[aarch64-port-dev ] RFR: 88158361: AArch64: Address calculation missed optimizations

[Andrew Haley]

On 23/06/17 10:50, Zhongwei Yao wrote:
> Hi, Andrew,
> 
> Besides pass jtreg on aarch64 and x86, for each pattern, I added one or two
> test cases, which will hit the testing pattern. And check the test cases'
> assembly output to ensure the hit pattern generates correct instructions.
> 
> Here is a test case for: AddExtL_uxtb_and_shift pattern:
> 
> // testrule: AddExtL_uxtb_and_shift
> // geninst: add.*x.*, x.*, w.*, uxtb #3
> public Flonglong adduxtb = new Flonglong() {
> public long func(long x, long y) {
> return y + ((x & 255) << 3);
> }
> };
> 
> And the "geninst" line defines this case's required generated assembly
> instruction pattern.
> 
> A script will check whether this case's generated C2 assembly has the
> required instruction "add.*x.*, x.*, w.*, uxtb #3". If yes, the test
> passes. And if there is a "nosense" on "// testrule" line, such check is
> skipped.
> 
> All test cases are at http://cr.openjdk.java.net/~njian/8158361/ExtTest.java

This looks great, just one problem.

I'm seeing this with current JDK10 HotSpot:

  0x000003ff95285b64: and	x10, x2, #0xff
  0x000003ff95285b68: add	x0, x3, x10, lsl #3  ;*ladd {reexecute=0 rethrow=0 return_oop=0}
                                                ; - ExtTest$1::func at 8 (line 25)

This happens in three of the patterns.

    public Flonglong adduxtb = new Flonglong() {
        public long func(long x, long y) {
            return y + ((x & 255) << 3);
        }
    };

    public Flonglong adduxtb2 = new Flonglong() {
       public long func(long x, long y) {
           return y + (((x << 56) >>> 56) << 4);
       }
    };

    public Flonglong subuxtb2 = new Flonglong() {
       public long func(long x, long y) {
           return y - (((x << 56) >>> 56) << 4);
       }
    };

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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