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* [ADT] NFC: Generalize GraphTraits requirement of "NodeType *" in interfaces ↵Tim Shen2016-08-011-0/+1
| | | | | | | | | | | | | | to "NodeRef", and migrate SCCIterator.h to use NodeRef Summary: By generalize the interface, users are able to inject more flexible Node token into the algorithm, for example, a pair of vector<Node>* and index integer. Currently I only migrated SCCIterator to use NodeRef, but more is coming. It's a NFC. Reviewers: dblaikie, chandlerc Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D22937 llvm-svn: 277399
* [FunctionAttrs] Correct the safety analysis for inference of 'returned'David Majnemer2016-07-191-0/+51
| | | | | | | | | | | | We skipped over ReturnInsts which didn't return an argument which would lead us to incorrectly conclude that an argument returned by another ReturnInst was 'returned'. This reverts commit r275756. This fixes PR28610. llvm-svn: 276008
* Revert r275678, "Revert "Revert r275027 - Let FuncAttrs infer the 'returned' ↵NAKAMURA Takumi2016-07-181-50/+0
| | | | | | | | | | argument attribute"" This reverts also r275029, "Update Clang tests after adding inference for the returned argument attribute" It broke LTO build. Seems miscompilation. llvm-svn: 275756
* Revert "Revert r275027 - Let FuncAttrs infer the 'returned' argument attribute"Hal Finkel2016-07-161-0/+50
| | | | | | | | | | | | | | | | This reverts commit r275042; the initial commit triggered self-hosting failures on ARM/AArch64. James Molloy identified the problematic backend code, which has been disabled in r275677. Trying again... Original commit message: Let FuncAttrs infer the 'returned' argument attribute A function can have one argument with the 'returned' attribute, indicating that the associated argument is always the return value of the function. Add FuncAttrs inference logic. llvm-svn: 275678
* Revert r275027 - Let FuncAttrs infer the 'returned' argument attributeHal Finkel2016-07-111-50/+0
| | | | | | Reverting r275027 and r275033. These seem to cause miscompiles on the AArch64 buildbot. llvm-svn: 275042
* Don't use a SmallSet for returned attribute inferenceHal Finkel2016-07-111-11/+19
| | | | | | | Suggested post-commit by David Majnemer on IRC (following-up on a pre-commit review comment). llvm-svn: 275033
* Let FuncAttrs infer the 'returned' argument attributeHal Finkel2016-07-101-0/+42
| | | | | | | | | | A function can have one argument with the 'returned' attribute, indicating that the associated argument is always the return value of the function. Add FuncAttrs inference logic. Differential Revision: http://reviews.llvm.org/D22202 llvm-svn: 275027
* [PM] Some preparatory refactoring to minimize the diff of D21921Sean Silva2016-07-031-14/+20
| | | | llvm-svn: 274456
* Remove dead TLI arg of isKnownNonNull and propagate deadness. NFC.Sean Silva2016-07-021-21/+6
| | | | | | | | | | | | | | This actually uncovered a surprisingly large chain of ultimately unused TLI args. From what I can gather, this argument is a remnant of when isKnownNonNull would look at the TLI directly. The current approach seems to be that InferFunctionAttrs runs early in the pipeline and uses TLI to annotate the TLI-dependent non-null information as return attributes. This also removes the dependence of functionattrs on TLI altogether. llvm-svn: 274455
* Apply clang-tidy's modernize-loop-convert to most of lib/Transforms.Benjamin Kramer2016-06-261-16/+11
| | | | | | Only minor manual fixes. No functionality change intended. llvm-svn: 273808
* [PM] Port ReversePostOrderFunctionAttrs to the new PMSean Silva2016-06-121-18/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Below are my super rough notes when porting. They can probably serve as a basic guide for porting other passes to the new PM. As I port more passes I'll expand and generalize this and make a proper docs/HowToPortToNewPassManager.rst document. There is also missing documentation for general concepts and API's in the new PM which will require some documentation. Once there is proper documentation in place we can put up a list of passes that have to be ported and game-ify/crowdsource the rest of the porting (at least of the middle end; the backend is still unclear). I will however be taking personal responsibility for ensuring that the LLD/ELF LTO pipeline is ported in a timely fashion. The remaining passes to be ported are (do something like `git grep "<the string in the bullet