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* This reverts commit r319096 and r319097.Rafael Espindola2017-11-281-147/+17
| | | | | | | | | Revert "[SROA] Propagate !range metadata when moving loads." Revert "[Mem2Reg] Clang-format unformatted parts of this file. NFCI." Davide says they broke a bot. llvm-svn: 319131
* [Mem2Reg] Clang-format unformatted parts of this file. NFCI.Davide Italiano2017-11-271-28/+23
| | | | llvm-svn: 319097
* [SROA] Propagate !range metadata when moving loads.Davide Italiano2017-11-271-15/+150
| | | | | | | | | | | | | This tries to propagate !range metadata to a pre-existing load when a load is optimized out. This is done instead of adding an assume because converting loads to and from assumes creates a lot of IR. Patch by Ariel Ben-Yehuda. Differential Revision: https://reviews.llvm.org/D37216 llvm-svn: 319096
* [Transforms] Fix some Clang-tidy modernize and Include What You Use ↵Eugene Zelenko2017-10-211-17/+27
| | | | | | warnings; other minor fixes (NFC). llvm-svn: 316253
* Re-land r313825: "[IR] Add llvm.dbg.addr, a control-dependent version of ↵Reid Kleckner2017-09-211-22/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | llvm.dbg.declare" The fix is to avoid invalidating our insertion point in replaceDbgDeclare: Builder.insertDeclare(NewAddress, DIVar, DIExpr, Loc, InsertBefore); + if (DII == InsertBefore) + InsertBefore = &*std::next(InsertBefore->getIterator()); DII->eraseFromParent(); I had to write a unit tests for this instead of a lit test because the use list order matters in order to trigger the bug. The reduced C test case for this was: void useit(int*); static inline void inlineme() { int x[2]; useit(x); } void f() { inlineme(); inlineme(); } llvm-svn: 313905
* Revert r313825: "[IR] Add llvm.dbg.addr, a control-dependent version of ↵Daniel Jasper2017-09-211-22/+22
| | | | | | | | | | | llvm.dbg.declare" .. as well as the two subsequent changes r313826 and r313875. This leads to segfaults in combination with ASAN. Will forward repro instructions to the original author (rnk). llvm-svn: 313876
* [IR] Add llvm.dbg.addr, a control-dependent version of llvm.dbg.declareReid Kleckner2017-09-201-22/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This implements the design discussed on llvm-dev for better tracking of variables that live in memory through optimizations: http://lists.llvm.org/pipermail/llvm-dev/2017-September/117222.html This is tracked as PR34136 llvm.dbg.addr is intended to be produced and used in almost precisely the same way as llvm.dbg.declare is today, with the exception that it is control-dependent. That means that dbg.addr should always have a position in the instruction stream, and it will allow passes that optimize memory operations on local variables to insert llvm.dbg.value calls to reflect deleted stores. See SourceLevelDebugging.rst for more details. The main drawback to generating DBG_VALUE machine instrs is that they usually cause LLVM to emit a location list for DW_AT_location. The next step will be to teach DwarfDebug.cpp how to recognize more DBG_VALUE ranges as not needing a location list, and possibly start setting DW_AT_start_offset for variables whose lifetimes begin mid-scope. Reviewers: aprantl, dblaikie, probinson Subscribers: eraman, hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D37768 llvm-svn: 313825
* Merge isKnownNonNull into isKnownNonZeroNuno Lopes2017-09-091-7/+8
| | | | | | | | | It now knows the tricks of both functions. Also, fix a bug that considered allocas of non-zero address space to be always non null Differential Revision: https://reviews.llvm.org/D37628 llvm-svn: 312869
* [Mem2Reg] Modernize code a bit.Benjamin Kramer2017-08-201-23/+11
| | | | | | No functionality change intended. llvm-svn: 311290
* Kill off the old SimplifyInstruction API by converting remaining users.Daniel Berlin2017-04-281-5/+4
| | | | llvm-svn: 301673
* [Mem2Reg] Remove AliasSetTracker updating logic from the pass.Davide Italiano2017-04-091-38/+6
| | | | | | No caller has been passing it for a long time. llvm-svn: 299827
* Preserve nonnull metadata on Loads through SROA & mem2reg.Luqman Aden2017-03-221-10/+47
