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* Reland "clang-misexpect: Profile Guided Validation of Performance ↵Petr Hosek2019-09-111-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Annotations in LLVM" This patch contains the basic functionality for reporting potentially incorrect usage of __builtin_expect() by comparing the developer's annotation against a collected PGO profile. A more detailed proposal and discussion appears on the CFE-dev mailing list (http://lists.llvm.org/pipermail/cfe-dev/2019-July/062971.html) and a prototype of the initial frontend changes appear here in D65300 We revised the work in D65300 by moving the misexpect check into the LLVM backend, and adding support for IR and sampling based profiles, in addition to frontend instrumentation. We add new misexpect metadata tags to those instructions directly influenced by the llvm.expect intrinsic (branch, switch, and select) when lowering the intrinsics. The misexpect metadata contains information about the expected target of the intrinsic so that we can check against the correct PGO counter when emitting diagnostics, and the compiler's values for the LikelyBranchWeight and UnlikelyBranchWeight. We use these branch weight values to determine when to emit the diagnostic to the user. A future patch should address the comment at the top of LowerExpectIntrisic.cpp to hoist the LikelyBranchWeight and UnlikelyBranchWeight values into a shared space that can be accessed outside of the LowerExpectIntrinsic pass. Once that is done, the misexpect metadata can be updated to be smaller. In the long term, it is possible to reconstruct portions of the misexpect metadata from the existing profile data. However, we have avoided this to keep the code simple, and because some kind of metadata tag will be required to identify which branch/switch/select instructions are influenced by the use of llvm.expect Patch By: paulkirth Differential Revision: https://reviews.llvm.org/D66324 llvm-svn: 371635
* Revert "clang-misexpect: Profile Guided Validation of Performance ↵Dmitri Gribenko2019-09-111-12/+0
| | | | | | | | | | | | | | | | | | | Annotations in LLVM" This reverts commit r371584. It introduced a dependency from compiler-rt to llvm/include/ADT, which is problematic for multiple reasons. One is that it is a novel dependency edge, which needs cross-compliation machinery for llvm/include/ADT (yes, it is true that right now compiler-rt included only header-only libraries, however, if we allow compiler-rt to depend on anything from ADT, other libraries will eventually get used). Secondly, depending on ADT from compiler-rt exposes ADT symbols from compiler-rt, which would cause ODR violations when Clang is built with the profile library. llvm-svn: 371598
* clang-misexpect: Profile Guided Validation of Performance Annotations in LLVMPetr Hosek2019-09-111-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch contains the basic functionality for reporting potentially incorrect usage of __builtin_expect() by comparing the developer's annotation against a collected PGO profile. A more detailed proposal and discussion appears on the CFE-dev mailing list (http://lists.llvm.org/pipermail/cfe-dev/2019-July/062971.html) and a prototype of the initial frontend changes appear here in D65300 We revised the work in D65300 by moving the misexpect check into the LLVM backend, and adding support for IR and sampling based profiles, in addition to frontend instrumentation. We add new misexpect metadata tags to those instructions directly influenced by the llvm.expect intrinsic (branch, switch, and select) when lowering the intrinsics. The misexpect metadata contains information about the expected target of the intrinsic so that we can check against the correct PGO counter when emitting diagnostics, and the compiler's values for the LikelyBranchWeight and UnlikelyBranchWeight. We use these branch weight values to determine when to emit the diagnostic to the user. A future patch should address the comment at the top of LowerExpectIntrisic.cpp to hoist the LikelyBranchWeight and UnlikelyBranchWeight values into a shared space that can be accessed outside of the LowerExpectIntrinsic pass. Once that is done, the misexpect metadata can be updated to be smaller. In the long term, it is possible to reconstruct portions of the misexpect metadata from the existing profile data. However, we have avoided this to keep the code simple, and because some kind of metadata tag will be required to identify which branch/switch/select instructions are influenced by the use of llvm.expect Patch By: paulkirth Differential Revision: https://reviews.llvm.org/D66324 llvm-svn: 371584
* Revert "clang-misexpect: Profile Guided Validation of Performance ↵Petr Hosek2019-09-101-12/+0
| | | | | | | | Annotations in LLVM" This reverts commit r371484: this broke sanitizer-x86_64-linux-fast bot. llvm-svn: 371488
