[ARM][AArch64] BTI,GCS,PAC Module flag update.

clang/lib/CodeGen/CodeGenModule.cpp

@@ -1182,22 +1182,29 @@ void CodeGenModule::Release() {
                               "tag-stack-memory-buildattr", 1);
 
   if (T.isARM() || T.isThumb() || T.isAArch64()) {
+    // Previously 1 is used and meant for the backed to derive the function
+    // attribute form it. 2 now means function attributes already set for all
+    // functions in this module, so no need to propagate those from the module
+    // flag. Value is only used in case of LTO module merge because the backend
+    // will see all required function attribute set already. Value is used
+    // before modules got merged. Any posive value means the feature is active
+    // and required binary markings need to be emit accordingly.
     if (LangOpts.BranchTargetEnforcement)
       getModule().addModuleFlag(llvm::Module::Min, "branch-target-enforcement",
-                                1);
+                                2);
     if (LangOpts.BranchProtectionPAuthLR)
       getModule().addModuleFlag(llvm::Module::Min, "branch-protection-pauth-lr",
-                                1);
+                                2);
     if (LangOpts.GuardedControlStack)
-      getModule().addModuleFlag(llvm::Module::Min, "guarded-control-stack", 1);
+      getModule().addModuleFlag(llvm::Module::Min, "guarded-control-stack", 2);
     if (LangOpts.hasSignReturnAddress())
-      getModule().addModuleFlag(llvm::Module::Min, "sign-return-address", 1);
+      getModule().addModuleFlag(llvm::Module::Min, "sign-return-address", 2);
     if (LangOpts.isSignReturnAddressScopeAll())
       getModule().addModuleFlag(llvm::Module::Min, "sign-return-address-all",
-                                1);
+                                2);
     if (!LangOpts.isSignReturnAddressWithAKey())
       getModule().addModuleFlag(llvm::Module::Min,
-                                "sign-return-address-with-bkey", 1);
+                                "sign-return-address-with-bkey", 2);
 
     if (getTriple().isOSLinux()) {
       assert(getTriple().isOSBinFormatELF());

clang/test/CodeGen/aarch64-sign-return-address.c

@@ -28,17 +28,17 @@
 // NONE-NOT:  !"branch-target-enforcement"
 // ALL-NOT:   !"branch-target-enforcement"
 // PART-NOT:  !"branch-target-enforcement"
-// BTE:       !{i32 8, !"branch-target-enforcement", i32 1}
+// BTE:       !{i32 8, !"branch-target-enforcement", i32 2}
 // B-KEY-NOT: !"branch-target-enforcement"
 
 // NONE-NOT:  !"sign-return-address"
-// ALL:   !{i32 8, !"sign-return-address", i32 1}
-// PART:  !{i32 8, !"sign-return-address", i32 1}
+// ALL:   !{i32 8, !"sign-return-address", i32 2}
+// PART:  !{i32 8, !"sign-return-address", i32 2}
 // BTE-NOT:   !"sign-return-address"
-// B-KEY: !{i32 8, !"sign-return-address", i32 1}
+// B-KEY: !{i32 8, !"sign-return-address", i32 2}
 
 // NONE-NOT:  !"sign-return-address-all"
-// ALL:   !{i32 8, !"sign-return-address-all", i32 1}
+// ALL:   !{i32 8, !"sign-return-address-all", i32 2}
 // PART-NOT:  !"sign-return-address-all"
 // BTE-NOT:   !"sign-return-address-all"
 // B-KEY-NOT: !"sign-return-address-all"
@@ -47,6 +47,6 @@
 // ALL-NOT:   !"sign-return-address-with-bkey"
 // PART-NOT:  !"sign-return-address-with-bkey"
 // BTE-NOT:   !"sign-return-address-with-bkey"
-// B-KEY: !{i32 8, !"sign-return-address-with-bkey", i32 1}
+// B-KEY: !{i32 8, !"sign-return-address-with-bkey", i32 2}
 
 void foo() {}

clang/test/CodeGen/arm-branch-protection-attr-2.c

@@ -23,16 +23,16 @@
 // NONE-NOT: !"branch-target-enforcement"
 // PART-NOT: !"branch-target-enforcement"
 // ALL-NOT:  !"branch-target-enforcement"
-// BTE:      !{i32 8, !"branch-target-enforcement", i32 1}
+// BTE:      !{i32 8, !"branch-target-enforcement", i32 2}
 
