Propagate whether `MDNode`s are 'distinct' through the other types of IR
(assembly and bitcode). This adds the `distinct` keyword to assembly.
Currently, no one actually calls `MDNode::getDistinct()`, so these nodes
only get created for:
- self-references, which are never uniqued, and
- nodes whose operands are replaced that hit a uniquing collision.
The concept of distinct nodes is still not quite first-class, since
distinct-ness doesn't yet survive across `MapMetadata()`.
Part of PR22111.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225474 91177308-0d34-0410-b5e6-96231b3b80d8
In order to make comdats always explicit in the IR, we decided to make
the syntax a bit more compact for the case of a GlobalObject in a
comdat with the same name.
Just dropping the $name causes problems for
@foo = globabl i32 0, comdat
$bar = comdat ...
and
declare void @foo() comdat
$bar = comdat ...
So the syntax is changed to
@g1 = globabl i32 0, comdat($c1)
@g2 = globabl i32 0, comdat
and
declare void @foo() comdat($c1)
declare void @foo() comdat
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225302 91177308-0d34-0410-b5e6-96231b3b80d8
Now that `Metadata` is typeless, reflect that in the assembly. These
are the matching assembly changes for the metadata/value split in
r223802.
- Only use the `metadata` type when referencing metadata from a call
intrinsic -- i.e., only when it's used as a `Value`.
- Stop pretending that `ValueAsMetadata` is wrapped in an `MDNode`
when referencing it from call intrinsics.
So, assembly like this:
define @foo(i32 %v) {
call void @llvm.foo(metadata !{i32 %v}, metadata !0)
call void @llvm.foo(metadata !{i32 7}, metadata !0)
call void @llvm.foo(metadata !1, metadata !0)
call void @llvm.foo(metadata !3, metadata !0)
call void @llvm.foo(metadata !{metadata !3}, metadata !0)
ret void, !bar !2
}
!0 = metadata !{metadata !2}
!1 = metadata !{i32* @global}
!2 = metadata !{metadata !3}
!3 = metadata !{}
turns into this:
define @foo(i32 %v) {
call void @llvm.foo(metadata i32 %v, metadata !0)
call void @llvm.foo(metadata i32 7, metadata !0)
call void @llvm.foo(metadata i32* @global, metadata !0)
call void @llvm.foo(metadata !3, metadata !0)
call void @llvm.foo(metadata !{!3}, metadata !0)
ret void, !bar !2
}
!0 = !{!2}
!1 = !{i32* @global}
!2 = !{!3}
!3 = !{}
I wrote an upgrade script that handled almost all of the tests in llvm
and many of the tests in cfe (even handling many `CHECK` lines). I've
attached it (or will attach it in a moment if you're speedy) to PR21532
to help everyone update their out-of-tree testcases.
This is part of PR21532.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224257 91177308-0d34-0410-b5e6-96231b3b80d8
We were already requiring 2.5, which meant that people on old linux distros
had to upgrade anyway.
Requiring python 2.6 will make supporting 3.X easier as we can use the 3.X
exception syntax.
According to the discussion on llvmdev, there is not much value is requiring
just 2.6, we may as well just require 2.7.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224129 91177308-0d34-0410-b5e6-96231b3b80d8
Introduce the ``llvm.instrprof_increment`` intrinsic and the
``-instrprof`` pass. These provide the infrastructure for writing
counters for profiling, as in clang's ``-fprofile-instr-generate``.
The implementation of the instrprof pass is ported directly out of the
CodeGenPGO classes in clang, and with the followup in clang that rips
that code out to use these new intrinsics this ends up being NFC.
Doing the instrumentation this way opens some doors in terms of
improving the counter performance. For example, this will make it
simple to experiment with alternate lowering strategies, and allows us
to try handling profiling specially in some optimizations if we want
to.
Finally, this drastically simplifies the frontend and puts all of the
lowering logic in one place.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223672 91177308-0d34-0410-b5e6-96231b3b80d8
a description of how to add debug information using DWARF and
DIBuilder to the language.
Thanks to David Blaikie for his assistance with this tutorial.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223671 91177308-0d34-0410-b5e6-96231b3b80d8
Patch by Ben Gamari!
