Fix calculation of mask for constant values #7507
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This fixes an error when a constant is being loaded into a flag. The constants associated with a flag value have their size set to zero. That causes the mask for the constant value to be all zeros. Due to that, getting the value of a zero sized constant will always return 0 even if it should be 1. This commit special cases the size of zero to create a mask of 1 which will correctly mask off the lowest byte and return that as the constant.
james-a-johnson
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Pull Request Overview
This PR fixes a bug in the mask calculation for constant values with zero size, which prevented correct retrieval of flag constant values. The fix special-cases size zero to return a mask of 1, ensuring the lowest byte is correctly extracted.
Key Changes
- Modified mask calculation logic to handle zero-sized constants by returning a mask value of 1
- Refactored the mask calculation from mutable variable assignment to an immutable conditional expression
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| mask = !mask; | ||
| } | ||
| let mask: u64 = if self.op.size == 0 { | ||
| 1 |
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A mask of 1 will only preserve the least significant bit, not the lowest byte. To correctly mask the lowest byte as described in the PR description, the mask should be 0xFF (255) instead of 1.
Suggested change
| 1 | |
| 0xFF |
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Nice catch. That is a bug in the wording of my MR message though and not the actual code.
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This fixes an error when a constant is being loaded into a flag. The constants associated with a flag value have their size set to zero. That causes the mask for the constant value to be all zeros. Due to that, getting the value of a zero sized constant will always return 0 even if it should be 1.
This commit special cases the size of zero to create a mask of 1 which will correctly mask off the lowest bit and return that as the constant.