Integrated: 8286314: Trampoline not created for far runtime targets outside small CodeCache

[Evgeny Astigeevich]

On Wed, 22 Jun 2022 11:50:36 GMT, Evgeny Astigeevich <duke at openjdk.org> wrote:

> `relocInfo::runtime_call_type` calls can have targets inside or outside CodeCache. If offsets to the targets are not in range, trampoline calls must be used. Currently trampolines for calls are generated based on the size of CodeCache and the maximum possible branch range. If the size of CodeCache is smaller than the range, no trampoline is generated. This works well if a target is inside CodeCache. It does not work if a target is outside CodeCache and CodeCache size is smaller than the maximum possible branch range.
> 
> ### Solution
> Runtime call sites are always in CodeCache. In case of a target outside small CodeCache, we can find the start of the longest possible branch from CodeCache. Then we check with `reachable_from_branch_at` whether a target is reachable. If not, a trampoline is needed.
> 
> ### Testing
> It is tested with the release and fastdebug builds. Release builds have the maximum possible branch range 128M. Fastdebug builds have it 2M for the purpose of testing trampolines.
> Results:
> - `gtest`: Passed
> - `tier1`: Passed

This pull request has now been integrated.

Changeset: bf0623b1
Author:    Evgeny Astigeevich <eastig at amazon.com>
Committer: Andrew Haley <aph at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/bf0623b11fd95f09fe953822af71d965bdab8d0f
Stats:     17 lines in 1 file changed: 15 ins; 0 del; 2 mod

8286314: Trampoline not created for far runtime targets outside small CodeCache

Reviewed-by: aph, phh

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PR: https://git.openjdk.org/jdk/pull/9235