Utility functions for appending to llvm.used/llvm.compiler.used.

llvm-svn: 285143

5 files changed, 69 insertions, 99 deletions

diff --git a/llvm/lib/LTO/LTOCodeGenerator.cpp b/llvm/lib/LTO/LTOCodeGenerator.cpp
index a07707cd38a..98ce550c7dd 100644
--- a/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -58,6 +58,7 @@
 #include "llvm/Transforms/IPO/Internalize.h"
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
 #include "llvm/Transforms/ObjCARC.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
 #include <system_error>
 using namespace llvm;
 
@@ -364,18 +365,10 @@ std::unique_ptr<TargetMachine> LTOCodeGenerator::createTargetMachine() {
 void LTOCodeGenerator::preserveDiscardableGVs(
     Module &TheModule,
     llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV) {
-  SetVector<Constant *> UsedValuesSet;
-  if (GlobalVariable *LLVMUsed =
-          TheModule.getGlobalVariable("llvm.compiler.used")) {
-    ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
-    for (auto &V : Inits->operands())
-      UsedValuesSet.insert(cast<Constant>(&V));
-    LLVMUsed->eraseFromParent();
-  }
-  llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(TheModule.getContext());
+  std::vector<GlobalValue *> Used;
   auto mayPreserveGlobal = [&](GlobalValue &GV) {
     if (!GV.isDiscardableIfUnused() || GV.isDeclaration() ||
-        !mustPreserveGV(GV)) 
+        !mustPreserveGV(GV))
       return;
     if (GV.hasAvailableExternallyLinkage())
       return emitWarning(
@@ -384,7 +377,7 @@ void LTOCodeGenerator::preserveDiscardableGVs(
     if (GV.hasInternalLinkage())
       return emitWarning((Twine("Linker asked to preserve internal global: '") +
                    GV.getName() + "'").str());
-    UsedValuesSet.insert(ConstantExpr::getBitCast(&GV, i8PTy));
+    Used.push_back(&GV);
   };
   for (auto &GV : TheModule)
     mayPreserveGlobal(GV);
@@ -393,15 +386,10 @@ void LTOCodeGenerator::preserveDiscardableGVs(
   for (auto &GV : TheModule.aliases())
     mayPreserveGlobal(GV);
 
-  if (UsedValuesSet.empty())
+  if (Used.empty())
     return;
 
-  llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, UsedValuesSet.size());
-  auto *LLVMUsed = new llvm::GlobalVariable(
-      TheModule, ATy, false, llvm::GlobalValue::AppendingLinkage,
-      llvm::ConstantArray::get(ATy, UsedValuesSet.getArrayRef()),
-      "llvm.compiler.used");
-  LLVMUsed->setSection("llvm.metadata");
+  appendToCompilerUsed(TheModule, Used);
 }
 
 void LTOCodeGenerator::applyScopeRestrictions() {
diff --git a/llvm/lib/LTO/UpdateCompilerUsed.cpp b/llvm/lib/LTO/UpdateCompilerUsed.cpp
index a574db6fb5a..b67d9ea5989 100644
--- a/llvm/lib/LTO/UpdateCompilerUsed.cpp
+++ b/llvm/lib/LTO/UpdateCompilerUsed.cpp
@@ -18,6 +18,7 @@
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
 #include "llvm/Transforms/IPO/Internalize.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
 
 using namespace llvm;
 
@@ -28,16 +29,16 @@ class PreserveLibCallsAndAsmUsed {
 public:
   PreserveLibCallsAndAsmUsed(const StringSet<> &AsmUndefinedRefs,
                              const TargetMachine &TM,
-                             SmallPtrSetImpl<const GlobalValue *> &LLVMUsed)
+                             std::vector<GlobalValue *> &LLVMUsed)
       : AsmUndefinedRefs(AsmUndefinedRefs), TM(TM), LLVMUsed(LLVMUsed) {}
 
-  void findInModule(const Module &TheModule) {
+  void findInModule(Module &TheModule) {
     initializeLibCalls(TheModule);
-    for (const Function &F : TheModule)
+    for (Function &F : TheModule)
       findLibCallsAndAsm(F);
-    for (const GlobalVariable &GV : TheModule.globals())
+    for (GlobalVariable &GV : TheModule.globals())
       findLibCallsAndAsm(GV);
-    for (const GlobalAlias &GA : TheModule.aliases())
+    for (GlobalAlias &GA : TheModule.aliases())
       findLibCallsAndAsm(GA);
   }
 
