[clang][frontend] Support applying the annotate attribute to statements (#111841)

By allowing AnnotateAttr to be applied to statements, users can place arbitrary information in the AST for later use

[clang][frontend] Support applying the annotate attribute to statements (#111841)

By allowing AnnotateAttr to be applied to statements, users can place arbitrary information in the AST for later use.

For example, this can be used for HW-targeted language extensions that involve specialized loop annotations.

show more ...

[clang] Improve ast-dumper text printing of TemplateArgument (#93431)

This improves and unifies our approach to printing all template
arguments.

The same approach to printing types is extended t

[clang] Improve ast-dumper text printing of TemplateArgument (#93431)

This improves and unifies our approach to printing all template
arguments.

The same approach to printing types is extended to all
TemplateArguments: A sugared version is printed in quotes, followed by
printing the canonical form, unless they would print the same.

Special improvements are done to add more detail to template template
arguments.

It's planned in a future patch to use this improved TemplateName printer
for other places besides TemplateArguments.

Note: The sugared/desugared printing does not show up for TemplateNames
in tests yet, because we do a poor job of preserving their type sugar.
This will be improved in a future patch.

show more ...

Complete the implementation of P2361 Unevaluated string literals

The attributes changes were left out of Clang 17.
Attributes that used to take a string literal now accept an unevaluated
string lite

Complete the implementation of P2361 Unevaluated string literals

The attributes changes were left out of Clang 17.
Attributes that used to take a string literal now accept an unevaluated
string literal instead, which means they reject numeric escape sequences
and strings literal with an encoding prefix - but the later was already
ill-formed in most cases.

We need to know that we are going to parse an unevaluated string literal
before we do - so we can reject numeric escape sequence,
so we derive from Attrs.td which attributes parameters are expected
to be string literals.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D156237

show more ...

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which go

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.

The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.

An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.

---

Troubleshooting list to deal with any breakage seen with this patch:

1) The most likely effect one would see by this patch is a change in how
a type is printed. The type printer will, by design and default,
print types as written. There are customization options there, but
not that many, and they mainly apply to how to print a type that we
somehow failed to track how it was written. This patch fixes a
problem where we failed to distinguish between a type
that was written without any elaborated-type qualifiers,
such as a 'struct'/'class' tags and name spacifiers such as 'std::',
and one that has been stripped of any 'metadata' that identifies such,
the so called canonical types.
Example:
```
namespace foo {
struct A {};
A a;
};
```
If one were to print the type of `foo::a`, prior to this patch, this
would result in `foo::A`. This is how the type printer would have,
by default, printed the canonical type of A as well.
As soon as you add any name qualifiers to A, the type printer would
suddenly start accurately printing the type as written. This patch
will make it print it accurately even when written without
qualifiers, so we will just print `A` for the initial example, as
the user did not really write that `foo::` namespace qualifier.

2) This patch could expose a bug in some AST matcher. Matching types
is harder to get right when there is sugar involved. For example,
if you want to match a type against being a pointer to some type A,
then you have to account for getting a type that is sugar for a
pointer to A, or being a pointer to sugar to A, or both! Usually
you would get the second part wrong, and this would work for a
very simple test where you don't use any name qualifiers, but
you would discover is broken when you do. The usual fix is to
either use the matcher which strips sugar, which is annoying
to use as for example if you match an N level pointer, you have
to put N+1 such matchers in there, beginning to end and between
all those levels. But in a lot of cases, if the property you want
to match is present in the canonical type, it's easier and faster
to just match on that... This goes with what is said in 1), if
you want to match against the name of a type, and you want
the name string to be something stable, perhaps matching on
the name of the canonical type is the better choice.

3) This patch could expose a bug in how you get the source range of some
TypeLoc. For some reason, a lot of code is using getLocalSourceRange(),
which only looks at the given TypeLoc node. This patch introduces a new,
and more common TypeLoc node which contains no source locations on itself.
This is not an inovation here, and some other, more rare TypeLoc nodes could
also have this property, but if you use getLocalSourceRange on them, it's not
going to return any valid locations, because it doesn't have any. The right fix
here is to always use getSourceRange() or getBeginLoc/getEndLoc which will dive
into the inner TypeLoc to get the source range if it doesn't find it on the
top level one. You can use getLocalSourceRange if you are really into
micro-optimizations and you have some outside knowledge that the TypeLocs you are
dealing with will always include some source location.

