Summary: Working towards Johannes's suggestion for fixme, in Attributor's Noalias attribute deduction.
(ii) Check whether the value is captured in the scope using AANoCapture.
FIXME: This is conservative though, it is better to look at CFG and
// check only uses possibly executed before this call site.
A Reachability abstract attribute answers the question "does execution at point A potentially reach point B". If this question is answered with false for all other uses of the value that might be captured, we know it is not *yet* captured and can continue with the noalias deduction. Currently, information AAReachability provides is completely pessimistic.
Reviewers: jdoerfert
Reviewed By: jdoerfert
Subscribers: uenoku, sstefan1, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D70233
This file lists every pass in LLVM, and is included by Pass.h, which is
very popular. Every time we add, remove, or rename a pass in LLVM, it
caused lots of recompilation.
I found this fact by looking at this table, which is sorted by the
number of times a file was changed over the last 100,000 git commits
multiplied by the number of object files that depend on it in the
current checkout:
recompiles touches affected_files header
342380 95 3604 llvm/include/llvm/ADT/STLExtras.h
314730 234 1345 llvm/include/llvm/InitializePasses.h
307036 118 2602 llvm/include/llvm/ADT/APInt.h
213049 59 3611 llvm/include/llvm/Support/MathExtras.h
170422 47 3626 llvm/include/llvm/Support/Compiler.h
162225 45 3605 llvm/include/llvm/ADT/Optional.h
158319 63 2513 llvm/include/llvm/ADT/Triple.h
140322 39 3598 llvm/include/llvm/ADT/StringRef.h
137647 59 2333 llvm/include/llvm/Support/Error.h
131619 73 1803 llvm/include/llvm/Support/FileSystem.h
Before this change, touching InitializePasses.h would cause 1345 files
to recompile. After this change, touching it only causes 550 compiles in
an incremental rebuild.
Reviewers: bkramer, asbirlea, bollu, jdoerfert
Differential Revision: https://reviews.llvm.org/D70211
Summary:
This patch introduces align attribute deduction for callsite argument, function argument, function returned and floating value based on must-be-executed-context.
Reviewers: jdoerfert, sstefan1
Reviewed By: jdoerfert
Subscribers: hiraditya, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69797
Summary: A helper function to get argument number of a arg operand Use.
Reviewers: jdoerfert, uenoku
Subscribers: hiraditya, lebedev.ri, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66844
Dependences between two abstract attributes SRC and TRG come naturally in
two flavors:
Either (1) "some" information of SRC is *required* for TRG to derive
information, or (2) SRC is just an *optional* way for TRG to derive
information.
While it is not strictly necessary to distinguish these types
explicitly, it can help us to converge faster, in terms of iterations,
and also cut down the number of `AbstractAttribute::update` calls.
As far as I can tell, we only use optional dependences for liveness so
far but that might change in the future. With this change the Attributor
can be informed about the "dependence class" and it will perform
appropriate actions when an Attribute is set to an invalid state, thus
one that cannot be used by others to derive information from.
BlockAddress users will not "call" the function so they do not qualify
as call sites in the first place. When we delete a function with
BlockAddress users we need to first remove the body so they are properly
discarded.
When we replace constant returns at the call site we did issue a cast in
the hopes it would be a no-op if the types are equal. Turns out that is
not the case and we have to check it ourselves first.
Reused an IPConstantProp test for coverage. No functional change to the
test wrt. IPConstantProp.
Even if the invoked function may-return, we can replace it with a call
and branch if it is nounwind. We had almost everything in place to do
this but did not which actually caused a crash when we removed the
landingpad from the actually dead unwind block.
Exposed by the IPConstantProp tests.
We did merge "known" and "assumed" liveness information into a single
set which caused various kinds of problems, especially because we did
not properly record when something was actually known. With this patch
we properly track the "known" bit and distinguish dead ends we know from
the ones we still need to explore in future updates.
We gave up on `noreturn` if `willreturn` was known for a while but we
now again try to always derive `noreturn`. This is useful because a
function that is `noreturn` + `willreturn` is basically dead as
executing it would lead to undefined behavior (UB).
This came up in the IPConstantProp cases where a function only contained
a unreachable but was not marked `noreturn` which caused missed
opportunities down the line.