@@ -51,7 +52,7 @@ private:
   StringSet<> Libcalls;
 
   // Output
-  SmallPtrSetImpl<const GlobalValue *> &LLVMUsed;
+  std::vector<GlobalValue *> &LLVMUsed;
 
   // Collect names of runtime library functions. User-defined functions with the
   // same names are added to llvm.compiler.used to prevent them from being
@@ -86,7 +87,7 @@ private:
     }
   }
 
-  void findLibCallsAndAsm(const GlobalValue &GV) {
+  void findLibCallsAndAsm(GlobalValue &GV) {
     // There are no restrictions to apply to declarations.
     if (GV.isDeclaration())
       return;
@@ -100,13 +101,15 @@ private:
     // optimizations like -globalopt, causing problems when later optimizations
     // add new library calls (e.g., llvm.memset => memset and printf => puts).
     // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
-    if (isa<Function>(GV) && Libcalls.count(GV.getName()))
-      LLVMUsed.insert(&GV);
+    if (isa<Function>(GV) && Libcalls.count(GV.getName())) {
+      LLVMUsed.push_back(&GV);
+      return;
+    }
 
     SmallString<64> Buffer;
     TM.getNameWithPrefix(Buffer, &GV, Mangler);
     if (AsmUndefinedRefs.count(Buffer))
-      LLVMUsed.insert(&GV);
+      LLVMUsed.push_back(&GV);
   }
 };
 
@@ -114,33 +117,12 @@ private:
 
 void llvm::updateCompilerUsed(Module &TheModule, const TargetMachine &TM,
                               const StringSet<> &AsmUndefinedRefs) {
-  SmallPtrSet<const GlobalValue *, 8> UsedValues;
+  std::vector<GlobalValue *> UsedValues;
   PreserveLibCallsAndAsmUsed(AsmUndefinedRefs, TM, UsedValues)
       .findInModule(TheModule);
 
   if (UsedValues.empty())
     return;
 
-  llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(TheModule.getContext());
-  std::vector<Constant *> UsedValuesList;
-  for (const auto *GV : UsedValues) {
-    Constant *c =
-        ConstantExpr::getBitCast(const_cast<GlobalValue *>(GV), i8PTy);
-    UsedValuesList.push_back(c);
-  }
-
-  GlobalVariable *LLVMUsed = TheModule.getGlobalVariable("llvm.compiler.used");
-  if (LLVMUsed) {
-    ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
-    for (auto &V : Inits->operands())
-      UsedValuesList.push_back(cast<Constant>(&V));
-    LLVMUsed->eraseFromParent();
-  }
-
-  llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, UsedValuesList.size());
-  LLVMUsed = new llvm::GlobalVariable(
-      TheModule, ATy, false, llvm::GlobalValue::AppendingLinkage,
-      llvm::ConstantArray::get(ATy, UsedValuesList), "llvm.compiler.used");
-
-  LLVMUsed->setSection("llvm.metadata");
+  appendToCompilerUsed(TheModule, UsedValues);
 }
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 586c399dbca..d77a0ae31b7 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1624,7 +1624,7 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
     StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr);
 
     // Keep the list of "Liveness" GV created to be added to llvm.compiler.used
-    SmallVector<Constant *, 16> LivenessGlobals;
+    SmallVector<GlobalValue *, 16> LivenessGlobals;
     LivenessGlobals.reserve(n);
 
     for (size_t i = 0; i < n; i++) {
@@ -1647,30 +1647,15 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
           M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
           Twine("__asan_binder_") + GVName);
       Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
-      LivenessGlobals.push_back(
-          ConstantExpr::getBitCast(Liveness, IRB.getInt8PtrTy()));
+      LivenessGlobals.push_back(Liveness);
     }
 
