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| ID | Category | Severity | Reproducibility | Date Submitted | Last Update | ||||
| 0007093 | [Squeak] Compiler | minor | always | 06-13-08 01:24 | 02-06-11 23:48 | ||||
| Reporter | nicolas cellier | View Status | public | ||||||
| Assigned To | nicolas cellier | ||||||||
| Priority | normal | Resolution | fixed | ||||||
| Status | closed | Product Version | 3.10 | ||||||
| Summary | 0007093: to:do: optimization is wrong when the block modifies the limit | ||||||||
| Description |
This loop would not end without a halt if compiled by regular (old) Compiler: | n | n := 2. 1 to: n do: [:i | (n := n+1)>10 ifTrue: [self halt: 'Should I get here?']]. ^n When you think in term of message send, well no, you should not get here. Of course, with parentheses you won't get there: | n | n := 2. (1 to: n) do: [:i | (n := n+1)>10 ifTrue: [self halt: 'You won''t get there']]. ^n Nor: | n | 1 to: (n := 2) do: [:i | (n := n+1)>10 ifTrue: [self halt: 'Nor will you get there']]. ^n Amazing isn't it? |
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| Additional Information |
Just as tricky, check this: | n | n := 2. 1 to: n by: 1 do: [:i | (n := n+1)>10 ifTrue: [self halt: 'Should I get here?']]. ^n But, subtle difference: | n inc | n := 2. inc := 1. 1 to: n by: inc do: [:i | (n := n+1)>10 ifTrue: [self halt: 'You won''t get there']]. ^n Problem is located into MessageNode>>transformToDo: Of course, if one corrects this bug, there is a pending Decompiler issue: testDecompileToDoWithMovingLimit | n i | n := 4. i := 1. [i <= n] whileTrue: [ n := n - 1. i := i + 1]. would decompile into: | n | n := 4. 1 to: n do: [:i | n := n - 1] |
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| Attached Files |
 M7093-MessageNode-transformToDo.st [^] (2,596 bytes) 09-07-10 22:14 |
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Notes |
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(0012296 - 54 - 54 - 54 - 146 - 146 - 146) nicolas cellier 06-13-08 01:54 |
If optimization of to:do: is to change, think of 0006456 |
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(0013864 - 177 - 216 - 216 - 216 - 216 - 216) nicolas cellier 09-07-10 19:21 |
The problem still exists in trunk... Following code halts when it should not. | n | n := 2. 1 to: n do: [:i | (n := n+1)>10 ifTrue: [self halt: 'Should I get here?']]. ^n |
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(0013870 - 44 - 44 - 44 - 44 - 44 - 44) nicolas cellier 09-07-10 22:15 |
Eliot fixed the Compiler bug, file attached. |
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(0013871 - 121 - 139 - 285 - 285 - 285 - 285) nicolas cellier 09-07-10 23:14 |
http://source.squeak.org/trunk/Tests-nice.93.mcz [^] Provides two non regression tests - 1 for compiler - 1 for decompiler |
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(0013872 - 384 - 420 - 574 - 574 - 574 - 574) nicolas cellier 09-07-10 23:38 |
http://source.squeak.org/trunk/Compiler-nice.173.mcz [^] includes Compiler fix The idea is to avoid optimizing a to:do: loop that does modify its limit inside the loop. Note: an alternate solution would be to create a shadow variable, assign it with the limit, and optimize the block. Note 2: the bug report also has a so far uncorrected Decompiler part and cannot be closed yet. |
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(0014044 - 72 - 72 - 226 - 226 - 226 - 226) nicolas cellier 02-03-11 23:32 |
Fixed during 4.2 in http://source.squeak.org/trunk/Compiler-nice.184.mcz [^] |
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Issue History |
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| Date Modified | Username | Field | Change |
| 06-13-08 01:24 | nicolas cellier | New Issue | |
| 06-13-08 01:54 | nicolas cellier | Note Added: 0012296 | |
| 09-07-10 19:21 | nicolas cellier | Note Added: 0013864 | |
| 09-07-10 22:14 | nicolas cellier | File Added: M7093-MessageNode-transformToDo.st | |
| 09-07-10 22:15 | nicolas cellier | Note Added: 0013870 | |
| 09-07-10 23:14 | nicolas cellier | Note Added: 0013871 | |
| 09-07-10 23:38 | nicolas cellier | Note Added: 0013872 | |
| 02-03-11 23:27 | nicolas cellier | Relationship added | related to 0006456 |
| 02-03-11 23:32 | nicolas cellier | Status | new => resolved |
| 02-03-11 23:32 | nicolas cellier | Fixed in Version | => trunk |
| 02-03-11 23:32 | nicolas cellier | Resolution | open => fixed |
| 02-03-11 23:32 | nicolas cellier | Assigned To | => nicolas cellier |
| 02-03-11 23:32 | nicolas cellier | Note Added: 0014044 | |
| 02-06-11 23:48 | leves | Status | resolved => closed |
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