This patch aims to match the changes introduced

in gcc by https://gcc.gnu.org/ml/gcc-cvs/2018-04/msg00534.html.
The -mibt feature flag is being removed, and the -fcf-protection
option now also defines a CET macro and causes errors when used
on non-X86 targets, while X86 targets no longer check for -mibt
and -mshstk to determine if -fcf-protection is supported. -mshstk
is now used only to determine availability of shadow stack intrinsics.

Comes with an LLVM patch (D46882).

Patch by mike.dvoretsky

Differential Revision: https://reviews.llvm.org/D46881



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@332704 91177308-0d34-0410-b5e6-96231b3b80d8

docs/ClangCommandLineReference.rst

@@ -2486,8 +2486,6 @@ X86
 
 .. option:: -mgfni, -mno-gfni
 
-.. option:: -mibt, -mno-ibt
-
 .. option:: -mlwp, -mno-lwp
 
 .. option:: -mlzcnt, -mno-lzcnt

include/clang/Basic/DiagnosticCommonKinds.td

@@ -206,6 +206,8 @@ def err_opt_not_valid_with_opt : Error<
   "option '%0' cannot be specified with '%1'">;
 def err_opt_not_valid_without_opt : Error<
   "option '%0' cannot be specified without '%1'">;
+def err_opt_not_valid_on_target : Error<
+  "option '%0' cannot be specified on this target">;
 
 // Source manager
 def err_cannot_open_file : Error<"cannot open file '%0': %1">, DefaultFatal;

include/clang/Basic/TargetInfo.h

@@ -1075,15 +1075,11 @@ public:
 
   /// Check if the target supports CFProtection branch.
   virtual bool
-  checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const {
-    return false;
-  }
+  checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const;
 
   /// Check if the target supports CFProtection branch.
   virtual bool
-  checkCFProtectionReturnSupported(DiagnosticsEngine &Diags) const {
-    return false;
-  }
+  checkCFProtectionReturnSupported(DiagnosticsEngine &Diags) const;
 
   /// Whether target allows to overalign ABI-specified preferred alignment
   virtual bool allowsLargerPreferedTypeAlignment() const { return true; }

include/clang/Driver/Options.td

@@ -2747,8 +2747,6 @@ def mxsaves : Flag<["-"], "mxsaves">, Group<m_x86_Features_Group>;
 def mno_xsaves : Flag<["-"], "mno-xsaves">, Group<m_x86_Features_Group>;
 def mshstk : Flag<["-"], "mshstk">, Group<m_x86_Features_Group>;
 def mno_shstk : Flag<["-"], "mno-shstk">, Group<m_x86_Features_Group>;
-def mibt : Flag<["-"], "mibt">, Group<m_x86_Features_Group>;
-def mno_ibt : Flag<["-"], "mno-ibt">, Group<m_x86_Features_Group>;
 def mretpoline : Flag<["-"], "mretpoline">, Group<m_x86_Features_Group>;
 def mno_retpoline : Flag<["-"], "mno-retpoline">, Group<m_x86_Features_Group>;
 def mretpoline_external_thunk : Flag<["-"], "mretpoline-external-thunk">, Group<m_x86_Features_Group>;

lib/Basic/TargetInfo.cpp

@@ -14,6 +14,7 @@
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Basic/AddressSpaces.h"
 #include "clang/Basic/CharInfo.h"
+#include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/LangOptions.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/STLExtras.h"
@@ -115,6 +116,18 @@ TargetInfo::TargetInfo(const llvm::Triple &T) : TargetOpts(), Triple(T) {
 // Out of line virtual dtor for TargetInfo.
 TargetInfo::~TargetInfo() {}
 
+bool
+TargetInfo::checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const {
+  Diags.Report(diag::err_opt_not_valid_on_target) << "cf-protection=branch";
+  return false;
+}
+
+bool
+TargetInfo::checkCFProtectionReturnSupported(DiagnosticsEngine &Diags) const {
+  Diags.Report(diag::err_opt_not_valid_on_target) << "cf-protection=return";
+  return false;
+}
+
 /// getTypeName - Return the user string for the specified integer type enum.
 /// For example, SignedShort -> "short".
 const char *TargetInfo::getTypeName(IntType T) {

lib/Basic/Targets/X86.cpp

@@ -102,26 +102,6 @@ bool X86TargetInfo::setFPMath(StringRef Name) {
   return false;
 }
 
