Convert "denormal-fp-math" and "denormal-fp-math-f32" into a first
class denormal_fpenv attribute. Previously the query for the effective
denormal mode involved two string attribute queries with parsing. I'm
introducing more uses of this, so it makes sense to convert this
to a more efficient encoding. The old representation was also awkward
since it was split across two separate attributes. The new encoding
just stores the default and float modes as bitfields, largely avoiding
the need to consider if the other mode is set.
The syntax in the common cases looks like this:
`denormal_fpenv(preservesign,preservesign)`
`denormal_fpenv(float: preservesign,preservesign)`
`denormal_fpenv(dynamic,dynamic float: preservesign,preservesign)`
I wasn't sure about reusing the float type name instead of adding a
new keyword. It's parsed as a type but only accepts float. I'm also
debating switching the name to subnormal to match the current
preferred IEEE terminology (also used by nofpclass and other
contexts).
This has a behavior change when using the command flag debug
options to set the denormal mode. The behavior of the flag
ignored functions with an explicit attribute set, per
the default and f32 version. Now that these are one attribute,
the flag logic can't distinguish which of the two components
were explicitly set on the function. Only one test appeared to
rely on this behavior, so I just avoided using the flags in it.
This also does not perform all the code cleanups this enables.
In particular the attributor handling could be cleaned up.
I also guessed at how to support this in MLIR. I followed
MemoryEffects as a reference; it appears bitfields are expanded
into arguments to attributes, so the representation there is
a bit uglier with the 2 2-element fields flattened into 4 arguments.
Corrected various spelling mistakes such as 'occurred', 'receiver',
'initialized', 'length', and others in comments, variable names,
function names, and documentation throughout the project. These
changes improve code readability and maintain consistency in naming
and documentation.
Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
This enables assumes to work. Somehow the most obvious example
I could think of does not work (return of assumed argument).
The context instruction for the return seems to be off by one.
This change adds full support for the ptx `barrier.cta.red` instruction,
following the same conventions as are already used for
`barrier.cta.sync` and `barrier.cta.arrive`.
In addition this MR removes the following intrinsics which are no longer
needed:
* llvm.nvvm.barrier0.popc -->
llvm.nvvm.barrier.cta.red.popc.aligned.all(0, c)
* llvm.nvvm.barrier0.and -->
llvm.nvvm.barrier.cta.red.and.aligned.all(0, z)
* llvm.nvvm.barrier0.or -->
llvm.nvvm.barrier.cta.red.or.aligned.all(0, z)
Calculating alignment for `make.buffer.rsrc` intrinsic. The logic is the
alignment on use of return value of `make.buffer.rsrc` should be capped
by the base operand's alignment of `make.buffer.rsrc`.
For example:
```ll
define float @foo(ptr addrspace(1) align X %ptr) {
%fat.ptr = call ptr addrspace(7) @llvm.amdgcn.make.buffer.rsrc.p7.p1(ptr addrspace(1) %ptr, i16 0, i32 C, i32 0)
%y = load float, ptr addrspace(7) %fat.ptr, align Y
ret float %y
}
```
We hopes that `Y = min(X, Y)`
---
After discussion, it seems improper for letting `Y = min(X, Y)` since it
contradict with the semantic of align on load.
So we would apply the origin behavior of align, which is letting `X` and
`Y` both equal to `max(X, Y)`
---------
Co-authored-by: Shilei Tian <i@tianshilei.me>
The attributor can infer the alignment of %p at the call-site in this
example [1]:
```
define void @f(ptr align 8 %p, i1 %c1, i1 %c2) {
entry:
br i1 %c1, label %bb.1, label %exit
bb.1:
call void (...) @llvm.fake.use(ptr %p)
br label %exit
exit:
ret void
}
```
but not when there's an additional conditional branch:
```
define void @f(ptr align 8 %p, i1 %c1, i1 %c2) {
entry:
br i1 %c1, label %bb.1, label %exit
bb.1:
br i1 %c2, label %bb.2, label %exit
bb.2:
call void (...) @llvm.fake.use(ptr %p)
br label %exit
exit:
ret void
}
```
unless `-attributor-annotate-decl-cs` is enabled. This patch extends
`followUsesInMBEC` to handle such recursive branches.
n.b. admittedly I wrote this patch before discovering inferring the
alignment in this example is already possible with
`-attributor-annotate-decl-cs`, I came to realise this once writing the
tests, but this seems like a gap regardless looking at existing FIXMEs,
plus the alignment can now be inferred in this particular example
without the flag.