4) Exposed a bug somewhere in the use of the normal clang type class API, where you
have some type, you want to see if that type is some particular kind, you try a
`dyn_cast` such as `dyn_cast<TypedefType>` and that fails because now you have an
ElaboratedType which has a TypeDefType inside of it, which is what you wanted to match.
Again, like 2), this would usually have been tested poorly with some simple tests with
no qualifications, and would have been broken had there been any other kind of type sugar,
be it an ElaboratedType or a TemplateSpecializationType or a SubstTemplateParmType.
The usual fix here is to use `getAs` instead of `dyn_cast`, which will look deeper
into the type. Or use `getAsAdjusted` when dealing with TypeLocs.
For some reason the API is inconsistent there and on TypeLocs getAs behaves like a dyn_cast.

5) It could be a bug in this patch perhaps.

Let me know if you need any help!

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Differential Revision: https://reviews.llvm.org/D112374

show more ...

Revert "[clang] Implement ElaboratedType sugaring for types written bare"

This reverts commit 7c51f02effdbd0d5e12bfd26f9c3b2ab5687c93f because it
stills breaks the LLDB tests. This was re-landed wi

Revert "[clang] Implement ElaboratedType sugaring for types written bare"

This reverts commit 7c51f02effdbd0d5e12bfd26f9c3b2ab5687c93f because it
stills breaks the LLDB tests. This was re-landed without addressing the
issue or even agreement on how to address the issue. More details and
discussion in https://reviews.llvm.org/D112374.

show more ...

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which go

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.

The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.

An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.

---

Troubleshooting list to deal with any breakage seen with this patch:

1) The most likely effect one would see by this patch is a change in how
a type is printed. The type printer will, by design and default,
print types as written. There are customization options there, but
not that many, and they mainly apply to how to print a type that we
somehow failed to track how it was written. This patch fixes a
problem where we failed to distinguish between a type
that was written without any elaborated-type qualifiers,
such as a 'struct'/'class' tags and name spacifiers such as 'std::',
and one that has been stripped of any 'metadata' that identifies such,
the so called canonical types.
Example:
```
namespace foo {
struct A {};
A a;
};
```
If one were to print the type of `foo::a`, prior to this patch, this
would result in `foo::A`. This is how the type printer would have,
by default, printed the canonical type of A as well.
As soon as you add any name qualifiers to A, the type printer would
suddenly start accurately printing the type as written. This patch
will make it print it accurately even when written without
qualifiers, so we will just print `A` for the initial example, as
the user did not really write that `foo::` namespace qualifier.

2) This patch could expose a bug in some AST matcher. Matching types
is harder to get right when there is sugar involved. For example,
if you want to match a type against being a pointer to some type A,
then you have to account for getting a type that is sugar for a
pointer to A, or being a pointer to sugar to A, or both! Usually
you would get the second part wrong, and this would work for a
very simple test where you don't use any name qualifiers, but
you would discover is broken when you do. The usual fix is to
either use the matcher which strips sugar, which is annoying
to use as for example if you match an N level pointer, you have
to put N+1 such matchers in there, beginning to end and between
all those levels. But in a lot of cases, if the property you want
to match is present in the canonical type, it's easier and faster
to just match on that... This goes with what is said in 1), if
you want to match against the name of a type, and you want
the name string to be something stable, perhaps matching on
the name of the canonical type is the better choice.

3) This patch could exposed a bug in how you get the source range of some
TypeLoc. For some reason, a lot of code is using getLocalSourceRange(),
which only looks at the given TypeLoc node. This patch introduces a new,
and more common TypeLoc node which contains no source locations on itself.
This is not an inovation here, and some other, more rare TypeLoc nodes could
also have this property, but if you use getLocalSourceRange on them, it's not
going to return any valid locations, because it doesn't have any. The right fix
here is to always use getSourceRange() or getBeginLoc/getEndLoc which will dive
into the inner TypeLoc to get the source range if it doesn't find it on the
top level one. You can use getLocalSourceRange if you are really into
micro-optimizations and you have some outside knowledge that the TypeLocs you are
dealing with will always include some source location.

