyObject's destructor is called but it isn't written
+explicitly. This information is useful to avoid to have counters on brackets when
+making code coverage.
+
 C/C++ global variable information
 ---------------------------------