| | | | | | | | | | | | | | | | | Summary: https://llvm.org/bugs/show_bug.cgi?id=31142 : SROA was dropping the nonnull metadata on loads from allocas that got optimized out. This patch simply preserves nonnull metadata on loads through SROA and mem2reg. Reviewers: chandlerc, efriedma Reviewed By: efriedma Subscribers: hfinkel, spatel, efriedma, arielb1, davide, llvm-commits Differential Revision: https://reviews.llvm.org/D27114 llvm-svn: 298540
* Revert @llvm.assume with operator bundles (r289755-r289757)Daniel Jasper2016-12-191-5/+8
| | | | | | | This creates non-linear behavior in the inliner (see more details in r289755's commit thread). llvm-svn: 290086
* Remove the AssumptionCacheHal Finkel2016-12-151-8/+5
| | | | | | | | | After r289755, the AssumptionCache is no longer needed. Variables affected by assumptions are now found by using the new operand-bundle-based scheme. This new scheme is more computationally efficient, and also we need much less code... llvm-svn: 289756
* Reapplying r281895 (and follow-up r281964) after fixing pr30468.Keith Walker2016-09-221-0/+2
| | | | | | | | | | | | | | | | The additional fix is: When adding debug information to a lowered phi node in mem2reg check that we have a valid insertion point after the phi for adding the debug information. This change addresses the issue in pr30468 where a lowered phi was added before a catchswitch and no debug information should be added after the phi in this case. Differential Revision: https://reviews.llvm.org/D24797 llvm-svn: 282155
* Revert r281895 "Add @llvm.dbg.value entries for the phi node created by ↵Hans Wennborg2016-09-211-2/+0
| | | | | | | | | | -mem2reg" (And follow-up r281964.) It caused PR30468. llvm-svn: 282077
* Add @llvm.dbg.value entries for the phi node created by -mem2regKeith Walker2016-09-191-0/+2
| | | | | | | | | | | | | | | | | | | | | | | When phi nodes are created in the -mem2reg phase, the @llvm.dbg.declare entries are converted to @llvm.dbg.value entries at the place where the store instructions existed. However no entry is created to describe the resulting value of the phi node. The effect of this is especially noticeable in for loops which have a constant for the intial value; the loop control variable's location would be described as the intial constant value in the loop body once the -mem2reg optimization phase was run. This change adds the creation of the @llvm.dbg.value entries to describe variables whose location is the result of a phi node created in -mem2reg. Also when the phi node is finally lowered to a machine instruction it is important that the lowered "load" instruction is placed before the associated DEBUG_VALUE entry describing the value loaded. Differential Revision: https://reviews.llvm.org/D23715 llvm-svn: 281895
* Correct IDF calculator for ReverseIDFDaniel Berlin2016-04-191-1/+1
| | | | | | | | | | | | | | Summary: Need to use predecessors for reverse graph, successors for forward graph. succ_iterator/pred_iterator are not compatible, this patch is all the work necessary to work around that (which is what everywhere else does). Not sure if there is a better way, so cc'ing some random folks to take a gander :) Reviewers: dblaikie, qcolombet, echristo Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D18796 llvm-svn: 266718
* Remove uses of builtin comma operator.Richard Trieu2016-02-181-1/+2
| | | | | | Cleanup for upcoming Clang warning -Wcomma. No functionality change intended. llvm-svn: 261270
* getParent() ^ 3 == getModule() ; NFCISanjay Patel2015-12-141-4/+2
| | | | llvm-svn: 255511
* TransformUtils: Remove implicit ilist iterator conversions, NFCDuncan P. N. Exon Smith2015-10-131-7/+6
| | | | | | | | | | | Continuing the work from last week to remove implicit ilist iterator conversions. First related commit was probably r249767, with some more motivation in r249925. This edition gets LLVMTransformUtils compiling without the implicit conversions. No functional change intended. llvm-svn: 250142
* Fix mem2reg to correctly handle allocas only used in a single blockMichael Kuperstein2015-07-221-15/+23
