RFR: 8293618: x86: Wrong code generation in class Assembler

[Vladimir Kozlov]

On Mon, 12 Sep 2022 15:30:01 GMT, Quan Anh Mai <duke at openjdk.org> wrote:

> Hi,
> 
> This patch fixes some issues in the code generation of x86 assembler:
> 
> - `Assembler::testl` misses `prefix(dst)`
> - `Assembler::addw` misses the 0x66 prefix
> - `Assembler::emit_operand` needs the length of the instruction from the address operand, this is often forgotten, making this parameter explicit to prevent potential issues
> - The assembler should not do optimisations that change the actual emitted instructions, these should be moved to `MacroAssembler` instead
> 
> AFAICT there is no failure due to these mistakes. Please take a look and give reviews.
> Thanks you very much.

Seems reasonable. I will test it.

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PR: https://git.openjdk.org/jdk/pull/10240