On Thu, 26 Feb 2026 09:20:19 GMT, Andrew Haley <[email protected]> wrote:
>> I was trying to use a similar structure to other `VSeq` methods, like
>> `vs_addv` for example. Could you say a bit more about why this other
>> approach would be preferable?
>
>> I was trying to use a similar structure to other VSeq methods, like vs_addv
>> for example.
>
> My comment applies to all such structures, not just these two.
>
>> Could you say a bit more about why this other approach would be preferable?
>
> There's the DRY principle: don't repeat yourself. We should be writing for
> the reader, who should not have to search to find out where the differences
> between two seemingly-identical are. That's where dangerous traps lie. These
> traps lead to failures in production.
>
> More profoundly, there's the matter of trying to get to a fundamental truth,
> by abstracting details so that the code expresses the common structure.
>
> Finally, there is the matter of the sheer number of lines of code. That's a
> burden to the maintainer. As Dijkstra put it, "we should not talk about the
> number of lines of code produced, but the number of lines of code used..."
> Think of poetry, rather than prose!
>
> To give you a more concrete idea of what I'm talking about, his is an
> assembler example that works well. First, we express the common structure,
> then we point out the minor differences.
>
>
> // Logical (immediate)
> #define INSN(NAME, decode, is32) \
> void NAME(Register Rd, Register Rn, uint64_t imm) { \
> starti; \
> uint32_t val = encode_logical_immediate(is32, imm); \
> f(decode, 31, 29), f(0b100100, 28, 23), f(val, 22, 10); \
> srf(Rd, 0), zrf(Rn, 5); \
> }
>
> INSN(andw, 0b000, true);
> INSN(orrw, 0b001, true);
> INSN(eorw, 0b010, true);
> INSN(andr, 0b100, false);
> INSN(orr, 0b101, false);
> INSN(eor, 0b110, false);
This all makes sense. Perhaps we could do a larger `VSeq` refactor in a
subsequent PR? @adinn also proposed some changes that would expand this
functionality to GPRs as well.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/27946#discussion_r2861442774
