Commit Graph

68 Commits

Author SHA1 Message Date
Justin Lebar c05f3c9942 [IR] [DAE] Copy comdats during DAE, and don't copy comdats in GlobalObject::copyAttributesFrom.
Summary: This reverts the changes to Globals.cpp and IRMover.cpp in
"[IR] Copy comdats in GlobalObject::copyAttributesFrom" (D20631,
rL270743).

The DeadArgElim test is left unchanged, and we change DAE to explicitly
copy comdats.

The reverted change breaks copyAttributesFrom when the destination lives
in a different module from the source.  The decision in D21255 was to
revert this patch and handle comdat copying separately from
copyAttributesFrom.

Reviewers: majnemer, rnk

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D21403

llvm-svn: 272855
2016-06-15 23:20:15 +00:00
Peter Collingbourne 96efdd6107 IR: Introduce local_unnamed_addr attribute.
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.html
http://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

llvm-svn: 272709
2016-06-14 21:01:22 +00:00
Peter Collingbourne cceae7feda Add support for metadata attachments for global variables.
This patch adds an IR, assembly and bitcode representation for metadata
attachments for globals. Future patches will port existing features to use
these new attachments.

Differential Revision: http://reviews.llvm.org/D20074

llvm-svn: 271348
2016-05-31 23:01:54 +00:00
Reid Kleckner c0a0363d5c [IR] Copy comdats in GlobalObject::copyAttributesFrom
This is probably correct for all uses except cross-module IR linking,
where we need to move the comdat from the source module to the
destination module.

Fixes PR27870.

Reviewers: majnemer

Differential Revision: http://reviews.llvm.org/D20631

llvm-svn: 270743
2016-05-25 18:36:22 +00:00
Rafael Espindola 83658d6e7a Return a StringRef from getSection.
This is similar to how getName is handled.

llvm-svn: 269218
2016-05-11 18:21:59 +00:00
Dmitry Polukhin a1feff7024 [GCC] Attribute ifunc support in llvm
This patch add support for GCC attribute((ifunc("resolver"))) for
targets that use ELF as object file format. In general ifunc is a
special kind of function alias with type @gnu_indirect_function. Patch
for Clang http://reviews.llvm.org/D15524

Differential Revision: http://reviews.llvm.org/D15525

llvm-svn: 265667
2016-04-07 12:32:19 +00:00
Dmitry Polukhin a3d5b0b218 [IFUNC] Use GlobalIndirectSymbol when aliases and ifuncs have something similar
Second part extracted from http://reviews.llvm.org/D15525

Use GlobalIndirectSymbol in all cases when aliases and ifuncs have
something in common.

Differential Revision: http://reviews.llvm.org/D18754

llvm-svn: 265382
2016-04-05 08:47:51 +00:00
Mehdi Amini b049431bec constify GlobalValue::getGUID() and GlobalValue::getGlobalIdentifier() (NFC)
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 265217
2016-04-02 05:25:27 +00:00
Dmitry Polukhin cd835ad876 [IFUNC] Introduce GlobalIndirectSymbol as a base class for alias and ifunc
This patch is a part of http://reviews.llvm.org/D15525

GlobalIndirectSymbol class contains common implementation for both
aliases and ifuncs. This patch should be NFC change that just prepare
common code for ifunc support.

Differential Revision: http://reviews.llvm.org/D18433

llvm-svn: 265016
2016-03-31 14:16:21 +00:00
Mehdi Amini 4f2bb50b20 Add GUID/getGlobalIdentifier() non-static API to global value
Summary:
These are just helpers calling their static counter part to
simplify client code.

Reviewers: tejohnson

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D18339

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 264382
2016-03-25 05:57:41 +00:00
Teresa Johnson b43027d1e0 Move global ID computation from Function to GlobalValue (NFC)
Since the static getGlobalIdentifier and getGUID methods are now called
for global values other than functions, reflect that by moving these
methods to the GlobalValue class.

llvm-svn: 263524
2016-03-15 02:13:19 +00:00
Mehdi Amini 8914d29008 Simplify handleOperandChangeImpl() removing last argument (NFC)
The Use argument was used to compute the operand number for a fast
path when replacing only one operand. However we always have to go
through all the operands. So the argument number can be recomputed
locally anyway.