| | | | | | | | | | | | | | | Currently, a load from an alloca that is used in as single block and is not preceded by a store is replaced by undef. This is not always correct if the single block is inside a loop. Fix the logic so that: 1) If there are no stores in the block, replace the load with an undef, as before. 2) If there is a store (regardless of where it is in the block w.r.t the load), bail out, and let the rest of mem2reg handle this alloca. Patch by: gil.rapaport@intel.com Differential Revision: http://reviews.llvm.org/D11355 llvm-svn: 242884
* Replace push_back(Constructor(foo)) with emplace_back(foo) for non-trivial typesBenjamin Kramer2015-05-291-2/+2
| | | | | | | | | | | | | | | | | | | | If the type isn't trivially moveable emplace can skip a potentially expensive move. It also saves a couple of characters. Call sites were found with the ASTMatcher + some semi-automated cleanup. memberCallExpr( argumentCountIs(1), callee(methodDecl(hasName("push_back"))), on(hasType(recordDecl(has(namedDecl(hasName("emplace_back")))))), hasArgument(0, bindTemporaryExpr( hasType(recordDecl(hasNonTrivialDestructor())), has(constructExpr()))), unless(isInTemplateInstantiation())) No functional change intended. llvm-svn: 238602
* Move IDF Calculation to a separate file, expose an interface to it.Daniel Berlin2015-04-211-130/+32
| | | | | | | | | | | | | | | Summary: MemorySSA uses this algorithm as well, and this enables us to reuse the code in both places. There are no actual algorithm or datastructure changes in here, just code movement. Reviewers: qcolombet, chandlerc Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D9118 llvm-svn: 235406
* Eliminate O(n^2) worst-case behavior in SSA constructionCameron Zwarich2015-04-081-3/+6
| | | | | | | | | The code uses a priority queue and a worklist, which share the same visited set, but the visited set is only updated when inserting into the priority queue. Instead, switch to using separate visited sets for the priority queue and worklist. llvm-svn: 234425
* DataLayout is mandatory, update the API to reflect it with references.Mehdi Amini2015-03-101-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Now that the DataLayout is a mandatory part of the module, let's start cleaning the codebase. This patch is a first attempt at doing that. This patch is not exactly NFC as for instance some places were passing a nullptr instead of the DataLayout, possibly just because there was a default value on the DataLayout argument to many functions in the API. Even though it is not purely NFC, there is no change in the validation. I turned as many pointer to DataLayout to references, this helped figuring out all the places where a nullptr could come up. I had initially a local version of this patch broken into over 30 independant, commits but some later commit were cleaning the API and touching part of the code modified in the previous commits, so it seemed cleaner without the intermediate state. Test Plan: Reviewers: echristo Subscribers: llvm-commits From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 231740
* [PM] Split the AssumptionTracker immutable pass into two separate APIs:Chandler Carruth2015-01-041-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | a cache of assumptions for a single function, and an immutable pass that manages those caches. The motivation for this change is two fold. Immutable analyses are really hacks around the current pass manager design and don't exist in the new design. This is usually OK, but it requires that the core logic of an immutable pass be reasonably partitioned off from the pass logic. This change does precisely that. As a consequence it also paves the way for the *many* utility functions that deal in the assumptions to live in both pass manager worlds by creating an separate non-pass object with its own independent API that they all rely on. Now, the only bits of the system that deal with the actual pass mechanics are those that actually need to deal with the pass mechanics. Once this separation is made, several simplifications become pretty obvious in the assumption cache itself. Rather than using a set and callback value handles, it can just be a vector of weak value handles. The callers can easily skip the handles that are null, and eventually we can wrap all of this up behind a filter iterator. For now, this adds boiler plate to the various passes, but this kind of boiler plate will end up making it possible to port these passes to the new pass manager, and so it will end up factored away pretty reasonably. llvm-svn: 225131