This redefines the `prefix` attribute introduced previously and
introduces a `prologue` attribute. There are a two primary usecases
that these attributes aim to serve,
1. Function prologue sigils
2. Function hot-patching: Enable the user to insert `nop` operations
at the beginning of the function which can later be safely replaced
with a call to some instrumentation facility
3. Runtime metadata: Allow a compiler to insert data for use by the
runtime during execution. GHC is one example of a compiler that
needs this functionality for its tables-next-to-code functionality.
Previously `prefix` served cases (1) and (2) quite well by allowing the user
to introduce arbitrary data at the entrypoint but before the function
body. Case (3), however, was poorly handled by this approach as it
required that prefix data was valid executable code.
Here we redefine the notion of prefix data to instead be data which
occurs immediately before the function entrypoint (i.e. the symbol
address). Since prefix data now occurs before the function entrypoint,
there is no need for the data to be valid code.
The previous notion of prefix data now goes under the name "prologue
data" to emphasize its duality with the function epilogue.
The intention here is to handle cases (1) and (2) with prologue data and
case (3) with prefix data.
References
----------
This idea arose out of discussions[1] with Reid Kleckner in response to a
proposal to introduce the notion of symbol offsets to enable handling of
case (3).
[1] http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-May/073235.html
Test Plan: testsuite
Differential Revision: http://reviews.llvm.org/D6454
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223189 91177308-0d34-0410-b5e6-96231b3b80d8
This is the fourth and final patch in the statepoint series. It contains the documentation for the statepoint intrinsics and their usage.
There's definitely still room to improve the documentation here, but I wanted to get this landed so it was available for others. There will likely be a series of small cleanup changes over the next few weeks as we work to clarify and revise the documentation. If you have comments or questions, please feel free to discuss them either in this commit thread, the original review thread, or on llvmdev. Comments are more than welcome.
Reviewed by: atrick, ributzka
Differential Revision: http://reviews.llvm.org/D5683
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223143 91177308-0d34-0410-b5e6-96231b3b80d8
Clarify the wording around !invariant.load to properly reflect the semantics of such loads with respect to control dependence and location lifetime. To the best of my knowledge, the revised wording respects the actual implementation and understanding of issues involved highlighted in the recent 'Optimization hints for "constant" loads' thread on LLVMDev.
In particular, I'm aiming for the following results:
- To clarify that an invariant.load can fault and must respect control dependence. In particular, it is not sound to unconditionally pull an invariant load out of a loop if that loop would potentially never execute.
- To clarify that the invariant nature of a given pointer does not preclude the modification of that location through a pointer which is unrelated to the load operand. In particular, initializing a location and then passing a pointer through an opaque intrinsic which produces a new unrelated pointer, should behave as expected provided that the intrinsic is memory dependent on the initializing store.
- To clarify that storing a value to an invariant location is defined. It can not, for example, be considered unreachable. The value stored can be assumed to be equal to the value of any previous (or following!) invariant load, but the store itself is defined.
I recommend that anyone interested in using !invariant.load, or optimizing for them, read over the discussion in the review thread. A number of motivating examples are discussed.
Differential Revision: http://reviews.llvm.org/D6346
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222700 91177308-0d34-0410-b5e6-96231b3b80d8
The previous description of the noalias attribute did not accurately specify
the implemented semantics, and the terminology used differed unnecessarily
from that used by the C specification to define the semantics of restrict. For
the argument attribute, the semantics can be precisely specified in terms of
objects accessed through pointers based on the arguments, and this is now what
is done.
Saying that the semantics are 'slightly weaker' than that provided by C99
restrict is not really useful without further elaboration, so that has been
removed from the sentence.
noalias on a return value is really used to mean that the function is
malloc-like (and, in fact, we use this attribute to represent
__attribute__((malloc)) in Clang), and this is a stronger guarantee than that
provided by restrict (because it is a property of the pointed-to memory region,
not just a guarantee on object access). Clarifying this is relevant to fixing
(and was motivated by the discussion on) PR21556.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222497 91177308-0d34-0410-b5e6-96231b3b80d8
This change makes use of the new "job pool" capability in cmake 3.0
with ninja generator to allow limiting the number of concurrent jobs
of a certain type.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222341 91177308-0d34-0410-b5e6-96231b3b80d8
- Make CallGraphSCCPass's paragraph about doFinalization refer to
runOnSCC instead of runOnFunction, since that's what it's about.