* clang-misexpect: Profile Guided Validation of Performance Annotations in LLVMPetr Hosek2019-09-101-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch contains the basic functionality for reporting potentially incorrect usage of __builtin_expect() by comparing the developer's annotation against a collected PGO profile. A more detailed proposal and discussion appears on the CFE-dev mailing list (http://lists.llvm.org/pipermail/cfe-dev/2019-July/062971.html) and a prototype of the initial frontend changes appear here in D65300 We revised the work in D65300 by moving the misexpect check into the LLVM backend, and adding support for IR and sampling based profiles, in addition to frontend instrumentation. We add new misexpect metadata tags to those instructions directly influenced by the llvm.expect intrinsic (branch, switch, and select) when lowering the intrinsics. The misexpect metadata contains information about the expected target of the intrinsic so that we can check against the correct PGO counter when emitting diagnostics, and the compiler's values for the LikelyBranchWeight and UnlikelyBranchWeight. We use these branch weight values to determine when to emit the diagnostic to the user. A future patch should address the comment at the top of LowerExpectIntrisic.cpp to hoist the LikelyBranchWeight and UnlikelyBranchWeight values into a shared space that can be accessed outside of the LowerExpectIntrinsic pass. Once that is done, the misexpect metadata can be updated to be smaller. In the long term, it is possible to reconstruct portions of the misexpect metadata from the existing profile data. However, we have avoided this to keep the code simple, and because some kind of metadata tag will be required to identify which branch/switch/select instructions are influenced by the use of llvm.expect Patch By: paulkirth Differential Revision: https://reviews.llvm.org/D66324 llvm-svn: 371484
* Use llvm::stable_sortFangrui Song2019-04-231-3/+1
| | | | | | While touching the code, simplify if feasible. llvm-svn: 358996
* [NFC] Fix unused variable warnings in Release buildsJohannes Doerfert2019-01-191-0/+2
| | | | llvm-svn: 351641
* Update the file headers across all of the LLVM projects in the monorepoChandler Carruth2019-01-191-4/+3
| | | | | | | | | | | | | | | | | to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
* AbstractCallSite -- A unified interface for (in)direct and callback callsJohannes Doerfert2019-01-191-0/+44
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
* [Metadata] Replace a SmallVector with an array; NFCGeorge Burgess IV2018-08-151-3/+4
| | | | | | MDNode::get takes an ArrayRef, so these should be equivalent. llvm-svn: 339824
* Remove \brief commands from doxygen comments.Adrian Prantl2018-05-011-5/+5
| | | | | | | | | | | | | | | | We've been running doxygen with the autobrief option for a couple of years now. This makes the \brief markers into our comments redundant. Since they are a visual distraction and we don't want to encourage more \brief markers in new code either, this patch removes them all. Patch produced by for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done Differential Revision: https://reviews.llvm.org/D46290 llvm-svn: 331272
* [IR] Fix creating mutable versions of TBAA access tagsIvan A. Kosarev2018-02-131-1/+1
| | | | | | | | | | Due to a typo in D41565, mutable TBAA tags created with createMutableTBAAAccessTag() lose their base types. This patch fixes that typo and updates tests respectively. Differential Revision: https://reviews.llvm.org/D42364 llvm-svn: 325008
* [Transforms] Support making mutable versions of new-format TBAA access tagsIvan A. Kosarev2018-01-171-0/+27
| | | | | | Differential Revision: https://reviews.llvm.org/D41565 llvm-svn: 322650
* Add a pass to generate synthetic function entry counts.Easwaran Raman2018-01-091-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | Summary: This pass synthesizes function entry counts by traversing the callgraph and using the relative block frequencies of the callsites. The intended use of these counts is in inlining to determine hot/cold callsites in the absence of profile information. The pass is split into two files with the code that propagates the counts in a callgraph in a Utils file. I plan to add support for propagation in the thinlto link phase and the propagation code will be shared and hence this split. I did not add support to the old PM since hot callsite determination in inlining is not possible in old PM (although we could use hot callee heuristic with synthetic counts in the old PM it is not worth the effort tuning it) Reviewers: davidxl, silvas Subscribers: mgorny, mehdi_amini, llvm-commits Differential Revision: https://reviews.llvm.org/D41604 llvm-svn: 322110
* [IR] Add MDBuilder helpers for the new TBAA metadata formatIvan A. Kosarev2017-12-181-1/+31
| | | | | | | | | | | The new helpers are supposed to be used in clang to generate TBAA information in the new format proposed in this thread: http://lists.llvm.org/pipermail/llvm-dev/2017-November/118748.html Differential Revision: https://reviews.llvm.org/D39956 llvm-svn: 320993
* Irreducible loop metadata for more accurate block frequency under PGO.Hiroshi Yamauchi2017-11-021-0/+7
| | | | | | | | | | | | | | | | | | | | | | | Summary: Currently the block frequency analysis is an approximation for irreducible loops. The new irreducible loop metadata is used to annotate the irreducible loop headers with their header weights based on the PGO profile (currently this is approximated to be evenly weighted) and to help improve the accuracy of the block frequency analysis for irreducible loops. This patch is a basic support for this. Reviewers: davidxl Reviewed By: davidxl Subscribers: mehdi_amini, llvm-commits, eraman Differential Revision: https://reviews.llvm.org/D39028 llvm-svn: 317278
