RFR: 8283726: x86 intrinsics for compare method in Integer and Long

[Jatin Bhateja]

On Sun, 27 Mar 2022 06:15:34 GMT, Vamsi Parasa <duke at openjdk.java.net> wrote:

> Implements x86 intrinsics for compare() method in java.lang.Integer and java.lang.Long.

src/hotspot/cpu/x86/x86_64.ad line 12107:

> 12105: instruct compareSignedI_rReg(rRegI dst, rRegI op1, rRegI op2, rRegI tmp, rFlagsReg cr)
> 12106: %{
> 12107:   match(Set dst (CompareSignedI op1 op2));

Please also include these patterns in x86_32.ad

src/hotspot/cpu/x86/x86_64.ad line 12125:

> 12123: 	  __ movl(tmp, 0);
> 12124:     __ bind(done);
> 12125:     __ movl(dest, tmp);

Please move this in macro-assembly routine.

src/hotspot/cpu/x86/x86_64.ad line 12178:

> 12176: 	  __ movl(tmp, 0);
> 12177:     __ bind(done);
> 12178:     __ movl(dest, tmp);

Please move this into a macro-assembly routine.

src/hotspot/cpu/x86/x86_64.ad line 12204:

> 12202: 	  __ movl(tmp, 0);
> 12203:     __ bind(done);
> 12204:     __ movl(dest, tmp);

Please move this into macro-assembly routine.

src/hotspot/share/classfile/vmIntrinsics.hpp line 239:

> 237:   do_intrinsic(_compareUnsigned_i,        java_lang_Integer,      compare_unsigned_name,   int2_int_signature,   F_S)   \
> 238:    do_name(     compare_unsigned_name,                             "compareUnsigned")                                   \
> 239:   do_intrinsic(_compareUnsigned_l,        java_lang_Long,         compare_unsigned_name,   long2_int_signature,   F_S)  \

Creating these methods as intrinsic will create a box around the underneath comparison logic, this shall prevent any regular constant folding which could have optimized out certain control paths, I would suggest to to handle constant folding for newly added nodes in associated Value routines.

src/hotspot/share/opto/comparenode.hpp line 67:

> 65:     CompareUnsignedLNode(Node* in1, Node* in2) : CompareNode(in1, in2) {}
> 66:     virtual int Opcode() const;
> 67: };

Intent here seems to be to enable further auto-vectorization of newly create IR nodes.

test/micro/org/openjdk/bench/java/lang/CompareInteger.java line 78:

> 76:                     input2[i] = tmp;
> 77:                 }
> 78:             }

Logic re-organization suggestion:- 
 

 for (int i = 0 ; i < BUFFER_SIZE; i++) {
    input1[i] = rng.nextLong();
 }

 if (mode.equals("equals") {
    GRADIANT = 0;
 } else if (mode.equals("greaterThanEquals")) {
    GRADIANT = 1;
 } else {
    assert mode.equals("lessThanEqual");
    GRADIANT = -1;
 }

 for(int i = 0 ; i < BUFFER_SIZE; i++) {
    input2[i] = input1[i] + i*GRADIANT;
 }

test/micro/org/openjdk/bench/java/lang/CompareLong.java line 5:

> 3:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
> 4:  *
> 5:  * This code is free software; you can redistribute it and/or modify it

We can unify this benchmark along with integer compare micro.

-------------

PR: https://git.openjdk.java.net/jdk/pull/7975