Fix GH-11245 (In some specific cases SWITCH with one default statement will cause segfault) #11251
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…ment will cause segfault) The block optimizer pass allows the use of sources of the preceding block if the block is a follower and not a target. This causes issues when trying to remove FREE instructions: if the source is not in the block of the FREE, then the FREE and source are still removed. Therefore the other successor blocks, which must consume or FREE the temporary, will still contain the FREE opline. This opline will now refer to a temporary that doesn't exist anymore, which most of the time results in a crash. For these kind of non-local scenarios, we'll let the SSA based optimizations handle those cases.
iluuu1994
reviewed
May 16, 2023
dstogov
approved these changes
May 22, 2023
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Merged with suggestion comment applied, thanks. |
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The block optimizer pass allows the use of sources of the preceding block if the block is a follower and not a target. This causes issues when trying to remove FREE instructions: if the source is not in the block of the FREE, then the FREE and source are still removed. Therefore the other successor blocks, which must consume or FREE the temporary, will still contain the FREE opline. This opline will now refer to a temporary that doesn't exist anymore, which most of the time results in a crash.
Fix it by checking if the source is in the same block as the FREE. For non-local optimizations, we'll let the SSA based optimizations handle those cases.