RFR: 8289046: Undefined Behaviour in x86 class Assembler [v4]

[Andrew Haley]

On Mon, 4 Jul 2022 10:32:51 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Andrew Haley has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   More
>
> src/hotspot/share/code/vmreg.hpp line 90:
> 
>> 88:   }
>> 89:   intptr_t value() const { return this - first(); }
>> 90:   static VMReg Bad() { return BAD_REG+first(); }
> 
> I was confused as to why is it `+first()`. We can probably do: `return as_VMReg(BAD_REG, true);`?

> I believe there are some compiler directives somewhere to silent the compiler of `nullptr` dereference, should we delete those also?

It depends on exactly what they are. I'll have a look.

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PR: https://git.openjdk.org/jdk/pull/9261