point below>"` to find the pass): General Scalar: [ ] Simplify the CFG [ ] Jump Threading [ ] MemCpy Optimization [ ] Promote Memory to Register [ ] MergedLoadStoreMotion [ ] Lazy Value Information Analysis General IPO: [ ] Dead Argument Elimination [ ] Deduce function attributes in RPO Loop stuff / vectorization stuff: [ ] Alignment from assumptions [ ] Canonicalize natural loops [ ] Delete dead loops [ ] Loop Access Analysis [ ] Loop Invariant Code Motion [ ] Loop Vectorization [ ] SLP Vectorizer [ ] Unroll loops Devirtualization / CFI: [ ] Cross-DSO CFI [ ] Whole program devirtualization [ ] Lower bitset metadata CGSCC passes: [ ] Function Integration/Inlining [ ] Remove unused exception handling info [ ] Promote 'by reference' arguments to scalars Please let me know if you are interested in working on any of the passes in the above list (e.g. reply to the post-commit thread for this patch). I'll probably be tackling "General Scalar" and "General IPO" first FWIW. Steps as I port "Deduce function attributes in RPO" --------------------------------------------------- (note: if you are doing any work based on these notes, please leave a note in the post-commit review thread for this commit with any improvements / suggestions / incompleteness you ran into!) Note: "Deduce function attributes in RPO" is a module pass. 1. Do preparatory refactoring. Do preparatory factoring. In this case all I had to do was to pull out a static helper (r272503). (TODO: give more advice here e.g. if pass holds state or something) 2. Rename the old pass class. llvm/lib/Transforms/IPO/FunctionAttrs.cpp Rename class ReversePostOrderFunctionAttrs -> ReversePostOrderFunctionAttrsLegacyPass in preparation for adding a class ReversePostOrderFunctionAttrs as the pass in the new PM. (edit: actually wait what? The new class name will be ReversePostOrderFunctionAttrsPass, so it doesn't conflict. So this step is sort of useless churn). llvm/include/llvm/InitializePasses.h llvm/lib/LTO/LTOCodeGenerator.cpp llvm/lib/Transforms/IPO/IPO.cpp llvm/lib/Transforms/IPO/FunctionAttrs.cpp Rename initializeReversePostOrderFunctionAttrsPass -> initializeReversePostOrderFunctionAttrsLegacyPassPass (note that the "PassPass" thing falls out of `s/ReversePostOrderFunctionAttrs/ReversePostOrderFunctionAttrsLegacyPass/`) Note that the INITIALIZE_PASS macro is what creates this identifier name, so renaming the class requires this renaming too. Note that createReversePostOrderFunctionAttrsPass does not need to be renamed since its name is not generated from the class name. 3. Add the new PM pass class. In the new PM all passes need to have their declaration in a header somewhere, so you will often need to add a header. In this case llvm/include/llvm/Transforms/IPO/FunctionAttrs.h is already there because PostOrderFunctionAttrsPass was already ported. The file-level comment from the .cpp file can be used as the file-level comment for the new header. You may want to tweak the wording slightly from "this file implements" to "this file provides" or similar. Add declaration for the new PM pass in this header: class ReversePostOrderFunctionAttrsPass : public PassInfoMixin<ReversePostOrderFunctionAttrsPass> { public: PreservedAnalyses run(Module &M, AnalysisManager<Module> &AM); }; Its name should end with `Pass` for consistency (note that this doesn't collide with the names of most old PM passes). E.g. call it `<name of the old PM pass>Pass`. Also, move the doxygen comment from the old PM pass to the declaration of this class in the header. Also, include the declaration for the new PM class `llvm/Transforms/IPO/FunctionAttrs.h` at the top of the file (in this case, it was already done when the other pass in this file was ported). Now define the `run` method for the new class. The main things here are: a) Use AM.getResult<...>(M) to get results instead of `getAnalysis<...>()` b) If the old PM pass would have returned "false" (i.e. `Changed == false`), then you should return PreservedAnalyses::all(); c) In the old PM getAnalysisUsage method, observe the calls `AU.addPreserved<...>();`. In the case `Changed == true`, for each preserved analysis you should do call `PA.preserve<...