RFR: 8308293: A linker should expose the layouts it supports [v5]

[ExE Boss]

On Wed, 24 May 2023 09:22:08 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> This patch adds an instance method on `Linker`, namely `Linker::canonicalLayouts` which returns all the layouts known by the linker as implementing some ABI type. For instance, if I call this on my machine (Linux/x64) I get this:
>> 
>> 
>> jshell> import java.lang.foreign.*;
>> 
>> jshell> Linker.nativeLinker().canonicalLayouts()
>> $2 ==> {char16_t=c16, int8_t=b8, long=j64, size_t=j64, bool=z8, int=i32, long long=j64, int64_t=j64, void*=a64, float=f32, char=b8, int16_t=s16, int32_t=i32, short=s16, double=d64}
>> 
>> 
>> This can be useful to discover the ABI types supported by a linker implementation, as well as for, in the future, add support for more exotic (and platform-dependent) linker types, such as `long double` or `complex long`.
>
> Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Drop "unsigned short"
>   Beef up javadoc

test/jdk/java/foreign/normalize/TestNormalize.java line 169:

> 167:             { JAVA_BOOLEAN, booleanToInt(true),     BOOLEAN_HOB_MASK, BOOLEAN_TO_INT, SAVE_BOOLEAN_AS_INT },
> 168:             { JAVA_BYTE,    byteToInt((byte) 42),   BYTE_HOB_MASK,    BYTE_TO_INT,    SAVE_BYTE_AS_INT    },
> 169:             { JAVA_SHORT,   shortToInt((short) 42), SHORT_HOB_MASK,   SHORT_TO_INT,   SAVE_SHORT_AS_INT   }

Since arrays support trailing commas, this can use that:
Suggestion:

            { JAVA_SHORT,   shortToInt((short) 42), SHORT_HOB_MASK,   SHORT_TO_INT,   SAVE_SHORT_AS_INT   },

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PR Review Comment: https://git.openjdk.org/jdk/pull/14037#discussion_r1204774626