In D69605 only the "cases" of a switch were handled but if none matched
we did not make the default case life. This is fixed now and properly
tested (with code from IPConstantProp/user-with-multiple-uses.ll).
We cannot simply replace arguments that carry attributes like `nest`,
`inalloca`, `sret`, and `byval`. Except for the last one, which we can
replace if it is not written, we bail for now.
Trying to deduce information for declarations and calls sites of
declarations is not useful in practice but only for testing. Add a flag
that disables this by default but also enable it in the tests.
The misc.ll test will verify the flag "works" as expected.
We cannot look at the subsuming positions and take their nocapture bit
as shown with the two tests for which we derived nocapture on the call
site argument and readonly on the argument of the second before.
Before we did not follow casts and geps when we looked at the users of a
pointer in the pointers must-be-executed-context. This caused us to fail
to determine if it was accessed for sure. With this change we follow
such users now.
The above extension exposed problems in getKnownNonNullAndDerefBytesForUse
which did not always check what the base pointer was. We also did not
handle negative offsets as conservative as we have to without explicit
loop handling. Finally, we should not derive a huge number if we access
a pointer that was traversed backwards first.
The problems exposed by this functional change are already tested in the
existing test cases as is the functional change.
Differential Revision: https://reviews.llvm.org/D69647
Summary:
In order to get context sensitivity from isKnownNonZero we need to
provide a context instruction *and* a dominator tree. The latter is
passed now to which actually allows to remove some initialization code.
Tests taken from PR43833.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69595
Summary:
If control is transferred to a successor is the key question when it
comes to liveness. The new implementation puts that question in the
focus and thereby providing a clean way to assume certain CFG edges are
dead or instructions will not transfer control.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69605
Summary:
This patch introduces liveness (AAIsDead) for all positions, thus for
all kinds of values. For now, we say an instruction is dead if it would
be removed assuming all users are dead. A call site return is different
as we just look at the users. If all call site returns have been
eliminated, the return values can return undef instead of their original
value, eliminating uses.
We try to recursively delete dead instructions now and we introduce a
simple check interface for use-traversal.
This is the idea tried out in D68626 but implemented in the right way.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68925
Deleting blocks will require us to deal with dead edges, e.g.,
`br i1 false, label %live, label %dead`
explicitly. For now we just clear the blocks and move on.
This will be revisited once we actually fold branches.
Summary:
If there is a unique free of the allocated that has to be reached from
the malloc, we can apply the heap-2-stack transformation even if the
pointer escapes.
Reviewers: hfinkel, sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68958
If an attribute did not query any optimistic (=non-fixed) information to
justify its state, we know the attribute state will not change anymore.
Thus, we can indicate an optimistic fixpoint.
We pretended IRPosition came either as mutable or immutable objects
while they are basically always immutable, with a single (existing)
unfortunate exceptions. This patch cleans up the uses to deal with the
immutable version.
To make IntegerState more flexible but also less error prone we split it
up into (1) incrementing, (2) decrementing, and (3) bit-tracking states.
This adds functionality compared to before and disallows misuse, e.g.,
"incrementing" updates on a bit-tracking state.
Part of the change is a single operator in the base class which
simplifies helper functions that deal with states.
There are certain functional changes but all of which should actually be
corrections.
AAReturnedValues, AAMemoryBehavior, and AANoUnwind, can provide
information that helps during the tracking or even justifies no-capture.
We now use this information and enable no-capture in some test cases
designed a long while a ago for these cases.
llvm-svn: 375382
No-return and will-return are exclusive, assuming the latter is more
prominent we can avoid updates of the former unless will-return is not
known for sure.
llvm-svn: 374739
Even if an argument is captured, we cannot have an effect the function
does not have. This is fine except for the special case of `inalloca` as
it does not behave by the rules.
