Home | History | Annotate | Line # | Download | only in AArch64 
      1 //=- AArch64MachineFunctionInfo.cpp - AArch64 Machine Function Info ---------=//
      2 
      3 //
      4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      5 // See https://llvm.org/LICENSE.txt for license information.
      6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      7 //
      8 //===----------------------------------------------------------------------===//
      9 ///
     10 /// \file
     11 /// This file implements AArch64-specific per-machine-function
     12 /// information.
     13 ///
     14 //===----------------------------------------------------------------------===//
     15 
     16 #include "AArch64MachineFunctionInfo.h"
     17 #include "AArch64InstrInfo.h"
     18 #include <llvm/IR/Metadata.h>
     19 #include <llvm/IR/Module.h>
     20 
     21 using namespace llvm;
     22 
     23 yaml::AArch64FunctionInfo::AArch64FunctionInfo(
     24     const llvm::AArch64FunctionInfo &MFI)
     25     : HasRedZone(MFI.hasRedZone()) {}
     26 
     27 void yaml::AArch64FunctionInfo::mappingImpl(yaml::IO &YamlIO) {
     28   MappingTraits<AArch64FunctionInfo>::mapping(YamlIO, *this);
     29 }
     30 
     31 void AArch64FunctionInfo::initializeBaseYamlFields(
     32     const yaml::AArch64FunctionInfo &YamlMFI) {
     33   if (YamlMFI.HasRedZone.hasValue())
     34     HasRedZone = YamlMFI.HasRedZone;
     35 }
     36 
     37 static std::pair<bool, bool> GetSignReturnAddress(const Function &F) {
     38   // The function should be signed in the following situations:
     39   // - sign-return-address=all
     40   // - sign-return-address=non-leaf and the functions spills the LR
     41   if (!F.hasFnAttribute("sign-return-address")) {
     42     const Module &M = *F.getParent();
     43     if (const auto *Sign = mdconst::extract_or_null<ConstantInt>(
     44             M.getModuleFlag("sign-return-address"))) {
     45       if (Sign->getZExtValue()) {
     46         if (const auto *All = mdconst::extract_or_null<ConstantInt>(
     47                 M.getModuleFlag("sign-return-address-all")))
     48           return {true, All->getZExtValue()};
     49         return {true, false};
     50       }
     51     }
     52     return {false, false};
     53   }
     54 
     55   StringRef Scope = F.getFnAttribute("sign-return-address").getValueAsString();
     56   if (Scope.equals("none"))
     57     return {false, false};
     58 
     59   if (Scope.equals("all"))
     60     return {true, true};
     61 
     62   assert(Scope.equals("non-leaf"));
     63   return {true, false};
     64 }
     65 
     66 static bool ShouldSignWithBKey(const Function &F) {
     67   if (!F.hasFnAttribute("sign-return-address-key")) {
     68     if (const auto *BKey = mdconst::extract_or_null<ConstantInt>(
     69             F.getParent()->getModuleFlag("sign-return-address-with-bkey")))
     70       return BKey->getZExtValue();
     71     return false;
     72   }
     73 
     74   const StringRef Key =
     75       F.getFnAttribute("sign-return-address-key").getValueAsString();
     76   assert(Key.equals_lower("a_key") || Key.equals_lower("b_key"));
     77   return Key.equals_lower("b_key");
     78 }
     79 
     80 AArch64FunctionInfo::AArch64FunctionInfo(MachineFunction &MF) : MF(MF) {
     81   // If we already know that the function doesn't have a redzone, set
     82   // HasRedZone here.
     83   if (MF.getFunction().hasFnAttribute(Attribute::NoRedZone))
     84     HasRedZone = false;
     85 
     86   const Function &F = MF.getFunction();
     87   std::tie(SignReturnAddress, SignReturnAddressAll) = GetSignReturnAddress(F);
     88   SignWithBKey = ShouldSignWithBKey(F);
     89 
     90   if (!F.hasFnAttribute("branch-target-enforcement")) {
     91     if (const auto *BTE = mdconst::extract_or_null<ConstantInt>(
     92             F.getParent()->getModuleFlag("branch-target-enforcement")))
     93       BranchTargetEnforcement = BTE->getZExtValue();
     94     return;
     95   }
     96 
     97   const StringRef BTIEnable = F.getFnAttribute("branch-target-enforcement").getValueAsString();
     98   assert(BTIEnable.equals_lower("true") || BTIEnable.equals_lower("false"));
     99   BranchTargetEnforcement = BTIEnable.equals_lower("true");
    100 }
    101 
    102 bool AArch64FunctionInfo::shouldSignReturnAddress(bool SpillsLR) const {
    103   if (!SignReturnAddress)
    104     return false;
    105   if (SignReturnAddressAll)
    106     return true;
    107   return SpillsLR;
    108 }
    109 
    110 bool AArch64FunctionInfo::shouldSignReturnAddress() const {
    111   return shouldSignReturnAddress(llvm::any_of(
    112       MF.getFrameInfo().getCalleeSavedInfo(),
    113       [](const auto &Info) { return Info.getReg() == AArch64::LR; }));
    114 }
    115