clang 20 complains:
../src/amd/compiler/aco_assembler.cpp:837:28: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
837 | vaddr[num_vaddr + i] = reg(ctx, instr->operands.back(), 8) + i + 1;
| ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/amd/compiler/aco_assembler.cpp:832:12: note: at offset 5 into destination object ‘vaddr’ of size 5
832 | uint8_t vaddr[5] = {0, 0, 0, 0, 0};
| ^~~~~
../src/amd/compiler/aco_assembler.cpp:837:28: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
837 | vaddr[num_vaddr + i] = reg(ctx, instr->operands.back(), 8) + i + 1;
| ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/amd/compiler/aco_assembler.cpp:832:12: note: at offset 6 into destination object ‘vaddr’ of size 5
832 | uint8_t vaddr[5] = {0, 0, 0, 0, 0};
| ^~~~~
../src/amd/compiler/aco_assembler.cpp:837:28: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
837 | vaddr[num_vaddr + i] = reg(ctx, instr->operands.back(), 8) + i + 1;
| ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/amd/compiler/aco_assembler.cpp:832:12: note: at offset 7 into destination object ‘vaddr’ of size 5
832 | uint8_t vaddr[5] = {0, 0, 0, 0, 0};
| ^~~~~
But `i < MIN2(instr->operands.back().size() - 1, 5 - num_vaddr)` means `i` is
at most `5 - num_vaddr - 1`, which means `vaddr[num_vaddr + i]` =>
`vaddr[num_vaddr + 5 - num_vaddr - 1]` => `vaddr[5 - 1]` => `vaddr[4]` which
is within the valid indices.
For some reason, using signed `int` instead allows clang to figure this
out, so let's do that since we don't need the extra range.
While at it, use ARRAY_SIZE(vaddr) instead of hard-coding the same `5`
in several places.
Backport-to: 25.0
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34625>
Eric Engestrom
2bcb55f3f6