>()` on a PreservedAnalyses object and return it. E.g.: PreservedAnalyses PA; PA.preserve<CallGraphAnalysis>(); return PA; Note that calls to skipModule/skipFunction are not supported in the new PM currently, so optnone and optimization bisect support do not work. You can just drop those calls for now. 4. Add the pass to the new PM pass registry to make it available in opt. In llvm/lib/Passes/PassBuilder.cpp add a #include for your header. `#include "llvm/Transforms/IPO/FunctionAttrs.h"` In this case there is already an include (from when PostOrderFunctionAttrsPass was ported). Add your pass to llvm/lib/Passes/PassRegistry.def In this case, I added `MODULE_PASS("rpo-functionattrs", ReversePostOrderFunctionAttrsPass())` The string is from the `INITIALIZE_PASS*` macros used in the old pass manager. Then choose a test that uses the pass and use the new PM `-passes=...` to run it. E.g. in this case there is a test that does: ; RUN: opt < %s -basicaa -functionattrs -rpo-functionattrs -S | FileCheck %s I have added the line: ; RUN: opt < %s -aa-pipeline=basic-aa -passes='require<targetlibinfo>,cgscc(function-attrs),rpo-functionattrs' -S | FileCheck %s The `-aa-pipeline=basic-aa` and `require<targetlibinfo>,cgscc(function-attrs)` are what is needed to run functionattrs in the new PM (note that in the new PM "functionattrs" becomes "function-attrs" for some reason). This is just pulled from `readattrs.ll` which contains the change from when functionattrs was ported to the new PM. Adding rpo-functionattrs causes the pass that was just ported to run. llvm-svn: 272505
* Factor out a helper. NFCSean Silva2016-06-121-5/+10
| | | | | | Prep for porting to new PM. llvm-svn: 272503
* [FunctionAttrs] Volatile loads should disable readonlyDavid Majnemer2016-05-251-0/+5
| | | | | | | | A volatile load has side effects beyond what callers expect readonly to signify. For example, it is not safe to reorder two function calls which each perform a volatile load to the same memory location. llvm-svn: 270671
* ReversePostOrderFunctionAttrs is not modifying the call graph, let's ↵Mehdi Amini2016-05-021-0/+1
| | | | | | | | | | preserve it. When running cc1 with -flto=thin, it is followed by GlobalOpt, which requires the callgraph. This saves rebuilding one. From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 268266
* Re-commit optimization bisect support (r267022) without new pass manager ↵Andrew Kaylor2016-04-221-0/+6
| | | | | | | | | | support. The original commit was reverted because of a buildbot problem with LazyCallGraph::SCC handling (not related to the OptBisect handling). Differential Revision: http://reviews.llvm.org/D19172 llvm-svn: 267231
* Revert "Initial implementation of optimization bisect support."Vedant Kumar2016-04-221-9/+0
| | | | | | | | This reverts commit r267022, due to an ASan failure: http://lab.llvm.org:8080/green/job/clang-stage2-cmake-RgSan_check/1549 llvm-svn: 267115
* Initial implementation of optimization bisect support.Andrew Kaylor2016-04-211-0/+9
| | | | | | | | | | | | This patch implements a optimization bisect feature, which will allow optimizations to be selectively disabled at compile time in order to track down test failures that are caused by incorrect optimizations. The bisection is enabled using a new command line option (-opt-bisect-limit). Individual passes that may be skipped call the OptBisect object (via an LLVMContext) to see if they should be skipped based on the bisect limit. A finer level of control (disabling individual transformations) can be managed through an addition OptBisect method, but this is not yet used. The skip checking in this implementation is based on (and replaces) the skipOptnoneFunction check. Where that check was being called, a new call has been inserted in its place which checks the bisect limit and the optnone attribute. A new function call has been added for module and SCC passes that behaves in a similar way. Differential Revision: http://reviews.llvm.org/D19172 llvm-svn: 267022
* Don't IPO over functions that can be de-refinedSanjoy Das2016-04-081-14/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Fixes PR26774. If you're aware of the issue, feel free to skip the "Motivation" section and jump directly to "This patch". Motivation: I define "refinement" as discarding behaviors from a program that the optimizer has license to discard. So transforming: ``` void f(unsigned x) { unsigned t = 5 / x; (void)t; } ``` to ``` void f(unsigned x) { } ``` is refinement, since the behavior went from "if x == 0 then undefined else nothing" to "nothing" (the optimizer has license to discard undefined behavior). Refinement is a fundamental aspect of many mid-level optimizations done by LLVM. For instance, transforming `x == (x + 1)` to `false` also involves refinement since the expression's value went from "if x is `undef` then { `true` or `false` } else { `false` }" to "`false`" (by definition, the optimizer has license to fold `undef` to any non-`undef` value). Unfortunately, refinement implies that the optimizer cannot assume that the implementation of a function it can see has all of the behavior an unoptimized or a differently optimized version of the same function can have. This is a problem for functions with comdat linkage, where a function can be replaced by an unoptimized or a differently optimized version of the same source level function. For instance, FunctionAttrs cannot assume a comdat function is actually `readnone` even if it does not have any loads or stores in it; since there may have been loads and stores in the "original function" that were refined out in the currently visible variant, and at the link step the linker may in fact choose an implementation with a load or a store. As an example, consider a function that does two atomic loads from the same memory location, and writes to memory only if the two values are not equal. The optimizer is allowed to refine this function by first CSE'ing the two loads, and the folding the comparision to always report that the two values are equal. Such a refined variant will look like it is `readonly`. However, the unoptimized version of the function can still write to memory (since the two loads //can// result in different values), and selecting the unoptimized version at link time will retroactively invalidate transforms we may have done under the assumption that the function does not write to memory. Note: this is not just a problem with atomics or with linking differently optimized object files. See PR26774 for more realistic examples that involved neither. This patch: This change introduces a new set of linkage types, predicated as `GlobalValue::mayBeDerefined` that returns true if the linkage type allows a function to be replaced by a differently optimized variant at link time. It then changes a set of IPO passes to bail out if they see such a function. Reviewers: chandlerc, hfinkel, dexonsmith, joker.eph, rnk Subscribers: mcrosier, llvm-commits Differential Revision: http://reviews.llvm.org/D18634 llvm-svn: 265762
* [attrs] Handle convergent CallSites.Justin Lebar2016-03-141-39/+34
| | | | | | | | | | | | | | | | | | | | | | | Summary: Previously we had a notion of convergent functions but not of convergent calls. This is insufficient to correctly analyze calls where the target is unknown, e.g. indirect calls. Now a call is convergent if it targets a known-convergent function, or if it's explicitly marked as convergent. As usual, we can remove convergent where we can prove that no convergent operations are performed in the call. Originally landed as r261544, then reverted in r261544 for (incidental) build breakage. Re-landed here with no changes. Reviewers: chandlerc, jingyue Subscribers: llvm-commits, tra, jhen, hfinkel Differential Revision: http://reviews.llvm.org/D17739 llvm-svn: 263481
* [PM] Make the AnalysisManager parameter to run methods a reference.Chandler Carruth2016-03-111-4/+4
| | | | | | | | | | | | This was originally a pointer to support pass managers which didn't use AnalysisManagers. However, that doesn't realistically come up much and the complexity of supporting it doesn't really make sense. In fact, *many* parts of the pass manager were just assuming the pointer was never null already. This at least makes it much more explicit and clear. llvm-svn: 263219
* [AA] Hoist the logic to reformulate various AA queries in terms of otherChandler Carruth2016-03-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | parts of the AA interface out of the base class of every single AA result object. Because this logic reformulates the query in terms of some other aspect of the API, it would easily cause O(n^2) query patterns in alias analysis. These could in turn be magnified further based on the number of call arguments, and then further based on the number of AA queries made for a particular call. This ended up causing problems for Rust that were actually noticable enough to get a bug (PR26564) and probably other places as well. When originally re-working the AA infrastructure, the desire was to regularize the pattern of refinement without losing any generality. While I think it was successful, that is clearly proving to be too