TODO: Maybe the special rule for `inalloca` is wrong after all.
llvm-svn: 374736
Summary:
This changes "CHECK" check lines to "ATTRIBUTOR" check lines where
necessary and also fixes the now exposed, mostly minor, problems.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68929
llvm-svn: 374735
Before, we eagerly split blocks even if it was not necessary, e.g., they
had a single unreachable instruction and only a single predecessor.
llvm-svn: 374703
We do not yet perform h2s because we know something is free'ed but we do
it because we know the pointer does not escape. Storing the pointer
allows it to escape so we have to prevent that.
llvm-svn: 374699
H2S did apply to mallocs of non-constant sizes if the uses were OK. This
is now forbidden through reording of the "good" and "bad" cases in the
conditional.
llvm-svn: 374698
The check for naked/optnone was insufficient for different reasons. We
now check before we initialize an abstract attribute and we do it for
all abstract attributes.
llvm-svn: 374694
Summary:
`null` in the default address space (=AS 0) cannot be captured nor can
it alias anything. We make this clear now as it can be important for
callbacks and other cases later on. In addition, this patch improves the
debug output for noalias deduction.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68624
llvm-svn: 374280
Summary:
In D65186 and related patches, MustBeExecutedContextExplorer is introduced. This enables us to traverse instructions guaranteed to execute from function entry. If we can know the argument is used as `dereferenceable` or `nonnull` in these instructions, we can mark `dereferenceable` or `nonnull` in the argument definition:
1. Memory instruction (similar to D64258)
Trace memory instruction pointer operand. Currently, only inbounds GEPs are traced.
```
define i64* @f(i64* %a) {
entry:
%add.ptr = getelementptr inbounds i64, i64* %a, i64 1
; (because of inbounds GEP we can know that %a is at least dereferenceable(16))
store i64 1, i64* %add.ptr, align 8
ret i64* %add.ptr ; dereferenceable 8 (because above instruction stores into it)
}
```
2. Propagation from callsite (similar to D27855)
If `deref` or `nonnull` are known in call site parameter attributes we can also say that argument also that attribute.
```
declare void @use3(i8* %x, i8* %y, i8* %z);
declare void @use3nonnull(i8* nonnull %x, i8* nonnull %y, i8* nonnull %z);
define void @parent1(i8* %a, i8* %b, i8* %c) {
call void @use3nonnull(i8* %b, i8* %c, i8* %a)
; Above instruction is always executed so we can say that@parent1(i8* nonnnull %a, i8* nonnull %b, i8* nonnull %c)
call void @use3(i8* %c, i8* %a, i8* %b)
ret void
}
```
Reviewers: jdoerfert, sstefan1, spatel, reames
Reviewed By: jdoerfert
Subscribers: xbolva00, hiraditya, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65402
llvm-svn: 374063
Summary: This patch introduces a generic way to compose two structured deductions. This will be used for composing generic deduction with `MustBeExecutedExplorer` and other existing generic deduction.
Reviewers: jdoerfert, sstefan1
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66645
llvm-svn: 374060
The initialization logic has become part of the Attributor but the
patches that introduced these calls here were in development when the
transition happened.
We also now clean up (undefine) the macros used to create attributes.
llvm-svn: 373987
Local linkage is internal or private, and private is a specialization of
internal, so either is fine for all our "local linkage" queries.
llvm-svn: 373986
Summary:
When we iterate over uses of functions and expect them to be call sites,
we now use abstract call sites to allow callback calls.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, hfinkel, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67871
llvm-svn: 373985
Summary:
This patch introduces `norecurse` function attribute deduction.
`norecurse` will be deduced if the following conditions hold:
* The size of SCC in which the function belongs equals to 1.
* The function doesn't have self-recursion.
* We have `norecurse` for all call site.
To avoid a large change, SCC is calculated using scc_iterator in InfoCache initialization for now.
Reviewers: jdoerfert, sstefan1
Reviewed By: jdoerfert
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67751
llvm-svn: 372475
Summary:
There were segfaults as we modified and iterated the instruction maps in
the cache at the same time. This was happening because we created new
instructions while we populated the cache. This fix changes the order
in which we perform these actions. First, the caches for the whole
module are created, then we start to create abstract attributes.
I don't have a unit test but the LLVM test suite exposes this problem.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67232
llvm-svn: 372105
Summary: This patch introduces a helper struct `AnalysisGetter` to put together analysis getters. In this patch, a getter for `AAResult` is also added for `noalias`.
Reviewers: jdoerfert, sstefan1
Reviewed By: jdoerfert
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67603
llvm-svn: 372072
D53362 gives a prototype heap-to-stack conversion pass. With addition of new attributes in the attributor, this can now be revisted and improved. This will place it in the Attributor to make it easier to use new attributes (eg. nofree, nosync, willreturn, etc.) and other attributor features.
