This isn't terribly useful at the moment because of the step=1 restriction but it should be functionally sound. This is mostly just making sure the codepaths don't diverge as we make other changes.
Apply loop guards to BTC before checking if the last iteration should be peeled off. This also adds an assert to make sure applying the guards does not pessimize the results. I checked on a large test set and it did not trigger there, but it adds an additional guard to catch potential cases where loop-guards pessimize results. Peels ~15% more loops. PR: https://github.com/llvm/llvm-project/pull/142605
Similar to https://github.com/llvm/llvm-project/commit/7e14161f49b32387988cf9d937bbfaa27d0fbdd5, the exiting value may be a non-local instruction or an argument. Closes https://github.com/llvm/llvm-project/issues/142895.
This reverts commit 580454526b936f7a576ddbc9bb932cf9be376ec4. The recommitted version contains an extra check to not peel if the latch exit is controlled by a pointer induction. Original message: Remove the restriction that the loop must be known to execute at least 2 iterations when peeling the last iteration. If we cannot prove at least 2 iterations are executed, a check and branch to skip the peeled loop is inserted. PR: https://github.com/llvm/llvm-project/pull/140792
This reverts commit 24b97756decb7bf0e26dcf0e30a7a9aaf27f417c. Also reverts ac9a466e39bf97ffeab127982aa7c405cb257551. Building CMake triggers a crash with the patch, revert while I investigate.
Make sure the new phis are inserted before any non-phi instructions. This fixes a crash when dbg_value instructions are present in the original exit block.
Remove the restriction that the loop must be known to execute at least 2 iterations when peeling the last iteration. If we cannot prove at least 2 iterations are executed, a check and branch to skip the peeled loop is inserted. PR: https://github.com/llvm/llvm-project/pull/140792
Follow-up to post-commit comment for (https://github.com/llvm/llvm-project/pull/139551. This should effectively be NFC, given the other existing restrictions.
Follow-up to post-commit comment for (https://github.com/llvm/llvm-project/pull/139551. This should effectively be NFC, given the other existing restrictions.
Update the check in canPeelLastIteration to make sure the exiting condition has a single use. When peeling the last iteration, we adjust the condition in the loop body to be true one iteration early, which would be incorrect for other users. Fixes https://github.com/llvm/llvm-project/issues/140444.