* IR: Split Metadata from ValueDuncan P. N. Exon Smith2014-12-091-3/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Split `Metadata` away from the `Value` class hierarchy, as part of PR21532. Assembly and bitcode changes are in the wings, but this is the bulk of the change for the IR C++ API. I have a follow-up patch prepared for `clang`. If this breaks other sub-projects, I apologize in advance :(. Help me compile it on Darwin I'll try to fix it. FWIW, the errors should be easy to fix, so it may be simpler to just fix it yourself. This breaks the build for all metadata-related code that's out-of-tree. Rest assured the transition is mechanical and the compiler should catch almost all of the problems. Here's a quick guide for updating your code: - `Metadata` is the root of a class hierarchy with three main classes: `MDNode`, `MDString`, and `ValueAsMetadata`. It is distinct from the `Value` class hierarchy. It is typeless -- i.e., instances do *not* have a `Type`. - `MDNode`'s operands are all `Metadata *` (instead of `Value *`). - `TrackingVH<MDNode>` and `WeakVH` referring to metadata can be replaced with `TrackingMDNodeRef` and `TrackingMDRef`, respectively. If you're referring solely to resolved `MDNode`s -- post graph construction -- just use `MDNode*`. - `MDNode` (and the rest of `Metadata`) have only limited support for `replaceAllUsesWith()`. As long as an `MDNode` is pointing at a forward declaration -- the result of `MDNode::getTemporary()` -- it maintains a side map of its uses and can RAUW itself. Once the forward declarations are fully resolved RAUW support is dropped on the ground. This means that uniquing collisions on changing operands cause nodes to become "distinct". (This already happened fairly commonly, whenever an operand went to null.) If you're constructing complex (non self-reference) `MDNode` cycles, you need to call `MDNode::resolveCycles()` on each node (or on a top-level node that somehow references all of the nodes). Also, don't do that. Metadata cycles (and the RAUW machinery needed to construct them) are expensive. - An `MDNode` can only refer to a `Constant` through a bridge called `ConstantAsMetadata` (one of the subclasses of `ValueAsMetadata`). As a side effect, accessing an operand of an `MDNode` that is known to be, e.g., `ConstantInt`, takes three steps: first, cast from `Metadata` to `ConstantAsMetadata`; second, extract the `Constant`; third, cast down to `ConstantInt`. The eventual goal is to introduce `MDInt`/`MDFloat`/etc. and have metadata schema owners transition away from using `Constant`s when the type isn't important (and they don't care about referring to `GlobalValue`s). In the meantime, I've added transitional API to the `mdconst` namespace that matches semantics with the old code, in order to avoid adding the error-prone three-step equivalent to every call site. If your old code was: MDNode *N = foo(); bar(isa <ConstantInt>(N->getOperand(0))); baz(cast <ConstantInt>(N->getOperand(1))); bak(cast_or_null <ConstantInt>(N->getOperand(2))); bat(dyn_cast <ConstantInt>(N->getOperand(3))); bay(dyn_cast_or_null<ConstantInt>(N->getOperand(4))); you can trivially match its semantics with: MDNode *N = foo(); bar(mdconst::hasa <ConstantInt>(N->getOperand(0))); baz(mdconst::extract <ConstantInt>(N->getOperand(1))); bak(mdconst::extract_or_null <ConstantInt>(N->getOperand(2))); bat(mdconst::dyn_extract <ConstantInt>(N->getOperand(3))); bay(mdconst::dyn_extract_or_null<ConstantInt>(N->getOperand(4))); and when you transition your metadata schema to `MDInt`: MDNode *N = foo(); bar(isa <MDInt>(N->getOperand(0))); baz(cast <MDInt>(N->getOperand(1))); bak(cast_or_null <MDInt>(N->getOperand(2))); bat(dyn_cast <MDInt>(N->getOperand(3))); bay(dyn_cast_or_null<MDInt>(N->getOperand(4))); - A `CallInst` -- specifically, intrinsic instructions -- can refer to metadata through a bridge called `MetadataAsValue`. This is a subclass of `Value` where `getType()->isMetadataTy()`. `MetadataAsValue` is the *only* class that can legally refer to a `LocalAsMetadata`, which is a bridged form of non-`Constant` values like `Argument` and `Instruction`. It can also refer to any other `Metadata` subclass. (I'll break all your testcases in a follow-up commit, when I propagate this change to assembly.) llvm-svn: 223802
