This reverts commit r319413. See PR35503.
We can't use "union member" as the access type here like this.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@319629 91177308-0d34-0410-b5e6-96231b3b80d8
The basic idea behind this patch is that since in strict aliasing
mode all accesses to union members require their outermost
enclosing union objects to be specified explicitly, then for a
couple given accesses to union members of the form
p->a.b.c...
q->x.y.z...
it is known they can only alias if both p and q point to the same
union type and offset ranges of members a.b.c... and x.y.z...
overlap. Note that the actual types of the members do not matter.
Specifically, in this patch we do the following:
* Make unions to be valid TBAA base access types. This enables
generation of TBAA type descriptors for unions.
* Encode union types as structures with a single member of a
special "union member" type. Currently we do not encode
information about sizes of types, but conceptually such union
members are considered to be of the size of the whole union.
* Encode accesses to direct and indirect union members, including
member arrays, as accesses to these special members. All
accesses to members of a union thus get the same offset, which
is the offset of the union they are part of. This means the
existing LLVM TBAA machinery is able to handle such accesses
with no changes.
While this is already an improvement comparing to the current
situation, that is, representing all union accesses as may-alias
ones, there are further changes planned to complete the support
for unions. One of them is storing information about access sizes
so we can distinct accesses to non-overlapping union members,
including accesses to different elements of member arrays.
Another change is encoding type sizes in order to make it
possible to compute offsets within constant-indexed array
elements. These enhancements will be addressed with separate
patches.
Differential Revision: https://reviews.llvm.org/D39455
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@319413 91177308-0d34-0410-b5e6-96231b3b80d8
The information about access and type sizes is necessary for
producing TBAA metadata in the new size-aware format. With this
patch, D39955 and D39956 in place we should be able to change
CodeGenTBAA::createScalarTypeNode() and
CodeGenTBAA::getBaseTypeInfo() to generate metadata in the new
format under the -new-struct-path-tbaa command-line option. For
now, this new information remains unused.
Differential Revision: https://reviews.llvm.org/D40176
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@319012 91177308-0d34-0410-b5e6-96231b3b80d8
This patch fixes various places in clang to propagate may-alias
TBAA access descriptors during construction of lvalues, thus
eliminating the need for the LValueBaseInfo::MayAlias flag.
This is part of D38126 reworked to be a separate patch to
simplify review.
Differential Revision: https://reviews.llvm.org/D39008
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@316988 91177308-0d34-0410-b5e6-96231b3b80d8
This patch is an attempt to clarify and simplify generation and
propagation of TBAA information. The idea is to pack all values
that describe a memory access, namely, base type, access type and
offset, into a single structure. This is supposed to make further
changes, such as adding support for unions and array members,
easier to prepare and review.
DecorateInstructionWithTBAA() is no more responsible for
converting types to tags. These implicit conversions not only
complicate reading the code, but also suggest assigning scalar
access tags while we generally prefer full-size struct-path tags.
TBAAPathTag is replaced with TBAAAccessInfo; the latter is now
the type of the keys of the cache map that translates access
descriptors to metadata nodes.
Fixed a bug with writing to a wrong map in
getTBAABaseTypeMetadata() (former getTBAAStructTypeInfo()).
We now check for valid base access types every time we
dereference a field. The original code only checks the top-level
base type. See isValidBaseType() / isTBAAPathStruct() calls.
Some entities have been renamed to sound more adequate and less
confusing/misleading in presence of path-aware TBAA information.
Now we do not lookup twice for the same cache entry in
getAccessTagInfo().
Refined relevant comments and descriptions.
Differential Revision: https://reviews.llvm.org/D37826
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@315048 91177308-0d34-0410-b5e6-96231b3b80d8
This patch makes it possible to produce access tags in a uniform
manner regardless whether the resulting tag will be a scalar or a
struct-path one. getAccessTagInfo() now takes care of the actual
translation of access descriptors to tags and can handle all
kinds of accesses. Facilities that specific to scalar accesses
are eliminated.
Some more details:
* DecorateInstructionWithTBAA() is not responsible for conversion
of types to access tags anymore. Instead, it takes an access
descriptor (TBAAAccessInfo) and generates corresponding access
tag from it.
* getTBAAInfoForVTablePtr() reworked to
getTBAAVTablePtrAccessInfo() that now returns the
virtual-pointer access descriptor and not the virtual-point
type metadata.
* Added function getTBAAMayAliasAccessInfo() that returns the
descriptor for may-alias accesses.