- Fix a reference in the FunctionPass paragraph.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222222 91177308-0d34-0410-b5e6-96231b3b80d8
This was done using the Sparc and PowerPC AsmParsers as guides. So far it
is very simple and only supports sopp instructions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221994 91177308-0d34-0410-b5e6-96231b3b80d8
The old examples had missing/incorrect flags that were causing failures on newer
versions of clang and the tutorial code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221419 91177308-0d34-0410-b5e6-96231b3b80d8
The given example was overflowing its alloca and segfaulting if actually run on
x86, so it's a good idea to provide something that works there too.
Patch by Ramkumar Ramachandra.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221077 91177308-0d34-0410-b5e6-96231b3b80d8
When several build targets, e.g. Debug+Asserts and Release+Asserts
are present, ocamldoc complains of duplicate interfaces.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220831 91177308-0d34-0410-b5e6-96231b3b80d8
These are named following the IEEE-754 names for these
functions, rather than the libm fmin / fmax to avoid
possible ambiguities. Some languages may implement something
resembling fmin / fmax which return NaN if either operand is
to propagate errors. These implement the IEEE-754 semantics
of returning the other operand if either is a NaN representing
missing data.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220341 91177308-0d34-0410-b5e6-96231b3b80d8
The newly introduced 'nonnull' metadata is analogous to existing 'nonnull' attributes, but applies to load instructions rather than call arguments or returns. Long term, it would be nice to combine these into a single construct. The value of the load is allowed to vary between successive loads, but null is not a valid value to be loaded by any load marked nonnull.
Reviewed by: Hal Finkel
Differential Revision: http://reviews.llvm.org/D5220
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220240 91177308-0d34-0410-b5e6-96231b3b80d8
llvm-symbolizer will consult one of the .dSYM paths passed via -dsym-hint
if it fails to find the .dSYM bundle at the default location.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220004 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
We currently emit an DW_AT_APPLE_property_attribute with a value that is a
bitfield describing the various attributes applied to an ObjectiveC property.
While trying to add testing to one of my dwarfdump patches that would pretty
print that, I realized this information looks totally broken and has maybe
never been correct.
As with every DWARF info, we have some enum in Dwarf.h that describes this
attribute (enum ApplePropertyAttributes). It seems however that the attribute
value is set from another definition of these flags in Sema/DeclSpec.h (enum
ObjCPropertyAttributeKind). And these 2 enums aren't in sync.
This patch updates the Dwarf.h values to the ones we are (and have been for
a very long time) emitting. We change some publicly (and even documented
in SourceLevelDebugging.rst) values, but I doubt this could be an issue as
the information has been wrong for so long...
Reviewers: echristo, dblaikie, aprantl
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D5653
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219311 91177308-0d34-0410-b5e6-96231b3b80d8
Update a couple of the examples of debug info metadata, and prune the
rest. Point to the true reference implementation in the source.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219051 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r218918, effectively reapplying r218914 after fixing
an Ocaml bindings test and an Asan crash. The root cause of the latter
was a tightened-up check in `DILexicalBlock::Verify()`, so I'll file a
PR to investigate who requires the loose check (and why).
Original commit message follows.
--
This patch addresses the first stage of PR17891 by folding constant
arguments together into a single MDString. Integers are stringified and
a `\0` character is used as a separator.
Part of PR17891.
Note: I've attached my testcases upgrade scripts to the PR. If I've
just broken your out-of-tree testcases, they might help.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219010 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
I changed various bits of the compilation of atomics recently, and forgot
updating the documentation. This patch just brings it up to date.
Test Plan: no change to the code
Reviewers: jfb
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D5590
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218937 91177308-0d34-0410-b5e6-96231b3b80d8
This patch addresses the first stage of PR17891 by folding constant
arguments together into a single MDString. Integers are stringified and
a `\0` character is used as a separator.
Part of PR17891.
Note: I've attached my testcases upgrade scripts to the PR. If I've
just broken your out-of-tree testcases, they might help.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218914 91177308-0d34-0410-b5e6-96231b3b80d8
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
Note: I accidentally committed a bogus older version of this patch previously.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218787 91177308-0d34-0410-b5e6-96231b3b80d8
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218778 91177308-0d34-0410-b5e6-96231b3b80d8
This format is simply a regular object file with the bitcode stored in a
section named ".llvmbc", plus any number of other (non-allocated) sections.
