removeUsers uses a work list to collect indirect users and call remove()
on those functions. However it has a bug (`if (!Visited.insert(UU).second)`).
Actually, we don't have to collect indirect users.
After the merge of F and G, G's callers will be considered (added to
Deferred). If G's callers can be merged, G's callers' callers will be
considered.
Update the test unnamed-addr-reprocessing.ll to make it clear we can
still merge indirect callers.
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We would previously drop the COMDAT on the thunk we generated when replacing a
function body with the forwarding thunk. This would result in a function that
may have been multiply emitted and multiply merged to be emitted with the same
name without the COMDAT. This is a hard error with PE/COFF where the COMDAT is
used for the deduplication of Value Witness functions for Swift.
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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.
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Thanks to Nikita Popov for pointing out this missed case.
This is a follow-up to r351411, which disabled function merging for
vararg functions outright due to a miscompile (see llvm.org/PR40345).
Differential Revision: https://reviews.llvm.org/D56865
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The function merging pass miscompiles identical vararg functions. The
forwarding thunk it emits doesn't forward the full variable-length list
of arguments. Disable merging for vararg functions for now.
I've filed llvm.org/PR40345 to track the issue.
rdar://47326238
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This modifies the IPO pass so that it respects any explicit function
address space specified in the data layout.
In targets with nonzero program address spaces, all functions should, by
default, be placed into the default program address space.
This is required for Harvard architectures like AVR. Without this, the
functions will be marked as residing in data space, and thus not be
callable.
This has no effect to any in-tree official backends, as none use an
explicit program address space in their data layouts.
Patch by Tim Neumann.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@349469 91177308-0d34-0410-b5e6-96231b3b80d8
The MergeFunctions pass was originally intended to emit aliases
instead of thunks where possible (unnamed_addr). However, for a
long time this functionality was behind a flag hardcoded to false,
bitrotted and was eventually removed in r309313.
Originally the functionality was first disabled in r108417 due to
lack of support for aliases in Mach-O. I believe that this is no
longer the case nowadays, but not really familiar with this area.
In the interest of being conservative, this patch reintroduces the
aliasing functionality behind a default disabled -mergefunc-use-aliases
flag.
Differential Revision: https://reviews.llvm.org/D53285
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347407 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
MergeFunctions currently tries to process strong functions before
weak functions, because weak functions can simply call strong
functions, while a strong/weak function cannot call a weak function
(a backing strong function is needed).
This patch additionally tries to process external functions before
local functions, because we definitely have to keep the external
function, but may be able to drop the local one (and definitely
can if it is also unnamed_addr).
Unfortunately, this exposes an existing bug in the implementation:
The FnTree and FNodesInTree structures can currently go out of
sync in the case where two weak functions are merged, because the
function in FnTree/FNodesInTree is RAUWed. This leaves it behind in
FnTree (this is intended, as it is the strong backing function which
should be used for further merges), while it is replaced in
FNodesInTree (this is not intended).
This is fixed by switching FNodesInTree from using a ValueMap to
using a DenseMap of AssertingVH.
This exposes another minor issue: Currently FNodesInTree is not
cleared after MergeFunctions finishes running. Currently, this is
potentially dangerous (e.g. if something else wants to RAUW a function
with a non-function), but at the very least it is unnecessary/inefficient.
After the change to use AssertingVH it becomes more problematic,
because there are certainly passes that remove functions.
This issue is fixed by clearing FNodesInTree at the end of the pass.
Reviewers: jfb, whitequark
Reviewed By: whitequark
Subscribers: rkruppe, llvm-commits
Differential Revision: https://reviews.llvm.org/D53271
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346386 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
For unnamed_addr functions we RAUW instead of only replacing direct callers. However, functions in which replacements were performed currently are not added back to the worklist, resulting in missed merging opportunities.
Fix this by calling removeUsers() prior to RAUW.
Reviewers: jfb, whitequark
Reviewed By: whitequark
Subscribers: rkruppe, llvm-commits
Differential Revision: https://reviews.llvm.org/D53262
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346385 91177308-0d34-0410-b5e6-96231b3b80d8
Currently SmallSet<PointerTy> inherits from SmallPtrSet<PointerTy>. This
patch replaces such types with SmallPtrSet, because IMO it is slightly
clearer and allows us to get rid of unnecessarily including SmallSet.h
Reviewers: dblaikie, craig.topper
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D47836
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334492 91177308-0d34-0410-b5e6-96231b3b80d8
When two interposable functions are merged, we cannot replace
uses and have to emit calls to a common internal function. However,
writeThunk() will not actually emit a thunk if the function is too
small. This leaves us in a broken state where mergeTwoFunctions
already rewired the functions, but writeThunk doesn't do anything.
This patch changes the implementation so that:
* writeThunk() does just that.