4) Exposed a bug somewhere in the use of the normal clang type class API, where you
have some type, you want to see if that type is some particular kind, you try a
`dyn_cast` such as `dyn_cast<TypedefType>` and that fails because now you have an
ElaboratedType which has a TypeDefType inside of it, which is what you wanted to match.
Again, like 2), this would usually have been tested poorly with some simple tests with
no qualifications, and would have been broken had there been any other kind of type sugar,
be it an ElaboratedType or a TemplateSpecializationType or a SubstTemplateParmType.
The usual fix here is to use `getAs` instead of `dyn_cast`, which will look deeper
into the type. Or use `getAsAdjusted` when dealing with TypeLocs.
For some reason the API is inconsistent there and on TypeLocs getAs behaves like a dyn_cast.

5) It could be a bug in this patch perhaps.

Let me know if you need any help!

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Differential Revision: https://reviews.llvm.org/D112374

show more ...

Revert "[clang] Implement ElaboratedType sugaring for types written bare"

This reverts commit bdc6974f92304f4ed542241b9b89ba58ba6b20aa because it
breaks all the LLDB tests that import the std module

Revert "[clang] Implement ElaboratedType sugaring for types written bare"

This reverts commit bdc6974f92304f4ed542241b9b89ba58ba6b20aa because it
breaks all the LLDB tests that import the std module.

import-std-module/array.TestArrayFromStdModule.py
import-std-module/deque-basic.TestDequeFromStdModule.py
import-std-module/deque-dbg-info-content.TestDbgInfoContentDequeFromStdModule.py
import-std-module/forward_list.TestForwardListFromStdModule.py
import-std-module/forward_list-dbg-info-content.TestDbgInfoContentForwardListFromStdModule.py
import-std-module/list.TestListFromStdModule.py
import-std-module/list-dbg-info-content.TestDbgInfoContentListFromStdModule.py
import-std-module/queue.TestQueueFromStdModule.py
import-std-module/stack.TestStackFromStdModule.py
import-std-module/vector.TestVectorFromStdModule.py
import-std-module/vector-bool.TestVectorBoolFromStdModule.py
import-std-module/vector-dbg-info-content.TestDbgInfoContentVectorFromStdModule.py
import-std-module/vector-of-vectors.TestVectorOfVectorsFromStdModule.py

https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/45301/

show more ...

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which go

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.

The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.

An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Differential Revision: https://reviews.llvm.org/D112374

show more ...

Allow parameter pack expansions and initializer lists in annotate attribute

These changes make the Clang parser recognize expression parameter pack
expansion and initializer lists in attribute argum

Allow parameter pack expansions and initializer lists in annotate attribute

These changes make the Clang parser recognize expression parameter pack
expansion and initializer lists in attribute arguments. Because
expression parameter pack expansion requires additional handling while
creating and instantiating templates, the support for them must be
explicitly supported through the AcceptsExprPack flag.

Handling expression pack expansions may require a delay to when the
arguments of an attribute are correctly populated. To this end,
attributes that are set to accept these - through setting the
AcceptsExprPack flag - will automatically have an additional variadic
expression argument member named DelayedArgs. This member is not
exposed the same way other arguments are but is set through the new
CreateWithDelayedArgs creator function generated for applicable
attributes.

To illustrate how to implement support for expression pack expansion
support, clang::annotate is made to support pack expansions. This is
done by making handleAnnotationAttr delay setting the actual attribute
arguments until after template instantiation if it was unable to
populate the arguments due to dependencies in the parsed expressions.

show more ...

[clang] retain type sugar in auto / template argument deduction

This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses th

[clang] retain type sugar in auto / template argument deduction

This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.

As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: rsmith, #libc, ldionne

Differential Revision: https://reviews.llvm.org/D110216

show more ...

Revert "[clang] retain type sugar in auto / template argument deduction"

This reverts commit 4d8fff477e024698facd89741cc6cf996708d598.

[clang] retain type sugar in auto / template argument deduction

This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses th

[clang] retain type sugar in auto / template argument deduction

This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.

As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D110216

show more ...

Revert "[clang] retain type sugar in auto / template argument deduction"

This reverts commit 9b6036deedf28e10d797fc4ca734d57680d18053.
Breaks two libc++ tests.

[clang] retain type sugar in auto / template argument deduction

This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses th

[clang] retain type sugar in auto / template argument deduction

This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.

As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D110216

show more ...

Allow dependent alias template specializations in the preferred_name
attribute.