[1] https://godbolt.org/z/aKoc75so5
Propagate alignment through ptrmask based on potential constant values
of mask and align of ptr.
---------
Co-authored-by: Shilei Tian <i@tianshilei.me>
Goal is simply to reduce direct usage of getLength and setLength so that
if we end up moving memset.pattern (whose length is in elements) there
are fewer places to audit.
std::make_optional<T> is a lot like std::make_unique<T> in that it
performs perfect forwarding of arguments for T's constructor. As a
result, we don't have to repeat type names twice.
Patched and tested the `AAInvariantLoadPointer` attributor from #141800,
which identifies pointers whose loads are eligible to be marked as
`!invariant.load`.
The bug in the attributor was due to `AAMemoryBehavior` always
identifying pointers obtained from `alloca`s as having no writes. I'm
not entirely sure why `AAMemoryBehavior` behaves this way, but it seems
to be beceause it identifies the scope of an `alloca` to be limited to
only that instruction (and, certainly, no memory writes occur within the
`alloca` instructin). This patch just adds a check to disallow all loads
from `alloca` pointers from being marked `!invariant.load` (since any
well-defined program will have to write to stack pointers at some
point).
Reverts llvm/llvm-project#141800
The implementation critically misunderstands the `AAMemoryBehavior`
attributor, which it relies on heavily.
@shiltian, since I do not have commit permissions.
The attributor conservatively marks pointers whose loads are eligible to
be marked as `!invariant.load`.
It does so by identifying:
1. Pointers marked `noalias` and `readonly`
2. Pointers whose underlying objects are all eligible for invariant
loads.
The attributor then manifests this attribute at non-atomic non-volatile
load instructions.
Note: This relands #140615 adding a ".count" suffix to the non-".all"
variants.
Our current intrinsic support for barrier intrinsics is confusing and
incomplete, with multiple intrinsics mapping to the same instruction and
intrinsic names not clearly conveying intrinsic semantics. Further, we
lack support for some variants. This change unifies the IR
representation to a single consistently named set of intrinsics.
- llvm.nvvm.barrier.cta.sync.aligned.all(i32)
- llvm.nvvm.barrier.cta.sync.aligned.count(i32, i32)
- llvm.nvvm.barrier.cta.arrive.aligned.count(i32, i32)
- llvm.nvvm.barrier.cta.sync.all(i32)
- llvm.nvvm.barrier.cta.sync.count(i32, i32)
- llvm.nvvm.barrier.cta.arrive.count(i32, i32)
The following Auto-Upgrade rules are used to maintain compatibility with
IR using the legacy intrinsics:
* llvm.nvvm.barrier0 --> llvm.nvvm.barrier.cta.sync.aligned.all(0)
* llvm.nvvm.barrier.n --> llvm.nvvm.barrier.cta.sync.aligned.all(x)
* llvm.nvvm.bar.sync --> llvm.nvvm.barrier.cta.sync.aligned.all(x)
* llvm.nvvm.barrier --> llvm.nvvm.barrier.cta.sync.aligned.count(x, y)
* llvm.nvvm.barrier.sync --> llvm.nvvm.barrier.cta.sync.all(x)
* llvm.nvvm.barrier.sync.cnt --> llvm.nvvm.barrier.cta.sync.count(x, y)
Our current intrinsic support for barrier intrinsics is confusing and
incomplete, with multiple intrinsics mapping to the same instruction and
intrinsic names not clearly conveying intrinsic semantics. Further, we
lack support for some variants. This change unifies the IR
representation to a single consistently named set of intrinsics.
