[MEMTAGABIELF64] Rewrite LDG as a logical operation - #412
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The `LDG(pointer)` operation is defined in terms of the runtime environment using the `ldg` instruction. In most cases using the ldg instruction will work on allocation tagged memory and untagged memory. However if the untagged memory cannot be read, such as when that memory is execute-only then `ldg` cannot be used. Rewrite `LDG(pointer) in terms of the underlying requirement which is that after the operation, `pointer` has the same logical tag as the allocation tag for *pointer. With memory that is not allocation tagged having a tag of 0000. fixes: ARM-software#411
DanielKristofKiss
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Aug 24, 2026
DanielKristofKiss
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DanielKristofKiss
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just a typo, otherwise LGTM
| - ``LDG(pointer)`` returns ``pointer`` with the correct logical tag | ||
| for the memory pointed to by ``pointer``. Memory without the | ||
| architectural memory attribute ``MemTag_AllocationTagged`` has a | ||
| logcal tag of ``0000``. For memory that is readable by the run-time |
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| logcal tag of ``0000``. For memory that is readable by the run-time | |
| logical tag of ``0000``. For memory that is readable by the run-time |
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Thanks for the spot, will fix.
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LDG(pointer)operation is defined in terms of the runtime environment using theldginstruction. In most cases using the ldg instruction will work on allocation tagged memory and untagged memory. However if the untagged memory cannot be read, such as when that memory is execute-only thenldgcannot be used.Rewrite
LDG(pointer) in terms of the underlying requirement which is that after the operation,pointer` has the same logical tag as the allocation tag for *pointer. With memory that is not allocation tagged having a tag of 0000.fixes: #411