 // NONE-NOT: !"sign-return-address"
-// PART:     !{i32 8, !"sign-return-address", i32 1}
-// ALL:      !{i32 8, !"sign-return-address", i32 1}
+// PART:     !{i32 8, !"sign-return-address", i32 2}
+// ALL:      !{i32 8, !"sign-return-address", i32 2}
 // BTE-NOT:  !"sign-return-address"
 
 // NONE-NOT: !"sign-return-address-all", i32 0}
 // PART-NOT: !"sign-return-address-all", i32 0}
-// ALL:      !{i32 8, !"sign-return-address-all", i32 1}
+// ALL:      !{i32 8, !"sign-return-address-all", i32 2}
 // BTE-NOT:  !"sign-return-address-all", i32 0}
 
 void foo() {}

clang/test/Frontend/arm-ignore-branch-protection-option.c

@@ -15,4 +15,4 @@ __attribute__((target("arch=cortex-m0"))) void f() {}
 // CHECK-NOT:  attributes { {{.*}} "branch-target-enforcement"
 
 /// Check that there are branch protection module attributes despite the warning.
-// CHECK: !{i32 8, !"branch-target-enforcement", i32 1}
+// CHECK: !{i32 8, !"branch-target-enforcement", i32 2}

llvm/include/llvm/IR/AutoUpgrade.h

@@ -89,6 +89,16 @@ namespace llvm {
   /// info. Return true if module is modified.
   bool UpgradeDebugInfo(Module &M);
 
+  /// Copies module attributes to the functions in the module.
+  /// Currently only effects ARM, Thumb and AArch64 targets.
+  /// Supported attributes:
+  ///  - branch-target-enforcement
+  ///  - branch-protection-pauth-lr
+  ///  - guarded-control-stack
+  ///  - sign-return-address
+  ///  - sign-return-address-with-bkey
+  void CopyModuleAttrToFunctions(Module &M);
+
   /// Check whether a string looks like an old loop attachment tag.
   inline bool mayBeOldLoopAttachmentTag(StringRef Name) {
     return Name.starts_with("llvm.vectorizer.");

llvm/lib/AsmParser/LLParser.cpp

@@ -449,6 +449,7 @@ bool LLParser::validateEndOfModule(bool UpgradeDebugInfo) {
 
   UpgradeModuleFlags(*M);
   UpgradeSectionAttributes(*M);
+  CopyModuleAttrToFunctions(*M);
 
   if (PreserveInputDbgFormat != cl::boolOrDefault::BOU_TRUE)
     M->setIsNewDbgInfoFormat(UseNewDbgInfoFormat);

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -7070,6 +7070,8 @@ Error BitcodeReader::materializeModule() {
 
   UpgradeARCRuntime(*TheModule);
 
+  CopyModuleAttrToFunctions(*TheModule);
+
   return Error::success();
 }
 

llvm/lib/IR/AutoUpgrade.cpp

@@ -5296,6 +5296,106 @@ void llvm::UpgradeFunctionAttributes(Function &F) {
   }
 }
 
