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ARM64: optimize PREPARE_EXTERNAL_VAR (#21)#8296
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There are multiple cases were we don't need just the pointer for an external variable but the value that is stored at this location. So far this was done with the PREPARE_EXTERNAL_VAR followed by an ldr x? [x?]. The PREPARE_EXTERNAL_VAR macro needs two instructions (adrp + add). As the ldr instruction supports an offset we can eliminate the add for this use case. The two new macros PREPARE_EXTERNAL_VAR_INDIRECT and PREPARE_EXTERNAL_VAR_INDIRECT_W make use of this.
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I know this might be some unnecessary over optimizing but if we already use assembler for these helpers saving some more cycles might not be worst we can do. |
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There are multiple cases were we don't need just the pointer for an external variable but the value that is stored at this location.
So far this was done with the PREPARE_EXTERNAL_VAR followed by an ldr x? [x?]. The PREPARE_EXTERNAL_VAR macro needs two instructions (adrp + add). As the ldr instruction supports an offset we can eliminate the add for this use case. The two new macros PREPARE_EXTERNAL_VAR_INDIRECT and PREPARE_EXTERNAL_VAR_INDIRECT_W make use of this.