add-discriminators: Fix handling of lexical scopes.

This fixes a bug in the handling of lexical scopes, when more than one
scope is defined on the same line or functions are inlined into call
sites that are on the same line as the function definition. This
situation can easily happen in macro expansions.

The problem is solved by introducing a SmallDenseMap<DIScope *,
DILexicalBlockFile *, 1> that keeps track of all the different lexical
scopes that share a line/file location.

Fixes PR30681.

llvm-svn: 284998

1 files changed, 13 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/Utils/AddDiscriminators.cpp b/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
index 45b4fab07ed..a9b5d7206b7 100644
--- a/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
+++ b/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
@@ -168,7 +168,8 @@ static bool addDiscriminators(Function &F) {
   DIBuilder Builder(*M, /*AllowUnresolved*/ false);
 
   typedef std::pair<StringRef, unsigned> Location;
-  typedef DenseMap<const BasicBlock *, Metadata *> BBScopeMap;
+  typedef SmallDenseMap<DIScope *, DILexicalBlockFile *, 1> ScopeMap;
+  typedef DenseMap<const BasicBlock *, ScopeMap> BBScopeMap;
   typedef DenseMap<Location, BBScopeMap> LocationBBMap;
   typedef DenseMap<Location, unsigned> LocationDiscriminatorMap;
   typedef DenseSet<Location> LocationSet;
@@ -186,20 +187,23 @@ static bool addDiscriminators(Function &F) {
       const DILocation *DIL = I.getDebugLoc();
       if (!DIL)
         continue;
+      DIScope *Scope = DIL->getScope();
       Location L = std::make_pair(DIL->getFilename(), DIL->getLine());
       auto &BBMap = LBM[L];
-      auto R = BBMap.insert(std::make_pair(&B, (Metadata *)nullptr));
+      auto R = BBMap.insert({&B, ScopeMap()});
       if (BBMap.size() == 1)
         continue;
       bool InsertSuccess = R.second;
-      Metadata *&NewScope = R.first->second;
-      // If we could insert a different block in the same location, a
+      ScopeMap &Scopes = R.first->second; 
+      // If we could insert more than one block with the same line+file, a
       // discriminator is needed to distinguish both instructions.
-      if (InsertSuccess) {
-        auto *Scope = DIL->getScope();
-        auto *File =
-            Builder.createFile(DIL->getFilename(), Scope->getDirectory());
-        NewScope = Builder.createLexicalBlockFile(Scope, File, ++LDM[L]);
+      auto R1 = Scopes.insert({Scope, nullptr});
+      DILexicalBlockFile *&NewScope = R1.first->second;
+      unsigned Discriminator = InsertSuccess ? ++LDM[L] : LDM[L];
+      if (!NewScope) {
+        auto *File = Builder.createFile(DIL->getFilename(),
+                                        Scope->getDirectory());
+        NewScope = Builder.createLexicalBlockFile(Scope, File, Discriminator);
       }
       I.setDebugLoc(DILocation::get(Ctx, DIL->getLine(), DIL->getColumn(),
                                     NewScope, DIL->getInlinedAt()));