This adds a function `statically_known_true` for `SymBool` that works
like inductor's `is_expr_static_and_true`. That is, it tries to simplify the
expression to a constant or returns `False` if it cannot be simplified.
This is useful in cases that can be optimized if the condition is met,
otherwise it doesn't effect correctness so we can avoid adding guards.
I also use this new function in inductor for `FakeTensorUpdater` and
`remove_noop_pass` which both generated unexpected guards previously.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/117359
Approved by: https://github.com/lezcano
Summary:
Fixes https://github.com/pytorch/pytorch/issues/117033
Sometimes the solution returned by `sympy.solvers.inequalities.reduce_inequalities` can contain sub-expressions of the form `CRootOf(...)`, denoting the complex root of some equation in `x`, where `x` is an arbitrary symbol. We will now gracefully fail when this happens, like we already do when the solver itself fails.
Test Plan: added a test
Differential Revision: D52715578
Pull Request resolved: https://github.com/pytorch/pytorch/pull/117310
Approved by: https://github.com/ezyang
Fixes#114310 and supersedes #114748.
There are two reasons why we have quite a few special cases for `round`:
1. `round` is actually two ops. With `ndigits=None` (default), `round` always returns an integer. When `ndigits` is an integer, the returned type is a float.
2. Although `round` takes two arguments, it is a unary function with a parameter rather than a binary one.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/115259
Approved by: https://github.com/peterbell10, https://github.com/lezcano
Summary:
The primary problem we are setting out to solve here is fake tensor freshness. Before this PR, fake tensors after dynamo represented fake tensors *at the end* of trace, so subsequent retraces like aot_autograd would start off with fake tensors in the wrong (end result) state, rather than their expected fresh state. The solution here is to start a fresh fake mode, and re-fakify the tensors. The nuance comes from ensuring that symbols are uniformly created for the symbolic sizes and strides of the tensor.
This PR is the result of *a lot* of back and forth with ezyang and eellison. Initially, the first pass at this was not super different from what we have in the PR - the broad strokes were the same:
1) We cache source->symbol in shape_env
2) We pass policy objects around, stored at dynamo fakificaiton time, and reused for later fakification
3) We create a new fake mode for backends
(from https://github.com/pytorch/pytorch/pull/113605/files)
This is ugly, and has some layering violations. We detoured our decision making through a few other alternatives. Immutable/mutable fake tensor mode was the most interesting alternative, https://github.com/pytorch/pytorch/pull/113653, and was struck down on concerns of complexity in fake mode combined with it not covering all edge cases. We also detoured on what to do about tensor memoization returning back potentially different tensors than requested, and if that was an anti pattern (it is) we want to hack in with the symbol cache (we don't).
We went back to the drawing board here, but with a few concessions:
1) the cache for source->symbol must live outside of shape_env, for both lifecycle, and layering reasons
2) A good amount of work needs to be done to pipe policy around fake_mode and meta_utils correctly, to cover all the cases (ezyang did this)
cc penguinwu EikanWang jgong5 Guobing-Chen XiaobingSuper zhuhaozhe blzheng wenzhe-nrv jiayisunx chenyang78 aakhundov kadeng
imported-using-ghimport
Test Plan: Imported from OSS
Reviewed By: huydhn, Chillee
Differential Revision: D51566250
Pulled By: voznesenskym
Pull Request resolved: https://github.com/pytorch/pytorch/pull/114526
Approved by: https://github.com/Chillee, https://github.com/huydhn
The primary problem we are setting out to solve here is fake tensor freshness. Before this PR, fake tensors after dynamo represented fake tensors *at the end* of trace, so subsequent retraces like aot_autograd would start off with fake tensors in the wrong (end result) state, rather than their expected fresh state. The solution here is to start a fresh fake mode, and re-fakify the tensors. The nuance comes from ensuring that symbols are uniformly created for the symbolic sizes and strides of the tensor.
This PR is the result of *a lot* of back and forth with @ezyang and @eellison. Initially, the first pass at this was not super different from what we have in the PR - the broad strokes were the same:
1) We cache source->symbol in shape_env
2) We pass policy objects around, stored at dynamo fakificaiton time, and reused for later fakification
3) We create a new fake mode for backends
(from https://github.com/pytorch/pytorch/pull/113605/files)
This is ugly, and has some layering violations. We detoured our decision making through a few other alternatives. Immutable/mutable fake tensor mode was the most interesting alternative, https://github.com/pytorch/pytorch/pull/113653, and was struck down on concerns of complexity in fake mode combined with it not covering all edge cases. We also detoured on what to do about tensor memoization returning back potentially different tensors than requested, and if that was an anti pattern (it is) we want to hack in with the symbol cache (we don't).
