BTI,GCS,PAC Module flag update.

DanielKristofKiss · DanielKristofKiss · commit f2f3356da08d · 2024-05-20T18:12:40.000+02:00
Module flag is used to indicate the feature to be propagated to the
function. As now the frontend emits all attributes accoringly let's
help the automerger to only do work when old and new bitcodes are
merged.
Autoupgrade function attributes from Module attributes when needed.
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1176,22 +1176,29 @@ 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());
diff --git a/clang/test/CodeGen/aarch64-sign-return-address.c b/clang/test/CodeGen/aarch64-sign-return-address.c
@@ -22,17 +22,17 @@
 // 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"
@@ -41,6 +41,6 @@
 // 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() {}
diff --git a/clang/test/CodeGen/arm-branch-protection-attr-2.c b/clang/test/CodeGen/arm-branch-protection-attr-2.c
@@ -18,16 +18,16 @@
 // 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() {}
diff --git a/clang/test/Frontend/arm-ignore-branch-protection-option.c b/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}
diff --git a/llvm/include/llvm/IR/AutoUpgrade.h b/llvm/include/llvm/IR/AutoUpgrade.h
@@ -89,6 +89,9 @@ namespace llvm {
   /// info. Return true if module is modified.
   bool UpgradeDebugInfo(Module &M);
 
+  /// Copies module attributes to the functions in the module.
+  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.");
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
@@ -438,6 +438,7 @@ bool LLParser::validateEndOfModule(bool UpgradeDebugInfo) {
 
   UpgradeModuleFlags(*M);
   UpgradeSectionAttributes(*M);
+  CopyModuleAttrToFunctions(*M);
 
   if (!Slots)
     return false;
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -6986,6 +6986,8 @@ Error BitcodeReader::materializeModule() {
 
   UpgradeARCRuntime(*TheModule);
 
+  CopyModuleAttrToFunctions(*TheModule);
+
   return Error::success();
 }
 
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/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)
diff --git a/llvm/lib/Linker/IRMover.cpp b/llvm/lib/Linker/IRMover.cpp
@@ -1608,6 +1608,11 @@ 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();
@@ -1772,6 +1777,11 @@ 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,
diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/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().
diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/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;
   }
diff --git a/llvm/test/Bitcode/upgrade-branch-protection.ll b/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}
diff --git a/llvm/test/CodeGen/Thumb2/pacbti-m-outliner-5.ll b/llvm/test/CodeGen/Thumb2/pacbti-m-outliner-5.ll
@@ -94,5 +94,5 @@ attributes #1 = { minsize nofree norecurse nounwind optsize "sign-return-address
 !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}
diff --git a/llvm/test/LTO/AArch64/Inputs/foo.ll b/llvm/test/LTO/AArch64/Inputs/foo.ll
diff --git a/llvm/test/LTO/AArch64/TestInputs/bar.ll b/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 %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:           hint
+; 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}
diff --git a/llvm/test/LTO/AArch64/TestInputs/foo.ll b/llvm/test/LTO/AArch64/TestInputs/foo.ll
@@ -0,0 +1,38 @@
+; This file contains the previous 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 %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 i32 @foo() #0 {
+entry:
+  ret i32 42
+}
+
+; CHECK-LABEL: foo:
+; CHECK:           hint    #27
+; CHECK:           mov
+; CHECK:           hint    #31
+; CHECK:           ret
+
+define i32 @fiz() #1 {
+entry:
+  ret i32 43
+}
+
+; CHECK-LABEL: fiz:
+; CHECK-NOT:       hint
+; CHECK-NOT:       bti
+; CHECK:           ret
+
+attributes #0 = { noinline nounwind optnone uwtable }
+attributes #1 = { noinline nounwind optnone uwtable "branch-target-enforcement"="false" "sign-return-address"="none" }
+
+!llvm.module.flags = !{!0, !1, !2, !3}
+
+!0 = !{i32 8, !"branch-target-enforcement", i32 1}
+!1 = !{i32 8, !"sign-return-address", i32 1}
+!2 = !{i32 8, !"sign-return-address-all", i32 1}
+!3 = !{i32 8, !"sign-return-address-with-bkey", i32 1}
diff --git a/llvm/test/LTO/AArch64/TestInputs/old.ll b/llvm/test/LTO/AArch64/TestInputs/old.ll
diff --git a/llvm/test/LTO/AArch64/link-branch-target-enforcement.ll b/llvm/test/LTO/AArch64/link-branch-target-enforcement.ll
diff --git a/llvm/test/LTO/AArch64/link-sign-return-address.ll b/llvm/test/LTO/AArch64/link-sign-return-address.ll
diff --git a/llvm/test/Linker/link-arm-and-thumb.ll b/llvm/test/Linker/link-arm-and-thumb.ll
diff --git a/llvm/test/ThinLTO/AArch64/aarch64_inline.ll b/llvm/test/ThinLTO/AArch64/aarch64_inline.ll
diff --git a/llvm/test/ThinLTO/AArch64/lit.local.cfg b/llvm/test/ThinLTO/AArch64/lit.local.cfg

Original file line number	Diff line number	Diff line change
`@@ -6986,6 +6986,8 @@ Error BitcodeReader::materializeModule() {`
`6986`	`6986`
`6987`	`6987`	`UpgradeARCRuntime(*TheModule);`
`6988`	`6988`
	`6989`	`+ CopyModuleAttrToFunctions(*TheModule);`
	`6990`	`+`
`6989`	`6991`	`return Error::success();`
`6990`	`6992`	`}`
`6991`	`6993`