This was intended to work, but didn't match the checks because these
types are modeled as TemplateSpecializationTypes

Allow dependent alias template specializations in the preferred_name
attribute.

This was intended to work, but didn't match the checks because these
types are modeled as TemplateSpecializationTypes not TypedefTypes.

show more ...

Add new 'preferred_name' attribute.

This attribute permits a typedef to be associated with a class template
specialization as a preferred way of naming that class template
specialization. This permi

Add new 'preferred_name' attribute.

This attribute permits a typedef to be associated with a class template
specialization as a preferred way of naming that class template
specialization. This permits us to specify that (for example) the
preferred way to express 'std::basic_string<char>' is as 'std::string'.

The attribute is applied to the various class templates in libc++ that have
corresponding well-known typedef names.

This is a re-commit. The previous commit was reverted because it exposed
a pre-existing bug that has since been fixed / worked around; see
PR48434.

Differential Revision: https://reviews.llvm.org/D91311

show more ...

Revert "Add new 'preferred_name' attribute."

This change exposed a pre-existing issue with deserialization cycles
caused by a combination of attributes and template instantiations
violating the dese

Revert "Add new 'preferred_name' attribute."

This change exposed a pre-existing issue with deserialization cycles
caused by a combination of attributes and template instantiations
violating the deserialization ordering restrictions; see PR48434 for
details.

A previous commit attempted to work around PR48434, but appears to have
only been a partial fix, and fixing this properly seems non-trivial.
Backing out for now to unblock things.

This reverts commit 98f76adf4e941738c0b9fe3b9965fa63603e9c89 and
commit a64c26a47a81b1b44e36d235ff3bc6a74a0bad9f.

show more ...

Fix deserialization cycle in preferred_name attribute.

This is really just a workaround for a more fundamental issue in the way
we deserialize attributes. See PR48434 for details.

Also fix tablegen

Fix deserialization cycle in preferred_name attribute.

This is really just a workaround for a more fundamental issue in the way
we deserialize attributes. See PR48434 for details.

Also fix tablegen code generator to produce more correct indentation to
resolve buildbot issues with -Werror=misleading-indentation firing
inside the generated code.

show more ...

Add new 'preferred_name' attribute.

This attribute permits a typedef to be associated with a class template
specialization as a preferred way of naming that class template
specialization. This permi

Add new 'preferred_name' attribute.

This attribute permits a typedef to be associated with a class template
specialization as a preferred way of naming that class template
specialization. This permits us to specify that (for example) the
preferred way to express 'std::basic_string<char>' is as 'std::string'.

The attribute is applied to the various class templates in libc++ that have
corresponding well-known typedef names.

Differential Revision: https://reviews.llvm.org/D91311

show more ...

Append new attributes to the end of an AttributeList.

Recommit of r335084 after revert in r335516.

... instead of prepending it at the beginning (the original behavior
since implemented in r122535

Append new attributes to the end of an AttributeList.

Recommit of r335084 after revert in r335516.

... instead of prepending it at the beginning (the original behavior
since implemented in r122535 2010-12-23). This builds up an
AttributeList in the the order in which the attributes appear in the
source.

The reverse order caused nodes for attributes in the AST (e.g. LoopHint)
to be in the reverse order, and therefore printed in the wrong order in
-ast-dump. Some TODO comments mention this. The order was explicitly
reversed for enable_if attribute overload resolution and name mangling,
which is not necessary anymore with this patch.

The change unfortunately has some secondary effect, especially on
diagnostic output. In the simplest cases, the CHECK lines or expected
diagnostic were changed to the the new output. If the kind of
error/warning changed, the attributes' order was changed instead.

This unfortunately causes some 'previous occurrence here' hints to be
textually after the main marker. This typically happens when attributes
are merged, but are incompatible to each other. Interchanging the role
of the the main and note SourceLocation will also cause the case where
two different declaration's attributes (in contrast to multiple
attributes of the same declaration) are merged to be reverse. There is
no easy fix because sometimes previous attributes are merged into a new
declaration's attribute list, sometimes new attributes are added to a
previous declaration's attribute list. Since 'previous occurrence here'
pointing to locations after the main marker is not rare, I left the
markers as-is; it is only relevant when the attributes are declared in
the same declaration anyway.