Reviewers: jdoerfert, uenoku, hfinkel, efriedma
Subscribers: lebedev.ri, xbolva00, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D65408
llvm-svn: 371942
Summary: This should be obsolete once the functionality in D66967 is integrated.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67231
llvm-svn: 371915
Summary:
We can query to Attributor whether the value is captured in the scope or not on the following way:
```
const auto & NoCapAA = A.getAAFor<AANoCapture>(*this, IRPosition::value(V));
```
And if V is CallSiteReturned then `getDeducedAttribute` will add `nocatpure` to the callsite returned value. It is not valid.
This patch checks the position is an argument or call site argument.
This is tested in D67286.
Reviewers: jdoerfert, sstefan1
Reviewed By: jdoerfert
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67342
llvm-svn: 371589
Summary:
This patch introduces initial `AAValueSimplify` which simplifies a value in a context.
example
- (for function returned) If all the return values are the same and constant, then we can replace callsite returned with the constant.
- If an internal function takes the same value(constant) as an argument in the callsite, then we can replace the argument with that constant.
Reviewers: jdoerfert, sstefan1
Reviewed By: jdoerfert
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66967
llvm-svn: 371291
Summary:
Instead of building attributes for internal functions which we do not
update as long as we assume they are dead, we now do not create
attributes until we assume the internal function to be live. This
improves the number of required iterations, as well as the number of
required updates, in real code. On our tests, the results are mixed.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66914
llvm-svn: 370924
Summary:
We create attributes on-demand so we need to check the white list
on-demand. This also unifies the location at which we create,
initialize, and eventually invalidate new abstract attributes.
The tests show mixed results, a few more call site attributes are
determined which can cause more iterations.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66913
llvm-svn: 370922
Summary:
Before we tried to rule out non-exact definitions early but that lead to
on-demand attributes created for them anyway. As a consequence we needed
to look at the definition in the initialize of each attribute again.
This patch centralized this lookup and tightens the condition under
which we give up on non-exact definitions.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67115
llvm-svn: 370917
Add the no-capture argument attribute deduction to the Attributor
fixpoint framework.
The new string attributed "no-capture-maybe-returned" is introduced to
allow deduction of no-capture through functions that "capture" an
argument but only by "returning" it. It is only used by the Attributor
for testing.
Differential Revision: https://reviews.llvm.org/D59922
llvm-svn: 370817
Summary:
Instead of recomputing information for call sites we now use the
function information directly. This is always valid and once we have
call site specific information we can improve here.
This patch also bootstraps attributes that are created on-demand through
an initial update call. Information that is known will then directly be
available in the new attribute without causing an iteration delay.
The tests show how this improves the iteration count.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66781
llvm-svn: 370480
Summary:
Any pointer could have load/store users not only floating ones so we
move the manifest logic for alignment into the AAAlignImpl class.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66922
llvm-svn: 370479
As dependences between abstract attributes can become stale, e.g., if
one was sufficient to imply another one at some point but it has since
been wakened to the point it is not usable for the formerly implied one.
To weed out spurious dependences, and thereby eliminate unneeded
updates, we introduce an option to determine how often the dependence
cache is cleared and recomputed during the fixpoint iteration.
Note that the initial value was determined such that we see a positive
result on our tests.
Differential Revision: https://reviews.llvm.org/D63315
llvm-svn: 370230
Summary:
Until we have proper call-site information we should not recompute
liveness and return information for each call site. This patch directly
uses the function versions and introduces TODOs at the usage sites.
The required iterations to get to the fixpoint are most of the time
reduced by this change and we always avoid work duplication.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66562
llvm-svn: 370208
Summary:
During the fixpoint iteration, including the manifest stage, we should
not delete stuff as other abstract attributes might have a reference to
the value. Through the API this can now be done safely at the very end.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66779
llvm-svn: 370014
Summary:
Try to verify how many iterations we need for a fixpoint in our tests.
This patch adjust the way we count to make it easier to follow. It also
adjusts the bounds to actually account for a fixpoint and not only the
minimum number to pass all checks.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66757
llvm-svn: 369945
By default, the Attributor tracks potential dependences between abstract
attributes based on the issued Attributor::getAAFor queries. This
simplifies the development of new abstract attributes but it can also
lead to spurious dependences that might increase compile time and make
internalization harder (D63312). With this patch, abstract attributes
can opt-out of implicit dependence tracking and instead register
dependences explicitly. It is up to the implementation to make sure all
existing dependences are registered.