- llvm.nvvm.barrier.cta.sync.aligned.all(i32)
- llvm.nvvm.barrier.cta.sync.aligned(i32, i32)
- llvm.nvvm.barrier.cta.arrive.aligned(i32, i32)
- llvm.nvvm.barrier.cta.sync.all(i32)
- llvm.nvvm.barrier.cta.sync(i32, i32)
- llvm.nvvm.barrier.cta.arrive(i32, i32)
The following Auto-Upgrade rules are used to maintain compatibility with
IR using the legacy intrinsics:
* llvm.nvvm.barrier0 --> llvm.nvvm.barrier.cta.sync.aligned.all(0)
* llvm.nvvm.barrier.n --> llvm.nvvm.barrier.cta.sync.aligned.all(x)
* llvm.nvvm.bar.sync --> llvm.nvvm.barrier.cta.sync.aligned.all(x)
* llvm.nvvm.barrier --> llvm.nvvm.barrier.cta.sync.aligned(x, y)
* llvm.nvvm.barrier.sync --> llvm.nvvm.barrier.cta.sync.all(x)
* llvm.nvvm.barrier.sync.cnt --> llvm.nvvm.barrier.cta.sync(x, y)
Remove the special case where comparing a dereferenceable_or_null
pointer with null results in captures(none) instead of
captures(address_is_null).
This special case is not entirely correct. Let's say we have an
allocated object of size 2 at address 1 and have a pointer `%p` pointing
either to address 1 or 2. Then passing `gep p, -1` to a
`dereferenceable_or_null(1)` function is well-defined, and allows us to
distinguish between the two possible pointers, capturing information
about the address.
Now that we ignore address captures in alias analysis, I think we're
ready to drop this special case. Additionally, if there are regressions
in other places, the fact that this is inferred as address_is_null
should allow us to easily address them if necessary.
These should not really have uselists, and it's not worth the compile
time of looking at all uses of trivial constants. The main observable
change of this is it no longer adds align attributes on constant null
uses, but those are not useful. Some of these cases should potentially
be more aggressive and not look at any Constant users.
DenseSet, SmallPtrSet, SmallSet, SetVector, and StringSet recently
gained C++23-style insert_range. This patch replaces:
Dest.insert(Src.begin(), Src.end());
with:
Dest.insert_range(Src);
This patch does not touch custom begin like succ_begin for now.
Relative to the previous attempt this includes two fixes:
* Adjust callCapturesBefore() to not skip captures(ret: address,
provenance) arguments, as these will not count as a capture
at the call-site.
* When visiting uses during stack slot optimization, don't skip
the ModRef check for passthru captures. Calls can both modref
and be passthru for captures.
------
This extends CaptureTracking to support inferring non-trivial
CaptureInfos. The focus of this patch is to only support FunctionAttrs,
other users of CaptureTracking will be updated in followups.
The key API changes here are:
* DetermineUseCaptureKind() now returns a UseCaptureInfo where the UseCC
component specifies what is captured at that Use and the ResultCC
component specifies what may be captured via the return value of the
User. Usually only one or the other will be used (corresponding to
previous MAY_CAPTURE or PASSTHROUGH results), but both may be set for
call captures.
* The CaptureTracking::captures() extension point is passed this
UseCaptureInfo as well and then can decide what to do with it by
returning an Action, which is one of: Stop: stop traversal.
ContinueIgnoringReturn: continue traversal but don't follow the
instruction return value. Continue: continue traversal and follow the
instruction return value if it has additional CaptureComponents.
For now, this patch retains the (unsound) special logic for comparison
of null with a dereferenceable pointer. I'd like to switch key code to
take advantage of address/address_is_null before dropping it.
This PR mainly intends to introduce necessary API changes and basic
inference support, there are various possible improvements marked with
TODOs.
