From 939993ff2fe38eca498b0806b22a35412222a0eb Mon Sep 17 00:00:00 2001
From: Dehao Chen <dehao@google.com>
Date: Mon, 29 Feb 2016 18:59:48 +0000
Subject: [PATCH] Move discriminator assignment to the right place.

Summary: Now discriminator is assigned per-function instead of per-module.

Reviewers: davidxl, dnovillo

Subscribers: dblaikie, llvm-commits

Differential Revision: http://reviews.llvm.org/D17664

llvm-svn: 262240
---
 llvm/include/llvm/IR/DebugInfoMetadata.h        |  9 ---------
 llvm/lib/IR/DebugInfoMetadata.cpp               | 17 -----------------
 llvm/lib/Transforms/Utils/AddDiscriminators.cpp | 11 +++++++----
 3 files changed, 7 insertions(+), 30 deletions(-)

diff --git a/llvm/include/llvm/IR/DebugInfoMetadata.h b/llvm/include/llvm/IR/DebugInfoMetadata.h
index 456313a70e83..2c031a5aeba2 100644
--- a/llvm/include/llvm/IR/DebugInfoMetadata.h
+++ b/llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -1192,15 +1192,6 @@ public:
   /// instructions that are on different basic blocks.
   inline unsigned getDiscriminator() const;
 
-  /// \brief Compute new discriminator in the given context.
-  ///
-  /// This modifies the \a LLVMContext that \c this is in to increment the next
-  /// discriminator for \c this's line/filename combination.
-  ///
-  /// FIXME: Delete this.  See comments in implementation and at the only call
-  /// site in \a AddDiscriminators::runOnFunction().
-  unsigned computeNewDiscriminator() const;
-
   Metadata *getRawScope() const { return getOperand(0); }
   Metadata *getRawInlinedAt() const {
     if (getNumOperands() == 2)
diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index 58e0abdd577c..3dca84d9e5c8 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -66,23 +66,6 @@ DILocation *DILocation::getImpl(LLVMContext &Context, unsigned Line,
                    Storage, Context.pImpl->DILocations);
 }
 
-unsigned DILocation::computeNewDiscriminator() const {
-  // FIXME: This seems completely wrong.
-  //
-  //  1. If two modules are generated in the same context, then the second
-  //     Module will get different discriminators than it would have if it were
-  //     generated in its own context.
-  //  2. If this function is called after round-tripping to bitcode instead of
-  //     before, it will give a different (and potentially incorrect!) return.
-  //
-  // The discriminator should instead be calculated from local information
-  // where it's actually needed.  This logic should be moved to
-  // AddDiscriminators::runOnFunction(), where it doesn't pollute the
-  // LLVMContext.
-  std::pair<const char *, unsigned> Key(getFilename().data(), getLine());
-  return ++getContext().pImpl->DiscriminatorTable[Key];
-}
-
 unsigned DINode::getFlag(StringRef Flag) {
   return StringSwitch<unsigned>(Flag)
 #define HANDLE_DI_FLAG(ID, NAME) .Case("DIFlag" #NAME, Flag##NAME)
diff --git a/llvm/lib/Transforms/Utils/AddDiscriminators.cpp b/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
index 3e585c623dd5..e0f58606d63f 100644
--- a/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
+++ b/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
@@ -173,8 +173,10 @@ bool AddDiscriminators::runOnFunction(Function &F) {
   typedef std::pair<StringRef, unsigned> Location;
   typedef DenseMap<const BasicBlock *, Metadata *> BBScopeMap;
   typedef DenseMap<Location, BBScopeMap> LocationBBMap;
+  typedef DenseMap<Location, unsigned> LocationDiscriminatorMap;
 
   LocationBBMap LBM;
+  LocationDiscriminatorMap LDM;
 
   // Traverse all instructions in the function. If the source line location
   // of the instruction appears in other basic block, assign a new
@@ -199,8 +201,7 @@ bool AddDiscriminators::runOnFunction(Function &F) {
         auto *Scope = DIL->getScope();
         auto *File =
             Builder.createFile(DIL->getFilename(), Scope->getDirectory());
-        NewScope = Builder.createLexicalBlockFile(
-            Scope, File, DIL->computeNewDiscriminator());
+        NewScope = Builder.createLexicalBlockFile(Scope, File, ++LDM[L]);
       }
       I.setDebugLoc(DILocation::get(Ctx, DIL->getLine(), DIL->getColumn(),
                                     NewScope, DIL->getInlinedAt()));
@@ -230,8 +231,10 @@ bool AddDiscriminators::runOnFunction(Function &F) {
           auto *Scope = FirstDIL->getScope();
           auto *File = Builder.createFile(FirstDIL->getFilename(),
                                           Scope->getDirectory());
-          auto *NewScope = Builder.createLexicalBlockFile(
-              Scope, File, FirstDIL->computeNewDiscriminator());
+          Location L =
+              std::make_pair(FirstDIL->getFilename(), FirstDIL->getLine());
+          auto *NewScope =
+              Builder.createLexicalBlockFile(Scope, File, ++LDM[L]);
           Current->setDebugLoc(DILocation::get(
               Ctx, CurrentDIL->getLine(), CurrentDIL->getColumn(), NewScope,
               CurrentDIL->getInlinedAt()));