We went back to the drawing board here, but with a few concessions:
1) the cache for source->symbol must live outside of shape_env, for both lifecycle, and layering reasons
2) A good amount of work needs to be done to pipe policy around fake_mode and meta_utils correctly, to cover all the cases (@ezyang did this)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/113926
Approved by: https://github.com/ezyang, https://github.com/eellison
Fixes https://github.com/pytorch/pytorch/issues/113393
Another chapter in the story of Python's horrible handling of int <-> bool interactions.
```python
print(True and 1) # 1
print(1 and True) # True
print(True or 1) # True
print(1 or True) # 1
```
For sanity's sake, since we have defined more sane type promotion rules, let's use those and ensure `out_hint` conforms to `SymNode`'s `pytype`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/113848
Approved by: https://github.com/ezyang
This PR fixes two cases when fx generated code is invalid in python (syntax error):
1. multiple type annotation in one line: `var1: annotation1, var2: annotation2 = function_call()`
2. invalid type annotation for scalars like `var1: f32[] = function_call()`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/113345
Approved by: https://github.com/ezyang
In https://github.com/pytorch/pytorch/pull/112156 I added support for creating replacements on unbacked SymInts, so if you asserted that `i0 == s0`, we would replace i0 with s0 (only ever replacing unbacked with backed.)
However, if we have assertions involving only unbacked SymInts, we can also replace in this case! E.g., `i0 == i1` or `i0 == i1 * 12`. The previous logic for generating replacements would reject these cases, because you're not allowed to replace unbacked with unbacked. Modifying the logic is not so easy though; ordinarily, we decide what substitution to prioritize by trying to replace the largest hinted symbol, but for unbacked integers we don't have this. To get around this problem, for now I only setup replacements for trivial symbol equals something else situations. Check the diff with whitespace ignored, the addition is quite small.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112653
Approved by: https://github.com/aakhundov
This PR:
- Moves TrueDiv, LShift, RShift, IsNonOverlappingAndDenseIndicator to `_sympy.functions.py`
- Moves SymNode to `fx.experimental.sym_node`.
- This file does not have any SymPy dependencies at import time
- It installs the magic methods in Sym{Bool,Int,Float}.
- N.b. With this split, we may be able to move Sym{Bool,Int,Float} to this file, and remove quite a few of the hacks around these classes
- Imports `sym_node` in `torch/__init__.py` rather than the whole `symbolic_shapes.py`.
This breaks the import-time dependency between torch and SymPy
Pull Request resolved: https://github.com/pytorch/pytorch/pull/112037
Approved by: https://github.com/peterbell10
ghstack dependencies: #112035, #112036
This PR supports sym_ite. This is useful for converting SymBool to SymInt in e.g. #109916. Internally, it uses sympy.Piecewise. We cannot use sympy.ITE because it expects the arguments and output all to be boolean type but we want return SymInt type when converting a SymBool to SymInt. So we use sympy.Piecewise to denote the symbolic relationship.
Note that this pr uses the range analysis for sympy.Piecewise implemented in https://github.com/pytorch/pytorch/blob/main/torch/utils/_sympy/value_ranges.py.
Test Plan:
See added test.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/111440
Approved by: https://github.com/ezyang
In this PR:
- Adds support for strides for jagged tensor (design doc for this coming soon)
- NestedTensor skips automatic dynamic
- Make use of @bdhirsh's subclass fakification logic by adding the __tensor_{un,}flatten__ functions.
- Additional logic for fakification: since existing subclass fakification logic does not handle the case where the outer tensor has an additional dimension. We insert one-off logic to (1) insert an extra SingletonSymInt onto the fakified NestedTensor. (2) make sure we call track_symint on both the sizes on the inner and outer tensor during guard creation.
Remaining things that are weird:
- Still need to skip some logic in meta utils for some reason (I was going to write this up more, but decided not to since we're not able to do this anyway for a immediate reason: we cannot arbitrarily compare singleton ints. For now I'm just following Brian's advise from [here](https://github.com/pytorch/pytorch/pull/109171#discussion_r1328137070) )
Pull Request resolved: https://github.com/pytorch/pytorch/pull/109171
Approved by: https://github.com/ezyang, https://github.com/bdhirsh
We want to be able to use SingletonSymNode to represent strides for Jagged layout tensor. The following is for 3D, but easily generalizable to higher dimensions.
Constraints:
- [B, x, D] (where x represents the "variably lengthed dim") can be strided in two ways [x, 1, sum(x)] and [dx, d, 1]. We need two different placeholder values depending on how the jagged tensor is strided.
