Integrated: 8291752: AArch64: Remove check_emit_size parameter from trampoline_call

[Evgeny Astigeevich]

On Fri, 5 Aug 2022 16:59:08 GMT, Evgeny Astigeevich <duke at openjdk.org> wrote:

> `MacroAssembler::trampoline_call` can skip generation of a trampoline stub if C2 phase output is in the checking emitted code size mode. If it is not C2 compilation, `trampoline_call` always generates a trampoline stub. 
> 
> `gen_continuation_enter` as a part of C2 compilation needed to disable the functionality above. Now `trampoline_call` has the `check_emit_size` which allows to disable the functionality completely. Its default value is `true` which means the functionality is enabled.
> 
> There are problems:
> - C2 specific code which must be properly guarded if it is not C2 compilation. The code has the risk of undefined behaviour (UB). It is done with `is_c2_compile`. [JDK-8291654](https://bugs.openjdk.org/browse/JDK-8291654) is an example of changes caused UB.
> - The default value of `check_emit_size`. The current value `true` allows C1 to access the C2 specific code. Setting the default value to `false` will require to review and to update every existing use of `trampoline_call`. It will complicate uses of `trampoline_call`: each time a decision needs to be done - use or not use the default.
> 
> Summary of changes:
> - Have a virtual `in_scratch_emit_size` returning `false` by default. It is privately overridden in `C2_MacroAssembler`. The overridden  version returns `true` if C2 phase output is in the checking emitted code size mode.
> - `check_emit_size` is removed because it is not needed any more.
> 
> Tested with fastdebug/release builds:
> - `gtest`: Passed.
> - `tier1`...`tier4`: Passed.

This pull request has now been integrated.

Changeset: cb37282a
Author:    Evgeny Astigeevich <eastig at amazon.com>
Committer: Volker Simonis <simonis at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/cb37282a12698ae66c27889db9251a5b278624b0
Stats:     48 lines in 5 files changed: 24 ins; 15 del; 9 mod

8291752: AArch64: Remove check_emit_size parameter from trampoline_call

Reviewed-by: kvn, aph

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PR: https://git.openjdk.org/jdk/pull/9782