[GlobalISel] Set stack protector index when translating Intrinsic::stackprotector

[petpav01]

Summary

Record the stack protector index in MachineFrameInfo when translating Intrinsic::stackprotector similarly as is done by SelectionDAG when processing the same intrinsic.

Setting this index allows the Prologue/Epilogue Insertion to recognize that the stack protection is enabled. The pass can then make sure that the stack protector comes before local variables on the stack and assigns potentially vulnerable objects first so they are close to the stack protector slot.

lib/CodeGen/GlobalISel/IRTranslator.cpp

case Intrinsic::stackguard:
     getStackGuard(getOrCreateVReg(CI), MIRBuilder);
     return true;
   case Intrinsic::stackprotector: {
     LLT PtrTy = getLLTForType(*CI.getArgOperand(0)->getType(), *DL);
     unsigned GuardVal = MRI->createGenericVirtualRegister(PtrTy);
     getStackGuard(GuardVal, MIRBuilder);
 
     AllocaInst *Slot = cast<AllocaInst>(CI.getArgOperand(1));
+    int FI = getOrCreateFrameIndex(*Slot);
+    MF->getFrameInfo().setStackProtectorIndex(FI);
+
     MIRBuilder.buildStore(
         GuardVal, getOrCreateVReg(*Slot),
-        *MF->getMachineMemOperand(
-            MachinePointerInfo::getFixedStack(*MF,
-                                              getOrCreateFrameIndex(*Slot)),
-            MachineMemOperand::MOStore | MachineMemOperand::MOVolatile,
+        *MF->getMachineMemOperand(MachinePointerInfo::getFixedStack(*MF, FI),
+                                  MachineMemOperand::MOStore |
+                                      MachineMemOperand::MOVolatile,
                                   PtrTy.getSizeInBits() / 8, 8));
     return true;
   }
   case Intrinsic::cttz:
   case Intrinsic::ctlz: {
     ConstantInt *Cst = cast<ConstantInt>(CI.getArgOperand(1));
     bool isTrailing = ID == Intrinsic::cttz;
     unsigned Opcode = isTrailing
                           ? Cst->isZero() ? TargetOpcode::G_CTTZ

test/CodeGen/AArch64/GlobalISel/arm64-irtranslator-stackprotect.ll

 ; RUN: llc -verify-machineinstrs -mtriple=aarch64-apple-ios %s -stop-after=irtranslator -o - -global-isel | FileCheck %s
 
 
 ; CHECK: name: test_stack_guard
 
+; CHECK: frameInfo:
+; CHECK: stackProtector:  '%stack.0.StackGuardSlot'
+
 ; CHECK: stack:
 ; CHECK:  - { id: 0, name: StackGuardSlot,  type: default, offset: 0, size: 8, alignment: 8,
 ; CHECK-NOT: id: 1
 
 ; CHECK: [[GUARD_SLOT:%[0-9]+]]:_(p0) = G_FRAME_INDEX %stack.0.StackGuardSlot
 ; CHECK: [[GUARD:%[0-9]+]]:gpr64sp(p0) = LOAD_STACK_GUARD :: (dereferenceable invariant load 8 from @__stack_chk_guard)
 ; CHECK: G_STORE [[GUARD]](p0), [[GUARD_SLOT]](p0) :: (volatile store 8 into %stack.0.StackGuardSlot)
 declare void @llvm.stackprotector(i8*, i8**)
 define void @test_stack_guard_remat2() {
   %StackGuardSlot = alloca i8*
   call void @llvm.stackprotector(i8* undef, i8** %StackGuardSlot)
   ret void
 }
 
 @__stack_chk_guard = external global i64*