RFR: 8290917: x86: Memory-operand arithmetic instructions have too low costs [v6]

[Vladimir Kozlov]

On Fri, 16 Sep 2022 05:33:59 GMT, Quan Anh Mai <duke at openjdk.org> wrote:

>> The pattern `AddI (LoadI mem) imm` should be matched by a load followed by an add with constant, instead, it is currently matched as a constant load followed by an add with memory. The reason is that the cost of `addI_rReg_mem` is too low, this patch fixes this by increasing the cost of this fused instruction.
>> 
>> Testing: Manually run the test case in the JBS and look at the compiled code.
>> 
>> I also do some small clean-ups in x86_64.ad:
>> 
>> - The `mulHiL` rules have unnecessary constraints on the input registers, these can be removed. The `no_rax_RegL` operand as a consequence can also be removed.
>> - The rules involving long division by a constant can be removed because it has been covered by the optimiser during idealisation.
>> - The pattern `SubI src imm` and the likes never match because they are converted to `AddI src -imm` by the optimiser. As a result, these rules can be removed
>> - The rules involving shifting the argument by 1 are covered by and exactly the same as the corresponding rules of shifting by an immediate. As a result, they can be removed.
>> - Some rules involving and-ing with a bit mask have unnecessary constraints on the target register.
>> 
>> Please kindly review, thank you very much.
>
> Quan Anh Mai has updated the pull request incrementally with one additional commit since the last revision:
> 
>   add jmhs

My testing passed.

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Marked as reviewed by kvn (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9791