* Add !callees metadataMatthew Simpson2017-10-161-0/+8
| | | | | | | | | This patch adds a new kind of metadata that indicates the possible callees of indirect calls. Differential Revision: https://reviews.llvm.org/D37354 llvm-svn: 315944
* [PGO] Fixed non-determinism with DenseSet storing function importing info.Ana Pazos2017-08-291-2/+7
| | | | | | | | | | | | | | | | | | | | Summary: r296498 introduced a DenseSet to store function importing info. Using this container causes a test failure in test/Transform/SampleProfile/import.ll when in Reverse Iteration mode. This patch orders IDs before iterating through this container. Reviewers: danielcdh, mgrang Reviewed By: danielcdh Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D37246 llvm-svn: 312012
* Add function importing info from samplepgo profile to the module summary.Dehao Chen2017-02-281-4/+9
| | | | | | | | | | | | | | Summary: For SamplePGO, the profile may contain cross-module inline stacks. As we need to make sure the profile annotation happens when all the hot inline stacks are expanded, we need to pass this info to the module importer so that it can import proper functions if necessary. This patch implemented this feature by emitting cross-module targets as part of function entry metadata. In the module-summary phase, the metadata is used to build call edges that points to functions need to be imported. Reviewers: mehdi_amini, tejohnson Reviewed By: tejohnson Subscribers: davidxl, llvm-commits Differential Revision: https://reviews.llvm.org/D30053 llvm-svn: 296498
* Use profile info to set function section prefix to group hot/cold functions.Dehao Chen2016-10-181-0/+6
| | | | | | | | | | | | | | | | Summary: The original implementation is in r261607, which was reverted in r269726 to accomendate the ProfileSummaryInfo analysis pass. The new implementation: 1. add a new metadata for function section prefix 2. query against ProfileSummaryInfo in CGP to set the correct section prefix for each function 3. output the section prefix set by CGP Reviewers: davidxl, eraman Subscribers: vsk, llvm-commits Differential Revision: https://reviews.llvm.org/D24989 llvm-svn: 284533
* Fix the assertion failure caused by http://reviews.llvm.org/D22118Dehao Chen2016-07-111-1/+1
| | | | | | | | | | | | Summary: http://reviews.llvm.org/D22118 uses metadata to store the call count, which makes it possible to have branch weight to have only one elements. Also fix the assertion failure in inliner when checking the instruction type to include "invoke" instruction. Reviewers: mkuper, dnovillo Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D22228 llvm-svn: 275079
* [MDBuilder] Simplify code using initializer lists. NFC.Benjamin Kramer2015-11-221-28/+16
| | | | llvm-svn: 253826
* add unpredictable metadata type for control flowSanjay Patel2015-09-021-0/+4
| | | | | | | | | | | | | | | This patch defines 'unpredictable' metadata. This metadata can be used to signal to the optimizer or backend that a branch or switch is unpredictable, and therefore, it's probably better to not split a compound predicate into multiple branches such as in CodeGenPrepare::splitBranchCondition(). This was discussed in: https://llvm.org/bugs/show_bug.cgi?id=23827 Dependent patches to alter codegen and expose this in clang to follow. Differential Revision; http://reviews.llvm.org/D12341 llvm-svn: 246688
* Add isConstant argument to MDBuilder::createTBAAStructTagNodeArtur Pilipenko2015-06-011-4/+11
| | | | | | | | | | According to the TBAA description struct-path tag node can have an optional IsConstant field. Add corresponding argument to MDBuilder::createTBAAStructTagNode. Reviewed By: hfinkel Differential Revision: http://reviews.llvm.org/D10160 llvm-svn: 238749
* Add function entry count metadata.Diego Novillo2015-05-131-0/+10
| | | | | | | | | | | | | | | | | | | | Summary: This adds three Function methods to handle function entry counts: setEntryCount() and getEntryCount(). Entry counts are stored under the MD_prof metadata node with the name "function_entry_count". They are unsigned 64 bit values set by profilers (instrumentation and sample profiler changes coming up). Added documentation for new profile metadata and tests. Reviewers: dexonsmith, bogner Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D9628 llvm-svn: 237260
* [IC] Turn non-null MD on pointer loads to range MD on integer loads.Charles Davis2015-02-251-3/+7
| | | | | | | | | | | | | | | | | Summary: This change fixes the FIXME that you recently added when you committed (a modified version of) my patch. When `InstCombine` combines a load and store of an pointer to those of an equivalently-sized integer, it currently drops any `!nonnull` metadata that might be present. This change replaces `!nonnull` metadata with `!range !{ 1, -1 }` metadata instead. Reviewers: chandlerc Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D7621 llvm-svn: 230462
* IR: Return unique_ptr from MDNode::getTemporary()Duncan P. N. Exon Smith2015-01-191-3/+3
| | | | | | | | | | | | Change `MDTuple::getTemporary()` and `MDLocation::getTemporary()` to return (effectively) `std::unique_ptr<T, MDNode::deleteTemporary>`, and clean up call sites. (For now, `DIBuilder` call sites just call `release()` immediately.) There's an accompanying change in each of clang and polly to use the new API. llvm-svn: 226504
