On Wed, 22 Jun 2022 03:01:36 GMT, Quan Anh Mai <[email protected]> wrote:
>> Hi,
>>
>> This patch implements intrinsics for `Integer/Long::compareUnsigned` using
>> the same approach as the JVM does for long and floating-point comparisons.
>> This allows efficient and reliable usage of unsigned comparison in Java,
>> which is a basic operation and is important for range checks such as
>> discussed in #8620 .
>>
>> Thank you very much.
>
> Quan Anh Mai has updated the pull request incrementally with one additional
> commit since the last revision:
>
> add comparison for direct value of compare
src/hotspot/cpu/x86/x86_64.ad line 13027:
> 13025: // Manifest a CmpU result in an integer register. Very painful.
> 13026: // This is the test to avoid.
> 13027: instruct cmpU3_reg_reg(rRegI dst, rRegI src1, rRegI src2, rFlagsReg
> flags)
Do you plan to add 32 bit support?
Integer pattern can be moved to common file x86.ad and 64 pattern can handled
in 32/64 bit AD files.
src/hotspot/cpu/x86/x86_64.ad line 13043:
> 13041: __ cmpl($src1$$Register, $src2$$Register);
> 13042: __ movl($dst$$Register, -1);
> 13043: __ jccb(Assembler::below, done);
By placing compare adjacent to conditional jump in-order frontend can trigger
macro-fusion.
Kindly refer section 3.4.2.2 of Intel's optimization manual.
src/hotspot/cpu/x86/x86_64.ad line 13095:
> 13093: __ cmpq($src1$$Register, $src2$$Register);
> 13094: __ movl($dst$$Register, -1);
> 13095: __ jccb(Assembler::below, done);
Same as above.
src/hotspot/share/opto/subnode.hpp line 185:
> 183: }
> 184: virtual int Opcode() const;
> 185: virtual uint ideal_reg() const { return Op_RegI; }
Value routine to handle constant folding.
src/hotspot/share/opto/subnode.hpp line 247:
> 245: init_class_id(Class_Sub);
> 246: }
> 247: virtual int Opcode() const;
In-lining may connect the inputs to constant, hence a Value routine may be
useful here.
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PR: https://git.openjdk.org/jdk/pull/9068