One immediate use case for this is to accommodate compilation processes
which expect the object file to contain metadata in non-allocated sections,
such as the ".go_export" section used by some Go compilers [1], although I
imagine that in the future we could consider compiling parts of the module
(such as large non-inlinable functions) directly into the object file to
improve LTO efficiency.
[1] http://golang.org/doc/install/gccgo#Imports
Differential Revision: http://reviews.llvm.org/D4371
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218078 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
They were used in the 'Module Structure' example but weren't otherwise
documented.
Credit to Reed Kotler for noticing.
Reviewers: hans
Reviewed By: hans
Subscribers: hans, llvm-commits
Differential Revision: http://reviews.llvm.org/D5191
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217583 91177308-0d34-0410-b5e6-96231b3b80d8
Approved by Jim Grosbach, Lang Hames, Rafael Espindola.
This reinstates commits r215111, 215115, 215116, 215117, 215136.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216982 91177308-0d34-0410-b5e6-96231b3b80d8
I've been assuming chain operands were always the first operand,
since the documentation says this. I was confused about why they
were missing after instruction selection. Apparently the convention
changes to using the last operand for MachineSDNodes and I've never
noticed before.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216934 91177308-0d34-0410-b5e6-96231b3b80d8
I've fixed most of the simple bugs and currently "check-llvm" test suite
has 26 failures, and "check-clang" suite has 5 failures.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216701 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
There is no functionality change here except in the way we assemble and
dump musttail calls in variadic functions. There's really no need to
separate out the bits for musttail and "is forwarding varargs" on call
instructions. A musttail call by definition has to forward the ellipsis
or it would fail verification.
Reviewers: chandlerc, nlewycky
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D4892
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216423 91177308-0d34-0410-b5e6-96231b3b80d8
Somewhat unnoticed in the original implementation of discriminators, but
it could cause instructions to end up in new, small,
DW_TAG_lexical_blocks due to the use of DILexicalBlock to track
discriminator changes.
Instead, use DILexicalBlockFile which we already use to track file
changes without introducing new scopes, so it works well to track
discriminator changes in the same way.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216239 91177308-0d34-0410-b5e6-96231b3b80d8
Implement `uselistorder` and `uselistorder_bb` assembly directives,
which allow the use-list order to be recovered when round-tripping to
assembly.
This is the bulk of PR20515.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216025 91177308-0d34-0410-b5e6-96231b3b80d8
I should have included this as part of r215986, which worked around this
corner by changing ArrayRef::equals() not to use std::equal. Alas.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215988 91177308-0d34-0410-b5e6-96231b3b80d8
auroraux.org is not resolving.
I will add this to the release notes as soon as I figure out where to put the
3.6 release notes :-)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215645 91177308-0d34-0410-b5e6-96231b3b80d8
treated as errors (which is still the default). This is useful when
working on documentation that has existing errors.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215634 91177308-0d34-0410-b5e6-96231b3b80d8
be deleted. This will be reapplied as soon as possible and before
the 3.6 branch date at any rate.
Approved by Jim Grosbach, Lang Hames, Rafael Espindola.
This reverts commits r215111, 215115, 215116, 215117, 215136.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215154 91177308-0d34-0410-b5e6-96231b3b80d8
I am sure we will be finding bits and pieces of dead code for years to
come, but this is a good start.
Thanks to Lang Hames for making MCJIT a good replacement!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215111 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch add a --show-xfail flag. If this flag is specified then each xfail test will be printed to output.
When it is not given xfail tests are ignored. Ignoring xfail tests is the current behavior.
This flag is meant to mirror the --show-unsupported flag that was recently added.
Reviewers: ddunbar, EricWF
Reviewed By: EricWF
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D4750
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214609 91177308-0d34-0410-b5e6-96231b3b80d8
variables (for example, by-value struct arguments passed in registers, or
large integer values split across several smaller registers).
On the IR level, this adds a new type of complex address operation OpPiece
to DIVariable that describes size and offset of a variable fragment.
