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Diffstat (limited to 'docs/WritingAnLLVMPass.rst')
| -rw-r--r-- | docs/WritingAnLLVMPass.rst | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/docs/WritingAnLLVMPass.rst b/docs/WritingAnLLVMPass.rst index 241066842b7bb..9e9d9f1703a59 100644 --- a/docs/WritingAnLLVMPass.rst +++ b/docs/WritingAnLLVMPass.rst @@ -525,6 +525,14 @@ interface. Implementing a loop pass is usually straightforward. these methods should return ``true`` if they modified the program, or ``false`` if they didn't. +A ``LoopPass`` subclass which is intended to run as part of the main loop pass +pipeline needs to preserve all of the same *function* analyses that the other +loop passes in its pipeline require. To make that easier, +a ``getLoopAnalysisUsage`` function is provided by ``LoopUtils.h``. It can be +called within the subclass's ``getAnalysisUsage`` override to get consistent +and correct behavior. Analogously, ``INITIALIZE_PASS_DEPENDENCY(LoopPass)`` +will initialize this set of function analyses. + The ``doInitialization(Loop *, LPPassManager &)`` method ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -1392,7 +1400,7 @@ some with solutions, some without. * Restarting the program breaks breakpoints. After following the information above, you have succeeded in getting some breakpoints planted in your pass. - Nex thing you know, you restart the program (i.e., you type "``run``" again), + Next thing you know, you restart the program (i.e., you type "``run``" again), and you start getting errors about breakpoints being unsettable. The only way I have found to "fix" this problem is to delete the breakpoints that are already set in your pass, run the program, and re-set the breakpoints once |