* The direct replacement of calls is moved into mergeTwoFunctions()
into the non-interposable case only.
* isThunkProfitable() is extracted and will be called for
the non-iterposable case always, and in the interposable case
only if uses are still left after replacement.
This issue has been introduced in https://reviews.llvm.org/D34806,
where the code for checking thunk profitability has been moved.
Differential Revision: https://reviews.llvm.org/D46804
Reviewed By: whitequark
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@332342 91177308-0d34-0410-b5e6-96231b3b80d8
The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.
In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.
Differential Revision: https://reviews.llvm.org/D43624
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MergeFunctions uses (through FunctionComparator) a map of GlobalValues
to identifiers because it needs to compare functions and globals
do not have an inherent total order. Thus, FunctionComparator
(through GlobalNumberState) has a ValueMap<GlobalValue *>.
r315852 added a RAUW on globals that may have been previously
encountered by the FunctionComparator, which would replace
a GlobalValue * key with a ConstantExpr *, which is illegal.
This commit adjusts that code path to remove the function being
replaced from the ValueMap as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316145 91177308-0d34-0410-b5e6-96231b3b80d8
This can result in significant code size savings in some cases,
e.g. an interrupt table all filled with the same assembly stub
in a certain Cortex-M BSP results in code blowup by a factor of 2.5.
Differential Revision: https://reviews.llvm.org/D34806
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315853 91177308-0d34-0410-b5e6-96231b3b80d8
The alias support was dead code since 2011. It was last touched
in r124182, where it was reintroduced after being removed
in r110434, and since then it was gated behind a HasGlobalAliases
flag that was permanently stuck as `false`.
It is also broken. I'm not sure if it bitrotted or was just broken
in the first place because it appears to have never been tested,
but the following IR results in a crash:
define internal i32 @a(i32 %a, i32 %b) unnamed_addr {
%c = add i32 %a, %b
%d = xor i32 %a, %c
ret i32 %c
}
define internal i32 @b(i32 %a, i32 %b) unnamed_addr {
%c = add i32 %a, %b
%d = xor i32 %a, %c
ret i32 %c
}
It seems safe to remove buggy untested code that no one cared about
for seven years.
Differential Revision: https://reviews.llvm.org/D34802
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Commits were:
"Use WeakVH instead of WeakTrackingVH in AliasSetTracker's UnkownInsts"
"Add a new WeakVH value handle; NFC"
"Rename WeakVH to WeakTrackingVH; NFC"
The changes assumed pointers are 8 byte aligned on all architectures.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301429 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
I plan to use WeakVH to mean "nulls itself out on deletion, but does
not track RAUW" in a subsequent commit.
Reviewers: dblaikie, davide
Reviewed By: davide
Subscribers: arsenm, mehdi_amini, mcrosier, mzolotukhin, jfb, llvm-commits, nhaehnle
Differential Revision: https://reviews.llvm.org/D32266
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301424 91177308-0d34-0410-b5e6-96231b3b80d8
Add hasParamAttribute() and use it instead of hasAttribute(ArgNo+1,
Kind) everywhere.
The fact that the AttributeList index for an argument is ArgNo+1 should
be a hidden implementation detail.
NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300272 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
For now, it just wraps AttributeSetNode*. Eventually, it will hold
AvailableAttrs as an inline bitset, and adding and removing enum
attributes will be super cheap.
This sinks AttributeSetNode back down to lib/IR/AttributeImpl.h.
Reviewers: pete, chandlerc
Subscribers: llvm-commits, jfb
Differential Revision: https://reviews.llvm.org/D31940
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300014 91177308-0d34-0410-b5e6-96231b3b80d8
This re-lands r299875.
I introduced a bug in Clang code responsible for replacing K&R, no
prototype declarations with a real function definition with a prototype.
The bug was here:
// Collect any return attributes from the call.
- if (oldAttrs.hasAttributes(llvm::AttributeList::ReturnIndex))
- newAttrs.push_back(llvm::AttributeList::get(newFn->getContext(),
- oldAttrs.getRetAttributes()));
+ newAttrs.push_back(oldAttrs.getRetAttributes());
Previously getRetAttributes() carried AttributeList::ReturnIndex in its
AttributeList. Now that we return the AttributeSetNode* directly, it no
longer carries that index, and we call this overload with a single node:
AttributeList::get(LLVMContext&, ArrayRef<AttributeSetNode*>)
That aborted with an assertion on x86_32 targets. I added an explicit
triple to the test and added CHECKs to help find issues like this in the
future sooner.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299899 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
AttributeList::get(Fn|Ret|Param)Attributes no longer creates a temporary
AttributeList just to hide the AttributeSetNode type.
I've also added a factory method to create AttributeLists from a
parallel array of AttributeSetNodes. I think this simplifies
construction of AttributeLists when rewriting function prototypes.
