8346868: RISC-V: compiler/sharedstubs tests fail after JDK-8332689

[RealFYang]

Hi, please review this change.

Here is the change history. JDK-8293011 shared stubs to interpreter for static calls. And JDK-8293770 further reused runtime call trampolines. So we have static constexpr bool supports_shared_stubs() { return true; }. And both cases are handled in CodeBuffer::pd_finalize_stubs.

bool CodeBuffer::pd_finalize_stubs() {
  return emit_shared_stubs_to_interp<MacroAssembler>(this, _shared_stub_to_interp_requests)
         && emit_shared_trampolines(this, _shared_trampoline_requests);
}

Then JDK-8332689 turned off uses of trampolines for far calls by default and changed this function into: static bool supports_shared_stubs() { return UseTrampolines; }. This will cause the two test failures as option UseTrampolines is off by default. Further, JDK-8343430 removed old trampoline call and option UseTrampolines as well. So now we have static bool supports_shared_stubs() { return false; } and a simplified CodeBuffer::pd_finalize_stubs.

bool CodeBuffer::pd_finalize_stubs() {
  return emit_shared_stubs_to_interp<MacroAssembler>(this, _shared_stub_to_interp_requests);
}

But JDK-8332689 is supposed to only make reusing of the runtime call trampolines depend on option UseTrampolines. It should not affect the use of shared stubs to interpreter for static calls. So this restores CodeBuffer::pd_finalize_stubs letting it return true and disables SharedTrampolineTest.java test for this platform. Tagging @robehn.

Testing on Premier P550 SBC:

• SharedStubToInterpTest.java (fastdebug)
• Tier1-3 and gtest:all (release)

---

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Issue

• JDK-8346868: RISC-V: compiler/sharedstubs tests fail after JDK-8332689 (Bug - P4)

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