- When doing operations we need the strides of output tensors to be expressable in terms of the strides and sizes of the inner tensors. Given [B, x, D] @ [D, D'], the output strides is [x * D', D', 1] rather than some opaque [x2, D', 1]. This constraint exists because if I'm tracing, I need a symint to represent the output stride. This symint needs to come from somewhere; I get it in several ways: (1) create a constant, (2) unbacked symint, (3) create a new input using a source, (4) output of an operation on an existing symint. It is clear that (4) is what we want here, which brings us to the design below.
Design:
Given the two constraints, the most straightforward way to implement this is actually to update SingletonSymNode to include some scalar factor, i.e. Morally, SingletonSymNode represents `factor * [s_0, s_1, …, s_n]` This enables us to symbolically compute strides from sizes.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110369
Approved by: https://github.com/ezyang
ghstack dependencies: #110044
Previously, something like j0 >= 3, would return False. In sympy however, it is not possible to make it so that both j0 >= 3 and j0 < 3 return False. In sympy, you only get to dispatch on Ge, and the remaining are derived, e.g. defining Ge(j0 >= 3) to be False would force Lt(j0, 3) to be True, which is not what we want.
In this PR, we make it so that both j0 >=3 and j0 < 3 error, so that in a future PR when we create the symbolic counterpart of this singleton, the behaviors can be the same.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110044
Approved by: https://github.com/ezyang
Our experience using `constraints` / `dynamic_dim` with the existing export API has found it to be (subjectively) clunky and (objectively) verbose in common cases.
This PR implements a new design for the export API that replaces the use of `constraints` / `dynamic_dim` with a new way of specifying dynamic shapes, involving the following concepts:
* a constructor `Dim` for first-class named dynamic dimensions with ranges (similar to `functorch.dim`, and analogous to internal symbolic sizes)
* a mechanism that uses the above in `export` calls to associate inputs to their dynamic shape specifications (`dynamic_shapes`)
Design doc: https://docs.google.com/presentation/d/168U7XK72C_WSsZpGESP6Cho9udh193fi0gfjxCNcJ4E/edit#slide=id.p (Meta-only). Note that we only implement Option 1 in that doc. An older version of this PR also implemented Option 3, which is an alternative way of specifying dynamic shapes using tensor type annotations on the exported callable; but we have moved that to future work for now.
See docs for these new features in `torch.export`. The existing `torch.export.export` is modified to use the new API, `torch._export.export__RC__`, whenever `constraints=None`. We have not deprecated the existing API yet, but will do in a follow-up.
Constraint violation errors arising through use of the new API will now contain suggested fixes using the new API. No longer do we need to report all specializations for static dimensions and suggest all constraints over dynamic dimensions to fix such errors. Instead, due to the redesign, the suggested fixes are much more concise, only involving modifying the definitions of relevant `Dim`s.
Differential Revision: [D48919204](https://our.internmc.facebook.com/intern/diff/D48919204/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108448
Approved by: https://github.com/suo, https://github.com/gmagogsfm
Bugfix:
- previously, SymBool does not implement `__eq__`, Python falls back to default `__eq__ `and `__hash__`
- in this PR, we make SymBool implement `__eq__`
- symbolic SymBool now raises an error when hashed just like SymInt/SymFloat
New feature:
- previously, SymInt and SymFloat are unhashable (even if you are singleton or constant)
- in this PR, SymInt and SymBool are hashable if singleton/constant
Stay the same:
- SymNode are hashable due to default Python behavior
Pull Request resolved: https://github.com/pytorch/pytorch/pull/109170
Approved by: https://github.com/ezyang
ghstack dependencies: #109169
In this PR:
- When Constant SymNode are detected in unary/binary ops demote them to plain int/bool before proceeding. Sometimes this means doing a unary op with a Constant SymNode would result in a plain bool.
- Introduce an is_symbolic method, only available from Python. We need this because isinstance(x, SymInt) is no longer sufficient to check whether a given int/SymInt is symbolic or not. See later PR in the stack to see how this is used.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/109169
Approved by: https://github.com/ezyang
This PR stops `SymNode` from mutating (i.e. simplifying) its expression. Instead, the
simplification (without mutation) is deferred to the `SymNode.maybe_as_int` method.
```python
- FakeTensor(size=(s0,), ...)
- FakeTensor(size=(s1, s2, s3), ...)
- Eq(s0, s1 + s2 + s3)
- FakeTensor(size=(s0,), ...)
- FakeTensor(size=(s1, s2, s3), ...)
