[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

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -3516,6 +3516,7 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
 
       unsigned Line = Record[0], Col = Record[1];
       unsigned ScopeID = Record[2], IAID = Record[3];
+      bool isImplicitCode = Record.size() == 5 && Record[4];
 
       MDNode *Scope = nullptr, *IA = nullptr;
       if (ScopeID) {
@@ -3528,7 +3529,7 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
         if (!IA)
           return error("Invalid record");
       }
-      LastLoc = DebugLoc::get(Line, Col, Scope, IA);
+      LastLoc = DebugLoc::get(Line, Col, Scope, IA, isImplicitCode);
       I->setDebugLoc(LastLoc);
       I = nullptr;
       continue;