Include translation unit filename in global ctor symbol names.

This makes it easier to see where a global ctor comes from, and it also makes
ASan's init order analyzer output easier to understand.  gcc does this too,
but only in -fPIC mode for some reason.  Don't do this for constructors with
explicit init priority.

Also prepend "sub_" before the 'I', that way regular constructors stay
lexicographically after symbols with init priority (because
ord('s') > ord('I')).  gold seems to ignore the name of constructor symbols,
and ld only looks at the symbol if it includes an init priority, which this
patch doesn't change.

Before: __GLOBAL_I_a
Now: __GLOBAL_sub_I_myfile.cc
llvm-svn: 208128

1 files changed, 16 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGDeclCXX.cpp b/clang/lib/CodeGen/CGDeclCXX.cpp
index 5f8e8747ab9..59129f6aeea 100644
--- a/clang/lib/CodeGen/CGDeclCXX.cpp
+++ b/clang/lib/CodeGen/CGDeclCXX.cpp
@@ -17,6 +17,7 @@
 #include "clang/Frontend/CodeGenOptions.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/IR/Intrinsics.h"
+#include "llvm/Support/Path.h"
 
 using namespace clang;
 using namespace CodeGen;
@@ -362,7 +363,7 @@ CodeGenModule::EmitCXXGlobalInitFunc() {
       // Compute the function suffix from priority. Prepend with zeroes to make
       // sure the function names are also ordered as priorities.
       std::string PrioritySuffix = llvm::utostr(Priority);
-      // Priority is always <= 65535 (enforced by sema)..
+      // Priority is always <= 65535 (enforced by sema).
       PrioritySuffix = std::string(6-PrioritySuffix.size(), '0')+PrioritySuffix;
       llvm::Function *Fn = 
         CreateGlobalInitOrDestructFunction(*this, FTy,
@@ -376,8 +377,20 @@ CodeGenModule::EmitCXXGlobalInitFunc() {
     }
   }
   
-  llvm::Function *Fn = 
-    CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__I_a");
+  // Include the filename in the symbol name. Including "sub_" matches gcc and
+  // makes sure these symbols appear lexicographically behind the symbols with
+  // priority emitted above.
+  SourceManager &SM = Context.getSourceManager();
+  SmallString<128> FileName(llvm::sys::path::filename(
+      SM.getFileEntryForID(SM.getMainFileID())->getName()));
+  for (size_t i = 0; i < FileName.size(); ++i) {
+    // Replace everything that's not [a-zA-Z0-9._] with a _. This set happens
+    // to be the set of C preprocessing numbers.
+    if (!isPreprocessingNumberBody(FileName[i]))
+      FileName[i] = '_';
+  }
+  llvm::Function *Fn = CreateGlobalInitOrDestructFunction(
+      *this, FTy, llvm::Twine("_GLOBAL__sub_I_", FileName));
 
   CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, CXXGlobalInits);
   AddGlobalCtor(Fn);