Differential Revision: https://reviews.llvm.org/D63314
llvm-svn: 369935
Summary:
We can now manifest alignment information in load/store instructions if
the pointer is known to have a better alignment.
Reviewers: uenoku, sstefan1, lebedev.ri
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66567
llvm-svn: 369804
Summary:
If the unique return value is a constant we now replace call uses with
that constant.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66551
llvm-svn: 369785
Summary:
If we have a loop in which the dereferenceability of a pointer decreases
we did slowly decrease it iteration by iteration, leading to a timeout.
With this patch we detect such circular reasoning and indicate a
fixpoint early.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66558
llvm-svn: 369784
Summary:
If we have a negative inbounds offset dereferenceabily "grows". However,
until we do not handle the overflow that can occur in the
dereferenceable bytes and the problem with loops, we simply do not grow
the state.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66557
llvm-svn: 369771
If the number of potentially returned values not change since the last
traversal we do not need to visit the returned values again. This works
as we only add values to the returned values set now.
Differential Revision: https://reviews.llvm.org/D66484
llvm-svn: 369770
Summary:
When we have new attributes and we end the fixpoint iteration because
the iteration limit is reached, we need to treat the new ones as if they
changed in the last iteration, as they might have.
This adds a test for which we should not derive anything regardless of
the iteration limit, e.g., if we abort there should not be any
attributes manifested in the IR.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66549
llvm-svn: 369768
Summary: In D65402, I want to get DerefState from AADereferenceable but it was not allowed. This patch moves DerefState definition into Attributor.h and makes AADerefenceable inherit StateWrapper.
Reviewers: jdoerfert, sstefan1
Reviewed By: jdoerfert
Subscribers: hiraditya, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66585
llvm-svn: 369653
For an internal function, if all its call sites are dead, the body of the function is considered dead.
Reviewers: jdoerfert, uenoku
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D66155
llvm-svn: 369470
Before, we create the set of abstract attributes initially and then
dealt with the fact hat a lookup could fail, e.g., return a nullptr.
This patch will ensure we always return a valid object from a lookup,
allowing us not only to remove the nullptr checks but also to grow the
set of abstract attributes "in-flight" on-demand.
One can now start from those that have the best chance of improving
performance without the need to specify all they might depend on.
While this introduces some boilerplate, the usage of attributes is much
easier and cleaner now.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66276
llvm-svn: 369331
Summary:
This is analogous to D66128 but for AADereferenceable. We have the logic
concentrated in the floating value updateImpl and we use the combiner
helper classes for arguments and return values.
The regressions will go away with "on-demand" attribute creation.
Improvements are already visible in the existing tests.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66272
llvm-svn: 369329
Summary:
What D66126 did for AAAlign, this patch does for AANonNull. Agian, the
logic becomes more concise and localized. Again, returned poiners are
not annotated properly but that will not be an issue if this lands with
the "on-demand" generation of attributes. First improvements due to the
genericValueTraversal are already visible.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66128
llvm-svn: 369328
The clamp operator should not take the known of the given state as the
known is potentially based on assumed information. This also adds TODOs
to guide improvements.
llvm-svn: 369327
This reverts commit cedd0d9a6e.
Re-apply the original commit but make sure the variables are initialized
(even if they are not used) so UBSan is not complaining.
llvm-svn: 369294
By partially resolving returned calls we did not record that they were
not fully resolved which caused odd behavior down the line. We could
also end up with some, but not all, returned values of the callee in the
returned values map of the caller, another odd behavior we want to
avoid.
llvm-svn: 369160
As a preparation to "on-demand" abstract attribute generation we need
implementations for all attributes (as they can be queried and then
created on-demand where we now fail to find one).
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66129
llvm-svn: 369155
Summary:
This is the first commit aiming to structure the attribute deduction.
The base idea is that we have default propagation patterns as listed
below on top of which we can add specific, e.g., context sensitive,
logic.
Deduction patterns used in this patch:
- argument states are determined from call site argument states,
see AAAlignArgument and AAArgumentFromCallSiteArguments.