* getTBAAStructTagInfo() renamed to getTBAAAccessTagInfo() as now
it is the only way to generate access tag by a given access
descriptor. It is capable of producing both scalar and
struct-path tags, depending on options and availability of the
base access type. getTBAAScalarTagInfo() and its cache
ScalarTagMetadataCache are eliminated.
* Now that we do not need to care about whether the resulting
access tag should be a scalar or struct-path one,
getTBAAStructTypeInfo() is renamed to getBaseTypeInfo().
* Added function getTBAAAccessInfo() that constructs access
descriptor by a given QualType access type.
This is part of D37826 reworked to be a separate patch to
simplify review.
Differential Revision: https://reviews.llvm.org/D38503
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@314979 91177308-0d34-0410-b5e6-96231b3b80d8
This patch makes it possible to produce access tags in a uniform
manner regardless whether the resulting tag will be a scalar or a
struct-path one. getAccessTagInfo() now takes care of the actual
translation of access descriptors to tags and can handle all
kinds of accesses. Facilities that specific to scalar accesses
are eliminated.
Some more details:
* DecorateInstructionWithTBAA() is not responsible for conversion
of types to access tags anymore. Instead, it takes an access
descriptor (TBAAAccessInfo) and generates corresponding access
tag from it.
* getTBAAInfoForVTablePtr() reworked to
getTBAAVTablePtrAccessInfo() that now returns the
virtual-pointer access descriptor and not the virtual-point
type metadata.
* Added function getTBAAMayAliasAccessInfo() that returns the
descriptor for may-alias accesses.
* getTBAAStructTagInfo() renamed to getTBAAAccessTagInfo() as now
it is the only way to generate access tag by a given access
descriptor. It is capable of producing both scalar and
struct-path tags, depending on options and availability of the
base access type. getTBAAScalarTagInfo() and its cache
ScalarTagMetadataCache are eliminated.
* Now that we do not need to care about whether the resulting
access tag should be a scalar or struct-path one,
getTBAAStructTypeInfo() is renamed to getBaseTypeInfo().
* Added function getTBAAAccessInfo() that constructs access
descriptor by a given QualType access type.
This is part of D37826 reworked to be a separate patch to
simplify review.
Differential Revision: https://reviews.llvm.org/D38503
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@314977 91177308-0d34-0410-b5e6-96231b3b80d8
With this patch we implement a concept of TBAA access descriptors
that are capable of representing both scalar and struct-path
accesses in a generic way.
This is part of D37826 reworked to be a separate patch to
simplify review.
Differential Revision: https://reviews.llvm.org/D38456
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@314780 91177308-0d34-0410-b5e6-96231b3b80d8
This patch fixes misleading names of entities related to getting,
setting and generation of TBAA access type descriptors.
This is effectively an attempt to provide a review for D37826 by
breaking it into smaller pieces.
Differential Revision: https://reviews.llvm.org/D38404
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@314657 91177308-0d34-0410-b5e6-96231b3b80d8
std::byte, when defined as an enum, needs to be given special treatment
with regards to its aliasing properties. An array of std::byte is
allowed to be used as storage for other types.
This fixes PR33916.
Differential Revision: https://reviews.llvm.org/D35824
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@309058 91177308-0d34-0410-b5e6-96231b3b80d8
Revert the two changes to thread CodeGenOptions into the TargetInfo allocation
and to fix the layering violation by moving CodeGenOptions into Basic.
Code Generation is arguably not particularly "basic". This addresses Richard's
post-commit review comments. This change purely does the mechanical revert and
will be followed up with an alternate approach to thread the desired information
into TargetInfo.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@265806 91177308-0d34-0410-b5e6-96231b3b80d8
This is a mechanical move of CodeGenOptions from libFrontend to libBasic. This
fixes the layering violation introduced earlier by threading CodeGenOptions into
TargetInfo. It should also fix the modules based self-hosting builds. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@265702 91177308-0d34-0410-b5e6-96231b3b80d8
This commit changes the root from "Simple C/C++ TBAA" to "Simple C++ TBAA" for
C++.
The problem is that the type name in the TBAA nodes is generated differently
for C vs C++. If we link an IR file for C with an IR file for C++, since they
have the same root and the type names are different, accesses to the two type
nodes will be considered no-alias, even though the two type nodes are from
the same type in a header file.
The fix is to use different roots for C and C++. Types from C will be treated
conservatively in respect to types from C++.
Follow-up commits will change the C root to "Simple C TBAA" plus some mangling
change for C types to make it a little more aggresive.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@260567 91177308-0d34-0410-b5e6-96231b3b80d8
After r244870 flush() will only compare two null pointers and return,
doing nothing but wasting run time. The call is not required any more
as the stream and its SmallString are always in sync.
