RFR: 8301739: AArch64: Add optimized rules for vector compare with immediate for SVE

[Andrew Haley]

On Tue, 28 Mar 2023 02:06:41 GMT, Chang Peng <duke at openjdk.org> wrote:

> We can use SVE compare-with-integer-immediate instructions like cmpgt(immediate)[1] to avoid the extra scalar2vector operations.
> 
> The following instruction sequence
> 
> 
> movi    v17.16b, #12
> cmpgt   p0.b, p7/z, z16.b, z17.b
> 
> 
> can be optimized to:
> 
> 
> cmpgt   p0.b, p7/z, z16.b, #12
> 
> 
> This patch does the following:
> 1. Add SVE compare-with-7bit-unsigned-immediate instructions to C2's backend.
> SVE cmp<cc>(immediate) instructions can support vector comparing with 7bit unsigned integer immediate (range from 0 to 
> 127)or 5bit signed integer immediate (range from -16 to 15).
> 
> 2. Add optimized match rules to generate the compare-with-immediate instructions.
> 
> [1]: https://developer.arm.com/documentation/ddi0596/2021-12/SVE-Instructions/CMP-cc---immediate---Compare-vector-to-immediate-

src/hotspot/cpu/aarch64/aarch64.ad line 4328:

> 4326: operand immI_cmpU_cond()
> 4327: %{
> 4328:   predicate(n->get_int() > (int)(BoolTest::unsigned_compare));

This function is in x86.ad. I suggest you move it to shared code, then use it here.

static inline bool is_unsigned_booltest_pred(int bt) {
  return  ((bt & BoolTest::unsigned_compare) == BoolTest::unsigned_compare);
}

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

PR Review Comment: https://git.openjdk.org/jdk/pull/13200#discussion_r1162473468