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6de5f0f936
From C11 and C++11 onwards, a forward-progress requirement has been introduced for both languages. In the case of C, loops with non-constant conditionals that do not have any observable side-effects (as defined by 6.8.5p6) can be assumed by the implementation to terminate, and in the case of C++, this assumption extends to all functions. The clang frontend will emit the `mustprogress` function attribute for C++ functions (D86233, D85393, D86841) and emit the loop metadata `llvm.loop.mustprogress` for every loop in C11 or later that has a non-constant conditional. This patch modifies LoopDeletion so that only loops with the `llvm.loop.mustprogress` metadata or loops contained in functions that are required to make progress (`mustprogress` or `willreturn`) are checked for observable side-effects. If these loops do not have an observable side-effect, then we delete them. Loops without observable side-effects that do not satisfy the above conditions will not be deleted. Reviewed By: jdoerfert Differential Revision: https://reviews.llvm.org/D86844 |
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| .. | ||
| AggressiveInstCombine | ||
| Coroutines | ||
| HelloNew | ||
| InstCombine | ||
| Instrumentation | ||
| IPO | ||
| Scalar | ||
| Utils | ||
| Vectorize | ||
| CFGuard.h | ||
| Coroutines.h | ||
| Instrumentation.h | ||
| IPO.h | ||
| ObjCARC.h | ||
| Scalar.h | ||
| Utils.h | ||
| Vectorize.h | ||