[foreign-memaccess+abi] RFR: 8308293: A linker should expose the layouts it supports

[Maurizio Cimadamore]

On Thu, 15 Jun 2023 16:31:09 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> For the fallback linker I agree, but for the other platforms, it seems that only the layout of `long` and `size_t` changes? I was thinking something like:
>> 
>> 
>> static Map<String, MemoryLayout> makeCanonicalLayouts(ValueLayout longLayout, ValueLayout sizeTLayout) {
>>     return Map.ofEntries(
>>             // specified canonical layouts
>>             Map.entry("bool", ValueLayout.JAVA_BOOLEAN),
>>             Map.entry("char", ValueLayout.JAVA_BYTE),
>>             Map.entry("short", ValueLayout.JAVA_SHORT),
>>             Map.entry("int", ValueLayout.JAVA_INT),
>>             Map.entry("float", ValueLayout.JAVA_FLOAT),
>>             Map.entry("long", longLayout),
>>             Map.entry("long long", ValueLayout.JAVA_LONG),
>>             Map.entry("double", ValueLayout.JAVA_DOUBLE),
>>             Map.entry("void*", ValueLayout.ADDRESS),
>>             Map.entry("size_t", sizeTLayout),
>>             // unspecified size-dependent layouts
>>             Map.entry("int8_t", ValueLayout.JAVA_BYTE),
>>             Map.entry("int16_t", ValueLayout.JAVA_SHORT),
>>             Map.entry("int32_t", ValueLayout.JAVA_INT),
>>             Map.entry("int64_t", ValueLayout.JAVA_LONG),
>>             // unspecified JNI layouts
>>             Map.entry("jboolean", ValueLayout.JAVA_BOOLEAN),
>>             Map.entry("jchar", ValueLayout.JAVA_CHAR),
>>             Map.entry("jbyte", ValueLayout.JAVA_BYTE),
>>             Map.entry("jshort", ValueLayout.JAVA_SHORT),
>>             Map.entry("jint", ValueLayout.JAVA_INT),
>>             Map.entry("jlong", ValueLayout.JAVA_LONG),
>>             Map.entry("jfloat", ValueLayout.JAVA_FLOAT),
>>             Map.entry("jdouble", ValueLayout.JAVA_DOUBLE)
>>     );
>> }
>> 
>> 
>> Then each linker can have:
>> 
>> 
>> private static final ValueLayout C_LONG = ...
>> private static final ValueLayout C_SIZE_T = ...
>> private static final Map<String, MemoryLayout> CANONICAL_LAYOUTS_MAP = SharedUtils.makeCanonicalLayouts(C_LONG, C_SIZE_T);
>> 
>> @Override
>> public Map<String, MemoryLayout> canonicalLayouts() {
>>     return CANONICAL_LAYOUTS_MAP;
>>  }
>
> And then the fallback linker could do it's own thing.

ok - I can try that

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PR Review Comment: https://git.openjdk.org/panama-foreign/pull/839#discussion_r1231308329