Differential Revision: https://reviews.llvm.org/D48100

llvm-svn: 338800

show more ...

Revert "Append new attributes to the end of an AttributeList."

This reverts commit r335084 as requested by David Jones and
Eric Christopher because of differences of emitted warnings.

llvm-svn: 335

Revert "Append new attributes to the end of an AttributeList."

This reverts commit r335084 as requested by David Jones and
Eric Christopher because of differences of emitted warnings.

llvm-svn: 335516

show more ...

Append new attributes to the end of an AttributeList.

... instead of prepending it at the beginning (the original behavior
since implemented in r122535 2010-12-23). This builds up an
AttributeList i

Append new attributes to the end of an AttributeList.

... instead of prepending it at the beginning (the original behavior
since implemented in r122535 2010-12-23). This builds up an
AttributeList in the the order in which the attributes appear in the
source.

The reverse order caused nodes for attributes in the AST (e.g. LoopHint)
to be in the reverse, and therefore printed in the wrong order by
-ast-dump. Some TODO comments mention this. The order was explicitly
reversed for enable_if attribute overload resolution and name mangling,
which is not necessary anymore with this patch.

The change unfortunately has some secondary effects, especially for
diagnostic output. In the simplest cases, the CHECK lines or expected
diagnostic were changed to the the new output. If the kind of
error/warning changed, the attribute's order was changed instead.

It also causes some 'previous occurrence here' hints to be textually
after the main marker. This typically happens when attributes are
merged, but are incompatible. Interchanging the role of the the main
and note SourceLocation will also cause the case where two different
declaration's attributes (in contrast to multiple attributes of the
same declaration) are merged to be reversed. There is no easy fix
because sometimes previous attributes are merged into a new
declaration's attribute list, sometimes new attributes are added to a
previous declaration's attribute list. Since 'previous occurrence here'
pointing to locations after the main marker is not rare, I left the
markers as-is; it is only relevant when the attributes are declared in
the same declaration anyway, which often is on the same line.

Differential Revision: https://reviews.llvm.org/D48100

llvm-svn: 335084

show more ...

Make attribute instantiation instantiate all attributes, not just the first of
each kind.

Attribute instantiation would previously default to instantiating each kind of
attribute only once. This was

Make attribute instantiation instantiate all attributes, not just the first of
each kind.

Attribute instantiation would previously default to instantiating each kind of
attribute only once. This was overridden by a flag whose intended purpose was
to permit attributes from a prior declaration to be inherited onto a new
declaration even if that new declaration had its own copy of the attribute.
This is the wrong behavior: when instantiating attributes from a template, we
should always instantiate all the attributes that were written on that
template.

This patch renames the flag in the Attr class (and TableGen sources) to more
clearly identify what it's actually for, and removes the usage of the flag from
template instantiation. I also removed the flag from AlignedAttr, which was
only added to work around the incorrect suppression of duplicate attribute
instantiation.

llvm-svn: 321834

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There is no such thing as __attribute__((align)); that's a __declspec attribute. Fixing these test cases to use the proper spelling for their syntax.

llvm-svn: 199141

Use attribute argument information to determine when to parse attribute arguments as expressions.

This change partly addresses a heinous problem we have with the
parsing of attribute arguments that

Use attribute argument information to determine when to parse attribute arguments as expressions.

This change partly addresses a heinous problem we have with the
parsing of attribute arguments that are a lone identifier. Previously,
we would end up parsing the 'align' attribute of this as an expression
"(Align)":

template<unsigned Size, unsigned Align>
class my_aligned_storage
{
__attribute__((align((Align)))) char storage[Size];
};

while this would parse as a "parameter name" 'Align':

template<unsigned Size, unsigned Align>
class my_aligned_storage
{
__attribute__((align(Align))) char storage[Size];
};

The code that handles the alignment attribute would completely ignore
the parameter name, so the while the first of these would do what's
expected, the second would silently be equivalent to

template<unsigned Size, unsigned Align>
class my_aligned_storage
{
__attribute__((align)) char storage[Size];
};

i.e., use the maximal alignment rather than the specified alignment.

Address this by sniffing the "Args" provided in the TableGen
description of attributes. If the first argument is "obviously"
something that should be treated as an expression (rather than an
identifier to be matched later), parse it as an expression.

Fixes <rdar://problem/13700933>.

llvm-svn: 180973

show more ...