On the DWARF emitter level, all pieces describing the same variable are
collected, sorted and emitted as DWARF expressions using the DW_OP_piece
and DW_OP_bit_piece operators.
http://reviews.llvm.org/D3373
rdar://problem/15928306
What this patch doesn't do / Future work:
- This patch only adds the backend machinery to make this work, patches
that change SROA and SelectionDAG's type legalizer to actually create
such debug info will follow. (http://reviews.llvm.org/D2680)
- Making the DIVariable complex expressions into an argument of dbg.value
will reduce the memory footprint of the debug metadata.
- The sorting/uniquing of pieces should be moved into DebugLocEntry,
to facilitate the merging of multi-piece entries.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214576 91177308-0d34-0410-b5e6-96231b3b80d8
Users keep emailing us about the difficulties of getting LD_LIBRARY_PATH
into their environment, which should be completely unecessary. Try to
strengthen the rpath recommentation by putting in an example cmake
invocation.
Speaking of which, we might want to make CMake the recommended build
system in GettingStarted.html.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214565 91177308-0d34-0410-b5e6-96231b3b80d8
I wrongly included a description of a patch that came in after 3.5 branched
and has not been backported.
Thanks,
Bill
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214404 91177308-0d34-0410-b5e6-96231b3b80d8
Here's my take on 3.5 changes for PowerPC. Others please feel free to add,
edit, delete as desired.
Thanks,
Bill
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214403 91177308-0d34-0410-b5e6-96231b3b80d8
Before this patch we had
@a = weak global ...
but
@b = alias weak ...
The patch changes aliases to look more like global variables.
Looking at some really old code suggests that the reason was that the old
bison based parser had a reduction for alias linkages and another one for
global variable linkages. Putting the alias first avoided the reduce/reduce
conflict.
The days of the old .ll parser are long gone. The new one parses just "linkage"
and a later check is responsible for deciding if a linkage is valid in a
given context.
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According to VectorType::isValidElementType, any integer, floating point
or pointer type is a valid vector element type.
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This is the first commit in a series that add an @llvm.assume intrinsic which
can be used to provide the optimizer with a condition it may assume to be true
(when the control flow would hit the intrinsic call). Some basic properties are added here:
- llvm.invariant(true) is dead.
- llvm.invariant(false) is unreachable (this directly corresponds to the
documented behavior of MSVC's __assume(0)), so is llvm.invariant(undef).
The intrinsic is tagged as writing arbitrarily, in order to maintain control
dependencies. BasicAA has been updated, however, to return NoModRef for any
particular location-based query so that we don't unnecessarily block code
motion.
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In the process of fixing the noalias parameter -> metadata conversion process
that will take place during inlining (which will be committed soon, but not
turned on by default), I have come to realize that the semantics provided by
yesterday's commit are not really what we want. Here's why:
void foo(noalias a, noalias b, noalias c, bool x) {
*q = x ? a : b;
*c = *q;
}
Generically, we know that *c does not alias with *a and with *b (so there is an
'and' in what we know we're not), and we know that *q might be derived from *a
or from *b (so there is an 'or' in what we know that we are). So we do not want
the semantics currently, where any noalias scope matching any alias.scope
causes a NoAlias return. What we want to know is that the noalias scopes form a
superset of the alias.scope list (meaning that all the things we know we're not
is a superset of all of things the other instruction might be).
Making that change, however, introduces a composibility problem. If we inline
once, adding the noalias metadata, and then inline again adding more, and we
append new scopes onto the noalias and alias.scope lists each time. But, this
means that we could change what was a NoAlias result previously into a MayAlias
result because we appended an additional scope onto one of the alias.scope
lists. So, instead of giving scopes the ability to have parents (which I had
borrowed from the TBAA implementation, but seems increasingly unlikely to be
useful in practice), I've given them domains. The subset/superset condition now
applies within each domain independently, and we only need it to hold in one
domain. Each time we inline, we add the new scopes in a new scope domain, and
everything now composes nicely. In addition, this simplifies the
implementation.
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This commit adds scoped noalias metadata. The primary motivations for this
feature are:
1. To preserve noalias function attribute information when inlining
2. To provide the ability to model block-scope C99 restrict pointers
Neither of these two abilities are added here, only the necessary
infrastructure. In fact, there should be no change to existing functionality,
only the addition of new features. The logic that converts noalias function
parameters into this metadata during inlining will come in a follow-up commit.
