When RUBY_DEBUG is enabled, shape ids are 16 bits. I would like to do 16 bit comparisons, so I need to load halfwords sometimes. This commit adds LDURH so that I can load halfwords. https://developer.arm.com/documentation/ddi0596/2021-12/Base-Instructions/LDURH--Load-Register-Halfword--unscaled--?lang=en I verified the bytes using clang: ``` $ cat asmthing.s .global _start .align 2 _start: ldurh w10, [x1] ldurh w10, [x1, #123] $ as asmthing.s -o asmthing.o && objdump --disassemble asmthing.o asmthing.o: file format mach-o arm64 Disassembly of section __TEXT,__text: 0000000000000000 <ltmp0>: 0: 2a 00 40 78 ldurh w10, [x1] 4: 2a b0 47 78 ldurh w10, [x1, #123] ```