[asan] Let the frontend disable gc-sections optimization for asan globals.

[eugenis]

Summary

Also extend -asan-globals-live-support flag to all binary formats.

Clang driver can use it based on things like -fno-data-sections and
-fno-integrated-as, which can make this optimization not beneficial
or even impossible.

[pcc]

LGTM

[eugenis]

r301226

include/llvm/Transforms/Instrumentation.h

 ModulePass *createInstrProfilingLegacyPass(
     const InstrProfOptions &Options = InstrProfOptions());
 
 // Insert AddressSanitizer (address sanity checking) instrumentation
 FunctionPass *createAddressSanitizerFunctionPass(bool CompileKernel = false,
                                                  bool Recover = false,
                                                  bool UseAfterScope = false);
 ModulePass *createAddressSanitizerModulePass(bool CompileKernel = false,
-                                             bool Recover = false);
+                                             bool Recover = false,
+                                             bool UseGlobalsGC = true);
 
 // Insert MemorySanitizer instrumentation (detection of uninitialized reads)
 FunctionPass *createMemorySanitizerPass(int TrackOrigins = 0,
                                         bool Recover = false);
 
 // Insert ThreadSanitizer (race detection) instrumentation
 FunctionPass *createThreadSanitizerPass();
 

lib/Transforms/Instrumentation/AddressSanitizer.cpp

 
 static cl::opt<bool>
     ClUsePrivateAliasForGlobals("asan-use-private-alias",
                                 cl::desc("Use private aliases for global"
                                          " variables"),
                                 cl::Hidden, cl::init(false));
 
 static cl::opt<bool>
-    ClUseMachOGlobalsSection("asan-globals-live-support",
-                             cl::desc("Use linker features to support dead "
-                                      "code stripping of globals "
-                                      "(Mach-O only)"),
-                             cl::Hidden, cl::init(true));
+    ClUseGlobalsGC("asan-globals-live-support",
+                            "code stripping of globals"),
 
 // Debug flags.
 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
                             cl::init(0));
 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
                                  cl::Hidden, cl::init(0));
 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
                                         cl::desc("Debug func"));
private:
   Value *LocalDynamicShadow;
   GlobalsMetadata GlobalsMD;
   DenseMap<const AllocaInst *, bool> ProcessedAllocas;
 
   friend struct FunctionStackPoisoner;
 };
 
 class AddressSanitizerModule : public ModulePass {
- public:
   explicit AddressSanitizerModule(bool CompileKernel = false,
-                                  bool Recover = false)
+                                  bool Recover = false,
+                                  bool UseGlobalsGC = true)
       : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
-        Recover(Recover || ClRecover) {}
+        Recover(Recover || ClRecover),
+        UseGlobalsGC(UseGlobalsGC && ClUseGlobalsGC) {}
   bool runOnModule(Module &M) override;
-  static char ID;  // Pass identification, replacement for typeid
+  static char ID; // Pass identification, replacement for typeid
   StringRef getPassName() const override { return "AddressSanitizerModule"; }
 
 private:
   void initializeCallbacks(Module &M);
 
   bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
   void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
                              ArrayRef<GlobalVariable *> ExtendedGlobals,
private:
   void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
   size_t MinRedzoneSizeForGlobal() const {
     return RedzoneSizeForScale(Mapping.Scale);
   }
 
   GlobalsMetadata GlobalsMD;
   bool CompileKernel;
   bool Recover;
+  bool UseGlobalsGC;
   Type *IntptrTy;
   LLVMContext *C;
   Triple TargetTriple;
   ShadowMapping Mapping;
   Function *AsanPoisonGlobals;
   Function *AsanUnpoisonGlobals;
   Function *AsanRegisterGlobals;
   Function *AsanUnregisterGlobals;

 
 char AddressSanitizerModule::ID = 0;
 INITIALIZE_PASS(
     AddressSanitizerModule, "asan-module",
     "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
     "ModulePass",
     false, false)
 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
-                                                   bool Recover) {
+                                                   bool Recover,
+                                                   bool UseGlobalsGC) {
   assert(!CompileKernel || Recover);
-  return new AddressSanitizerModule(CompileKernel, Recover);
+  return new AddressSanitizerModule(CompileKernel, Recover, UseGlobalsGC);
 }
 
