[jdk18] RFR: 8272058: 25 Null pointer dereference defect groups in 4 files

[Boris Ulasevich]

On Mon, 20 Dec 2021 20:50:14 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

> A small refactoring to resolve a Parfait complaint about the return value from
> `MacroAssembler::target_addr_for_insn(address insn_addr, unsigned insn)`
> on AARCH64. The logic that supports returning `nullptr` as the target addr for
> a particular instruction is moved from
> `MacroAssembler::target_addr_for_insn(address insn_addr, unsigned insn)` to
> `MacroAssembler::target_addr_for_insn_allow_null_ret(address insn_addr, unsigned insn)`.
> A couple of `target_addr_for_insn()` call sites that can tolerate a `nullptr` are
> converted to use `target_addr_for_insn_allow_null_ret()`.
> 
> This fix has been tested with Mach5 Tier[1-3].

src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp line 293:

> 291: 
> 292: address MacroAssembler::target_addr_for_insn_allow_null_ret(address insn_addr, unsigned insn) {
> 293:   if (Instruction_aarch64::extract(insn, 31, 22) == 0b1011100101 &&

Consider replacing raw constants check with NativeInstruction::is_ldrw_to_zr function call which performs the same check.

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PR: https://git.openjdk.java.net/jdk18/pull/51