8358655: AArch64: Simplify Interpreter::profile_taken_branch

[chadrako]

JDK-8358655

The aarch64 version of JDK-8357434

The counter is 64-bit, never practically overflows, and no other code cares about it so it is safe to remove

Additional Testing:

• Linux aarch64 fastdebug tier 1
• Linux aarch64 fastdebug tier 2
• Linux aarch64 fastdebug tier 3
• Linux aarch64 fastdebug tier 4

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8358655: AArch64: Simplify Interpreter::profile_taken_branch (Enhancement - P4)

Reviewers

• Andrew Haley (@theRealAph - Reviewer) 🔄 Re-review required (review applies to ae31d0fb)
• Aleksey Shipilev (@shipilev - Reviewer) 🔄 Re-review required (review applies to ae31d0fb)

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/25906/head:pull/25906
$ git checkout pull/25906

Update a local copy of the PR:
$ git checkout pull/25906
$ git pull https://git.openjdk.org/jdk.git pull/25906/head

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Checkout this PR locally:
$ git pr checkout 25906

View PR using the GUI difftool:
$ git pr show -t 25906

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Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/25906.diff

Using Webrev

Link to Webrev Comment

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[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (c2d5ef37)
• 00: Full (ae31d0fb)

[shipilev]

Looks fine. I also think r1 saves are now unnecessary, right, @theRealAph?

    // ECN: FIXME: This code smells
    // check if MethodCounters exists
    Label has_counters;
    __ ldr(rscratch1, Address(rmethod, Method::method_counters_offset()));
    __ cbnz(rscratch1, has_counters);
    __ push(r0);
    __ push(r1); // <--- here
    __ push(r2);
    __ call_VM(noreg, CAST_FROM_FN_PTR(address,
            InterpreterRuntime::build_method_counters), rmethod);
    __ pop(r2);
    __ pop(r1);  // <--- here
    __ pop(r0);

[theRealAph]

Looks fine. I also think r1 saves are now unnecessary, right, @theRealAph?

    // ECN: FIXME: This code smells
    // check if MethodCounters exists
    Label has_counters;
    __ ldr(rscratch1, Address(rmethod, Method::method_counters_offset()));
    __ cbnz(rscratch1, has_counters);
    __ push(r0);
    __ push(r1); // <--- here
    __ push(r2);
    __ call_VM(noreg, CAST_FROM_FN_PTR(address,
            InterpreterRuntime::build_method_counters), rmethod);
    __ pop(r2);
    __ pop(r1);  // <--- here
    __ pop(r0);

I thinks so, but at a first glance r1 seems to be clobbered on all code paths immediately after this, so I don't think it's needed anyway,