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authorDimitry Andric <dim@FreeBSD.org>2022-05-28 21:26:37 +0000
committerDimitry Andric <dim@FreeBSD.org>2022-05-28 21:26:37 +0000
commit6a5eebc190ab98de98ed7977cbdee3218758376e (patch)
treed09a2ee4fc09a00412e25513f5bddaea33b2961b /lib
parent3735f9cff1e8a7ce7079b957bc3b37f0f886caed (diff)
Apply clang fix for assertion failure building putty 0.77 on i386
Merge commit 45084eab5e63 from llvm git (by Arthur Eubanks): [clang] Fix some clang->llvm type cache invalidation issues Take the following as an example struct z { z (*p)(); }; z f(); When we attempt to get the LLVM type of f, we recurse into z. z itself has a function pointer with the same type as f. Given the recursion, Clang simply treats z::p as a pointer to an empty struct `{}*`. The LLVM type of f is as expected. So we have two different potential LLVM types for a given Clang type. If we store one of those into the cache, when we access the cache with a different context (e.g. we are/aren't recursing on z) we may get an incorrect result. There is some attempt to clear the cache in these cases, but it doesn't seem to handle all cases. This change makes it so we only use the cache when we are not in any sort of function context, i.e. `noRecordsBeingLaidOut() && FunctionsBeingProcessed.empty()`, which are the cases where we may decide to choose a different LLVM type for a given Clang type. LLVM types for builtin types are never recursive so they're always ok. This allows us to clear the type cache less often (as seen with the removal of one of the calls to `TypeCache.clear()`). We still need to clear it when we use a placeholder type then replace it later with the final type and other dependent types need to be recalculated. I've added a check that the cached type matches what we compute. It triggered in this test case without the fix. It's currently not check-clang clean so it's not on by default for something like expensive checks builds. This change uncovered another issue where the LLVM types for an argument and its local temporary don't match. For example in type-cache-3, when expanding z::dc's argument into a temporary alloca, we ConvertType() the type of z::p which is `void ({}*)*`, which doesn't match the alloca GEP type of `{}*`. No noticeable compile time changes: https://llvm-compile-time-tracker.com/compare.php?from=3918dd6b8acf8c5886b9921138312d1c638b2937&to=50bdec9836ed40e38ece0657f3058e730adffc4c&stat=instructions Fixes #53465. Reviewed By: rnk Differential Revision: https://reviews.llvm.org/D118744 PR: 264318 Reported by: mandree MFC after: 3 days
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