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
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.
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 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:
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:
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
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:
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
Summary:
To be able to track how many iterations we need to manifest all
information we check for we now make the maximum iteration count
explicit. The count is set tightly now and should be kept that way.
Reviewers: uenoku, sstefan1
Subscribers: bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66554
llvm-svn: 369586
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:
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
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
For consistency with normal instructions and clarity when reading IR,
it's best to print the %0, %1, ... names of function arguments in
definitions.
Also modifies the parser to accept IR in that form for obvious reasons.
llvm-svn: 367755
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
Hideto Ueno