 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
   size_t Res = countTrailingZeros(TypeSize / 8);
   assert(Res < kNumberOfAccessSizes);
   return Res;
 }
 
bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
 
   return true;
 }
 
 // On Mach-O platforms, we emit global metadata in a separate section of the
 // binary in order to allow the linker to properly dead strip. This is only
 // supported on recent versions of ld64.
 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
-  if (!ClUseMachOGlobalsSection)
-    return false;
-
   if (!TargetTriple.isOSBinFormatMachO())
     return false;
 
   if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
     return true;
   if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
     return true;
   if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
for (size_t i = 0; i < n; i++) {
 
     if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
 
     DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
 
     Initializers[i] = Initializer;
   }
 
-  if (TargetTriple.isOSBinFormatCOFF()) {
+  if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
     InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
-  } else if (ShouldUseMachOGlobalsSection()) {
+  } else if (UseGlobalsGC && ShouldUseMachOGlobalsSection()) {
     InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
   } else {
     InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
   }
 
   // Create calls for poisoning before initializers run and unpoisoning after.
   if (HasDynamicallyInitializedGlobals)
     createInitializerPoisonCalls(M, ModuleName);

test/Instrumentation/AddressSanitizer/global_metadata_array.ll

+; RUN: opt < %s -asan -asan-module -asan-globals-live-support=0 -mtriple=x86_64-unknown-linux-gnu -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -asan-globals-live-support=0 -mtriple=x86_64-apple-macosx10.11.0 -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -asan-globals-live-support=0 -mtriple=x86_64-pc-windows-msvc19.0.24215 -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; Globals:
+@global = global i32 0, align 4
+@dyn_init_global = global i32 0, align 4
+@blacklisted_global = global i32 0, align 4
+@_ZZ4funcvE10static_var = internal global i32 0, align 4
+@.str = private unnamed_addr constant [14 x i8] c"Hello, world!\00", align 1
[e-mail]_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @_GLOBAL__sub_I_asan_globals.cpp, i8* null }]
+
+; Check that globals were instrumented:
+; CHECK: @global = global { i32, [60 x i8] } zeroinitializer, align 32
+; CHECK: @.str = internal unnamed_addr constant { [14 x i8], [50 x i8] } { [14 x i8] c"Hello, world!\00", [50 x i8] zeroinitializer }{{.*}}, align 32
+
+; Check emitted location descriptions:
+; CHECK: [[VARNAME:@__asan_gen_.[0-9]+]] = private unnamed_addr constant [7 x i8] c"global\00", align 1
+; CHECK: [[FILENAME:@__asan_gen_.[0-9]+]] = private unnamed_addr constant [22 x i8] c"/tmp/asan-globals.cpp\00", align 1
+; CHECK: [[LOCDESCR:@__asan_gen_.[0-9]+]] = private unnamed_addr constant { [22 x i8]*, i32, i32 } { [22 x i8]* [[FILENAME]], i32 5, i32 5 }
+
+; Check that location descriptors and global names were passed into __asan_register_globals:
+; CHECK: i64 ptrtoint ([7 x i8]* [[VARNAME]] to i64)
+; CHECK: i64 ptrtoint ({ [22 x i8]*, i32, i32 }* [[LOCDESCR]] to i64)
+
+; Function Attrs: nounwind sanitize_address
+define internal void @__cxx_global_var_init() #0 section ".text.startup" {
+entry:
+  %0 = load i32, i32* @global, align 4
+  store i32 %0, i32* @dyn_init_global, align 4
+  ret void
+}
+
+; Function Attrs: nounwind sanitize_address
+define void @_Z4funcv() #1 {
+entry:
+  %literal = alloca i8*, align 8
+  store i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i32 0, i32 0), i8** %literal, align 8
+  ret void
+}
+
+; Function Attrs: nounwind sanitize_address
+define internal void @_GLOBAL__sub_I_asan_globals.cpp() #0 section ".text.startup" {
+entry:
+  call void @__cxx_global_var_init()
+  ret void
+}
+
+attributes #0 = { nounwind sanitize_address }
+attributes #1 = { nounwind sanitize_address "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-realign-stack" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.asan.globals = !{!0, !1, !2, !3, !4}
+!llvm.ident = !{!5}
+
+!0 = !{i32* @global, !6, !"global", i1 false, i1 false}
+!1 = !{i32* @dyn_init_global, !7, !"dyn_init_global", i1 true, i1 false}
+!2 = !{i32* @blacklisted_global, null, null, i1 false, i1 true}
+!3 = !{i32* @_ZZ4funcvE10static_var, !8, !"static_var", i1 false, i1 false}
+!4 = !{[14 x i8]* @.str, !9, !"<string literal>", i1 false, i1 false}
+
+!5 = !{!"clang version 3.5.0 (211282)"}
+
+!6 = !{!"/tmp/asan-globals.cpp", i32 5, i32 5}
+!7 = !{!"/tmp/asan-globals.cpp", i32 7, i32 5}
+!8 = !{!"/tmp/asan-globals.cpp", i32 12, i32 14}
+!9 = !{!"/tmp/asan-globals.cpp", i32 14, i32 25}