- call site argument states are determined as if they were floating
values, see AAAlignCallSiteArgument and AAAlignFloating.
- floating value states are determined by traversing the def-use chain
and combining the states determined for the leaves, see
AAAlignFloating and genericValueTraversal.
- call site return states are determined from function return states,
see AAAlignCallSiteReturned and AACallSiteReturnedFromReturned.
- function return states are determined from returned value states,
see AAAlignReturned and AAReturnedFromReturnedValues.
Through this strategy all logic for alignment is concentrated in the
AAAlignFloating::updateImpl method.
Note: This commit works on its own but is part of a larger change that
involves "on-demand" creation of abstract attributes that will
participate in the fixpoint iteration. Without this part, we sometimes
do not have an AAAlign abstract attribute to query, loosing information
we determined before. All tests have appropriate FIXMEs and the
information will be recovered once we added all parts.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66126
llvm-svn: 369144
Until we have call site specific liveness and/or value information there
is no need to do call site specific deduction. Though, we need the
symbols in follow up patches that make Attributor::getAAFor return a
reference.
llvm-svn: 369143
Summary:
This patch should not change the behavior except that the added
initialize methods might indicate an optimistic fixpoint earlier. The
code movement is done to keep the attribute definitions in a single
block where it makes sense. No functional changes intended there.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66258
llvm-svn: 369142
Summary:
Instead of constantly keeping track of the nonnull status with the
dereferenceable information we can simply query the nonnull attribute
whenever we need the information (debug + manifest).
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66113
llvm-svn: 368924
Summary:
As one of the first attributes, and one of the complex ones,
AAReturnedValues was not using liveness but we filtered the result after
the fact. This change adds liveness usage during the creation. The
algorithm is also improved and shorter.
The new algorithm will collect returned values over time using the
generic facilities that work with liveness already, e.g.,
genericValueTraversal which does not look at dead PHI node predecessors.
A test to show how this leads to better results is included.
Note: Unresolved calls and resolved calls are now tracked explicitly.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66120
llvm-svn: 368922
Summary:
If the associated context instruction is assumed dead we do not need to
update or manifest the state.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66116
llvm-svn: 368921
Summary:
The next attempt to clean up the Attributor interface before we grow it
further.
Before, we used a combination of two values (associated + anchor) and an
argument number (or -1) to determine a location. This was very fragile.
The new system uses exclusively IR positions and we restrict the
generation of IR positions to special constructor methods that verify
internal constraints we have. This will catch misuse early.
The auto-conversion, e.g., in getAAFor, is now performed through the
SubsumingPositionIterator. This iterator takes an IR position and allows
to visit all IR positions that "subsume" the given one, e.g., function
attributes "subsume" argument attributes of that function. For a
detailed breakdown see the class comment of SubsumingPositionIterator.
This patch also introduces the IRPosition::getAttrs() to extract IR
attributes at a certain position. The method knows how to look up in
different positions that are equivalent, e.g., the argument position for
call site arguments. We also introduce three new positions kinds such
that we have all IR positions where attributes can be placed and one for
"floating" values.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65977
llvm-svn: 368919
Summary:
The ever growing switch required Attribute::AttrKind values but they
might not be available for all abstract attributes we deduce. With the
new method we track statistics at the abstract attribute level. The
provided macros simplify the usage and make the messages uniform.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65732
llvm-svn: 368227
Summary:
The wrapper reduces boilerplate code and also provide a nice way to
determine the state type used by an abstract attributes statically via
AAType::StateType.
This was already discussed as part of the review of D65711.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65786
llvm-svn: 368224
If we know everything is live there is no need to query for liveness.
Indicating a pessimistic fixpoint will cause the state to be "invalid"
which will cause the Attributor to not return the AAIsDead on request,
which will prevent us from querying isAssumedDead().
llvm-svn: 368223
Summary:
So far, whenever one wants to look at returned values, one had to deal
with the AAReturnedValues and potentially with the AAIsDead attribute.
In the same spirit as other checkForAllXXX methods, we add this
functionality now to the Attributor. By adopting the use sites we got
better results when return instructions were dead.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65733
llvm-svn: 368222
Commit r368064 was necessary after r367953 (D65712) broke the module
build. That happened, apparently, because the template class IRAttribute
defined in the header had a virtual method defined in the corresponding
source file (IRAttribute::manifest). To unbreak the situation this patch
introduces a helper function IRAttributeManifest::manifestAttrs which
is used to implement IRAttribute::manifest in the header. The deifnition
of the helper function is still in the source file.
