================
@@ -622,6 +628,40 @@ class MCPlusBuilder {
return std::make_pair(getNoRegister(), getNoRegister());
}
+ /// Analyzes if a pointer is checked to be valid by the end of BB.
+ ///
+ /// It is possible for pointer authentication instructions not to terminate
+ /// the program abnormally on authentication failure and return some *invalid
+ /// pointer* instead (like it is done on AArch64 when FEAT_FPAC is not
+ /// implemented). This might be enough to crash on invalid memory access
+ /// when the pointer is later used as the destination of load/store or branch
+ /// instruction. On the other hand, when the pointer is not used right away,
+ /// it may be important for the compiler to check the address explicitly not
+ /// to introduce signing or authentication oracle.
+ ///
+ /// If this function returns a (Reg, Inst) pair, then it is known that in any
+ /// successor of BB either
+ /// * Reg is trusted, provided it was safe-to-dereference before Inst, or
+ /// * the program is terminated abnormally without introducing any signing
+ /// or authentication oracles
+ virtual std::optional<std::pair<MCPhysReg, MCInst *>>
----------------
kbeyls wrote:
Before reading the rest of this patch, I would guess that in theory there could
be multiple such (Reg, Inst) pairs in a single basic block? If so, should this
return a list/vector/... instead of an optional?
https://github.com/llvm/llvm-project/pull/134146
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