Previously we would test if a particular index had attributes, and
conditionally add a temporary attribute list to a vector. Now the
attribute set vector is parallel to the argument vector already that
these passes already construct.
My long term vision is to wrap AttributeSetNode* inside an AttributeSet
type that holds the enum attributes, but that will come in a follow up
change.
I haven't done any performance measurements for this change because
profiling hasn't shown that any of the affected code is hot.
Reviewers: pete, chandlerc, sanjoy, hfinkel
Reviewed By: pete
Subscribers: jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D31198
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299875 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This class is a list of AttributeSetNodes corresponding the function
prototype of a call or function declaration. This class used to be
called ParamAttrListPtr, then AttrListPtr, then AttributeSet. It is
typically accessed by parameter and return value index, so
"AttributeList" seems like a more intuitive name.
Rename AttributeSetImpl to AttributeListImpl to follow suit.
It's useful to rename this class so that we can rename AttributeSetNode
to AttributeSet later. AttributeSet is the set of attributes that apply
to a single function, argument, or return value.
Reviewers: sanjoy, javed.absar, chandlerc, pete
Reviewed By: pete
Subscribers: pete, jholewinski, arsenm, dschuff, mehdi_amini, jfb, nhaehnle, sbc100, void, llvm-commits
Differential Revision: https://reviews.llvm.org/D31102
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298393 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Under option -mergefunc-preserve-debug-info we:
- Do not create a new function for a thunk.
- Retain the debug info for a thunk's parameters (and associated
instructions for the debug info) from the entry block.
Note: -debug will display the algorithm at work.
- Create debug-info for the call (to the shared implementation) made by
a thunk and its return value.
- Erase the rest of the function, retaining the (minimally sized) entry
block to create a thunk.
- Preserve a thunk's call site to point to the thunk even when both occur
within the same translation unit, to aid debugability. Note that this
behaviour differs from the underlying -mergefunc implementation which
modifies the thunk's call site to point to the shared implementation
when both occur within the same translation unit.
Reviewers: echristo, eeckstein, dblaikie, aprantl, friss
Reviewed By: aprantl
Subscribers: davide, fhahn, jfb, mehdi_amini, llvm-commits
Differential Revision: https://reviews.llvm.org/D28075
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This is pure refactoring. NFC.
This change moves the FunctionComparator (together with the GlobalNumberState
utility) in to a separate file so that it can be used by other passes.
For example, the SwiftMergeFunctions pass in the Swift compiler:
https://github.com/apple/swift/blob/master/lib/LLVMPasses/LLVMMergeFunctions.cpp
Details of the change:
*) The big part is just moving code out of MergeFunctions.cpp into FunctionComparator.h/cpp
*) Make FunctionComparator member functions protected (instead of private)
so that a derived comparator class can use them.
Following refactoring helps to share code between the base FunctionComparator
class and a derived class:
*) Add a beginCompare() function
*) Move some basic function property comparisons into a separate function compareSignature()
*) Do the GEP comparison inside cmpOperations() which now has a new
needToCmpOperands reference parameter
https://reviews.llvm.org/D25385
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If a local_unnamed_addr attribute is attached to a global, the address
is known to be insignificant within the module. It is distinct from the
existing unnamed_addr attribute in that it only describes a local property
of the module rather than a global property of the symbol.
This attribute is intended to be used by the code generator and LTO to allow
the linker to decide whether the global needs to be in the symbol table. It is
possible to exclude a global from the symbol table if three things are true:
- This attribute is present on every instance of the global (which means that
the normal rule that the global must have a unique address can be broken without
being observable by the program by performing comparisons against the global's
address)
- The global has linkonce_odr linkage (which means that each linkage unit must have
its own copy of the global if it requires one, and the copy in each linkage unit
must be the same)
- It is a constant or a function (which means that the program cannot observe that
the unique-address rule has been broken by writing to the global)
Although this attribute could in principle be computed from the module
contents, LTO clients (i.e. linkers) will normally need to be able to compute
this property as part of symbol resolution, and it would be inefficient to
materialize every module just to compute it.
See:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.htmlhttp://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html
for earlier discussion.
Part of the fix for PR27553.
Differential Revision: http://reviews.llvm.org/D20348
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The assumption, made in insert() that weak functions are always inserted after strong functions,
is only true in the first round of adding functions.
In subsequent rounds this is no longer guaranteed , because we might remove a strong function from the tree (because it's modified) and add it later,
where an equivalent weak function already exists in the tree.
This change removes the assert in insert() and explicitly enforces a weak->strong order.
This also removes the need of two separate loops in runOnModule().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271299 91177308-0d34-0410-b5e6-96231b3b80d8
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
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Some of the comparators were const others weren't making it annoying to add new comparators which call existing ones.
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