Patch by jdoerfert (Johannes Doerfert)
Differential Revision: https://reviews.llvm.org/D65821
llvm-svn: 368076
Summary:
Similar to `Attributor::checkForAllCallSites`, we now provide such
functionality for instructions of a certain opcode through
`Attributor::checkForAllInstructions` and the convenient wrapper
`Attributor::checkForAllCallLikeInstructions`. This cleans up code,
avoids duplication, and simplifies the usage of liveness information.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65731
llvm-svn: 367961
Summary:
Certain properties, e.g., an AttrKind, are not shared among all abstract
attributes. This patch extracts the functionality into a helper struct.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65712
llvm-svn: 367953
To remove boilerplate, mostly passing through values to the
AbstractAttriubute base class, we extract the state into an IRPosition
helper. There is no function change intended but the IRPosition struct
will provide more functionality down the line.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65711
llvm-svn: 367952
Summary:
The new scheme is similar to the pass manager and dyn_cast scheme where
we identify classes by the address of a static member. This is better
than the old scheme in which we had to "invent" new Attributor enums if
there was no corresponding one.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65710
llvm-svn: 367951
Summary:
Instead of storing the reference to the InformationCache we now pass it
whenever it might be needed.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65709
llvm-svn: 367950
A function is "no-return" if we never reach a return instruction, either
because there are none or the ones that exist are dead.
Test have been adjusted:
- either noreturn was added, or
- noreturn was avoided by modifying the code.
The new noreturn_{sync,async} test make sure we do handle invoke
instructions with a noreturn (and potentially nowunwind) callee
correctly, even in the presence of potential asynchronous exceptions.
llvm-svn: 367948
When we remove instructions cached references could still be live. This
patch avoids removing invoke instructions that are replaced by calls and
instead keeps them around but in a dead block.
llvm-svn: 367933
Similar to other places where we transform invokes to calls we need to
be careful if the handler (=personality) can catch asynchronous
exceptions as they are not modeled as part of nounwind.
This is tested with D59978.
llvm-svn: 367931
Summary:
This contains various fixes:
- Explicitly determine and return the next noreturn instruction.
- If an invoke calls a noreturn function which is not nounwind we
keep the unwind destination live. This also means we require an
invoke. Though we can still add the unreachable to the normal
destination block.
- Check if the return instructions are dead after we look for calls
to avoid triggering an optimistic fixpoint in the presence of
assumed liveness information.
- Make the interface work with "const" pointers.
- Some simplifications
While additional tests are included, full coverage is achieved only with
D59978.
Reviewers: sstefan1, uenoku
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65701
llvm-svn: 367791
When a fixpoint is indicated the change status is known due to the
fixpoint kind. This simplifies a common code pattern by making the
connection explicit.
llvm-svn: 367790
Summary:
If the DerefBytesState (and thereby the DerefState) is invalid, we
reached a fixpoint for the whole DerefState as we will not
manifest/provide information then.
Reviewers: uenoku, sstefan1
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65586
llvm-svn: 367789
Modifying other AbstractAttributes to use Liveness AA and skip dead instructions.
Reviewers: jdoerfert, uenoku
Subscribers: hiraditya, llvm-commits
Differential revision: https://reviews.llvm.org/D65243
llvm-svn: 367725
User of AAReturnedValues need to know if HasOverdefinedReturnedCalls
changed from false to true as it will impact the result of the return
value traversal (calls are not ignored anymore).
This will be tested with the tests in D59978.
llvm-svn: 367581
Summary:
Deduce dereferenceable attribute in Attributor.
These will be added in a later patch.
* dereferenceable(_or_null)_globally (D61652)
* Deduction based on load instruction (similar to D64258)
Reviewers: jdoerfert, sstefan1
Reviewed By: jdoerfert
Subscribers: hiraditya, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64876
llvm-svn: 366788
[Attributor] Liveness analysis.
Liveness analysis abstract attribute used to indicate which BasicBlocks are dead and can therefore be ignored.
Right now we are only looking at noreturn calls.
