diff options
Diffstat (limited to 'llvm/lib/Target/AArch64/AArch64InstrInfo.cpp')
| -rw-r--r-- | llvm/lib/Target/AArch64/AArch64InstrInfo.cpp | 296 |
1 files changed, 8 insertions, 288 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp index 1121c6f6878..3575f4b5d1e 100644 --- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp +++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp @@ -5483,99 +5483,8 @@ AArch64InstrInfo::findRegisterToSaveLRTo(const outliner::Candidate &C) const { return 0u; } -static bool -outliningCandidatesSigningScopeConsensus(const outliner::Candidate &a, - const outliner::Candidate &b) { - const Function &Fa = a.getMF()->getFunction(); - const Function &Fb = b.getMF()->getFunction(); - - // If none of the functions have the "sign-return-address" attribute their - // signing behaviour is equal - if (!Fa.hasFnAttribute("sign-return-address") && - !Fb.hasFnAttribute("sign-return-address")) { - return true; - } - - // If both functions have the "sign-return-address" attribute their signing - // behaviour is equal, if the values of the attributes are equal - if (Fa.hasFnAttribute("sign-return-address") && - Fb.hasFnAttribute("sign-return-address")) { - StringRef ScopeA = - Fa.getFnAttribute("sign-return-address").getValueAsString(); - StringRef ScopeB = - Fb.getFnAttribute("sign-return-address").getValueAsString(); - return ScopeA.equals(ScopeB); - } - - // If function B doesn't have the "sign-return-address" attribute but A does, - // the functions' signing behaviour is equal if A's value for - // "sign-return-address" is "none" and vice versa. - if (Fa.hasFnAttribute("sign-return-address")) { - StringRef ScopeA = - Fa.getFnAttribute("sign-return-address").getValueAsString(); - return ScopeA.equals("none"); - } - - if (Fb.hasFnAttribute("sign-return-address")) { - StringRef ScopeB = - Fb.getFnAttribute("sign-return-address").getValueAsString(); - return ScopeB.equals("none"); - } - - llvm_unreachable("Unkown combination of sign-return-address attributes"); -} - -static bool -outliningCandidatesSigningKeyConsensus(const outliner::Candidate &a, - const outliner::Candidate &b) { - const Function &Fa = a.getMF()->getFunction(); - const Function &Fb = b.getMF()->getFunction(); - - // If none of the functions have the "sign-return-address-key" attribute - // their keys are equal - if (!Fa.hasFnAttribute("sign-return-address-key") && - !Fb.hasFnAttribute("sign-return-address-key")) { - return true; - } - - // If both functions have the "sign-return-address-key" attribute their - // keys are equal if the values of "sign-return-address-key" are equal - if (Fa.hasFnAttribute("sign-return-address-key") && - Fb.hasFnAttribute("sign-return-address-key")) { - StringRef KeyA = - Fa.getFnAttribute("sign-return-address-key").getValueAsString(); - StringRef KeyB = - Fb.getFnAttribute("sign-return-address-key").getValueAsString(); - return KeyA.equals(KeyB); - } - - // If B doesn't have the "sign-return-address-key" attribute, both keys are - // equal, if function a has the default key (a_key) - if (Fa.hasFnAttribute("sign-return-address-key")) { - StringRef KeyA = - Fa.getFnAttribute("sign-return-address-key").getValueAsString(); - return KeyA.equals_lower("a_key"); - } - - if (Fb.hasFnAttribute("sign-return-address-key")) { - StringRef KeyB = - Fb.getFnAttribute("sign-return-address-key").getValueAsString(); - return KeyB.equals_lower("a_key"); - } - - llvm_unreachable("Unkown combination of sign-return-address-key attributes"); -} - -static bool outliningCandidatesV8_3OpsConsensus(const