costly. And the cost is needless: we gain no actual improvement for this generality of making a direct query to tbaa actually be able to re-use some other alias analysis's refinement logic for one of the other APIs, or some such. In short, this is entirely wasted work. To the extent possible, delegation to other API surfaces should be done at the aggregation layer so that we can avoid re-walking the aggregation. In fact, this significantly simplifies the logic as we no longer need to smuggle the aggregation layer into each alias analysis (or the TargetLibraryInfo into each alias analysis just so we can form argument memory locations!). However, we also have some delegation logic inside of BasicAA and some of it even makes sense. When the delegation logic is baking in specific knowledge of aliasing properties of the LLVM IR, as opposed to simply reformulating the query to utilize a different alias analysis interface entry point, it makes a lot of sense to restrict that logic to a different layer such as BasicAA. So one aspect of the delegation that was in every AA base class is that when we don't have operand bundles, we re-use function AA results as a fallback for callsite alias results. This relies on the IR properties of calls and functions w.r.t. aliasing, and so seems a better fit to BasicAA. I've lifted the logic up to that point where it seems to be a natural fit. This still does a bit of redundant work (we query function attributes twice, once via the callsite and once via the function AA query) but it is *exactly* twice here, no more. The end result is that all of the delegation logic is hoisted out of the base class and into either the aggregation layer when it is a pure retargeting to a different API surface, or into BasicAA when it relies on the IR's aliasing properties. This should fix the quadratic query pattern reported in PR26564, although I don't have a stand-alone test case to reproduce it. It also seems general goodness. Now the numerous AAs that don't need target library info don't carry it around and depend on it. I think I can even rip out the general access to the aggregation layer and only expose that in BasicAA as it is the only place where we re-query in that manner. However, this is a non-trivial change to the AA infrastructure so I want to get some additional eyes on this before it lands. Sadly, it can't wait long because we should really cherry pick this into 3.8 if we're going to go this route. Differential Revision: http://reviews.llvm.org/D17329 llvm-svn: 262490
* Revert "[attrs] Handle convergent CallSites."Justin Lebar2016-02-221-25/+37
| | | | | | | This reverts r261544, which was causing a test failure in Transforms/FunctionAttrs/readattrs.ll. llvm-svn: 261549
* [attrs] Handle convergent CallSites.Justin Lebar2016-02-221-37/+25
| | | | | | | | | | | | | | | | | | | | Summary: Previously we had a notion of convergent functions but not of convergent calls. This is insufficient to correctly analyze calls where the target is unknown, e.g. indirect calls. Now a call is convergent if it targets a known-convergent function, or if it's explicitly marked as convergent. As usual, we can remove convergent where we can prove that no convergent operations are performed in the call. Reviewers: chandlerc, jingyue Subscribers: hfinkel, jhen, tra, llvm-commits Differential Revision: http://reviews.llvm.org/D17317 llvm-svn: 261544
* ADT: Remove == and != comparisons between ilist iterators and pointersDuncan P. N. Exon Smith2016-02-211-1/+1
| | | | | | | | | | | | | | I missed == and != when I removed implicit conversions between iterators and pointers in r252380 since they were defined outside ilist_iterator. Since they depend on getNodePtrUnchecked(), they indirectly rely on UB. This commit removes all uses of these operators. (I'll delete the operators themselves in a separate commit so that it can be easily reverted if necessary.) There should be NFC here. llvm-svn: 261498
* [PM] Port the PostOrderFunctionAttrs pass to the new pass manager andChandler Carruth2016-02-181-34/+97
