================
@@ -562,35 +562,55 @@ class MCPlusBuilder {
return {};
}
- virtual ErrorOr<MCPhysReg> getAuthenticatedReg(const MCInst &Inst) const {
- llvm_unreachable("not implemented");
- return getNoRegister();
- }
-
- virtual bool isAuthenticationOfReg(const MCInst &Inst,
- MCPhysReg AuthenticatedReg) const {
+ /// Returns the register where an authenticated pointer is written to by
Inst,
+ /// or std::nullopt if not authenticating any register.
+ ///
+ /// Sets IsChecked if the instruction always checks authenticated pointer,
+ /// i.e. it either writes a successfully authenticated pointer or terminates
+ /// the program abnormally (such as "ldra x0, [x1]!" on AArch64, which
crashes
+ /// on authentication failure even if FEAT_FPAC is not implemented).
+ virtual std::optional<MCPhysReg>
+ getWrittenAuthenticatedReg(const MCInst &Inst, bool &IsChecked) const {
llvm_unreachable("not implemented");
- return false;
+ return std::nullopt;
}
- virtual MCPhysReg getSignedReg(const MCInst &Inst) const {
+ /// Returns the register signed by Inst, or std::nullopt if not signing any
+ /// register.
+ ///
+ /// The returned register is assumed to be both input and output operand,
+ /// as it is done on AArch64.
+ virtual std::optional<MCPhysReg> getSignedReg(const MCInst &Inst) const {
llvm_unreachable("not implemented");
- return getNoRegister();
+ return std::nullopt;
}
- virtual ErrorOr<MCPhysReg> getRegUsedAsRetDest(const MCInst &Inst) const {
+ /// Returns the register used as a return address. Returns std::nullopt if
+ /// not applicable, such as reading the return address from a system register
+ /// or from the stack.
+ ///
+ /// Sets IsAuthenticatedInternally if the instruction accepts a signed
+ /// pointer as its operand and authenticates it internally.
+ ///
+ /// Should only be called when isReturn(Inst) is true.
+ virtual std::optional<MCPhysReg>
+ getRegUsedAsRetDest(const MCInst &Inst,
+ bool &IsAuthenticatedInternally) const {
llvm_unreachable("not implemented");
- return getNoRegister();
+ return std::nullopt;
}
/// Returns the register used as the destination of an indirect branch or
call
/// instruction. Sets IsAuthenticatedInternally if the instruction accepts
/// a signed pointer as its operand and authenticates it internally.
+ ///
+ /// Should only be called if isIndirectCall(Inst) or isIndirectBranch(Inst)
+ /// returns true.
virtual MCPhysReg
getRegUsedAsIndirectBranchDest(const MCInst &Inst,
bool &IsAuthenticatedInternally) const {
llvm_unreachable("not implemented");
- return getNoRegister();
+ return 0;
----------------
kbeyls wrote:
I'm trying to understand why returning `0` is better than `getNoRegister()`
here?
I don't have a strong opinion, just that I'm not immediately seeing why `0`
would be better?
https://github.com/llvm/llvm-project/pull/136147
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