outliner::Candidate &a, - const outliner::Candidate &b) { - const AArch64Subtarget &SubtargetA = - a.getMF()->getSubtarget<AArch64Subtarget>(); - const AArch64Subtarget &SubtargetB = - b.getMF()->getSubtarget<AArch64Subtarget>(); - return SubtargetA.hasV8_3aOps() == SubtargetB.hasV8_3aOps(); -} - -outliner::OutlinedFunction AArch64InstrInfo::getOutliningCandidateInfo( +outliner::OutlinedFunction +AArch64InstrInfo::getOutliningCandidateInfo( std::vector<outliner::Candidate> &RepeatedSequenceLocs) const { outliner::Candidate &FirstCand = RepeatedSequenceLocs[0]; unsigned SequenceSize = @@ -5583,99 +5492,12 @@ outliner::OutlinedFunction AArch64InstrInfo::getOutliningCandidateInfo( [this](unsigned Sum, const MachineInstr &MI) { return Sum + getInstSizeInBytes(MI); }); - unsigned NumBytesToCreateFrame = 0; - - // We only allow outlining for functions having exactly matching return - // address signing attributes, i.e., all share the same value for the - // attribute "sign-return-address" and all share the same type of key they - // are signed with. - // Additionally we require all functions to simultaniously either support - // v8.3a features or not. Otherwise an outlined function could get signed - // using dedicated v8.3 instructions and a call from a function that doesn't - // support v8.3 instructions would therefore be invalid. - if (std::adjacent_find( - RepeatedSequenceLocs.begin(), RepeatedSequenceLocs.end(), - [](const outliner::Candidate &a, const outliner::Candidate &b) { - // Return true if a and b are non-equal w.r.t. return address - // signing or support of v8.3a features - if (outliningCandidatesSigningScopeConsensus(a, b) && - outliningCandidatesSigningKeyConsensus(a, b) && - outliningCandidatesV8_3OpsConsensus(a, b)) { - return false; - } - return true; - }) != RepeatedSequenceLocs.end()) { - return outliner::OutlinedFunction(); - } - - // Since at this point all candidates agree on their return address signing - // picking just one is fine. If the candidate functions potentially sign their - // return addresses, the outlined function should do the same. Note that in - // the case of "sign-return-address"="non-leaf" this is an assumption: It is - // not certainly true that the outlined function will have to sign its return - // address but this decision is made later, when the decision to outline - // has already been made. - // The same holds for the number of additional instructions we need: On - // v8.3a RET can be replaced by RETAA/RETAB and no AUT instruction is - // necessary. However, at this point we don't know if the outlined function - // will have a RET instruction so we assume the worst. - const Function &FCF = FirstCand.getMF()->getFunction(); - const TargetRegisterInfo &TRI = getRegisterInfo(); - if (FCF.hasFnAttribute("sign-return-address")) { - // One PAC and one AUT instructions - NumBytesToCreateFrame += 8; - - // We have to check if sp modifying instructions would get outlined. - // If so we only allow outlining if sp is unchanged overall, so matching - // sub and add instructions are okay to outline, all other sp modifications - // are not - auto hasIllegalSPModification = [&TRI](outliner::Candidate &C) { - int SPValue = 0; - MachineBasicBlock::iterator MBBI = C.front(); - for (;;) { - if (MBBI->modifiesRegister(AArch64::SP, &TRI)) { - switch (MBBI->getOpcode()) { - case AArch64::ADDXri: - case AArch64::ADDWri: - assert(MBBI->getNumOperands() == 4 && "Wrong number of operands"); - assert(MBBI->getOperand(2).isImm() && - "Expected