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 260454
2016-02-10 22:47:15 +00:00
Manuel Jacob 5f6eaac611 GlobalValue: use getValueType() instead of getType()->getPointerElementType().
Reviewers: mjacob

Subscribers: jholewinski, arsenm, dsanders, dblaikie

Patch by Eduard Burtescu.

Differential Revision: http://reviews.llvm.org/D16260

llvm-svn: 257999
2016-01-16 20:30:46 +00:00
James Y Knight ac03dca412 Stop increasing alignment of externally-visible globals on ELF
platforms.

With ELF, the alignment of a global variable in a shared library will
get copied into an executables linked against it, if the executable even
accesss the variable. So, it's not possible to implicitly increase
alignment based on access patterns, or you'll break existing binaries.

This happened to affect libc++'s std::cout symbol, for example. See
thread: http://thread.gmane.org/gmane.comp.compilers.clang.devel/45311

(This is a re-commit of r257719, without the bug reported in
PR26144. I've tweaked the code to not assert-fail in
enforceKnownAlignment when computeKnownBits doesn't recurse far enough
to find the underlying Alloca/GlobalObject value.)

Differential Revision: http://reviews.llvm.org/D16145

llvm-svn: 257902
2016-01-15 16:33:06 +00:00
James Y Knight 582f556251 Revert "Stop increasing alignment of externally-visible globals on ELF platforms."
This reverts commit r257719, due to PR26144.

llvm-svn: 257775
2016-01-14 16:33:21 +00:00
James Y Knight 9de6d7becc Stop increasing alignment of externally-visible globals on ELF
platforms.

With ELF, the alignment of a global variable in a shared library will
get copied into an executables linked against it, if the executable even
accesss the variable. So, it's not possible to implicitly increase
alignment based on access patterns, or you'll break existing binaries.

This happened to affect libc++'s std::cout symbol, for example. See
thread: http://thread.gmane.org/gmane.comp.compilers.clang.devel/45311

llvm-svn: 257719
2016-01-13 23:59:19 +00:00
Rafael Espindola 18c63b0f18 Drop support for dematerializing.
It was only used on lib/Linker and the use was "dead" since it was used on a
function the IRMover had just moved.

llvm-svn: 256019
2015-12-18 19:57:26 +00:00
Rafael Espindola 769efe621a Don't copy information from aliasee to alias.
They are independent.

llvm-svn: 254541
2015-12-02 20:03:17 +00:00
Duncan P. N. Exon Smith 52888a6738 IR: Remove implicit iterator conversions from lib/IR, NFC
Stop converting implicitly between iterators and pointers/references in
lib/IR.  For convenience, I've added a `getIterator()` accessor to
`ilist_node` so that callers don't need to know how to spell the
iterator class (i.e., they can use `X.getIterator()` instead of
`Function::iterator(X)`).

I'll eventually disallow these implicit conversions entirely, but
there's a lot of code, so it doesn't make sense to do it all in one
patch.  One library or so at a time.

Why?  To root out cases of `getNextNode()` and `getPrevNode()` being
used in iterator logic.  The design of `ilist` makes that invalid when
the current node could be at the back of the list, but it happens to
"work" right now because of a bug where those functions never return
`nullptr` if you're using a half-node sentinel.  Before I can fix the
function, I have to remove uses of it that rely on it misbehaving.
(Maybe the function should just be deleted anyway?  But I don't want
deleting it -- potentially a huge project -- to block fixing
ilist/iplist.)

llvm-svn: 249782
2015-10-08 23:49:46 +00:00
David Blaikie 798f3079d4 [opaque pointer types] Add an explicit value type to GlobalObject
This is needed by all GlobalObjects (GlobalAlias, Function,
GlobalVariable), see the GlobalObject::getValueType which is used in
many places. If at some point that can be removed, then we can remove
this member.

llvm-svn: 247621
2015-09-14 21:47:27 +00:00
David Blaikie 16a2f3e302 Revert "[opaque pointer type] Pass GlobalAlias the actual pointer type rather than decomposing it into pointee type + address space"
This was a flawed change - it just caused the getElementType call to be
deferred until later, when we really need to remove it. Now that the IR
for GlobalAliases has been updated, the root cause is addressed that way
instead and this change is no longer needed (and in fact gets in the way
- because we want to pass the pointee type directly down further).

