[X86] Support -mstack-protector-guard-symbol

5 files changed, 68 insertions, 2 deletions

diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index 1268cc7..03d964e 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -221,6 +221,12 @@ Changes to the DAG infrastructure
 ---------------------------------
 
 
+Changes to the Metadata Info
+---------------------------------
+
+* Add Module Flags Metadata ``stack-protector-guard-symbol`` which specify a
+  symbol for addressing the stack-protector guard.
+
 Changes to the Debug Info
 ---------------------------------
 
diff --git a/llvm/include/llvm/IR/Module.h b/llvm/include/llvm/IR/Module.h
index fc2d609..24da08d 100644
--- a/llvm/include/llvm/IR/Module.h
+++ b/llvm/include/llvm/IR/Module.h
@@ -911,6 +911,10 @@ public:
   StringRef getStackProtectorGuardReg() const;
   void setStackProtectorGuardReg(StringRef Reg);
 
+  /// Get/set a symbol to use as the stack protector guard.
+  StringRef getStackProtectorGuardSymbol() const;
+  void setStackProtectorGuardSymbol(StringRef Symbol);
+
   /// Get/set what offset from the stack protector to use.
   int getStackProtectorGuardOffset() const;
   void setStackProtectorGuardOffset(int Offset);
diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp
index 5cd74d5..b51ea45 100644
--- a/llvm/lib/IR/Module.cpp
+++ b/llvm/lib/IR/Module.cpp
@@ -714,6 +714,18 @@ void Module::setStackProtectorGuardReg(StringRef Reg) {
   addModuleFlag(ModFlagBehavior::Error, "stack-protector-guard-reg", ID);
 }
 
+StringRef Module::getStackProtectorGuardSymbol() const {
+  Metadata *MD = getModuleFlag("stack-protector-guard-symbol");
+  if (auto *MDS = dyn_cast_or_null<MDString>(MD))
+    return MDS->getString();
+  return {};
+}
+
+void Module::setStackProtectorGuardSymbol(StringRef Symbol) {
+  MDString *ID = MDString::get(getContext(), Symbol);
+  addModuleFlag(ModFlagBehavior::Error, "stack-protector-guard-symbol", ID);
+}
+
 int Module::getStackProtectorGuardOffset() const {
   Metadata *MD = getModuleFlag("stack-protector-guard-offset");
   if (auto *CI = mdconst::dyn_extract_or_null<ConstantInt>(MD))
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 047ac0d..6dc823f 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -2845,6 +2845,21 @@ Value *X86TargetLowering::getIRStackGuard(IRBuilderBase &IRB) const {
         AddressSpace = X86AS::FS;
       else if (GuardReg == "gs")
         AddressSpace = X86AS::GS;
+
+      // Use symbol guard if user specify.
+      StringRef GuardSymb = M->getStackProtectorGuardSymbol();
+      if (!GuardSymb.empty()) {
+        GlobalVariable *GV = M->getGlobalVariable(GuardSymb);
+        if (!GV) {
+          Type *Ty = Subtarget.is64Bit() ? Type::getInt64Ty(M->getContext())
+                                         : Type::getInt32Ty(M->getContext());
+          GV = new GlobalVariable(*M, Ty, false, GlobalValue::ExternalLinkage,
+                                  nullptr, GuardSymb, nullptr,
+                                  GlobalValue::NotThreadLocal, AddressSpace);
+        }
+        return GV;
+      }
+
       return SegmentOffset(IRB, Offset, AddressSpace);
     }
   }
diff --git a/llvm/test/CodeGen/X86/stack-protector-3.ll b/llvm/test/CodeGen/X86/stack-protector-3.ll
index 82e1157..59f583b 100644
--- a/llvm/test/CodeGen/X86/stack-protector-3.ll
+++ b/llvm/test/CodeGen/X86/stack-protector-3.ll
@@ -6,6 +6,8 @@
 ; RUN: cat %t/main.ll %t/e.ll > %t/e2.ll
 ; RUN: cat %t/main.ll %t/f.ll > %t/f2.ll
 ; RUN: cat %t/main.ll %t/g.ll > %t/g2.ll
+; RUN: cat %t/main.ll %t/h.ll > %t/h2.ll
+; RUN: cat %t/existedGV.ll %t/main.ll %t/h.ll > %t/i2.ll
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/a2.ll | FileCheck --check-prefix=CHECK-TLS-FS-40 %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/b2.ll | FileCheck --check-prefix=CHECK-TLS-FS-40 %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/c2.ll | FileCheck --check-prefix=CHECK-GLOBAL %s
@@ -13,8 +15,8 @@
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/e2.ll | FileCheck --check-prefix=CHECK-GS %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/f2.ll | FileCheck --check-prefix=CHECK-OFFSET %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/g2.ll | FileCheck --check-prefix=CHECK-NEGATIVE-OFFSET %s
-
-;--- main.ll
+; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/h2.ll | FileCheck --check-prefix=CHECK-SYM %s
+; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/i2.ll | FileCheck --check-prefix=CHECK-SYMGV %s
 
 ; CHECK-TLS-FS-40:       movq    %fs:40, %rax
 ; CHECK-TLS-FS-40:       movq    %fs:40, %rax
@@ -57,7 +59,31 @@
 ; CHECK-GLOBAL-NEXT:  .cfi_def_cfa_offset 32
 ; CHECK-GLOBAL-NEXT:  callq   __stack_chk_fail
 
+; CHECK-SYM:         movq    __woof@GOTPCREL(%rip), %rax
+; CHECK-SYM-NEXT:    movq    %fs:(%rax), %rcx
+; CHECK-SYM-NEXT:    movq    %rcx, 16(%rsp)
+; CHECK-SYM:         movq    %fs:(%rax), %rax
+; CHECK-SYM-NEXT:    cmpq    16(%rsp), %rax
+; CHECK-SYM-NEXT:    jne     .LBB0_2
+; CHECK-SYM:         .LBB0_2:
+; CHECK-SYM-NEXT:    .cfi_def_cfa_offset 32
+; CHECK-SYM-NEXT:    callq   __stack_chk_fai
+
+; CHECK-SYMGV:       movq    __woof(%rip), %rax
+; CHECK-SYMGV-NEXT:  movq    %rax, 16(%rsp)
+; CHECK-SYMGV:       cmpq    16(%rsp), %rax
+; CHECK-SYMGV-NEXT:  jne     .LBB0_2
+; CHECK-SYMGV:       .LBB0_2:
+; CHECK-SYMGV-NEXT:  .cfi_def_cfa_offset 32
+; CHECK-SYMGV-NEXT:  callq   __stack_chk_fail
+
 ; ModuleID = 't.c'
+;--- existedGV.ll
+
+@__woof = dso_local local_unnamed_addr global ptr null, align 8
+
+;--- main.ll
+
 @.str = private unnamed_addr constant [14 x i8] c"stackoverflow\00", align 1
 @a = dso_local local_unnamed_addr global ptr null, align 8
 
@@ -104,3 +130,6 @@ attributes #2 = { nounwind }
 ;--- g.ll
 !llvm.module.flags = !{!1}
 !1 = !{i32 2, !"stack-protector-guard-offset", i32 -20}
+;--- h.ll
+!llvm.module.flags = !{!1}
+!1 = !{i32 2, !"stack-protector-guard-symbol", !"__woof"}