operand to be immediate"); - SPValue += MBBI->getOperand(2).getImm(); - break; - case AArch64::SUBXri: - case AArch64::SUBWri: - assert(MBBI->getNumOperands() == 4 && "Wrong number of operands"); - assert(MBBI->getOperand(2).isImm() && - "Expected operand to be immediate"); - SPValue -= MBBI->getOperand(2).getImm(); - break; - default: - return true; - } - } - if (MBBI == C.back()) - break; - ++MBBI; - } - if (SPValue) - return true; - return false; - }; - // Remove candidates with illegal stack modifying instructions - RepeatedSequenceLocs.erase(std::remove_if(RepeatedSequenceLocs.begin(), - RepeatedSequenceLocs.end(), - hasIllegalSPModification), - RepeatedSequenceLocs.end()); - - // If the sequence doesn't have enough candidates left, then we're done. - if (RepeatedSequenceLocs.size() < 2) - return outliner::OutlinedFunction(); - } // Properties about candidate MBBs that hold for all of them. unsigned FlagsSetInAll = 0xF; // Compute liveness information for each candidate, and set FlagsSetInAll. + const TargetRegisterInfo &TRI = getRegisterInfo(); std::for_each(RepeatedSequenceLocs.begin(), RepeatedSequenceLocs.end(), [&FlagsSetInAll](outliner::Candidate &C) { FlagsSetInAll &= C.Flags; @@ -5731,7 +5553,7 @@ outliner::OutlinedFunction AArch64InstrInfo::getOutliningCandidateInfo( }; unsigned FrameID = MachineOutlinerDefault; - NumBytesToCreateFrame += 4; + unsigned NumBytesToCreateFrame = 4; bool HasBTI = any_of(RepeatedSequenceLocs, [](outliner::Candidate &C) { return C.getMF()->getFunction().hasFnAttribute("branch-target-enforcement"); @@ -6000,19 +5822,6 @@ AArch64InstrInfo::getOutliningType(MachineBasicBlock::iterator &MIT, MachineFunction *MF = MBB->getParent(); AArch64FunctionInfo *FuncInfo = MF->getInfo<AArch64FunctionInfo>(); - // Don't outline anything used for return address signing. The outlined - // function will get signed later if needed - switch (MI.getOpcode()) { - case AArch64::PACIASP: - case AArch64::PACIBSP: - case AArch64::AUTIASP: - case AArch64::AUTIBSP: - case AArch64::RETAA: - case AArch64::RETAB: - case AArch64::EMITBKEY: - return outliner::InstrType::Illegal; - } - // Don't outline LOHs. if (FuncInfo->getLOHRelated().count(&MI)) return outliner::InstrType::Illegal; @@ -6165,59 +5974,6 @@ void AArch64InstrInfo::fixupPostOutline(MachineBasicBlock &MBB) const { } } -static void signOutlinedFunction(MachineFunction &MF, MachineBasicBlock &MBB, - bool ShouldSignReturnAddr, - bool ShouldSignReturnAddrWithAKey) { - if (ShouldSignReturnAddr) { - MachineBasicBlock::iterator MBBPAC = MBB.begin(); - MachineBasicBlock::iterator MBBAUT = MBB.getFirstTerminator(); - const AArch64Subtarget &Subtarget = MF.getSubtarget<AArch64Subtarget>(); - const TargetInstrInfo *TII = Subtarget.getInstrInfo(); - DebugLoc DL; - - if (MBBAUT != MBB.end()) - DL = MBBAUT->getDebugLoc(); - - // At the very beginning of the basic block we insert the following - // depending on the key type - // - // a_key: b_key: - // PACIASP EMITBKEY - // CFI_INSTRUCTION PACIBSP - // CFI_INSTRUCTION - if (ShouldSignReturnAddrWithAKey) { - BuildMI(MBB, MBBPAC, DebugLoc(), TII->get(AArch64::PACIASP)) - .setMIFlag(MachineInstr::FrameSetup); - } else { - BuildMI(MBB, MBBPAC, DebugLoc(), TII->get(AArch64::EMITBKEY)) - .setMIFlag(MachineInstr::FrameSetup); - BuildMI(MBB, MBBPAC, DebugLoc(), TII->get(AArch64::PACIBSP)) - .setMIFlag(MachineInstr::FrameSetup); - } - unsigned CFIIndex = - MF.addFrameInst(MCCFIInstruction::createNegateRAState(nullptr)); - BuildMI(MBB, MBBPAC, DebugLoc(), TII->get(AArch64::CFI_INSTRUCTION)) - .addCFIIndex(CFIIndex) - .setMIFlags(MachineInstr::FrameSetup); - - // If