Following the work in PR #107279, this patch applies the annotative DebugLocs, which indicate that a particular instruction is intentionally missing a location for a given reason, to existing sites in the compiler where their conditions apply. This is NFC in ordinary LLVM builds (each function `DebugLoc::getFoo()` is inlined as `DebugLoc()`), but marks the instruction in coverage-tracking builds so that it will be ignored by Debugify, allowing only real errors to be reported. From a developer standpoint, it also communicates the intentionality and reason for a missing DebugLoc. Some notes for reviewers: - The difference between `I->dropLocation()` and `I->setDebugLoc(DebugLoc::getDropped())` is that the former _may_ decide to keep some debug info alive, while the latter will always be empty; in this patch, I always used the latter (even if the former could technically be correct), because the former could result in some (barely) different output, and I'd prefer to keep this patch purely NFC. - I've generally documented the uses of `DebugLoc::getUnknown()`, with the exception of the vectorizers - in summary, they are a huge cause of dropped source locations, and I don't have the time or the domain knowledge currently to solve that, so I've plastered it all over them as a form of "fixme".
Use combineMetadataForCSE instead of manually enumerating known metadata kinds. This is a typical sinking transform for which combineMetadataForCSE is safe to use (with DoesKMove=true). Part of https://github.com/llvm/llvm-project/issues/121495.
This patch fixes a couple of places where memprof-related metadata (!memprof and !callsite) were being dropped, and one place where PGO metadata (!prof) was being dropped. All were due to instances of combineMetadata() being invoked. That function drops all metadata not in the list provided by the client, and also drops any not in its switch statement. Memprof metadata needed a case in the combineMetadata switch statement. For now we simply keep the metadata of the instruction being kept, which doesn't retain all the profile information when two calls with memprof metadata are being combined, but at least retains some. For the memprof metadata being dropped during call CSE, add memprof and callsite metadata to the list of known ids in combineMetadataForCSE. Neither memprof nor regular prof metadata were in the list of known ids for the callsite in MemCpyOptimizer, which was added to combine AA metadata after optimization of byval arguments fed by memcpy instructions, and similar types of optimizations of memcpy uses. There is one other callsite of combineMetadata, but it is only invoked on load instructions, which do not carry these types of metadata.
A miscompilation issue has been addressed with refined checking. Fixes: https://github.com/llvm/llvm-project/issues/115149.
In current visitPHINode function during InstCombine, it can remove dead phi cycles (all phis have one use, which is another phi). However, it cannot deal with the case when the phis form a web (all phis have one or more uses, and all the uses are phi). This change extends the algorithm so that it can also deal with the dead phi web.
When looking at PHI operand for combining, only look at instructions and arguments. The loop later iteraters over Arg's users, which is not useful if Arg is a constant -- it's users are not meaningful and might be in different functions, which causes problems for the dominates() query. Pull Request: https://github.com/llvm/llvm-project/pull/103302
Reverts the above commit, as it updates a common header function and did not update all callsites: https://lab.llvm.org/buildbot/#/builders/29/builds/382 This reverts commit 6481dc57612671ebe77fe9c34214fba94e1b3b27.
Uses the new InsertPosition class (added in #94226) to simplify some of the IRBuilder interface, and removes the need to pass a BasicBlock alongside a BasicBlock::iterator, using the fact that we can now get the parent basic block from the iterator even if it points to the sentinel. This patch removes the BasicBlock argument from each constructor or call to setInsertPoint. This has no functional effect, but later on as we look to remove the `Instruction *InsertBefore` argument from instruction-creation (discussed [here](https://discourse.llvm.org/t/psa-instruction-constructors-changing-to-iterator-only-insertion/77845)), this will simplify the process by allowing us to deprecate the InsertPosition constructor directly and catch all the cases where we use instructions rather than iterators.