AArch64: Deprecate -mpc-relative-literal-loads.
The option `-mpc-relative-literal-loads` is now deprecated for AArch64 due to issues with special symbols in the text section.
The -mpc-relative-literal-loads option for AArch64 is now deprecated. Emitting special symbols in the text section can cause issues, and given that GCC now uses anchors for literals, this relatively obscure option is no longer necessary. Users employing this option will now receive a deprecation warning.
In Details
The -mpc-relative-literal-loads option controlled whether the compiler emitted special symbols in the text section for PC-relative literal loads. The motivation for deprecation is PR123791 regarding issues caused by these special symbols. GCC now uses anchors, making the option redundant.
For Context
This commit deprecates a specific compiler option (-mpc-relative-literal-loads) for the AArch64 architecture. This option affected how the compiler handled loading constant values, but it introduced issues with how code was laid out in memory. Since the compiler now uses a different, more reliable method for handling these loads, the old option is no longer needed and is being removed to simplify the compiler and avoid potential problems.