Thursday, September 12, 2024 Martin Storsjö <mar...@martin.st> wrote:
> This looks very reasonable - I presume this will make sure that you only > use the other code form if the offset actually is larger than 1 MB. > > For the case when the offset actually is larger than 1 MB, I guess this > also ends up generating some other instruction sequence than just a "add > x0, x0, #imm", as the #imm is limited to <= 4096. From reading the code, > it looks like it generates something like "mov x16, #imm; add x0, x0, > x16"? That's probably quite reasonable. The generated code will stay unchanged for the offset less than 1MB: adrp x0, symbol + offset add x0, x0, :lo12:symbol + offset When the offset is >= 1MB: adrp x0, symbol + offset % (1 << 20) // it prevents relocation overflow in IMAGE_REL_ARM64_PAGEBASE_REL21 add x0, x0, (offset & ~0xfffff) >> 12, lsl #12 // a workaround to support 4GB offset add x0, x0, :lo12:symbol + offset % (1 << 20) Regards, Evgeny