-bool X86TargetInfo::checkCFProtectionReturnSupported(
-    DiagnosticsEngine &Diags) const {
-  if (HasSHSTK)
-    return true;
-
-  Diags.Report(diag::err_opt_not_valid_without_opt) << "cf-protection=return"
-                                                    << "-mshstk";
-  return false;
-}
-
-bool X86TargetInfo::checkCFProtectionBranchSupported(
-    DiagnosticsEngine &Diags) const {
-  if (HasIBT)
-    return true;
-
-  Diags.Report(diag::err_opt_not_valid_without_opt) << "cf-protection=branch"
-                                                    << "-mibt";
-  return false;
-}
-
 bool X86TargetInfo::initFeatureMap(
     llvm::StringMap<bool> &Features, DiagnosticsEngine &Diags, StringRef CPU,
     const std::vector<std::string> &FeaturesVec) const {
@@ -781,8 +761,6 @@ bool X86TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
       HasMPX = true;
     } else if (Feature == "+shstk") {
       HasSHSTK = true;
-    } else if (Feature == "+ibt") {
-      HasIBT = true;
     } else if (Feature == "+movbe") {
       HasMOVBE = true;
     } else if (Feature == "+sgx") {
@@ -1175,8 +1153,6 @@ void X86TargetInfo::getTargetDefines(const LangOptions &Opts,
     Builder.defineMacro("__MPX__");
   if (HasSHSTK)
     Builder.defineMacro("__SHSTK__");
-  if (HasIBT)
-    Builder.defineMacro("__IBT__");
   if (HasSGX)
     Builder.defineMacro("__SGX__");
   if (HasPREFETCHWT1)
@@ -1394,7 +1370,6 @@ bool X86TargetInfo::hasFeature(StringRef Feature) const {
       .Case("fsgsbase", HasFSGSBASE)
       .Case("fxsr", HasFXSR)
       .Case("gfni", HasGFNI)
-      .Case("ibt", HasIBT)
       .Case("lwp", HasLWP)
       .Case("lzcnt", HasLZCNT)
       .Case("mm3dnow", MMX3DNowLevel >= AMD3DNow)

lib/Basic/Targets/X86.h

@@ -81,7 +81,6 @@ class LLVM_LIBRARY_VISIBILITY X86TargetInfo : public TargetInfo {
   bool HasSHA = false;
   bool HasMPX = false;
   bool HasSHSTK = false;
-  bool HasIBT = false;
   bool HasSGX = false;
   bool HasCX16 = false;
   bool HasFXSR = false;
@@ -171,10 +170,15 @@ public:
   bool validateInputSize(StringRef Constraint, unsigned Size) const override;
 
   virtual bool
-  checkCFProtectionReturnSupported(DiagnosticsEngine &Diags) const override;
+  checkCFProtectionReturnSupported(DiagnosticsEngine &Diags) const override {
+    return true;
+  };
 
   virtual bool
-  checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const override;
+  checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const override {
+    return true;
+  };
+
 
   virtual bool validateOperandSize(StringRef Constraint, unsigned Size) const;
 

lib/Frontend/CompilerInvocation.cpp

@@ -2829,6 +2829,17 @@ static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
     }
   }
 
+  // Add the __CET__ macro if a CFProtection option is set.
+  if (const Arg *A = Args.getLastArg(OPT_fcf_protection_EQ)) {
+    StringRef Name = A->getValue();
+    if (Name == "branch")
+      Opts.addMacroDef("__CET__=1");
+    else if (Name == "return")
+      Opts.addMacroDef("__CET__=2");
+    else if (Name == "full")
+      Opts.addMacroDef("__CET__=3");
+  }
+
   // Add macros from the command line.
   for (const auto *A : Args.filtered(OPT_D, OPT_U)) {
     if (A->getOption().matches(OPT_D))

test/CodeGen/attributes.c

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -emit-llvm -fcf-protection=branch -target-feature +ibt -triple i386-linux-gnu -o %t %s
+// RUN: %clang_cc1 -emit-llvm -fcf-protection=branch -triple i386-linux-gnu -o %t %s
 // RUN: FileCheck --input-file=%t %s
 