* Update SetVector to rely on the underlying set's insert to return a ↵David Blaikie2014-11-191-4/+4
| | | | | | | | | | | | | pair<iterator, bool> This is to be consistent with StringSet and ultimately with the standard library's associative container insert function. This lead to updating SmallSet::insert to return pair<iterator, bool>, and then to update SmallPtrSet::insert to return pair<iterator, bool>, and then to update all the existing users of those functions... llvm-svn: 222334
* Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)Hal Finkel2014-09-071-5/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change, which allows @llvm.assume to be used from within computeKnownBits (and other associated functions in ValueTracking), adds some (optional) parameters to computeKnownBits and friends. These functions now (optionally) take a "context" instruction pointer, an AssumptionTracker pointer, and also a DomTree pointer, and most of the changes are just to pass this new information when it is easily available from InstSimplify, InstCombine, etc. As explained below, the significant conceptual change is that known properties of a value might depend on the control-flow location of the use (because we care that the @llvm.assume dominates the use because assumptions have control-flow dependencies). This means that, when we ask if bits are known in a value, we might get different answers for different uses. The significant changes are all in ValueTracking. Two main changes: First, as with the rest of the code, new parameters need to be passed around. To make this easier, I grouped them into a structure, and I made internal static versions of the relevant functions that take this structure as a parameter. The new code does as you might expect, it looks for @llvm.assume calls that make use of the value we're trying to learn something about (often indirectly), attempts to pattern match that expression, and uses the result if successful. By making use of the AssumptionTracker, the process of finding @llvm.assume calls is not expensive. Part of the structure being passed around inside ValueTracking is a set of already-considered @llvm.assume calls. This is to prevent a query using, for example, the assume(a == b), to recurse on itself. The context and DT params are used to find applicable assumptions. An assumption needs to dominate the context instruction, or come after it deterministically. In this latter case we only handle the specific case where both the assumption and the context instruction are in the same block, and we need to exclude assumptions from being used to simplify their own ephemeral values (those which contribute only to the assumption) because otherwise the assumption would prove its feeding comparison trivial and would be removed. This commit adds the plumbing and the logic for a simple masked-bit propagation (just enough to write a regression test). Future commits add more patterns (and, correspondingly, more regression tests). llvm-svn: 217342
* Use range based for loops to avoid needing to re-mention SmallPtrSet size.Craig Topper2014-08-241-4/+2
| | | | llvm-svn: 216351
* Repace SmallPtrSet with SmallPtrSetImpl in function arguments to avoid ↵Craig Topper2014-08-211-4/+4
| | | | | | needing to mention the size. llvm-svn: 216158
* Revert "Repace SmallPtrSet with SmallPtrSetImpl in function arguments to ↵Craig Topper2014-08-181-4/+4
| | | | | | | | avoid needing to mention the size." Getting a weird buildbot failure that I need to investigate. llvm-svn: 215870
* Repace SmallPtrSet with SmallPtrSetImpl in function arguments to avoid ↵Craig Topper2014-08-171-4/+4
| | | | | | needing to mention the size. llvm-svn: 215868
* Revert "[C++11] Add predecessors(BasicBlock *) / successors(BasicBlock *) ↵Duncan P. N. Exon Smith2014-07-211-3/+6