Follow up patches to push this through GlobalValue, bitcode format, etc,
will come along soon.

This reverts commit 236160.

llvm-svn: 247585
2015-09-14 18:01:59 +00:00
David Blaikie d583b19569 [opaque pointer types] Push the passing of value types up from Function/GlobalVariable to GlobalObject
(coming next, pushing this up into GlobalValue, so it can store the
value type directly)

llvm-svn: 245742
2015-08-21 21:35:28 +00:00
Pete Cooper 5815b1fd56 Devirtualize Constant::replaceUsesOfWithOnConstant.
This is part of the work to devirtualize Value.

The old pattern was to call replaceUsesOfWithOnConstant which was overridden by
subclasses.  Those could then call replaceUsesOfWithOnConstantImpl on Constant
to handle deleting the current value.

To be consistent with other parts of the code, this has been changed so that we
call the method on Constant, and that dispatches to an Impl on subclasses.

As part of this, it made sense to rename the methods to be more descriptive.  The
new name is Constant::handleOperandChange, and it requires that all subclasses of
Constant implement handleOperandChangeImpl, even if they just throw an error if
they shouldn't be called.

Reviewed by Duncan Exon Smith.

llvm-svn: 240567
2015-06-24 18:55:24 +00:00
Pete Cooper a272f7fca9 Remove unused GlobalVariable::replaceUsesOfWithOnConstant. NFC.
The only caller of this method is Value::replaceAllUsesWith which
explicitly checks that we are not a GlobalValue.  So replace the
body with an unreachable to ensure that we never call it.

The unreachable itself is moved to GlobalValue not GlobalVariable
as that is the base class of all the globals we don't want to call
this method on.

Note, this patch is short lived as i'll soon refactor all callers
of this method.

llvm-svn: 240486
2015-06-24 00:05:07 +00:00
Pete Cooper 86dd4cf5a1 Devirtualize Constant::destroyConstant.
This reorganizes destroyConstant and destroyConstantImpl.

Now there is only destroyConstant in Constant itself, while
subclasses are required to implement destroyConstantImpl.

destroyConstantImpl no longer calls delete but is instead only
responsible for removing the constant from any maps in which it
is contained.

Reviewed by Duncan Exon Smith.

llvm-svn: 240471
2015-06-23 21:55:11 +00:00
Pete Cooper b4eede2c07 Rename NumOperands to make it clear its managed by the User. NFC.
This is to try make it very clear that subclasses shouldn't be changing
the value directly.  Now that OperandList for normal instructions is computed
using the NumOperands, its critical that the NumOperands is accurate or we
could compute the wrong offset to the first operand.

I looked over all places which update NumOperands and they are all safe.
Hung off use User's don't use NumOperands to compute the OperandList so they
are safe to continue to manipulate it.  The only other User which changed it
was GlobalVariable which has an optional init list but always allocated space
for a single Use.  It was correctly setting NumOperands to 1 before setting an
initializer, and setting it to 0 after clearing the init list, so the order was safe.

Added some comments to that code to make sure that this isn't changed in future
without being aware of this constraint.

Reviewed by Duncan Exon Smith.

llvm-svn: 239621
2015-06-12 17:48:10 +00:00
Eric Christopher 97cb56572a While in GlobalValue fix the function(s) that don't follow the
naming convention and update users.

llvm-svn: 237461
2015-05-15 18:20:14 +00:00
David Blaikie f64246be72 [opaque pointer type] Pass GlobalAlias the actual pointer type rather than decomposing it into pointee type + address space
Many of the callers already have the pointer type anyway, and for the
couple of callers that don't it's pretty easy to call PointerType::get
on the pointee type and address space.

