contrib/llvm-project/llvm/lib/Target/ARM/ARMMachineFunctionInfo.cpp

   1 //===-- ARMMachineFunctionInfo.cpp - ARM machine function info ------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "ARMMachineFunctionInfo.h"
  10 #include "ARMSubtarget.h"
  11
  12 using namespace llvm;
  13
  14 void ARMFunctionInfo::anchor() {}
  15
  16 static bool GetBranchTargetEnforcement(const Function &F,
  17                                        const ARMSubtarget *Subtarget) {
  18   if (!Subtarget->isMClass() || !Subtarget->hasV7Ops())
  19     return false;
  20
  21   if (!F.hasFnAttribute("branch-target-enforcement")) {
  22     if (const auto *BTE = mdconst::extract_or_null<ConstantInt>(
  23             F.getParent()->getModuleFlag("branch-target-enforcement")))
  24       return BTE->getZExtValue();
  25     return false;
  26   }
  27
  28   const StringRef BTIEnable =
  29       F.getFnAttribute("branch-target-enforcement").getValueAsString();
  30   assert(BTIEnable.equals_insensitive("true") ||
  31          BTIEnable.equals_insensitive("false"));
  32   return BTIEnable.equals_insensitive("true");
  33 }
  34
  35 // The pair returns values for the ARMFunctionInfo members
  36 // SignReturnAddress and SignReturnAddressAll respectively.
  37 static std::pair<bool, bool> GetSignReturnAddress(const Function &F) {
  38   if (!F.hasFnAttribute("sign-return-address")) {
  39     const Module &M = *F.getParent();
  40     if (const auto *Sign = mdconst::extract_or_null<ConstantInt>(
  41             M.getModuleFlag("sign-return-address"))) {
  42       if (Sign->getZExtValue()) {
  43         if (const auto *All = mdconst::extract_or_null<ConstantInt>(
  44                 M.getModuleFlag("sign-return-address-all")))
  45           return {true, All->getZExtValue()};
  46         return {true, false};
  47       }
  48     }
  49     return {false, false};
  50   }
  51
  52   StringRef Scope = F.getFnAttribute("sign-return-address").getValueAsString();
  53   if (Scope.equals("none"))
  54     return {false, false};
  55
  56   if (Scope.equals("all"))
  57     return {true, true};
  58
  59   assert(Scope.equals("non-leaf"));
  60   return {true, false};
  61 }
  62
  63 ARMFunctionInfo::ARMFunctionInfo(const Function &F,
  64                                  const ARMSubtarget *Subtarget)
  65     : isThumb(Subtarget->isThumb()), hasThumb2(Subtarget->hasThumb2()),
  66       IsCmseNSEntry(F.hasFnAttribute("cmse_nonsecure_entry")),
  67       IsCmseNSCall(F.hasFnAttribute("cmse_nonsecure_call")),
  68       BranchTargetEnforcement(GetBranchTargetEnforcement(F, Subtarget)) {
  69   if (Subtarget->isMClass() && Subtarget->hasV7Ops())
  70     std::tie(SignReturnAddress, SignReturnAddressAll) = GetSignReturnAddress(F);
  71 }
  72
  73 MachineFunctionInfo *
  74 ARMFunctionInfo::clone(BumpPtrAllocator &Allocator, MachineFunction &DestMF,
  75                        const DenseMap<MachineBasicBlock *, MachineBasicBlock *>
  76                            &Src2DstMBB) const {
  77   return DestMF.cloneInfo<ARMFunctionInfo>(*this);
  78 }