From 30c2d8e3a6505ed6699216833441eccaeedf02ad Mon Sep 17 00:00:00 2001
From: Yang Chen <chenyang@cs.utah.edu>
Date: Sat, 14 Jan 2017 02:08:05 -0800
Subject: [PATCH] Fixed a crash due to overwriting the same location

In some cases (most likely for ill-declared templates),
we may rewrite the same location multiple times, and
hence trigger an ICE. This is now fixed.

Upstream-Commit: https://github.com/csmith-project/creduce/commit/30c2d8e3a6505ed6699216833441eccaeedf02ad
---
 clang_delta/RemoveUnusedFunction.cpp | 23 ++++++++++++++++++++++-
 clang_delta/RemoveUnusedFunction.h   |  7 ++++++-
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/clang_delta/RemoveUnusedFunction.cpp b/clang_delta/RemoveUnusedFunction.cpp
index f9be26f..b38fe51 100644
--- a/clang_delta/RemoveUnusedFunction.cpp
+++ b/clang_delta/RemoveUnusedFunction.cpp
@@ -388,6 +388,8 @@ SourceLocation RemoveUnusedFunction::getFunctionOuterLocStart(
                  const FunctionDecl *FD)
 {
   SourceLocation LocStart = FD->getLocStart();
+  bool RecordLoc = false;
+
   // check if FD is from a function template
   if (FunctionTemplateDecl *FTD = FD->getDescribedFunctionTemplate()) {
     // get FTD->getLocStart() only if it is less than FD->getLocStart,
@@ -396,8 +398,10 @@ SourceLocation RemoveUnusedFunction::getFunctionOuterLocStart(
     //   template<typename T> template<typename T1> void S<T>::foo() { }
     // where
     //   FTD->getLocStart() points to the begining of "template<typename T1>"
-    if (hasValidOuterLocStart(FTD, FD))
+    if (hasValidOuterLocStart(FTD, FD)) {
       LocStart = FTD->getLocStart();
+      RecordLoc = true;
+    }
   }
 
   if (LocStart.isMacroID())
@@ -406,6 +410,17 @@ SourceLocation RemoveUnusedFunction::getFunctionOuterLocStart(
   // this is ugly, but how do we get the location of __extension__? e.g.:
   // __extension__ void foo();
   LocStart = getExtensionLocStart(LocStart);
+
+  // In some cases where the given input is not well-formed, we may
+  // end up with duplicate locations for the FunctionTemplateDecl
+  // case. In such cases, we simply return an invalid SourceLocation,
+  // which will ben skipped by the caller of getFunctionOuterLocStart.
+  if (RecordLoc) {
+    if (VisitedLocations.count(LocStart))
+      return SourceLocation();
+    VisitedLocations.insert(LocStart);
+  }
+
   return LocStart;
 }
 
@@ -468,6 +483,8 @@ void RemoveUnusedFunction::removeOneFunctionDecl(const FunctionDecl *FD)
     LocEnd = SrcManager->getExpansionLoc(LocEnd);
   if (!FD->isInExternCContext() && !FD->isInExternCXXContext()) {
     SourceLocation FuncLocStart = getFunctionOuterLocStart(FD);
+    if (FuncLocStart.isInvalid())
+      return;
     LocEnd = getFunctionLocEnd(FuncLocStart, LocEnd, FD);
     if (SrcManager->isWrittenInMainFile(FuncLocStart) &&
         SrcManager->isWrittenInMainFile(LocEnd))
@@ -479,6 +496,8 @@ void RemoveUnusedFunction::removeOneFunctionDecl(const FunctionDecl *FD)
   const LinkageSpecDecl *Linkage = dyn_cast<LinkageSpecDecl>(Ctx);
   if (!Linkage) {
     SourceLocation FuncLocStart = getFunctionOuterLocStart(FD);
+    if (FuncLocStart.isInvalid())
+      return;
     LocEnd = getFunctionLocEnd(FuncLocStart, LocEnd, FD);
     TheRewriter.RemoveText(SourceRange(FuncLocStart, LocEnd));
     return;
@@ -488,6 +507,8 @@ void RemoveUnusedFunction::removeOneFunctionDecl(const FunctionDecl *FD)
   // namespace { using ::foo; }
   if (Linkage->hasBraces()) {
     SourceLocation FuncLocStart = getFunctionOuterLocStart(FD);
+    if (FuncLocStart.isInvalid())
+      return;
     TheRewriter.RemoveText(SourceRange(FuncLocStart, LocEnd));
     return;
   }
diff --git a/clang_delta/RemoveUnusedFunction.h b/clang_delta/RemoveUnusedFunction.h
index d724aeb..ded12d7 100644
--- a/clang_delta/RemoveUnusedFunction.h
+++ b/clang_delta/RemoveUnusedFunction.h
@@ -14,8 +14,9 @@
 #include <string>
 #include <map>
 #include <set>
-#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallSet.h"
 #include "Transformation.h"
 #include "clang/Basic/SourceLocation.h"
 
@@ -98,6 +99,8 @@ friend class ExtraReferenceVisitorWrapper;
 
   typedef std::set<std::string> SystemFunctionsSet;
 
+  typedef llvm::SmallSet<clang::SourceLocation, 5> LocSet;
+
   virtual void Initialize(clang::ASTContext &context);
 
   virtual void HandleTranslationUnit(clang::ASTContext &Ctx);
@@ -188,6 +191,8 @@ friend class ExtraReferenceVisitorWrapper;
 
   SystemFunctionsSet ExistingSystemFunctions;
 
+  LocSet VisitedLocations;
+
   FunctionDeclVector AllValidFunctionDecls;
 
   RUFAnalysisVisitor *AnalysisVisitor;