v8.3a features are available we can replace a RET instruction by - // RETAA or RETAB and omit the AUT instructions - if (Subtarget.hasV8_3aOps() && MBBAUT != MBB.end() && - MBBAUT->getOpcode() == AArch64::RET) { - BuildMI(MBB, MBBAUT, DL, - TII->get(ShouldSignReturnAddrWithAKey ? AArch64::RETAA - : AArch64::RETAB)) - .copyImplicitOps(*MBBAUT); - MBB.erase(MBBAUT); - } else { - BuildMI(MBB, MBBAUT, DL, - TII->get(ShouldSignReturnAddrWithAKey ? AArch64::AUTIASP - : AArch64::AUTIBSP)) - .setMIFlag(MachineInstr::FrameDestroy); - } - } -} - void AArch64InstrInfo::buildOutlinedFrame( MachineBasicBlock &MBB, MachineFunction &MF, const outliner::OutlinedFunction &OF) const { @@ -6233,19 +5989,16 @@ void AArch64InstrInfo::buildOutlinedFrame( TailOpcode = AArch64::TCRETURNriALL; } MachineInstr *TC = BuildMI(MF, DebugLoc(), get(TailOpcode)) - .add(Call->getOperand(0)) - .addImm(0); + .add(Call->getOperand(0)) + .addImm(0); MBB.insert(MBB.end(), TC); Call->eraseFromParent(); } - bool IsLeafFunction = true; - // Is there a call in the outlined range? - auto IsNonTailCall = [](const MachineInstr &MI) { + auto IsNonTailCall = [](MachineInstr &MI) { return MI.isCall() && !MI.isReturn(); }; - if (std::any_of(MBB.instr_begin(), MBB.instr_end(), IsNonTailCall)) { // Fix up the instructions in the range, since we're going to modify the // stack. @@ -6253,8 +6006,6 @@ void AArch64InstrInfo::buildOutlinedFrame( "Can only fix up stack references once"); fixupPostOutline(MBB); - IsLeafFunction = false; - // LR has to be a live in so that we can save it. MBB.addLiveIn(AArch64::LR); @@ -6301,47 +6052,16 @@ void AArch64InstrInfo::buildOutlinedFrame( Et = MBB.insert(Et, LDRXpost); } - // If a bunch of candidates reach this point they must agree on their return - // address signing. It is therefore enough to just consider the signing - // behaviour of one of them - const Function &CF = OF.Candidates.front().getMF()->getFunction(); - bool ShouldSignReturnAddr = false; - if (CF.hasFnAttribute("sign-return-address")) { - StringRef Scope = - CF.getFnAttribute("sign-return-address").getValueAsString(); - if (Scope.equals("all")) - ShouldSignReturnAddr = true; - else if (Scope.equals("non-leaf") && !IsLeafFunction) - ShouldSignReturnAddr = true; - } - - // a_key is the default - bool ShouldSignReturnAddrWithAKey = true; - if (CF.hasFnAttribute("sign-return-address-key")) { - const StringRef Key = - CF.getFnAttribute("sign-return-address-key").getValueAsString(); - // Key can either be a_key or b_key - assert((Key.equals_lower("a_key") || Key.equals_lower("b_key")) && - "Return address signing key must be either a_key or b_key"); - ShouldSignReturnAddrWithAKey = Key.equals_lower("a_key"); - } - // If this is a tail call outlined function, then there's already a return. if (OF.FrameConstructionID == MachineOutlinerTailCall || - OF.FrameConstructionID == MachineOutlinerThunk) { - signOutlinedFunction(MF, MBB, ShouldSignReturnAddr, - ShouldSignReturnAddrWithAKey); + OF.FrameConstructionID == MachineOutlinerThunk) return; - } // It's not a tail call, so we have to insert the return ourselves. MachineInstr *ret = BuildMI(MF, DebugLoc(), get(AArch64::RET)) .addReg(AArch64::LR, RegState::Undef); MBB.insert(MBB.end(), ret); - signOutlinedFunction(MF, MBB, ShouldSignReturnAddr, - ShouldSignReturnAddrWithAKey); - // Did we have to modify the stack by saving the link register? if (OF.FrameConstructionID != MachineOutlinerDefault) return; |