| | | | | | | | | | | | | | | | | | | | | | | | | | convert one test to use this. This is a particularly significant milestone because it required a working per-function AA framework which can be queried over each function from within a CGSCC transform pass (and additionally a module analysis to be accessible). This is essentially *the* point of the entire pass manager rewrite. A CGSCC transform is able to query for multiple different function's analysis results. It works. The whole thing appears to actually work and accomplish the original goal. While we were able to hack function attrs and basic-aa to "work" in the old pass manager, this port doesn't use any of that, it directly leverages the new fundamental functionality. For this to work, the CGSCC framework also has to support SCC-based behavior analysis, etc. The only part of the CGSCC pass infrastructure not sorted out at this point are the updates in the face of inlining and running function passes that mutate the call graph. The changes are pretty boring and boiler-plate. Most of the work was factored into more focused preperatory patches. But this is what wires it all together. llvm-svn: 261203
* [attrs] Move the norecurse deduction to operate on the node set ratherChandler Carruth2016-02-131-15/+16
| | | | | | | | | | | | | | | | | | than the SCC object, and have it scan the instruction stream directly rather than relying on call records. This makes the behavior of this routine consistent between libc routines and LLVM intrinsics for libc routines. We can go and start teaching it about those being norecurse, but we should behave the same for the intrinsic and the libc routine rather than differently. I chatted with James Molloy and the inconsistency doesn't seem intentional and likely is due to intrinsic calls not being modelled in the call graph analyses. This also fixes a bug where we would deduce norecurse on optnone functions, when generally we try to handle optnone functions as-if they were replaceable and thus unanalyzable. llvm-svn: 260813
* [attrs] Simplify the convergent removal to directly use the pre-builtChandler Carruth2016-02-121-22/+10
| | | | | | | | | | | | | | node set rather than walking the SCC directly. This directly exposes the functions and has already had null entries filtered out. We also don't need need to handle optnone as it has already been handled in the caller -- we never try to remove convergent when there are optnone functions in the SCC. With this change, the code for removing convergent should work with the new pass manager and a different SCC analysis. llvm-svn: 260668
* [attrs] Consolidate the test for a non-SCC, non-convergent function callChandler Carruth2016-02-121-20/+14
| | | | | | | | | | | | | | | | with the test for a non-convergent intrinsic call. While it is possible to use the call records to search for function calls, we're going to do an instruction scan anyways to find the intrinsics, we can handle both cases while scanning instructions. This will also make the logic more amenable to the new pass manager which doesn't use the same call graph structure. My next patch will remove use of CallGraphNode entirely and allow this code to work with both the old and new pass manager. Fortunately, it should also get strictly simpler without changing functionality. llvm-svn: 260666
* [attrs] Run clang-format over a newly added routine in function-attrsChandler Carruth2016-02-121-12/+16
| | | | | | before I update it to be friendly with the new pass manager. llvm-svn: 260653
* Add convergent-removing bits to FunctionAttrs pass.Justin Lebar2016-02-091-0/+63
| | | | | | | | | | | | | | | | | Summary: Remove the convergent attribute on any functions which provably do not contain or invoke any convergent functions. After this change, we'll be able to modify clang to conservatively add 'convergent' to all functions when compiling CUDA. Reviewers: jingyue, joker.eph Subscribers: llvm-commits, tra, jhen, hfinkel, resistor, chandlerc, arsenm Differential Revision: http://reviews.llvm.org/D17013 llvm-svn: 260319
* [FunctionAttrs] Fix SCC logic around operand bundlesSanjoy Das2016-02-091-2/+6
| | | | | | | | | | | FunctionAttrs does an "optimistic" analysis of SCCs as a unit, which means normally it is able to disregard calls from an SCC into itself. However, calls and invokes with operand bundles are allowed to have memory effects not fully described by the memory effects on the call target, so we can't be optimistic around operand-bundled calls from an SCC into itself. llvm-svn: 260244
* Add an "addUsedAAAnalyses" helper functionSanjoy Das2016-02-091-0/+1