* IR: Split Metadata from ValueDuncan P. N. Exon Smith2014-12-091-15/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Simplify creation of a bunch of ArrayRefs by using None, makeArrayRef or ↵Craig Topper2014-08-271-1/+1
| | | | | | just letting them be implicitly created. llvm-svn: 216525
* Simplify and improve scoped-noalias metadata semanticsHal Finkel2014-07-251-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the process of fixing the noalias parameter -> metadata conversion process that will take place during inlining (which will be committed soon, but not turned on by default), I have come to realize that the semantics provided by yesterday's commit are not really what we want. Here's why: void foo(noalias a, noalias b, noalias c, bool x) { *q = x ? a : b; *c = *q; } Generically, we know that *c does not alias with *a and with *b (so there is an 'and' in what we know we're not), and we know that *q might be derived from *a or from *b (so there is an 'or' in what we know that we are). So we do not want the semantics currently, where any noalias scope matching any alias.scope causes a NoAlias return. What we want to know is that the noalias scopes form a superset of the alias.scope list (meaning that all the things we know we're not is a superset of all of things the other instruction might be). Making that change, however, introduces a composibility problem. If we inline once, adding the noalias metadata, and then inline again adding more, and we append new scopes onto the noalias and alias.scope lists each time. But, this means that we could change what was a NoAlias result previously into a MayAlias result because we appended an additional scope onto one of the alias.scope lists. So, instead of giving scopes the ability to have parents (which I had borrowed from the TBAA implementation, but seems increasingly unlikely to be useful in practice), I've given them domains. The subset/superset condition now applies within each domain independently, and we only need it to hold in one domain. Each time we inline, we add the new scopes in a new scope domain, and everything now composes nicely. In addition, this simplifies the implementation. llvm-svn: 213948
* Add scoped-noalias metadataHal Finkel2014-07-241-3/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds scoped noalias metadata. The primary motivations for this feature are: 1. To preserve noalias function attribute information when inlining 2. To provide the ability to model block-scope C99 restrict pointers Neither of these two abilities are added here, only the necessary infrastructure. In fact, there should be no change to existing functionality, only the addition of new features. The logic that converts noalias function parameters into this metadata during inlining will come in a follow-up commit. What is added here is the ability to generally specify noalias memory-access sets. Regarding the metadata, alias-analysis scopes are defined similar to TBAA nodes: !scope0 = metadata !{ metadata !"scope of foo()" } !scope1 = metadata !{ metadata !"scope 1", metadata !scope0 } !scope2 = metadata !{ metadata !"scope 2", metadata !scope0 } !scope3 = metadata !{ metadata !"scope 2.1", metadata !scope2 } !scope4 = metadata !{ metadata !"scope 2.2", metadata !scope2 } Loads and stores can be tagged with an alias-analysis scope, and also, with a noalias tag for a specific scope: ... = load %ptr1, !alias.scope !{ !scope1 } ... = load %ptr2, !alias.scope !{ !scope1, !scope2 }, !noalias !{ !scope1 } When evaluating an aliasing query, if one of the instructions is associated with an alias.scope id that is identical to the noalias scope associated with the other instruction, or is a descendant (in the scope hierarchy) of the noalias scope associated with the other instruction, then the two memory accesses are assumed not to alias. Note that is the first element of the scope metadata is a string, then it can be combined accross functions and translation units. The string can be replaced by a self-reference to create globally unqiue scope identifiers. [Note: This overview is slightly stylized, since the metadata nodes really need to just be numbers (!0 instead of !scope0), and the scope lists are also global unnamed metadata.] Existing noalias metadata in a callee is "cloned" for use by the inlined code. This is necessary because the aliasing scopes are unique to each call site (because of possible control dependencies on the aliasing properties). For example, consider a function: foo(noalias a, noalias b) { *a = *b; } that gets inlined into bar() { ... if (...) foo(a1, b1); ... if (...) foo(a2, b2); } -- now just because we know that a1 does not alias with b1 at the first call site, and a2 does not alias with b2 at the second call site, we cannot let inlining these functons have the metadata imply that a1 does not alias with b2. llvm-svn: 213864
* [C++11] More 'nullptr' conversion. In some cases just using a boolean check ↵Craig Topper2014-04-151-1/+1
| | | | | | instead of comparing to nullptr. llvm-svn: 206252
* Move MDBuilder's methods out of line.Benjamin Kramer2014-04-121-0/+139
Making them inline was a historical accident, they're neither hot nor templated. llvm-svn: 206109
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