[next] SH: Use bitwise OR with mask for sign extension

[lhsazevedo]

Cherry pick of #2371 to next branch

[XVilka]

Though SH disassembler generates clang-tidy warnings:

/home/runner/work/capstone/capstone/arch/SH/SHDisassembler.c:102:9: warning: va_arg() is called on an uninitialized va_list [clang-analyzer-valist.Uninitialized]
                grp = va_arg(g, sh_insn_group);
                      ^
/usr/lib/llvm-14/lib/clang/14.0.0/include/stdarg.h:19:29: note: expanded from macro 'va_arg'
#define va_arg(ap, type)    __builtin_va_arg(ap, type)
                            ^~~~~~~~~~~~~~~~~~~~~~~~~~
/home/runner/work/capstone/capstone/arch/SH/SHDisassembler.c:100:9: note: Assuming 'n' is > 0
        while (n > 0) {
               ^~~~~
/home/runner/work/capstone/capstone/arch/SH/SHDisassembler.c:100:2: note: Loop condition is true.  Entering loop body
        while (n > 0) {
        ^
/home/runner/work/capstone/capstone/arch/SH/SHDisassembler.c:102:9: note: va_arg() is called on an uninitialized va_list
                grp = va_arg(g, sh_insn_group);
                      ^
/usr/lib/llvm-14/lib/clang/14.0.0/include/stdarg.h:19:29: note: expanded from macro 'va_arg'
#define va_arg(ap, type)    __builtin_va_arg(ap, type)
                            ^~~~~~~~~~~~~~~~~~~~~~~~~~
/home/runner/work/capstone/capstone/arch/SH/SHDisassembler.c:937:4: warning: Value stored to 'insn' is never read [clang-analyzer-deadcode.DeadStores]
                        insn = SH_INS_JMP;
                        ^      ~~~~~~~~~~
/home/runner/work/capstone/capstone/arch/SH/SHDisassembler.c:937:4: note: Value stored to 'insn' is never read
                        insn = SH_INS_JMP;
                        ^      ~~~~~~~~~~

cc @Rot127

[Rot127]

@lhsazevedo Please test it with clang-tidy-18. The CI Ubuntu only has version 14 or something. Which reports false positives for the va_args.
If everything is fine with clang-tidy-18 it can be ignored.

[lhsazevedo]

@Rot127 clang-tidy 18 also warns about uninitialized va_args. Perhaps it is a bug in clang-tidy?

/home/lhsazevedo/code/tweaking/capstone/arch/AArch64/AArch64Mapping.c:2162:14: warning: va_arg() is called on an uninitialized va_list [clang-analyzer-valist.Uninitialized]
 2162 |                 int Tile = va_arg(args, int);
/home/lhsazevedo/code/tweaking/capstone/arch/AArch64/AArch64Mapping.c:2211:18: warning: va_arg() is called on an uninitialized va_list [clang-analyzer-valist.Uninitialized]
 2211 |                 int8_t First = va_arg(args, int);
/home/lhsazevedo/code/tweaking/capstone/arch/SH/SHDisassembler.c:102:9: warning: va_arg() is called on an uninitialized va_list [clang-analyzer-valist.Uninitialized]
  102 |                 grp = va_arg(g, sh_insn_group);

There are more warnings for SHDisassembler, but they all seem to be unrelated to this change

[Rot127]

Sorry, those AArch64 ones can be ignored. I fixed them in the AArch64 update. Just check the SH one please.

[lhsazevedo]

@Rot127, I haven't had time to check the SH disassembler yet as the warnings are from a different part of the code. I'll get on it as soon as I can. Thanks for your patience!