Expr: Add missing simplification for read over copyslice #877
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When we have concrete size and destination index, we can determine that reading past the slice is just reading from the destination directly. Source and source offset can still be symbolic.
msooseth
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Sep 29, 2025
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msooseth
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Nice catch, actually! Thanks :)
| readWord i@(Lit x) (CopySlice _ (Lit dstOffset) _ _ dst) | dstOffset >= x+32 = | ||
| readWord i dst | ||
| readWord i@(Lit x) (CopySlice _ (Lit dstOffset) _ _ dst) | dstOffset >= x+32 = readWord i dst | ||
| readWord i@(Lit x) (CopySlice _ (Lit dstOffset) (Lit size) _ dst) | x >= dstOffset + size = readWord i dst |
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Let's say we read Word (i.e. 32 bytes) starting at byte 10. So x=10. There's a CopySlice with dstoffset 8 and size 2. So it will write to bytes 8 and 9. Therefore from byte 10 we can read.
So this is correct :)
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Description
When we have concrete size and destination index, we can determine that reading past the slice is just reading from the destination directly.
Source and source offset can still be symbolic.
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