While thinking about the one-definition-rule and trying

to find a tiny mouse hole to squeeze through, it struck
me that globals without a name can be considered internal
since they can't be referenced from outside the current
module.  This patch makes GlobalOpt give them internal
linkage.  Also done for aliases even though they always
have names, since in my opinion anonymous aliases should
be allowed for consistency with global variables and
functions.  So if that happens one day, this code is ready!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66267 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 23 insertions, 3 deletions

diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 0a35fa9..b93eb6b 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -67,7 +67,7 @@ namespace {
     GlobalVariable *FindGlobalCtors(Module &M);
     bool OptimizeFunctions(Module &M);
     bool OptimizeGlobalVars(Module &M);
-    bool ResolveAliases(Module &M);
+    bool OptimizeGlobalAliases(Module &M);
     bool OptimizeGlobalCtorsList(GlobalVariable *&GCL);
     bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI);
   };
@@ -1808,6 +1808,9 @@ bool GlobalOpt::OptimizeFunctions(Module &M) {
   // Optimize functions.
   for (Module::iterator FI = M.begin(), E = M.end(); FI != E; ) {
     Function *F = FI++;
+    // Functions without names cannot be referenced outside this module.
+    if (!F->hasName() && !F->isDeclaration())
+      F->setLinkage(GlobalValue::InternalLinkage);
     F->removeDeadConstantUsers();
     if (F->use_empty() && (F->hasLocalLinkage() ||
                            F->hasLinkOnceLinkage())) {
@@ -1844,6 +1847,9 @@ bool GlobalOpt::OptimizeGlobalVars(Module &M) {
   for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
        GVI != E; ) {
     GlobalVariable *GV = GVI++;
+    // Global variables without names cannot be referenced outside this module.
+    if (!GV->hasName() && !GV->isDeclaration())
+      GV->setLinkage(GlobalValue::InternalLinkage);
     if (!GV->isConstant() && GV->hasLocalLinkage() &&
         GV->hasInitializer())
       Changed |= ProcessInternalGlobal(GV, GVI);
@@ -2371,12 +2377,15 @@ bool GlobalOpt::OptimizeGlobalCtorsList(GlobalVariable *&GCL) {
   return true;
 }
 
-bool GlobalOpt::ResolveAliases(Module &M) {
+bool GlobalOpt::OptimizeGlobalAliases(Module &M) {
   bool Changed = false;
 
   for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
        I != E;) {
     Module::alias_iterator J = I++;
+    // Aliases without names cannot be referenced outside this module.
+    if (!J->hasName() && !J->isDeclaration())
+      J->setLinkage(GlobalValue::InternalLinkage);
     // If the aliasee may change at link time, nothing can be done - bail out.
     if (J->mayBeOverridden())
       continue;
@@ -2447,7 +2456,7 @@ bool GlobalOpt::runOnModule(Module &M) {
     LocalChange |= OptimizeGlobalVars(M);
 
     // Resolve aliases, when possible.
-    LocalChange |= ResolveAliases(M);
+    LocalChange |= OptimizeGlobalAliases(M);
     Changed |= LocalChange;
   }
   
diff --git a/test/Transforms/GlobalOpt/2009-03-06-Anonymous.ll b/test/Transforms/GlobalOpt/2009-03-06-Anonymous.ll
new file mode 100644
index 0000000..ea13d29
--- /dev/null
+++ b/test/Transforms/GlobalOpt/2009-03-06-Anonymous.ll
@@ -0,0 +1,11 @@
+; RUN: llvm-as < %s | opt -globalopt | llvm-dis | grep internal | count 2
+
+global i32 0
+define i32* @1() {
+	ret i32* @0
+}
+define i32* @f() {
+entry:
+	call i32* @1()
+	ret i32* %0
+}