implement a new magic global "llvm.compiler.used" which is like llvm.used, but

doesn't cause ".no_dead_strip" to be emitted on darwin.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76399 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 23 insertions, 25 deletions

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index a2d154f1ee..80bdf04e8e 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -466,13 +466,13 @@ void AsmPrinter::printPICJumpTableEntry(const MachineJumpTableInfo *MJTI,
 /// special global used by LLVM.  If so, emit it and return true, otherwise
 /// do nothing and return false.
 bool AsmPrinter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
-  if (GV->getName() == "llvm.used") {
+  if (GV->isName("llvm.used")) {
     if (TAI->getUsedDirective() != 0)    // No need to emit this at all.
       EmitLLVMUsedList(GV->getInitializer());
     return true;
   }
 
-  // Ignore debug and non-emitted data.
+  // Ignore debug and non-emitted data.  This handles llvm.compiler.used.
   if (GV->getSection() == "llvm.metadata" ||
       GV->hasAvailableExternallyLinkage())
     return true;
diff --git a/lib/CodeGen/AsmPrinter/DwarfException.cpp b/lib/CodeGen/AsmPrinter/DwarfException.cpp
index 1af3b11846..fdec97ac6a 100644
--- a/lib/CodeGen/AsmPrinter/DwarfException.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfException.cpp
@@ -229,7 +229,7 @@ void DwarfException::EmitEHFrame(const FunctionEHFrameInfo &EHFrameInfo) {
     // retains the function in this case, and there is code around that depends
     // on unused functions (calling undefined externals) being dead-stripped to
     // link correctly.  Yes, there really is.
-    if (MMI->getUsedFunctions().count(EHFrameInfo.function))
+    if (MMI->isUsedFunction(EHFrameInfo.function))
       if (const char *UsedDirective = TAI->getUsedDirective())
         O << UsedDirective << EHFrameInfo.FnName << "\n\n";
   }
diff --git a/lib/CodeGen/MachineModuleInfo.cpp b/lib/CodeGen/MachineModuleInfo.cpp
index 66dd8375eb..20b819e823 100644
--- a/lib/CodeGen/MachineModuleInfo.cpp
+++ b/lib/CodeGen/MachineModuleInfo.cpp
@@ -88,7 +88,8 @@ void MachineModuleInfo::EndFunction() {
 /// AnalyzeModule - Scan the module for global debug information.
 ///
 void MachineModuleInfo::AnalyzeModule(Module &M) {
-  // Insert functions in the llvm.used array into UsedFunctions.
+  // Insert functions in the llvm.used array (but not llvm.compiler.used) into
+  // UsedFunctions.
   GlobalVariable *GV = M.getGlobalVariable("llvm.used");
   if (!GV || !GV->hasInitializer()) return;
 
diff --git a/lib/Transforms/IPO/Internalize.cpp b/lib/Transforms/IPO/Internalize.cpp
index 9bc9172517..da92634abf 100644
--- a/lib/Transforms/IPO/Internalize.cpp
+++ b/lib/Transforms/IPO/Internalize.cpp
@@ -138,7 +138,9 @@ bool InternalizePass::runOnModule(Module &M) {
 
   // Never internalize the llvm.used symbol.  It is used to implement
   // attribute((used)).
+  // FIXME: Shouldn't this just filter on llvm.metadata section??
   ExternalNames.insert("llvm.used");
+  ExternalNames.insert("llvm.compiler.used");
 
   // Never internalize anchors used by the machine module info, else the info
   // won't find them.  (see MachineModuleInfo.)
diff --git a/lib/Transforms/IPO/StripSymbols.cpp b/lib/Transforms/IPO/StripSymbols.cpp
index 82a0952aa2..8f3a7f4a64 100644
--- a/lib/Transforms/IPO/StripSymbols.cpp
+++ b/lib/Transforms/IPO/StripSymbols.cpp
@@ -157,32 +157,26 @@ static void StripTypeSymtab(TypeSymbolTable &ST, bool PreserveDbgInfo) {
 }
 
 /// Find values that are marked as llvm.used.
-void findUsedValues(Module &M,
-                    SmallPtrSet<const GlobalValue*, 8>& llvmUsedValues) {
-  if (GlobalVariable *LLVMUsed = M.getGlobalVariable("llvm.used")) {
-    llvmUsedValues.insert(LLVMUsed);
-    // Collect values that are preserved as per explicit request.
-    // llvm.used is used to list these values.
-    if (ConstantArray *Inits = 
-        dyn_cast<ConstantArray>(LLVMUsed->getInitializer())) {
-      for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i) {
-        if (GlobalValue *GV = dyn_cast<GlobalValue>(Inits->getOperand(i)))
-          llvmUsedValues.insert(GV);
-        else if (ConstantExpr *CE =
-                 dyn_cast<ConstantExpr>(Inits->getOperand(i)))
-          if (CE->getOpcode() == Instruction::BitCast)
-            if (GlobalValue *GV = dyn_cast<GlobalValue>(CE->getOperand(0)))
-              llvmUsedValues.insert(GV);
-      }
-    }
-  }
+static void findUsedValues(GlobalVariable *LLVMUsed,
+                           SmallPtrSet<const GlobalValue*, 8> &UsedValues) {
+  if (LLVMUsed == 0) return;
+  UsedValues.insert(LLVMUsed);
+  
+  ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
+  if (Inits == 0) return;
+  
+  for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
+    if (GlobalValue *GV = 
+          dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
+      UsedValues.insert(GV);
 }
 
 /// StripSymbolNames - Strip symbol names.
 bool StripSymbolNames(Module &M, bool PreserveDbgInfo) {
 
   SmallPtrSet<const GlobalValue*, 8> llvmUsedValues;
-  findUsedValues(M, llvmUsedValues);
+  findUsedValues(M.getGlobalVariable("llvm.used"), llvmUsedValues);
+  findUsedValues(M.getGlobalVariable("llvm.compiler.used"), llvmUsedValues);
 
   for (Module::global_iterator I = M.global_begin(), E = M.global_end();
        I != E; ++I) {
@@ -210,7 +204,8 @@ bool StripSymbolNames(Module &M, bool PreserveDbgInfo) {
 bool StripDebugInfo(Module &M) {
 
   SmallPtrSet<const GlobalValue*, 8> llvmUsedValues;
-  findUsedValues(M, llvmUsedValues);
+  findUsedValues(M.getGlobalVariable("llvm.used"), llvmUsedValues);
+  findUsedValues(M.getGlobalVariable("llvm.compiler.used"), llvmUsedValues);
 
   SmallVector<GlobalVariable *, 2> CUs;
   SmallVector<GlobalVariable *, 4> GVs;