+// Check if the module attribute is present and set to one.
+static bool isModuleAttributeOne(Module &M, const StringRef &ModAttr) {
+  const auto *Attr =
+      mdconst::extract_or_null<ConstantInt>(M.getModuleFlag(ModAttr));
+  return Attr && Attr->isOne();
+}
+
+// Check if the module attribute is present and set to two.
+static bool isModuleAttributeTwo(Module &M, const StringRef &ModAttr) {
+  const auto *Attr =
+      mdconst::extract_or_null<ConstantInt>(M.getModuleFlag(ModAttr));
+  return Attr && Attr->getZExtValue() == 2;
+}
+
+// Check if the function attribute is not present and set it.
+static void SetFunctionAttrIfNotSet(Function &F, StringRef FnAttrName,
+                                    StringRef Value) {
+  if (!F.hasFnAttribute(FnAttrName))
+    F.addFnAttr(FnAttrName, Value);
+}
+
+// Check if the function attribute is not present and set it if needed.
+// If the attribute is "false" then removes it.
+// If the attribute is "true" resets it to a valueless attribute.
+static void ConvertFunctionAttr(Function &F, bool Set, StringRef FnAttrName) {
+  if (!F.hasFnAttribute(FnAttrName)) {
+    if (Set)
+      F.addFnAttr(FnAttrName);
+  } else {
+    auto A = F.getFnAttribute(FnAttrName);
+    if ("false" == A.getValueAsString())
+      F.removeFnAttr(FnAttrName);
+    else if ("true" == A.getValueAsString()) {
+      F.removeFnAttr(FnAttrName);
+      F.addFnAttr(FnAttrName);
+    }
+  }
+}
+
+void llvm::CopyModuleAttrToFunctions(Module &M) {
+  Triple T(M.getTargetTriple());
+  if (!T.isThumb() && !T.isARM() && !T.isAArch64())
+    return;
+
+  if (isModuleAttributeTwo(M, "branch-target-enforcement"))
+    return;
+  if (isModuleAttributeTwo(M, "branch-protection-pauth-lr"))
+    return;
+  if (isModuleAttributeTwo(M, "guarded-control-stack"))
+    return;
+  if (isModuleAttributeTwo(M, "sign-return-address"))
+    return;
+
+  bool BTE = isModuleAttributeOne(M, "branch-target-enforcement");
+  bool BPPLR = isModuleAttributeOne(M, "branch-protection-pauth-lr");
+  bool GCS = isModuleAttributeOne(M, "guarded-control-stack");
+  bool SRA = isModuleAttributeOne(M, "sign-return-address");
+
+  StringRef SignTypeValue = "non-leaf";
+  if (SRA && isModuleAttributeOne(M, "sign-return-address-all"))
+    SignTypeValue = "all";
+
+  StringRef SignKeyValue = "a_key";
+  if (SRA && isModuleAttributeOne(M, "sign-return-address-with-bkey"))
+    SignKeyValue = "b_key";
+
+  for (Function &F : M.getFunctionList()) {
+    if (F.isDeclaration())
+      continue;
+
+    if (SRA) {
+      SetFunctionAttrIfNotSet(F, "sign-return-address", SignTypeValue);
+      SetFunctionAttrIfNotSet(F, "sign-return-address-key", SignKeyValue);
+    } else {
+      if (auto A = F.getFnAttribute("sign-return-address");
+          A.isValid() && "none" == A.getValueAsString()) {
+        F.removeFnAttr("sign-return-address");
+        F.removeFnAttr("sign-return-address-key");
+      }
+    }
+    ConvertFunctionAttr(F, BTE, "branch-target-enforcement");
+    ConvertFunctionAttr(F, BPPLR, "branch-protection-pauth-lr");
+    ConvertFunctionAttr(F, GCS, "guarded-control-stack");
+  }
+
+  if (BTE)
+    M.setModuleFlag(llvm::Module::Min, "branch-target-enforcement", 2);
+  if (BPPLR)
+    M.setModuleFlag(llvm::Module::Min, "branch-protection-pauth-lr", 2);
+  if (GCS)
+    M.setModuleFlag(llvm::Module::Min, "guarded-control-stack", 2);
+  if (SRA) {
+    M.setModuleFlag(llvm::Module::Min, "sign-return-address", 2);
+    if (isModuleAttributeOne(M, "sign-return-address-all"))
+      M.setModuleFlag(llvm::Module::Min, "sign-return-address-all", 2);
+    if (isModuleAttributeOne(M, "sign-return-address-with-bkey"))
+      M.setModuleFlag(llvm::Module::Min, "sign-return-address-with-bkey", 2);
+  }
+}
+
 static bool isOldLoopArgument(Metadata *MD) {
   auto *T = dyn_cast_or_null<MDTuple>(MD);
   if (!T)

llvm/lib/Linker/IRMover.cpp

@@ -1606,6 +1606,11 @@ Error IRLinker::run() {
   // Loop over all of the linked values to compute type mappings.
   computeTypeMapping();
 
+  // Convert module level attributes to function level attributes because
+  // after merging modules the attributes might change and would have different
+  // effect on the functions as the original module would have.
+  CopyModuleAttrToFunctions(*SrcM);
+
   std::reverse(Worklist.begin(), Worklist.end());
   while (!Worklist.empty()) {
     GlobalValue *GV = Worklist.back();
@@ -1770,6 +1775,11 @@ IRMover::IRMover(Module &M) : Composite(M) {
   for (const auto *MD : StructTypes.getVisitedMetadata()) {
     SharedMDs[MD].reset(const_cast<MDNode *>(MD));
   }
+
+  // Convert module level attributes to function level attributes because
+  // after merging modules the attributes might change and would have different
+  // effect on the functions as the original module would have.
+  CopyModuleAttrToFunctions(M);
 }
 