This avoids LLParser from using PointerType::getElementType when parsing
GlobalAliases from IR.

llvm-svn: 236160
2015-04-29 21:22:39 +00:00
Mehdi Amini 9a9738f6e5 Remove getDataLayout() from Instruction/GlobalValue/BasicBlock/Function
Summary:
This does not conceptually belongs here. Instead provide a shortcut
getModule() that provides access to the DataLayout.

Reviewers: chandlerc, echristo

Reviewed By: echristo

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8027

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231147
2015-03-03 22:01:13 +00:00
Rafael Espindola 366e5c1bf1 The leak detector is dead, long live asan and valgrind.
In resent times asan and valgrind have found way more memory management bugs
in llvm than the special purpose leak detector.

llvm-svn: 224703
2014-12-22 13:00:36 +00:00
Rafael Espindola 75b809c9b6 Copy externally_initialized in GlobalVariable::copyAttributesFrom.
Patch by Kevin Frei!

llvm-svn: 221620
2014-11-10 18:41:59 +00:00
Rafael Espindola 5a52e6dc9e Modernize the error handling of the Materialize function.
llvm-svn: 220600
2014-10-24 22:50:48 +00:00
Rafael Espindola d4bcefc7d9 Don't ever call materializeAllPermanently during LTO.
To do this, change the representation of lazy loaded functions.

The previous representation cannot differentiate between a function whose body
has been removed and one whose body hasn't been read from the .bc file. That
means that in order to drop a function, the entire body had to be read.

llvm-svn: 220580
2014-10-24 18:13:04 +00:00
David Majnemer dad0a645a7 IR: Add COMDATs to the IR
This new IR facility allows us to represent the object-file semantic of
a COMDAT group.

COMDATs allow us to tie together sections and make the inclusion of one
dependent on another. This is required to implement features like MS
ABI VFTables and optimizing away certain kinds of initialization in C++.

This functionality is only representable in COFF and ELF, Mach-O has no
similar mechanism.

Differential Revision: http://reviews.llvm.org/D4178

llvm-svn: 211920
2014-06-27 18:19:56 +00:00
Rafael Espindola ccf10727b0 Make getBaseObject static.
Thanks to David Majnemer for noticing.

llvm-svn: 211208
2014-06-18 19:08:47 +00:00
Patrik Hagglund 3154171d2d Fix gcc -Wparentheses warning.
llvm-svn: 210178
2014-06-04 11:21:11 +00:00
Rafael Espindola 64c1e18033 Allow alias to point to an arbitrary ConstantExpr.
This  patch changes GlobalAlias to point to an arbitrary ConstantExpr and it is
up to MC (or the system assembler) to decide if that expression is valid or not.

This reduces our ability to diagnose invalid uses and how early we can spot
them, but it also lets us do things like

@test5 = alias inttoptr(i32 sub (i32 ptrtoint (i32* @test2 to i32),
                                 i32 ptrtoint (i32* @bar to i32)) to i32*)

An important implication of this patch is that the notion of aliased global
doesn't exist any more. The alias has to encode the information needed to
access it in its metadata (linkage, visibility, type, etc).

Another consequence to notice is that getSection has to return a "const char *".
It could return a NullTerminatedStringRef if there was such a thing, but when
that was proposed the decision was to just uses "const char*" for that.

llvm-svn: 210062
2014-06-03 02:41:57 +00:00
Rafael Espindola 59f7eba2b5 [pr19844] Add thread local mode to aliases.
This matches gcc's behavior. It also seems natural given that aliases
contain other properties that govern how it is accessed (linkage,
visibility, dll storage).

