Skip to content

Comments

feat: add support for ARMv7 pointers#23

Open
cfung89 wants to merge 2 commits intoRubixDev:mainfrom
cfung89:feat_addresses
Open

feat: add support for ARMv7 pointers#23
cfung89 wants to merge 2 commits intoRubixDev:mainfrom
cfung89:feat_addresses

Conversation

@cfung89
Copy link
Contributor

@cfung89 cfung89 commented Nov 1, 2025

Hello, I found several errors regarding pointers in ARMv7 (or missing features). Here are several examples underlining the different issues that I have attempted to solve.

For LDR A3, [A1, V2]:

Before:

(program ; [0, 0] - [1, 0]
  (instruction ; [0, 0] - [0, 16]
    kind: (word) ; [0, 0] - [0, 3]
    (ident ; [0, 4] - [0, 6]
      (reg ; [0, 4] - [0, 6]
        (word))) ; [0, 4] - [0, 6]
    (ptr ; [0, 8] - [0, 16]
      (ERROR ; [0, 9] - [0, 12]
        (reg ; [0, 9] - [0, 11]
          (word))) ; [0, 9] - [0, 11]
      (reg ; [0, 13] - [0, 15]
        (word))))) ; [0, 13] - [0, 15]

After:

(program ; [0, 0] - [1, 0]
  (instruction ; [0, 0] - [0, 16]
    kind: (word) ; [0, 0] - [0, 3]
    (ident ; [0, 4] - [0, 6]
      (reg ; [0, 4] - [0, 6]
        (word))) ; [0, 4] - [0, 6]
    (ptr ; [0, 8] - [0, 16]
      (reg ; [0, 9] - [0, 11]
        (word)) ; [0, 9] - [0, 11]
      (reg ; [0, 13] - [0, 15]
        (word))))) ; [0, 13] - [0, 15]

Here, only integers were expected in the second argument of the pointer, whereas other registers are also aloud too.

For LDR A3, [A1, V2, LSL#2]:

Before:

(program ; [0, 0] - [1, 0]
  (instruction ; [0, 0] - [0, 7]
    kind: (word) ; [0, 0] - [0, 3]
    (ident ; [0, 4] - [0, 6]
      (reg ; [0, 4] - [0, 6]
        (word)))) ; [0, 4] - [0, 6]
  (ERROR ; [0, 8] - [1, 0]
    (reg ; [0, 9] - [0, 11]
      (word)) ; [0, 9] - [0, 11]
    (word) ; [0, 13] - [0, 15]
    (word) ; [0, 17] - [0, 20]
    (line_comment))) ; [0, 20] - [0, 23]

After:

(program ; [0, 0] - [1, 0]
  (instruction ; [0, 0] - [0, 23]
    kind: (word) ; [0, 0] - [0, 3]
    (ident ; [0, 4] - [0, 6]
      (reg ; [0, 4] - [0, 6]
        (word))) ; [0, 4] - [0, 6]
    (ptr ; [0, 8] - [0, 23]
      (reg ; [0, 9] - [0, 11]
        (word)) ; [0, 9] - [0, 11]
      (reg ; [0, 13] - [0, 15]
        (word)) ; [0, 13] - [0, 15]
      (instruction ; [0, 17] - [0, 20]
        kind: (word)) ; [0, 17] - [0, 20]
      (int)))) ; [0, 20] - [0, 22]

Here, LSL was considered as a register, and #2 as a comment, whereas LSL should be an instruction and #2 should be an integer. This is an ARMv7 feature used to shift the offset of a pointer (if present, the third argument is always some shift instruction followed by an integer).

For: LDR A3, [A2], V3, LSL#2

Before:

(program ; [0, 0] - [1, 0]
  (instruction ; [0, 0] - [0, 21]
    kind: (word) ; [0, 0] - [0, 3]
    (ident ; [0, 4] - [0, 6]
      (reg ; [0, 4] - [0, 6]
        (word))) ; [0, 4] - [0, 6]
    (ptr ; [0, 8] - [0, 12]
      (reg ; [0, 9] - [0, 11]
        (word))) ; [0, 9] - [0, 11]
    (ident ; [0, 14] - [0, 16]
      (reg ; [0, 14] - [0, 16]
        (word))) ; [0, 14] - [0, 16]
    (ident ; [0, 18] - [0, 21]
      (reg ; [0, 18] - [0, 21]
        (word)))) ; [0, 18] - [0, 21]
  (line_comment)) ; [0, 21] - [0, 23]

After:

(program ; [0, 0] - [1, 0]
  (instruction ; [0, 0] - [0, 23]
    kind: (word) ; [0, 0] - [0, 3]
    (ident ; [0, 4] - [0, 6]
      (reg ; [0, 4] - [0, 6]
        (word))) ; [0, 4] - [0, 6]
    (ptr ; [0, 8] - [0, 23]
      (reg ; [0, 9] - [0, 11]
        (word)) ; [0, 9] - [0, 11]
      (reg ; [0, 14] - [0, 16]
        (word)) ; [0, 14] - [0, 16]
      (instruction ; [0, 18] - [0, 21]
        kind: (word)) ; [0, 18] - [0, 21]
      (int)))) ; [0, 21] - [0, 23]

The error here was similar to the 2nd example. However, I added support for post-increment of the register pointer (which is outside of the square brackets).

Thank you very much! Let me know if there are any changes/improvements you would like me to make!

RubixDev
RubixDev requested changes Nov 6, 2025
View reviewed changes
Copy link
Owner

@RubixDev RubixDev left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This will need to be rebased on main, and I've got a couple of questions, but otherwise looks good :)

@cfung89
Copy link
Contributor Author

cfung89 commented Nov 14, 2025

Thanks for the quick review. I made the requested changes. Let me know if I need to fix anything else!

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@RubixDev RubixDev RubixDev requested changes

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@cfung89 @RubixDev