What is added here is the ability to generally specify noalias memory-access
sets. Regarding the metadata, alias-analysis scopes are defined similar to TBAA
nodes:
!scope0 = metadata !{ metadata !"scope of foo()" }
!scope1 = metadata !{ metadata !"scope 1", metadata !scope0 }
!scope2 = metadata !{ metadata !"scope 2", metadata !scope0 }
!scope3 = metadata !{ metadata !"scope 2.1", metadata !scope2 }
!scope4 = metadata !{ metadata !"scope 2.2", metadata !scope2 }
Loads and stores can be tagged with an alias-analysis scope, and also, with a
noalias tag for a specific scope:
... = load %ptr1, !alias.scope !{ !scope1 }
... = load %ptr2, !alias.scope !{ !scope1, !scope2 }, !noalias !{ !scope1 }
When evaluating an aliasing query, if one of the instructions is associated
with an alias.scope id that is identical to the noalias scope associated with
the other instruction, or is a descendant (in the scope hierarchy) of the
noalias scope associated with the other instruction, then the two memory
accesses are assumed not to alias.
Note that is the first element of the scope metadata is a string, then it can
be combined accross functions and translation units. The string can be replaced
by a self-reference to create globally unqiue scope identifiers.
[Note: This overview is slightly stylized, since the metadata nodes really need
to just be numbers (!0 instead of !scope0), and the scope lists are also global
unnamed metadata.]
Existing noalias metadata in a callee is "cloned" for use by the inlined code.
This is necessary because the aliasing scopes are unique to each call site
(because of possible control dependencies on the aliasing properties). For
example, consider a function: foo(noalias a, noalias b) { *a = *b; } that gets
inlined into bar() { ... if (...) foo(a1, b1); ... if (...) foo(a2, b2); } --
now just because we know that a1 does not alias with b1 at the first call site,
and a2 does not alias with b2 at the second call site, we cannot let inlining
these functons have the metadata imply that a1 does not alias with b2.
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We previously supported the align attribute on all (pointer) parameters, but we
only used it for byval parameters. However, it is completely consistent at the
IR level to treat 'align n' on all pointer parameters as an alignment
assumption on the pointer, and now we wll. Specifically, this causes
computeKnownBits to use the align attribute on all pointer parameters, not just
byval parameters. I've also added an explicit parameter attribute test for this
to test/Bitcode/attributes.ll.
And I've updated the LangRef to document the align parameter attribute (as it
turns out, it was not documented at all previously, although the byval
documentation mentioned that it could be used).
There are (at least) two benefits to doing this:
- It allows enhancing alignment based on the pointer alignment after inlining callees.
- It allows simplification of pointer arithmetic.
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to globally be controlled. Individual targets (e.g. ExceptionDemo) can
still override this by using LLVM_REQUIRE_RTTI and LLVM_REQUIRE_EH if
they need to be compiled with RTTI or exception handling respectively.
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- When CMake builds the documentation with sphinx-build it treats
warnings as errors. We should be consistent with what we do in
CMake.
- Having warnings treated as errors will hopefully encourage
developers to write documentation correctly.
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This reverts commit r213474 (and r213475), which causes a miscompile on
a stage2 LTO build. I'll reply on the list in a moment.
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Summary: This patch introduces two new iterator ranges and updates existing code to use it. No functional change intended.
Test Plan: All tests (make check-all) still pass.
Reviewers: dblaikie
Reviewed By: dblaikie
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D4481
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This attribute indicates that the parameter or return pointer is
dereferenceable. Practically speaking, loads from such a pointer within the
associated byte range are safe to speculatively execute. Such pointer
parameters are common in source languages (C++ references, for example).
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This optional dependency on the udis86 library was added some time back to aid
JIT development, but doesn't make much sense to link into LLVM binaries these
days.
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Convert the operand to int if possible, i.e. if the value is properly
initialized. (I suppose there is further room for improvement here to also
peform the shift if the uninitialized bits are shifted out.)
With this little change we can now compute the scaling factor for compressed
displacement with pure tablegen code in the X86 backend. This is useful
because both the X86-disassembler-specific part of tablegen and the assembler
need this and TD is the natural sharing place.
The patch also adds the missing documentation for the shift and add operator.
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