```
In summary, this PR:
- Replaces `SymNode._expr` by `SymNode.expr`, removing the old property function
- This makes it so `SymNode` instances never update their expression
- Creates `SymNode.simplified_expr()` method for actually calling `ShapeEnv.replace` on
its expression. Note that this doesn't updates `SymNode.expr`
- Changes how `tensor.size()` gets converted to its Python `torch.Size` type
- Instead of calling `SymInt::maybe_as_int()` method, we create a new
`SymInt::is_symbolic()` method for checking whether it is actually a symbolic value
- This is needed so that when we call `tensor.size()` in the Python side, the returned
sequence is faithful to the actual data, instead of possibly simplifying it and
returning an integer
- 2 files needs this modification:
- _torch/csrc/Size.cpp_: for handling `torch.Tensor.size` Python calls
- _torch/csrc/utils/pybind.cpp_: for handling `symint.cast()` C++ calls
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107492
Approved by: https://github.com/ezyang
ghstack dependencies: #107523
Here's what it does from the comments:
```
Assume that a boolean is true for the purposes of subsequent symbolic
reasoning. This will keep track of corresponding runtime checks to verify
that the result is upheld: either as a regular guard, or as a special set
of asserts which are triggered when an unbacked SymInt is allocated.
DO NOT use this function for these cases:
- This is inappropriate for "branching" conditions (where both
true and false result in valid programs). We will always assume
the condition evaluates true, and so it will never be possible
to trace the false condition when you use it. For true branching
on unbacked SymInts, you must use torch.cond.
- This is inappropriate for situations where you know some other system
invariant guarantees that this property holds, since you don't
really need to insert a runtime check in that case. Use something
like constrain_range in that case.
This API has a hitch. To avoid having to reimplement error reporting
capabilities, this function CAN return False. The invariant is that
the surrounding code must raise an error when this function returns
False. This is quite low level, so we recommend using other functions
like check() which enforce this in a more intuitive way.
By the way, this name is a nod to the __builtin_expect likely macro,
which is used similarly (but unlike __builtin_expect, you MUST fail
in the unlikely branch.)
```
We don't do anything with this right now, except use it to discharge regular guards. Follow up PRs to (1) use it at important error checking sites, (2) actually ensure the runtime asserts make there way into the exported IR / inductor generated code.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106720
Approved by: https://github.com/ysiraichi, https://github.com/voznesenskym
Follow-up: #101173
This PR fixes the bug presented in #101173 by creating a special case for `sympy.Rational`
divisors, inside `FloorDiv` evaluation. In summary:
```python
FloorDiv(a, Rational(1, b))
a * b
```
Besides that, this PR also does 2 other things:
- Replaces the use of the old `sympy.Mod` by the internal `Mod` (there were a few places
that were still looking for the SymPy one)
- Introduces debugging logs to the translation validator. These can be seen by setting the
environment variable: `TORCH_LOGS=+torch.fx.experimental.validator`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106644
Approved by: https://github.com/ezyang
ghstack dependencies: #106643
Previously, x.size(0) could return a SymInt, even when the internal
sympy expression was actually already constant (e.g., due to an
introduced guard.) We now allow to query the Python object with
maybe_as_int which allows us to transmute these objects back to
int when possible.
It is still possible to end up with a constant SymInt even after this
change, e.g., if you get out a SymInt and while holding onto it
specialize it, but casual users are more likely to get ints when they
want to.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/104828
Approved by: https://github.com/Skylion007
Previously, x.size(0) could return a SymInt, even when the internal
sympy expression was actually already constant (e.g., due to an
introduced guard.) We now allow to query the Python object with
maybe_as_int which allows us to transmute these objects back to
int when possible.
It is still possible to end up with a constant SymInt even after this
change, e.g., if you get out a SymInt and while holding onto it
specialize it, but casual users are more likely to get ints when they
want to.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/104828
Approved by: https://github.com/Skylion007
Previously, x.size(0) could return a SymInt, even when the internal
sympy expression was actually already constant (e.g., due to an
introduced guard.) We now allow to query the Python object with
maybe_as_int which allows us to transmute these objects back to
int when possible.
It is still possible to end up with a constant SymInt even after this
change, e.g., if you get out a SymInt and while holding onto it
specialize it, but casual users are more likely to get ints when they
want to.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/104828
Approved by: https://github.com/Skylion007
We do not raise constraint violations for complex binary conditions, such as conditions involving `%`. Moreover, while these constraints are discovered by our solver, the solver does not inject new constraint violations. This can result in cases where export passes, appropriate assertions are not added, and we get runtime crashes.
Now, when the solver discovers constraints that are too complex, we force-specialize the involved dimensions and raise a constraint violation when such dimensions are marked dynamic. This forces the user to remove the dynamic marking, and causes the appropriate specialization assertions to be added.
Differential Revision: [D46415786](https://our.internmc.facebook.com/intern/diff/D46415786/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/102897
Approved by: https://github.com/tugsbayasgalan
