> Found while working on JDK-8369699. > > In general, the Vector API documentation is a bit vague around part numbers. > There was considerable confusion around expansion/contraction: are we talking > about logical, physical or output expansion/contraction? Confusingly, in some > places we called expansions things that go from more to fewer bits, and we > called contractions that went from fewer to more bits. > > And exception messages are not very helpful, for example they don't provide > the legal range. > > @rose00 took a first stab at improving things > (https://github.com/openjdk/jdk/pull/29306), and I eventually took over the > project. > > -------------------------------------- > > Principles: > - Expansion means fewer->more bits. > - Contraction means more->fewer bits. > - Be clear about input, logical result and output. > - We primarily use: > - conversion lanewise expansion (logical) > - conversion lanewise contraction (logical) > - conversion lanewise in-place (logical) > - reinterpret (logical) > - select, for truncation (output) > - insert, for padding (output) > - in-place, logical fits output (output) > > Please review this PR in this order: > - Changes in the "Expansions, contractions, and partial results" section of > `Vector.java`. We must first agree on the definitions here, before we go and > disagree elsewhere ;) > - Changes in affected methods `convertShape`, `convert`, and > `reinterpretShape`. > - Internal changes in `AbstractVector.java`: adjust nomenclature and > exception message. > - New test. I think it is necessary, I caught some mistakes I made. And when > I wanted to add tests for `unslice` I realized that it does not throw for out > of bounds `part`. So I think it is justified. > > In general, I'm a bit worried that the documentation is a bit too long, and > feels a bit heavy/overwhelming. > To a large degree, this is due to the complexity of part numbers. > We could drop some paragraphs and some repetition. Let me know what you think > is too much. > More explanations may help make things clearer, but also risk being too much > and overwhelming. > I'm open to cut things down more, and any other constructive suggestions ;) > > ----------------------- > > While reading the documentation and testing for `unslice`, I found out that > https://github.com/openjdk/jdk/pull/3804 accidentally removed the bounds > checks for `part`. But we did not notice, because there were no tests for it. > I'm adding the bounds check back in and adding tests for it as well.
Emanuel Peter has updated the pull request incrementally with one additional commit since the last revision: fix small issues, by Paul ------------- Changes: - all: https://git.openjdk.org/jdk/pull/30113/files - new: https://git.openjdk.org/jdk/pull/30113/files/0eda6a9b..f71b3008 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=30113&range=05 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=30113&range=04-05 Stats: 7 lines in 1 file changed: 0 ins; 0 del; 7 mod Patch: https://git.openjdk.org/jdk/pull/30113.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/30113/head:pull/30113 PR: https://git.openjdk.org/jdk/pull/30113