-    if (!LivenessGlobals.empty()) {
-      // Update llvm.compiler.used, adding the new liveness globals. This is
-      // needed so that during LTO these variables stay alive. The alternative
-      // would be to have the linker handling the LTO symbols, but libLTO
-      // current
-      // API does not expose access to the section for each symbol.
-      if (GlobalVariable *LLVMUsed =
-              M.getGlobalVariable("llvm.compiler.used")) {
-        ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
-        for (auto &V : Inits->operands())
-          LivenessGlobals.push_back(cast<Constant>(&V));
-        LLVMUsed->eraseFromParent();
-      }
-      llvm::ArrayType *ATy =
-          llvm::ArrayType::get(IRB.getInt8PtrTy(), LivenessGlobals.size());
-      auto *LLVMUsed = new llvm::GlobalVariable(
-          M, ATy, false, llvm::GlobalValue::AppendingLinkage,
-          llvm::ConstantArray::get(ATy, LivenessGlobals), "llvm.compiler.used");
-      LLVMUsed->setSection("llvm.metadata");
-    }
+    // Update llvm.compiler.used, adding the new liveness globals. This is
+    // needed so that during LTO these variables stay alive. The alternative
+    // would be to have the linker handling the LTO symbols, but libLTO
+    // current API does not expose access to the section for each symbol.
+    if (!LivenessGlobals.empty())
+      appendToCompilerUsed(M, LivenessGlobals);
   } else {
     // On all other platfoms, we just emit an array of global metadata
     // structures.
diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index f3345a69fe8..8b3e4fc9fe1 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -553,31 +553,8 @@ void InstrProfiling::emitRuntimeHook() {
 }
 
 void InstrProfiling::emitUses() {
-  if (UsedVars.empty())
-    return;
-
-  GlobalVariable *LLVMUsed = M->getGlobalVariable("llvm.used");
-  std::vector<Constant *> MergedVars;
-  if (LLVMUsed) {
-    // Collect the existing members of llvm.used.
-    ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
-    for (unsigned I = 0, E = Inits->getNumOperands(); I != E; ++I)
-      MergedVars.push_back(Inits->getOperand(I));
-    LLVMUsed->eraseFromParent();
-  }
-
-  Type *i8PTy = Type::getInt8PtrTy(M->getContext());
-  // Add uses for our data.
-  for (auto *Value : UsedVars)
-    MergedVars.push_back(
-        ConstantExpr::getBitCast(cast<Constant>(Value), i8PTy));
-
-  // Recreate llvm.used.
-  ArrayType *ATy = ArrayType::get(i8PTy, MergedVars.size());
-  LLVMUsed =
-      new GlobalVariable(*M, ATy, false, GlobalValue::AppendingLinkage,
-                         ConstantArray::get(ATy, MergedVars), "llvm.used");
-  LLVMUsed->setSection("llvm.metadata");
+  if (!UsedVars.empty())
+    appendToUsed(*M, UsedVars);
 }
 
 void InstrProfiling::emitInitialization() {
diff --git a/llvm/lib/Transforms/Utils/ModuleUtils.cpp b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
index eb918851862..4f8737e9b93 100644
--- a/llvm/lib/Transforms/Utils/ModuleUtils.cpp
+++ b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
@@ -89,6 +89,44 @@ void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority, Constant *D
   appendToGlobalArray("llvm.global_dtors", M, F, Priority, Data);
 }
 
+static void appendToUsedList(Module &M, StringRef Name, ArrayRef<GlobalValue *> Values) {
+  GlobalVariable *GV = M.getGlobalVariable(Name);
+  SmallPtrSet<Constant *, 16> InitAsSet;
+  SmallVector<Constant *, 16> Init;
+  if (GV) {
+    ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
+    for (auto &Op : CA->operands()) {
+      Constant *C = cast_or_null<Constant>(Op);
+      if (InitAsSet.insert(C).second)
+        Init.push_back(C);
+    }
+    GV->eraseFromParent();
+  }
+
+  Type *Int8PtrTy = llvm::Type::getInt8PtrTy(M.getContext());
+  for (auto *V : Values) {
+    Constant *C = ConstantExpr::getBitCast(V, Int8PtrTy);
+    if (InitAsSet.insert(C).second)
+      Init.push_back(C);
+  }
+
+  if (Init.empty())
+    return;
+
+  ArrayType *ATy = ArrayType::get(Int8PtrTy, Init.size());
+  GV = new llvm::GlobalVariable(M, ATy, false, GlobalValue::AppendingLinkage,
+                                ConstantArray::get(ATy, Init), Name);
+  GV->setSection("llvm.metadata");
+}
+
+void llvm::appendToUsed(Module &M, ArrayRef<GlobalValue *> Values) {
+  appendToUsedList(M, "llvm.used", Values);
+}
+
+void llvm::appendToCompilerUsed(Module &M, ArrayRef<GlobalValue *> Values) {
+  appendToUsedList(M, "llvm.compiler.used", Values);
+}
+
 Function *llvm::checkSanitizerInterfaceFunction(Constant *FuncOrBitcast) {
   if (isa<Function>(FuncOrBitcast))
     return cast<Function>(FuncOrBitcast);