Reviewers: jdoerfert, uenoku
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D64162
llvm-svn: 366769
[Attributor] Liveness analysis.
Liveness analysis abstract attribute used to indicate which BasicBlocks are dead and can therefore be ignored.
Right now we are only looking at noreturn calls.
Reviewers: jdoerfert, uenoku
Subscribers: hiraditya, llvm-commits
Differential revision: https://reviews.llvm.org/D64162
llvm-svn: 366753
Liveness analysis abstract attribute used to indicate which BasicBlocks are dead and can therefore be ignored.
Right now we are only looking at noreturn calls.
Reviewers: jdoerfert, uenoku
Subscribers: hiraditya, llvm-commits
Differential revision: https://reviews.llvm.org/D64162
llvm-svn: 366736
Porting function return value attribute noalias to attributor.
This will be followed with a patch for callsite and function argumets.
Reviewers: jdoerfert
Subscribers: lebedev.ri, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D63067
llvm-svn: 366728
Summary:
Deduce the "willreturn" attribute for functions.
For now, intrinsics are not willreturn. More annotation will be done in another patch.
Reviewers: jdoerfert
Subscribers: jvesely, nhaehnle, nicholas, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63046
llvm-svn: 366335
Attributor::getAAFor will now only return AbstractAttributes with a
valid AbstractState. This simplifies call sites as they only need to
check if the returned pointer is non-null. It also reduces the potential
for accidental misuse.
llvm-svn: 365983
Some function in the Attributor framework are unnecessarily
marked virtual. This patch removes virtual keyword
Reviewers: jdoerfert
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D64637
llvm-svn: 365925
Introduce and deduce "nosync" function attribute to indicate that a function
does not synchronize with another thread in a way that other thread might free memory.
Reviewers: jdoerfert, jfb, nhaehnle, arsenm
Subscribers: wdng, hfinkel, nhaenhle, mehdi_amini, steven_wu,
dexonsmith, arsenm, uenoku, hiraditya, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D62766
llvm-svn: 365830
Deduce the "returned" argument attribute by collecting all potentially
returned values.
Not only the unique return value, if any, can be used by subsequent
attributes but also the set of all potentially returned values as well
as the mapping from returned values to return instructions that they
originate from (see AAReturnedValues::checkForallReturnedValues).
Change in statistics (-stats) for LLVM-TS + Spec2006, totaling ~19% more "returned" arguments.
ADDED: attributor NumAttributesManifested n/a -> 637
ADDED: attributor NumAttributesValidFixpoint n/a -> 25545
ADDED: attributor NumFnArgumentReturned n/a -> 637
ADDED: attributor NumFnKnownReturns n/a -> 25545
ADDED: attributor NumFnUniqueReturned n/a -> 14118
CHANGED: deadargelim NumRetValsEliminated 470 -> 449 ( -4.468%)
REMOVED: functionattrs NumReturned 535 -> n/a
CHANGED: indvars NumElimIdentity 138 -> 164 ( +18.841%)
Reviewers: homerdin, hfinkel, fedor.sergeev, sanjoy, spatel, nlopes, nicholas, reames, efriedma, chandlerc
Subscribers: hiraditya, bollu, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D59919
llvm-svn: 365407
@jdoerfert Looks like these are placeholders for incoming abstract attributes patches so I've just commented the code out, even though this is usually frowned upon.
llvm-svn: 362592
NOTE: Note that no attributes are derived yet. This patch will not go in
alone but only with others that derive attributes. The framework is
split for review purposes.
This commit introduces the Attributor pass infrastructure and fixpoint
iteration framework. Further patches will introduce abstract attributes
into this framework.
In a nutshell, the Attributor will update instances of abstract
arguments until a fixpoint, or a "timeout", is reached. Communication
between the Attributor and the abstract attributes that are derived is
restricted to the AbstractState and AbstractAttribute interfaces.
Please see the file comment in Attributor.h for detailed information
including design decisions and typical use case. Also consider the class
documentation for Attributor, AbstractState, and AbstractAttribute.
Reviewers: chandlerc, homerdin, hfinkel, fedor.sergeev, sanjoy, spatel, nlopes, nicholas, reames
Subscribers: mehdi_amini, mgorny, hiraditya, bollu, steven_wu, dexonsmith, dang, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59918
llvm-svn: 362578
Pankaj Gode