[ARM] Add support for MSVC stack cookie checking

[mstorsjo]

Summary

Heavily based on the same for AArch64, from SVN r346469.

[compnerd]

lib/Target/ARM/ARMISelLowering.cpp

15122

Would you mind flipping the condition on L15107 and doing an early return?

if (!Subtarget->getTargetTriple().isWindowsMSVCEnvironment())
  return TargetLowering::insertSSPDeclarations(M);

[mstorsjo]

lib/Target/ARM/ARMISelLowering.cpp

15122

Sure, I can do that

[MaskRay]

@mstorsjo stack-protector-msvc.ll fails in a debug build (CLI.CS may not be set by setCallee). I fixed that in rL365299 but am not sure that is appropriate. Can you take a look? Thanks!

lib/Target/ARM/ARMISelLowering.h

public:
     bool shouldExpandAtomicStoreInIR(StoreInst *SI) const override;
     TargetLoweringBase::AtomicExpansionKind
     shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const override;
     TargetLoweringBase::AtomicExpansionKind
     shouldExpandAtomicCmpXchgInIR(AtomicCmpXchgInst *AI) const override;
 
     bool useLoadStackGuardNode() const override;
 
+    void insertSSPDeclarations(Module &M) const override;
+    Value *getSDagStackGuard(const Module &M) const override;
+    Function *getSSPStackGuardCheck(const Module &M) const override;
+
     bool canCombineStoreAndExtract(Type *VectorTy, Value *Idx,
                                    unsigned &Cost) const override;
 
     bool canMergeStoresTo(unsigned AddressSpace, EVT MemVT,
                           const SelectionDAG &DAG) const override {
       // Do not merge to larger than i32.
       return (MemVT.getSizeInBits() <= 32);
     }

lib/Target/ARM/ARMISelLowering.cpp

   return InsertFencesForAtomic;
 }
 
 // This has so far only been implemented for MachO.
 bool ARMTargetLowering::useLoadStackGuardNode() const {
   return Subtarget->isTargetMachO();
 }
 
+void ARMTargetLowering::insertSSPDeclarations(Module &M) const {
+  // MSVC CRT provides functionalities for stack protection.
+  if (Subtarget->getTargetTriple().isWindowsMSVCEnvironment()) {
+    // MSVC CRT has a global variable holding security cookie.
+    M.getOrInsertGlobal("__security_cookie",
+                        Type::getInt8PtrTy(M.getContext()));
+
+    // MSVC CRT has a function to validate security cookie.
+    FunctionCallee SecurityCheckCookie = M.getOrInsertFunction(
+        "__security_check_cookie", Type::getVoidTy(M.getContext()),
+        Type::getInt8PtrTy(M.getContext()));
+    if (Function *F = dyn_cast<Function>(SecurityCheckCookie.getCallee())) {
+      F->setCallingConv(CallingConv::ARM_AAPCS);
+      F->addAttribute(1, Attribute::AttrKind::InReg);
+    }
+    return;
+  }
+  TargetLowering::insertSSPDeclarations(M);
+}
+
+Value *ARMTargetLowering::getSDagStackGuard(const Module &M) const {
+  // MSVC CRT has a global variable holding security cookie.
+  if (Subtarget->getTargetTriple().isWindowsMSVCEnvironment())
+    return M.getGlobalVariable("__security_cookie");
+  return TargetLowering::getSDagStackGuard(M);
+}
+
+Function *ARMTargetLowering::getSSPStackGuardCheck(const Module &M) const {
+  // MSVC CRT has a function to validate security cookie.
+  if (Subtarget->getTargetTriple().isWindowsMSVCEnvironment())
+    return M.getFunction("__security_check_cookie");
+  return TargetLowering::getSSPStackGuardCheck(M);
+}
+
 bool ARMTargetLowering::canCombineStoreAndExtract(Type *VectorTy, Value *Idx,
                                                   unsigned &Cost) const {
   // If we do not have NEON, vector types are not natively supported.
   if (!Subtarget->hasNEON())
     return false;
 
   // Floating point values and vector values map to the same register file.
   // Therefore, although we could do a store extract of a vector type, this is

test/CodeGen/ARM/Windows/stack-protector-msvc.ll

+; RUN: llc -mtriple=thumbv7-windows-msvc < %s -o - | FileCheck --check-prefix=MSVC %s
+; RUN: llc -mtriple=thumbv7-windows-msvc -O0 < %s -o - | FileCheck --check-prefix=MSVC %s
+
+define void @_Z1fv() sspreq {
+entry:
+  %x = alloca i32, align 4
+  %0 = bitcast i32* %x to i8*
+  call void @_Z7CapturePi(i32* nonnull %x)
+  ret void
+}
+
+declare void @_Z7CapturePi(i32*)
+
+; MSVC: movw r0, :lower16:__security_cookie
+; MSVC: movt r0, :upper16:__security_cookie
+; MSVC: ldr r0, [r0]
+; MSVC: str r0, [sp, #4]
+; MSVC: bl  _Z7CapturePi
+; MSVC: ldr r0, [sp, #4]
+; MSVC: bl  __security_check_cookie