Commit Graph

82 Commits

Author SHA1 Message Date
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
Rafael Espindola 8fbbfbbec3 Be more strict about not allowing setSection on aliases.
llvm-svn: 208095
2014-05-06 14:59:14 +00:00
Rafael Espindola a7d9c69cc8 Be more strict about not calling setAlignment on global aliases.
The fact that GlobalAlias::setAlignment exists at all is a side effect of
how the classes are organized, it should never be used.

llvm-svn: 208094
2014-05-06 14:51:36 +00:00
Craig Topper c620761ca5 [C++11] More 'nullptr' conversion or in some cases just using a boolean check instead of comparing to nullptr.
llvm-svn: 205831
2014-04-09 06:08:46 +00:00
Rafael Espindola 24a669d225 Prevent alias from pointing to weak aliases.
This adds back r204781.

Original message:

Aliases are just another name for a position in a file. As such, the
regular symbol resolutions are not applied. For example, given

define void @my_func() {
  ret void
}
@my_alias = alias weak void ()* @my_func
@my_alias2 = alias void ()* @my_alias

We produce without this patch:

        .weak   my_alias
my_alias = my_func
        .globl  my_alias2
my_alias2 = my_alias

That is, in the resulting ELF file my_alias, my_func and my_alias are
just 3 names pointing to offset 0 of .text. That is *not* the
semantics of IR linking. For example, linking in a

@my_alias = alias void ()* @other_func

would require the strong my_alias to override the weak one and
my_alias2 would end up pointing to other_func.

There is no way to represent that with aliases being just another
name, so the best solution seems to be to just disallow it, converting
a miscompile into an error.

llvm-svn: 204934
2014-03-27 15:26:56 +00:00
Rafael Espindola 65481d7b97 Revert "Prevent alias from pointing to weak aliases."
This reverts commit r204781.

I will follow up to with msan folks to see what is what they
were trying to do with aliases to weak aliases.

llvm-svn: 204784
2014-03-26 06:14:40 +00:00
Rafael Espindola 3b712a84a9 Prevent alias from pointing to weak aliases.
Aliases are just another name for a position in a file. As such, the
regular symbol resolutions are not applied. For example, given

define void @my_func() {
  ret void
}
@my_alias = alias weak void ()* @my_func
@my_alias2 = alias void ()* @my_alias

We produce without this patch:

        .weak   my_alias
my_alias = my_func
        .globl  my_alias2
my_alias2 = my_alias

That is, in the resulting ELF file my_alias, my_func and my_alias are
just 3 names pointing to offset 0 of .text. That is *not* the
semantics of IR linking. For example, linking in a

@my_alias = alias void ()* @other_func

would require the strong my_alias to override the weak one and
my_alias2 would end up pointing to other_func.

There is no way to represent that with aliases being just another
name, so the best solution seems to be to just disallow it, converting
a miscompile into an error.

llvm-svn: 204781
2014-03-26 04:48:47 +00:00
Chandler Carruth 4b6845c7e7 [Modules] Move the LeakDetector header into the IR library where the
source file had already been moved. Also move the unittest into the IR
unittest library.

This may seem an odd thing to put in the IR library but we only really
use this with instructions and it needs the LLVM context to work, so it
is intrinsically tied to the IR library.

llvm-svn: 202842
2014-03-04 12:46:06 +00:00
Rafael Espindola 339430f993 Use DataLayout from the module when easily available.
Eventually DataLayoutPass should go away, but for now that is the only easy
way to get a DataLayout in some APIs. This patch only changes the ones that
have easy access to a Module.

One interesting issue with sometimes using DataLayoutPass and sometimes
fetching it from the Module is that we have to make sure they are equivalent.
We can get most of the way there by always constructing the pass with a Module.
In fact, the pass could be changed to point to an external DataLayout instead
of owning one to make this stricter.

Unfortunately, the C api passes a DataLayout, so it has to be up to the caller
to make sure the pass and the module are in sync.

llvm-svn: 202204
2014-02-25 23:25:17 +00:00
Rafael Espindola 79c3ab7c5e Check that GlobalAliases don't have section or alignment.
An alias is always in the section of its aliasee and has the same alignment
(since it has the same address).

llvm-svn: 201354
2014-02-13 18:26:41 +00:00
Rafael Espindola 75ec01f3de Copy dll storage in copyAttributes.
llvm-svn: 201295
2014-02-13 05:11:35 +00:00
Hans Wennborg 4a4be11e62 Copy the ThreadLocalMode in GlobalVariable::copyAttributesFrom
This fixes the oversight from r159077.

llvm-svn: 201098
2014-02-10 17:13:56 +00:00
Matt Arsenault 00436ea156 Allow addrspacecast in global aliases
llvm-svn: 198349
2014-01-02 20:55:01 +00:00
Shuxin Yang 2e1890e18b Revert r193251 : Use address-taken to disambiguate global variable and indirect memops.
llvm-svn: 193489
2013-10-27 03:08:44 +00:00
Shuxin Yang e4fb375995 Use address-taken to disambiguate global variable and indirect memops.
Major steps include:
 1). introduces a not-addr-taken bit-field in GlobalVariable
 2). GlobalOpt pass sets "not-address-taken" if it proves a global varirable 
    dosen't have its address taken.
 3). AA use this info for disambiguation. 

llvm-svn: 193251
2013-10-23 17:28:19 +00:00
Peter Collingbourne f708c87078 Introduce non-const overloads for GlobalAlias::{get,resolve}AliasedGlobal.
llvm-svn: 188725
2013-08-19 23:13:33 +00:00
Michael Gottesman 4c4ffd7783 Added instance variable/initializers/getter/setters for new keyword externally initialized to GlobalVariable. No *TRUE* functionality change.
I am going to add in the actual test cases with the actual functionality
changes in a later patch because I want to include some test cases.

To be clear when I say no *TRUE* functionality change I mean that this
patch (like it says in the title) only contains getters/setters and sets
up a default initial value of the instance variable to false so that
this patch does not affect any other uses of Global Variable.h.

llvm-svn: 174295
2013-02-03 21:54:38 +00:00
Chandler Carruth 9fb823bbd4 Move all of the header files which are involved in modelling the LLVM IR
into their new header subdirectory: include/llvm/IR. This matches the
directory structure of lib, and begins to correct a long standing point
of file layout clutter in LLVM.

There are still more header files to move here, but I wanted to handle
them in separate commits to make tracking what files make sense at each
layer easier.

The only really questionable files here are the target intrinsic
tablegen files. But that's a battle I'd rather not fight today.

I've updated both CMake and Makefile build systems (I think, and my
tests think, but I may have missed something).

I've also re-sorted the includes throughout the project. I'll be
committing updates to Clang, DragonEgg, and Polly momentarily.

llvm-svn: 171366
2013-01-02 11:36:10 +00:00
Chandler Carruth ef860a2488 Rename VMCore directory to IR.
Aside from moving the actual files, this patch only updates the build
system and the source file comments under lib/... that are relevant.

I'll be updating other docs and other files in smaller subsequnet
commits.

While I've tried to test this, but it is entirely possible that there
will still be some build system fallout.

Also, note that I've not changed the library name itself: libLLVMCore.a
is still the library name. I'd be interested in others' opinions about
whether we should rename this as well (I think we should, just not sure
what it might break)

llvm-svn: 171359
2013-01-02 09:10:48 +00:00