 Error IRMover::move(std::unique_ptr<Module> Src,

llvm/lib/Target/ARM/ARMAsmPrinter.cpp

@@ -793,7 +793,7 @@ void ARMAsmPrinter::emitAttributes() {
 
     auto *BTIValue = mdconst::extract_or_null<ConstantInt>(
         SourceModule->getModuleFlag("branch-target-enforcement"));
-    if (BTIValue && BTIValue->isOne()) {
+    if (BTIValue && !BTIValue->isZero()) {
       // If "+pacbti" is used as an architecture extension,
       // Tag_BTI_extension is emitted in
       // ARMTargetStreamer::emitTargetAttributes().

llvm/lib/Transforms/IPO/LowerTypeTests.cpp

@@ -1211,7 +1211,7 @@ bool LowerTypeTestsModule::hasBranchTargetEnforcement() {
     // the module flags.
     if (const auto *BTE = mdconst::extract_or_null<ConstantInt>(
           M.getModuleFlag("branch-target-enforcement")))
-      HasBranchTargetEnforcement = (BTE->getZExtValue() != 0);
+      HasBranchTargetEnforcement = !BTE->isZero();
     else
       HasBranchTargetEnforcement = 0;
   }

llvm/test/Bitcode/upgrade-branch-protection.ll

@@ -1,16 +1,19 @@
-;; Test that module flags "branch-target-enforcement" and "sign-return-address"  can be upgraded to
-;; are upgraded from Error to Min.
+;; Test that module flags "branch-target-enforcement" and "sign-return-address"
+;; can be upgraded to are upgraded from Error to Min and the value is changed 2
+;; as the module is converted to the semantic.
 
 ; RUN: llvm-as %s -o - | llvm-dis - | FileCheck %s
 
+target triple = "aarch64-unknown-linux-gnu"
+
 !llvm.module.flags = !{!0, !1, !2, !3}
 
 !0 = !{i32 1, !"branch-target-enforcement", i32 1}
 !1 = !{i32 1, !"sign-return-address", i32 1}
 !2 = !{i32 1, !"sign-return-address-all", i32 1}
 !3 = !{i32 1, !"sign-return-address-with-bkey", i32 1}
 
-;CHECK: !0 = !{i32 8, !"branch-target-enforcement", i32 1}
-;CHECK: !1 = !{i32 8, !"sign-return-address", i32 1}
-;CHECK: !2 = !{i32 8, !"sign-return-address-all", i32 1}
-;CHECK: !3 = !{i32 8, !"sign-return-address-with-bkey", i32 1}
+;CHECK: !0 = !{i32 8, !"branch-target-enforcement", i32 2}
+;CHECK: !1 = !{i32 8, !"sign-return-address", i32 2}
+;CHECK: !2 = !{i32 8, !"sign-return-address-all", i32 2}
+;CHECK: !3 = !{i32 8, !"sign-return-address-with-bkey", i32 2}

llvm/test/CodeGen/Thumb2/pacbti-m-outliner-5.ll

@@ -94,5 +94,5 @@ attributes #1 = { minsize nofree norecurse nounwind optsize }
 !llvm.module.flags = !{!0, !1, !2}
 
 !0 = !{i32 8, !"branch-target-enforcement", i32 0}
-!1 = !{i32 8, !"sign-return-address", i32 1}
+!1 = !{i32 8, !"sign-return-address", i32 2}
 !2 = !{i32 8, !"sign-return-address-all", i32 0}

llvm/test/LTO/AArch64/TestInputs/bar.ll

@@ -0,0 +1,35 @@
+;; This file contains the new semantic of the branch-target-enforcement, sign-return-address.
+;; Used for test mixing a mixed link case and also verify the import too in llc.
+
+; RUN: llc -mattr=+pauth -mattr=+bti %s -o - | FileCheck %s
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-unknown-linux-gnu"
+
+define dso_local void @bar() #0 {
+entry:
+  ret void
+}
+; CHECK-LABEL: bar:
+; CHECK-NOT:       hint
+; CHECK-NOT:       bti
+; CHECK:           ret
+
+define dso_local void @baz() #1 {
+entry:
+  ret void
+}
+
+; CHECK-LABEL: baz:
+; CHECK:           bti c
+; CHECK:           ret
+
+attributes #0 = { noinline nounwind optnone uwtable }
+attributes #1 = { noinline nounwind optnone uwtable "branch-target-enforcement" }
+
+!llvm.module.flags = !{!0, !1, !2, !3}
+
+!0 = !{i32 8, !"branch-target-enforcement", i32 2}
+!1 = !{i32 8, !"sign-return-address", i32 2}
+!2 = !{i32 8, !"sign-return-address-all", i32 2}
+!3 = !{i32 8, !"sign-return-address-with-bkey", i32 2}