Relative to the previous attempt, this adjusts isEscapeSource()
to not treat calls with captures(ret: address, provenance) or similar
arguments as escape sources. This addresses the miscompile reported at:
https://github.com/llvm/llvm-project/pull/125880#issuecomment-2656632577
The implementation uses a helper function on CallBase to make this
check a bit more efficient (e.g. by skipping the byval checks) as
checking attributes on all arguments if fairly expensive.
------
This extends CaptureTracking to support inferring non-trivial
CaptureInfos. The focus of this patch is to only support FunctionAttrs,
other users of CaptureTracking will be updated in followups.
The key API changes here are:
* DetermineUseCaptureKind() now returns a UseCaptureInfo where the UseCC
component specifies what is captured at that Use and the ResultCC
component specifies what may be captured via the return value of the
User. Usually only one or the other will be used (corresponding to
previous MAY_CAPTURE or PASSTHROUGH results), but both may be set for
call captures.
* The CaptureTracking::captures() extension point is passed this
UseCaptureInfo as well and then can decide what to do with it by
returning an Action, which is one of: Stop: stop traversal.
ContinueIgnoringReturn: continue traversal but don't follow the
instruction return value. Continue: continue traversal and follow the
instruction return value if it has additional CaptureComponents.
For now, this patch retains the (unsound) special logic for comparison
of null with a dereferenceable pointer. I'd like to switch key code to
take advantage of address/address_is_null before dropping it.
This PR mainly intends to introduce necessary API changes and basic
inference support, there are various possible improvements marked with
TODOs.
This extends CaptureTracking to support inferring non-trivial
CaptureInfos. The focus of this patch is to only support FunctionAttrs,
other users of CaptureTracking will be updated in followups.
The key API changes here are:
* DetermineUseCaptureKind() now returns a UseCaptureInfo where the UseCC
component specifies what is captured at that Use and the ResultCC
component specifies what may be captured via the return value of the
User. Usually only one or the other will be used (corresponding to
previous MAY_CAPTURE or PASSTHROUGH results), but both may be set for
call captures.
* The CaptureTracking::captures() extension point is passed this
UseCaptureInfo as well and then can decide what to do with it by
returning an Action, which is one of: Stop: stop traversal.
ContinueIgnoringReturn: continue traversal but don't follow the
instruction return value. Continue: continue traversal and follow the
instruction return value if it has additional CaptureComponents.
For now, this patch retains the (unsound) special logic for comparison
of null with a dereferenceable pointer. I'd like to switch key code to
take advantage of address/address_is_null before dropping it.
This PR mainly intends to introduce necessary API changes and basic
inference support, there are various possible improvements marked with
TODOs.
This PR removes the old `nocapture` attribute, replacing it with the new
`captures` attribute introduced in #116990. This change is
intended to be essentially NFC, replacing existing uses of `nocapture`
with `captures(none)` without adding any new analysis capabilities.
Making use of non-`none` values is left for a followup.
Some notes:
* `nocapture` will be upgraded to `captures(none)` by the bitcode
reader.
* `nocapture` will also be upgraded by the textual IR reader. This is to
make it easier to use old IR files and somewhat reduce the test churn in
this PR.
* Helper APIs like `doesNotCapture()` will check for `captures(none)`.
* MLIR import will convert `captures(none)` into an `llvm.nocapture`
attribute. The representation in the LLVM IR dialect should be updated
separately.
As part of the "RemoveDIs" project, BasicBlock::iterator now carries a
debug-info bit that's needed when getFirstNonPHI and similar feed into
instruction insertion positions. Call-sites where that's necessary were
updated a year ago; but to ensure some type safety however, we'd like to
have all calls to moveBefore use iterators.
This patch adds a (guaranteed dereferenceable) iterator-taking
moveBefore, and changes a bunch of call-sites where it's obviously safe
to change to use it by just calling getIterator() on an instruction
pointer. A follow-up patch will contain less-obviously-safe changes.
We'll eventually deprecate and remove the instruction-pointer
insertBefore, but not before adding concise documentation of what
considerations are needed (very few).