Thanks to David Blaikie for reviewing.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@244928 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
RTTI is not yet implemented for the Microsoft C++ ABI and isn't expected
soon. We could easily add the mangling, but the error is what prevents
us from silently miscompiling code that expects RTTI.
Instead, add a new mangleTypeName entry point that simply forwards to
mangleName or mangleType to produce a string that isn't part of the ABI.
Itanium can continue to use RTTI names to avoid unecessary test
breakage.
This also seems like the right design. The fact that TBAA names happen
to be RTTI names is now an implementation detail of the mangler, rather
than part of TBAA.
Differential Revision: http://llvm-reviews.chandlerc.com/D2153
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@195168 91177308-0d34-0410-b5e6-96231b3b80d8
An updated version of r191586 with bug fix.
Struct-path aware TBAA generates tags to specify the access path,
while scalar TBAA only generates tags to scalar types.
We should not generate a TBAA tag with null being the first field. When
a TBAA type node is null, the tag should be null too. Make sure we
don't decorate an instruction with a null TBAA tag.
Added a testing case for the bug reported by Richard with -relaxed-aliasing
and -fsanitizer=thread.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@192145 91177308-0d34-0410-b5e6-96231b3b80d8
Struct-path aware TBAA generates tags to specify the access path,
while scalar TBAA only generates tags to scalar types.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191586 91177308-0d34-0410-b5e6-96231b3b80d8
With r185721, calling mangleCXXRTTIName on C code will cause crashes.
This commit fixes crashes on C testing cases when turning on struct-path TBAA.
For C code, we simply use the Decl name without the context. This can
cause two different structs having the same name, and may cause inaccurate but
conservative alias results.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188930 91177308-0d34-0410-b5e6-96231b3b80d8
This changes the TBAA code so it doesn't use mangleCXXRTTIName in C,
because it doesn't really make sense there. Also, as sort of a
defense-in-depth change, fix the mangler so it handles C RecordDecls
correctly.
No tests because I don't know the TBAA code well enough to write a test,
and I don't know how else to trigger mangling a local struct in C.
Fixes a crash with r185450 reported by Joerg Sonnenberger.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185721 91177308-0d34-0410-b5e6-96231b3b80d8
The old implementation of ms_struct in RecordLayoutBuilder was a
complete mess: it depended on complicated conditionals which didn't
really reflect the underlying logic, and placed a burden on users of
the resulting RecordLayout. This commit rips out almost all of the
old code, and replaces it with simple checks in
RecordLayoutBuilder::LayoutBitField.
This commit also fixes <rdar://problem/14252115>, a bug where class
inheritance would cause us to lay out bitfields incorrectly.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185018 91177308-0d34-0410-b5e6-96231b3b80d8
This patch renames getLinkage to getLinkageInternal. Only code that
needs to handle UniqueExternalLinkage specially should call this.
Linkage, as defined in the c++ standard, is provided by
getFormalLinkage. It maps UniqueExternalLinkage to ExternalLinkage.
Most places in the compiler actually want isExternallyVisible, which
handles UniqueExternalLinkage as internal.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181677 91177308-0d34-0410-b5e6-96231b3b80d8
We switch the order of offset and field type to make TBAAStructType node
(name, parent node, offset) similar to scalar TBAA node (name, parent node).
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180653 91177308-0d34-0410-b5e6-96231b3b80d8
For ms structs, zero-length bitfields following non-bitfield members are
completely ignored, we should not increase the field index.
Before the fix, we will have an assertion failure.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180038 91177308-0d34-0410-b5e6-96231b3b80d8
For struct-path aware TBAA, we used to use scalar type node as the scalar tag,
which has an incompatible format with the struct path tag. We now use the same
format: base type, access type and offset.
We also uniformize the scalar type node and the struct type node: name, a list
of pairs (offset + pointer to MDNode). For scalar type, we have a single pair.
These are to make implementaiton of aliasing rules easier.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179335 91177308-0d34-0410-b5e6-96231b3b80d8
Added TBAABaseType and TBAAOffset in LValue. These two fields are initialized to
the actual type and 0, and are updated in EmitLValueForField.
Path-aware TBAA tags are enabled for EmitLoadOfScalar and EmitStoreOfScalar.
Added command line option -struct-path-tbaa.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178797 91177308-0d34-0410-b5e6-96231b3b80d8
Required to pull some functions out of line, but this shouldn't have a perf impact.
No functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@169092 91177308-0d34-0410-b5e6-96231b3b80d8
Ivan A. Kosarev