| | | | | | | | | iterator ranges." This reverts commit r213474 (and r213475), which causes a miscompile on a stage2 LTO build. I'll reply on the list in a moment. llvm-svn: 213562
* [C++11] Add predecessors(BasicBlock *) / successors(BasicBlock *) iterator ↵Manuel Jacob2014-07-201-6/+3
| | | | | | | | | | | | | | | | | | ranges. Summary: This patch introduces two new iterator ranges and updates existing code to use it. No functional change intended. Test Plan: All tests (make check-all) still pass. Reviewers: dblaikie Reviewed By: dblaikie Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D4481 llvm-svn: 213474
* [C++] Use 'nullptr'. Transforms edition.Craig Topper2014-04-251-10/+11
| | | | llvm-svn: 207196
* Remove more default address space argument usage.Matt Arsenault2014-04-231-2/+3
| | | | | | These places are inconsequential in practice. llvm-svn: 207021
* [Modules] Fix potential ODR violations by sinking the DEBUG_TYPEChandler Carruth2014-04-221-1/+2
| | | | | | | | | | | | | | | | | definition below all of the header #include lines, lib/Transforms/... edition. This one is tricky for two reasons. We again have a couple of passes that define something else before the includes as well. I've sunk their name macros with the DEBUG_TYPE. Also, InstCombine contains headers that need DEBUG_TYPE, so now those headers #define and #undef DEBUG_TYPE around their code, leaving them well formed modular headers. Fixing these headers was a large motivation for all of these changes, as "leaky" macros of this form are hard on the modules implementation. llvm-svn: 206844
* [C++11] Add range based accessors for the Use-Def chain of a Value.Chandler Carruth2014-03-091-17/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This requires a number of steps. 1) Move value_use_iterator into the Value class as an implementation detail 2) Change it to actually be a *Use* iterator rather than a *User* iterator. 3) Add an adaptor which is a User iterator that always looks through the Use to the User. 4) Wrap these in Value::use_iterator and Value::user_iterator typedefs. 5) Add the range adaptors as Value::uses() and Value::users(). 6) Update *all* of the callers to correctly distinguish between whether they wanted a use_iterator (and to explicitly dig out the User when needed), or a user_iterator which makes the Use itself totally opaque. Because #6 requires churning essentially everything that walked the Use-Def chains, I went ahead and added all of the range adaptors and switched them to range-based loops where appropriate. Also because the renaming requires at least churning every line of code, it didn't make any sense to split these up into multiple commits -- all of which would touch all of the same lies of code. The result is still not quite optimal. The Value::use_iterator is a nice regular iterator, but Value::user_iterator is an iterator over User*s rather than over the User objects themselves. As a consequence, it fits a bit awkwardly into the range-based world and it has the weird extra-dereferencing 'operator->' that so many of our iterators have. I think this could be fixed by providing something which transforms a range of T&s into a range of T*s, but that *can* be separated into another patch, and it isn't yet 100% clear whether this is the right move. However, this change gets us most of the benefit and cleans up a substantial amount of code around Use and User. =] llvm-svn: 203364
* [Layering] Move DebugInfo.h into the IR library where its implementationChandler Carruth2014-03-061-1/+1
| | | | | | already lives. llvm-svn: 203046
* [Layering] Move DIBuilder.h into the IR library where its implementationChandler Carruth2014-03-061-1/+1
| | | | | | already lives. llvm-svn: 203038
* [Modules] Move CFG.h to the IR library as it defines graph traits overChandler Carruth2014-03-041-1/+1
| | | | | | IR types. llvm-svn: 202827
* [C++11] Replace llvm::next and llvm::prior with std::next and std::prev.Benjamin Kramer2014-03-021-1/+1
| | | | | | Remove the old functions. llvm-svn: 202636
* [cleanup] Move the Dominators.h and Verifier.h headers into the IRChandler Carruth2014-01-131-1/+1