| | | | | | | | | | | | | | | | | | | Summary: Passes that call `getAnalysisIfAvailable<T>` also need to call `addUsedIfAvailable<T>` in `getAnalysisUsage` to indicate to the legacy pass manager that it uses `T`. This contract was being violated by passes that used `createLegacyPMAAResults`. This change fixes this by exposing a helper in AliasAnalysis.h, `addUsedAAAnalyses`, that is complementary to createLegacyPMAAResults and does the right thing when called from `getAnalysisUsage`. Reviewers: chandlerc Subscribers: mcrosier, llvm-commits Differential Revision: http://reviews.llvm.org/D17010 llvm-svn: 260183
* [attrs] Split the late-revisit pattern for deducing norecurse inChandler Carruth2016-01-081-59/+107
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a top-down manner into a true top-down or RPO pass over the call graph. There are specific patterns of function attributes, notably the norecurse attribute, which are most effectively propagated top-down because all they us caller information. Walk in RPO over the call graph SCCs takes the form of a module pass run immediately after the CGSCC pass managers postorder walk of the SCCs, trying again to deduce norerucrse for each singular SCC in the call graph. This removes a very legacy pass manager specific trick of using a lazy revisit list traversed during finalization of the CGSCC pass. There is no analogous finalization step in the new pass manager, and a lazy revisit list is just trying to produce an RPO iteration of the call graph. We can do that more directly if more expensively. It seems unlikely that this will be the expensive part of any compilation though as we never examine the function bodies here. Even in an LTO run over a very large module, this should be a reasonable fast set of operations over a reasonably small working set -- the function call graph itself. In the future, if this really is a compile time performance issue, we can look at building support for both post order and RPO traversals directly into a pass manager that builds and maintains the PO list of SCCs. Differential Revision: http://reviews.llvm.org/D15785 llvm-svn: 257163
* [attrs] Extract the pure inference of function attributes intoChandler Carruth2015-12-271-852/+1
| | | | | | | | | | | | | | | | | | | | | | | | | a standalone pass. There is no call graph or even interesting analysis for this part of function attributes -- it is literally inferring attributes based on the target library identification. As such, we can do it using a much simpler module pass that just walks the declarations. This can also happen much earlier in the pass pipeline which has benefits for any number of other passes. In the process, I've cleaned up one particular aspect of the logic which was necessary in order to separate the two passes cleanly. It now counts inferred attributes independently rather than just counting all the inferred attributes as one, and the counts are more clearly explained. The two test cases we had for this code path are both ... woefully inadequate and copies of each other. I've kept the superset test and updated it. We need more testing here, but I had to pick somewhere to stop fixing everything broken I saw here. Differential Revision: http://reviews.llvm.org/D15676 llvm-svn: 256466
* [attrs] Split off the forced attributes utility into its own pass thatChandler Carruth2015-12-271-66/+0
| | | | | | | | | | | | | | | is (by default) run much earlier than FuncitonAttrs proper. This allows forcing optnone or other widely impactful attributes. It is also a bit simpler as the force attribute behavior needs no specific iteration order. I've added the pass into the default module pass pipeline and LTO pass pipeline which mirrors where function attrs itself was being run. Differential Revision: http://reviews.llvm.org/D15668 llvm-svn: 256465
* Revert "[FunctionAttrs] Remove redundant assignment."Tilmann Scheller2015-11-201-0/+2
| | | | | | | | | | This reverts r253661. Turns out that the assignment is not redundant (despite the Clang static analyzer claiming the opposite). The variable is being used by the lambda function AddUsersToWorklistIfCapturing(). llvm-svn: 253696
* [FunctionAttrs] Remove redundant assignment.Tilmann Scheller2015-11-201-2/+0
| | | | | | Identified by the Clang static analyzer. llvm-svn: 253661
* [FunctionAttrs] Provide a mechanism for adding function attributes from the ↵James Molloy2015-11-191-0/+67
| | | | | | | | | | | | command line This provides a way to force a function to have certain attributes from the command line. This can be useful when debugging or doing workload exploration, where manually editing IR is tedious or not possible (due to build systems etc). The syntax is -force-attribute=function_name:attribute_name All function attributes are parsed except alignstack as it requires an argument. llvm-svn: 253550
