RFR: 8311847: Fix -Wconversion for assembler.hpp emit_int8,16 callers

[Dean Long]

On Tue, 11 Jul 2023 01:26:44 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Please review changes to fix -Wconversion warnings that come from assembler_<cpu>.cpp by adding narrow_casts to the emit_int8,16,24, and 32 functions.  And some other fixups with checked_cast.
> 
> Ran tier1 on Oracle platforms, and tier1-4 on linux-x64-debug, linux-aarch64-debug, windows-x64-debug.

src/hotspot/cpu/aarch64/assembler_aarch64.hpp line 265:

> 263:     int64_t chk = val >> (nbits - 1);
> 264:     guarantee (chk == -1 || chk == 0, "Field too big for insn");
> 265:     uint64_t uval = val;

Suggestion:

    unsigned uval = checked_cast<unsigned>((uint64_t)val);

src/hotspot/cpu/aarch64/assembler_aarch64.hpp line 268:

> 266:     unsigned mask = checked_cast<unsigned>(right_n_bits(nbits));
> 267:     uval &= mask;
> 268:     f(checked_cast<unsigned>(uval), lsb + nbits - 1, lsb);

Suggestion:

    f(uval, lsb + nbits - 1, lsb);

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/14822#discussion_r1259096829
PR Review Comment: https://git.openjdk.org/jdk/pull/14822#discussion_r1259097036