RFR: 8276314: [JVMCI] check alignment of call displacement during code installation

[Tom Rodriguez]

On Wed, 3 Nov 2021 16:39:22 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> It's deeply hidden.  in x86_64.ad, it specifies the call alignment as [4](https://github.com/tkrodriguez/jdk/blob/master/src/hotspot/cpu/x86/x86_64.ad#L13028) and in [compute_padding](https://github.com/tkrodriguez/jdk/blob/master/src/hotspot/cpu/x86/x86_64.ad#L493) it uses that alignment value to align the offset of the displacement.
>
> Should we fix C1 and JVMCI to do the same as C2? As separate RFE.

There's nothing to fix on the JVMCI side other than ensuring that we're asserting the correct alignment restrictions.  Reducing the alignment to 4 instead of 8 would be a pure Graal change.

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PR: https://git.openjdk.java.net/jdk/pull/6218