* Vector of pointers in function attributes calculationElena Demikhovsky2015-11-171-1/+1
| | | | | | | | | While setting function attributes we check all instructions that may access memory. For a call instruction we check all arguments. The special check is required for pointers. I added vector-of-pointers to the call arguments types that should be checked. Differential Revision: http://reviews.llvm.org/D14693 llvm-svn: 253363
* Revert "Revert "[FunctionAttrs] Identify norecurse functions""James Molloy2015-11-121-1/+78
| | | | | | This reapplies this patch, with test fixes. llvm-svn: 252871
* Revert "[FunctionAttrs] Identify norecurse functions"James Molloy2015-11-121-78/+1
| | | | | | This reverts commit r252862. This introduced test failures and I'm reverting while I investigate how this happened. llvm-svn: 252863
* [FunctionAttrs] Identify norecurse functionsJames Molloy2015-11-121-1/+78
| | | | | | | | | | | | | A function can be marked as norecurse if: * The SCC to which it belongs has cardinality 1; and either a) It does not call any non-norecurse function. This includes self-recursion; or b) It only has one callsite and the function that callsite is within is marked norecurse. a) is best propagated bottom-up and b) is best propagated top-down. We build up the norecurse attributes bottom-up using the existing SCC pass, and mark functions with no obvious recursion (but not provably norecurse) to sweep later, top-down. llvm-svn: 252862
* Unbreak the buildSanjoy Das2015-11-071-1/+1
| | | | | | | My code clashed with some ilist iterator changes upstream. Fix by adding an explicit "&*" coercion. llvm-svn: 252392
* [FunctionAttrs] Add comment and clarify assertion message; NFCSanjoy Das2015-11-071-1/+6
| | | | llvm-svn: 252389
* [FunctionAttrs] Add handling for operand bundlesSanjoy Das2015-11-071-4/+31
| | | | | | | | | | | | | | Summary: Teach the FunctionAttrs to do the right thing for IR with operand bundles. Reviewers: reames, chandlerc Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D14408 llvm-svn: 252387
* [FunctionAttrs] Fix an iterator wraparound bugSanjoy Das2015-11-071-18/+19
| | | | | | | | | | | | | | | | | | | Summary: This change fixes an iterator wraparound bug in `determinePointerReadAttrs`. Ideally, ++'ing off the `end()` of an iplist should result in a failed assert, but currently iplist seems to silently wrap to the head of the list on `end()++`. This is why the bad behavior is difficult to demonstrate. Reviewers: chandlerc, reames Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D14350 llvm-svn: 252386
* ADT: Remove last implicit ilist iterator conversions, NFCDuncan P. N. Exon Smith2015-11-071-1/+1
| | | | | | | | | | Some implicit ilist iterator conversions have crept back into Analysis, Transforms, Hexagon, and llvm-stress. This removes them. I'll commit a patch immediately after this to disallow them (in a separate patch so that it's easy to revert if necessary). llvm-svn: 252371
* [FunctionAttrs] Remove a loop, NFC refactorSanjoy Das2015-11-051-16/+14
| | | | | | | | | | | | | | | | | | | | | | Summary: Remove the loop over the uses of the CallSite in ArgumentUsesTracker. Since we have the `Use *` for actual argument operand, we can just use pointer subtraction. The time complexity remains the same though (except for a vararg argument) -- `std::advance` is O(UseIndex) for the ArgumentList iterator. The real motivation is to make a later change adding support for operand bundles simpler. Reviewers: reames, chandlerc, nlewycky Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D14363 llvm-svn: 252141
* [FunctionAttrs] Inline the prototype attribute inference to an existingChandler Carruth2015-10-311-21/+6
| | | | | | | | loop over the SCC. The separate function wasn't really adding much, NFC. llvm-svn: 251728
* [FunctionAttrs] Separate another chunk of the logic for functionattrsChandler Carruth2015-10-301-10/+16
| | | | | | | | | | | from its pass harness by providing a lambda to query for AA results. This allows the legacy pass to easily provide a lambda that uses the special helpers to construct function AA results from a legacy CGSCC pass. With the new pass manager (the next patch) the lambda just directly wraps the intuitive query API. llvm-svn: 251715
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