 // CHECK: @t5 = weak global i32 2

test/CodeGen/builtins-x86.c

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -DUSE_64 -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -target-feature +clzero -target-feature +ibt -target-feature +shstk -target-feature +wbnoinvd -target-feature +cldemote -emit-llvm -o %t %s
-// RUN: %clang_cc1 -DUSE_ALL -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -target-feature +ibt -target-feature +shstk -target-feature +clzero -target-feature +wbnoinvd -target-feature +cldemote -fsyntax-only -o %t %s
+// RUN: %clang_cc1 -DUSE_64 -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -target-feature +clzero -target-feature +shstk -target-feature +wbnoinvd -target-feature +cldemote -emit-llvm -o %t %s
+// RUN: %clang_cc1 -DUSE_ALL -triple x86_64-unknown-unknown -target-feature +fxsr -target-feature +avx -target-feature +xsaveopt -target-feature +xsaves -target-feature +xsavec -target-feature +mwaitx -target-feature +shstk -target-feature +clzero -target-feature +wbnoinvd -target-feature +cldemote -fsyntax-only -o %t %s
 
 #ifdef USE_ALL
 #define USE_3DNOW

test/CodeGen/x86-cf-protection.c

@@ -1,6 +1,8 @@
-// RUN: not %clang_cc1 -fsyntax-only -S -o %t -triple i386-unknown-unknown -fcf-protection=return %s 2>&1 | FileCheck %s --check-prefix=RETURN
-// RUN: not %clang_cc1 -fsyntax-only -S -o %t -triple i386-unknown-unknown -fcf-protection=branch %s 2>&1 | FileCheck %s --check-prefix=BRANCH
+// RUN: %clang -target i386-unknown-unknown -x c -E -dM -o - -fcf-protection=return %s | FileCheck %s --check-prefix=RETURN
+// RUN: %clang -target i386-unknown-unknown -x c -E -dM -o - -fcf-protection=branch %s | FileCheck %s --check-prefix=BRANCH
+// RUN: %clang -target i386-unknown-unknown -x c -E -dM -o - -fcf-protection=full %s   | FileCheck %s --check-prefix=FULL
 
-// RETURN: error: option 'cf-protection=return' cannot be specified without '-mshstk'
-// BRANCH: error: option 'cf-protection=branch' cannot be specified without '-mibt'
+// RETURN: #define __CET__ 2
+// BRANCH: #define __CET__ 1
+// FULL: #define __CET__ 3
 void foo() {}

test/Driver/x86-target-features.c

@@ -80,11 +80,6 @@
 // CETSS: "-target-feature" "+shstk"
 // NO-CETSS: "-target-feature" "-shstk"
 
-// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mibt %s -### -o %t.o 2>&1 | FileCheck -check-prefix=CETIBT %s
-// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-ibt %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-CETIBT %s
-// CETIBT: "-target-feature" "+ibt"
-// NO-CETIBT: "-target-feature" "-ibt"
-
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -msgx %s -### -o %t.o 2>&1 | FileCheck -check-prefix=SGX %s
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-sgx %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-SGX %s
 // SGX: "-target-feature" "+sgx"

test/Preprocessor/x86_target_features.c

@@ -380,10 +380,6 @@
 
 // SHSTK: #define __SHSTK__ 1
 
-// RUN: %clang -target i386-unknown-unknown -mibt -x c -E -dM -o - %s | FileCheck -match-full-lines --check-prefix=IBT %s
-
-// IBT: #define __IBT__ 1
-
 // RUN: %clang -target i386-unknown-unknown -march=atom -mrdseed -x c -E -dM -o - %s | FileCheck -match-full-lines --check-prefix=RDSEED %s
 
 // RDSEED: #define __RDSEED__ 1

test/Sema/attr-nocf_check.c

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -verify -fcf-protection=branch -target-feature +ibt -fsyntax-only %s
+// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -verify -fcf-protection=branch -fsyntax-only %s
 
 // Function pointer definition.
 typedef void (*FuncPointerWithNoCfCheck)(void) __attribute__((nocf_check)); // no-warning

test/Sema/attr-nocf_check.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple=i386-unknown-unknown -verify -fcf-protection=branch -target-feature +ibt -std=c++11 -fsyntax-only %s
+// RUN: %clang_cc1 -triple=i386-unknown-unknown -verify -fcf-protection=branch -std=c++11 -fsyntax-only %s
 
 // Function pointer definition.
 [[gnu::nocf_check]] typedef void (*FuncPointerWithNoCfCheck)(void); // no-warning