| | | | | | | | | | | | | | | | | | directory. These passes are already defined in the IR library, and it doesn't make any sense to have the headers in Analysis. Long term, I think there is going to be a much better way to divide these matters. The dominators code should be fully separated into the abstract graph algorithm and have that put in Support where it becomes obvious that evn Clang's CFGBlock's can use it. Then the verifier can manually construct dominance information from the Support-driven interface while the Analysis library can provide a pass which both caches, reconstructs, and supports a nice update API. But those are very long term, and so I don't want to leave the really confusing structure until that day arrives. llvm-svn: 199082
* Correct word hyphenationsAlp Toker2013-12-051-2/+2
| | | | | | | This patch tries to avoid unrelated changes other than fixing a few hyphen-related ambiguities and contractions in nearby lines. llvm-svn: 196471
* Add a function object to compare the first or second component of a std::pair.Benjamin Kramer2013-08-241-26/+5
| | | | | | Replace instances of this scattered around the code base. llvm-svn: 189169
* Fix a really terrifying but improbable bug in mem2reg. If you have seenChandler Carruth2013-08-141-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | extremely subtle miscompilations (such as a load getting replaced with the value stored *below* the load within a basic block) related to promoting an alloca to an SSA value, there is the dim possibility that you hit this. Please let me know if you won this unfortunate lottery. The first half of mem2reg's core logic (as it is used both in the standalone mem2reg pass and in SROA) builds up a mapping from 'Instruction *' to the index of that instruction within its basic block. This allows quickly establishing which store dominate a particular load even for large basic blocks. We cache this information throughout the run of mem2reg over a function in order to amortize the cost of computing it. This is not in and of itself a strange pattern in LLVM. However, it introduces a very important constraint: absolutely no instruction can be deleted from the program without updating the mapping. Otherwise a newly allocated instruction might get the same pointer address, and then end up with a wrong index. Yes, LLVM routinely suffers from a *single threaded* variant of the ABA problem. Most places in LLVM don't find avoiding this an imposition because they don't both delete and create new instructions iteratively, but mem2reg *loves* to do this... All the time. Fortunately, the mem2reg code was really careful about updating this cache to handle this eventuallity... except when it comes to the debug declare intrinsic. Oops. The fix is to invalidate that pointer in the cache when we delete it, the same as we do when deleting alloca instructions and other instructions. I've also caused the same bug in new code while working on a fix to PR16867, so this seems to be a really unfortunate pattern. Hopefully in subsequent patches the deletion of dead instructions can be consolidated sufficiently to make it less likely that we'll see future occurences of this bug. Sorry for not having a test case, but I have literally no idea how to reliably trigger this kind of thing. It may be single-threaded, but it remains an ABA problem. It would require a really amazing number of stars to align. llvm-svn: 188367
* Revert r187191, which broke opt -mem2reg on the testcases included in PR16867.Nick Lewycky2013-08-131-164/+98
| | | | | | | | | | | | However, opt -O2 doesn't run mem2reg directly so nobody noticed until r188146 when SROA started sending more things directly down the PromoteMemToReg path. In order to revert r187191, I also revert dependent revisions r187296, r187322 and r188146. Fixes PR16867. Does not add the testcases from that PR, but both of them should get added for both mem2reg and sroa when this revert gets unreverted. llvm-svn: 188327
* Thread DataLayout through the callers and into mem2reg. This will beChandler Carruth2013-07-281-8/+13
| | | | | | | useful in a subsequent patch, but causes an unfortunate amount of noise, so I pulled it out into a separate patch. llvm-svn: 187322
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