Clang still has to be updated to expose this feature to C.

llvm-svn: 209759
2014-05-28 18:15:43 +00:00
Rafael Espindola f1bedd3747 Use create methods since msvc doesn't handle delegating constructors.
llvm-svn: 209076
2014-05-17 21:29:57 +00:00
Rafael Espindola 8370565820 Reduce abuse of default values in the GlobalAlias constructor.
This is in preparation for adding an optional offset.

llvm-svn: 209073
2014-05-17 19:57:46 +00:00
Rafael Espindola e0098928c9 Delete getAliasedGlobal.
llvm-svn: 209040
2014-05-16 22:37:03 +00:00
Rafael Espindola 6b238633b7 Fix most of PR10367.
This patch changes the design of GlobalAlias so that it doesn't take a
ConstantExpr anymore. It now points directly to a GlobalObject, but its type is
independent of the aliasee type.

To avoid changing all alias related tests in this patches, I kept the common
syntax

@foo = alias i32* @bar

to mean the same as now. The cases that used to use cast now use the more
general syntax

@foo = alias i16, i32* @bar.

Note that GlobalAlias now behaves a bit more like GlobalVariable. We
know that its type is always a pointer, so we omit the '*'.

For the bitcode, a nice surprise is that we were writing both identical types
already, so the format change is minimal. Auto upgrade is handled by looking
through the casts and no new fields are needed for now. New bitcode will
simply have different types for Alias and Aliasee.

One last interesting point in the patch is that replaceAllUsesWith becomes
smart enough to avoid putting a ConstantExpr in the aliasee. This seems better
than checking and updating every caller.

A followup patch will delete getAliasedGlobal now that it is redundant. Another
patch will add support for an explicit offset.

llvm-svn: 209007
2014-05-16 19:35:39 +00:00
Rafael Espindola 4fe0094fd1 Change the GlobalAlias constructor to look a bit more like GlobalVariable.
This is part of the fix for pr10367. A GlobalAlias always has a pointer type,
so just have the constructor build the type.

llvm-svn: 208983
2014-05-16 13:34:04 +00:00
Rafael Espindola 5a52b9f139 Revert "Implement global merge optimization for global variables."
This reverts commit r208934.

The patch depends on aliases to GEPs with non zero offsets. That is not
supported and fairly broken.

The good news is that GlobalAlias is being redesigned and will have support
for offsets, so this patch should be a nice match for it.

llvm-svn: 208978
2014-05-16 13:02:18 +00:00
Jiangning Liu 932e1c3924 Implement global merge optimization for global variables.
This commit implements two command line switches -global-merge-on-external
and -global-merge-aligned, and both of them are false by default, so this
optimization is disabled by default for all targets.

For ARM64, some back-end behaviors need to be tuned to get this optimization
further enabled.

llvm-svn: 208934
2014-05-15 23:45:42 +00:00
Rafael Espindola 99e05cf163 Split GlobalValue into GlobalValue and GlobalObject.
This allows code to statically accept a Function or a GlobalVariable, but
not an alias. This is already a cleanup by itself IMHO, but the main
reason for it is that it gives a lot more confidence that the refactoring to fix
the design of GlobalAlias is correct. That will be a followup patch.

llvm-svn: 208716
2014-05-13 18:45:48 +00:00
Rafael Espindola b2ea33975f Run clang-format in small sections of code to make a patch easier to read.
llvm-svn: 208419
2014-05-09 15:49:02 +00:00
Rafael Espindola a03c599666 Delete trailing white space.
llvm-svn: 208415
2014-05-09 14:31:07 +00:00
Rafael Espindola 8d8f100c57 Special case aliases in GlobalValue::getSection.
This is similar to the getAlignment patch, but is done just for
completeness. It looks like we never call getSection on an alias. All the
tests still pass if the if is replaced with an assert.

llvm-svn: 208139
2014-05-06 22:44:30 +00:00
Rafael Espindola 52dc5d828f Special case aliases in GlobalValue::getAlignment.
An alias has the address of what it points to, so it also has the same
alignment.

This allows a few optimizations to see past aliases for free.

llvm-svn: 208103
2014-05-06 16:48:58 +00:00