Summary:
**wins**
on torchrec benchmark, for 2K nodes it save 40seconds
with the recent sympy changes (https://www.internalfb.com/diff/D65883538) we save around 13 second ( with the max opt on).
```
buck2 run fbcode//mode/opt fbcode//torchrec/distributed/tests:pt2_compile_benchmark -- --num-features=200
```
This diff optimizes construction expressions of the form
a+b+c... (all unique symbols).
which are very common in torchrec models.
**How**
Expressions of the form a+b+c are not optimized by add, the only needed optimization is sorting them.
If we have a+b+c and we are adding (d) to it, we can do a binary search to know
the position of (d) and avoid optimizing the new expression by passing the new order.
**Extensions**:
1. support constant terms.
2. support 10a+10b+.. (this will give even more wins will extend the support in second PR)
Differential Revision: D66008482
Pull Request resolved: https://github.com/pytorch/pytorch/pull/140822
Approved by: https://github.com/ezyang
Summary:
There's 2 concepts of unsupported sympy.Functions in symbolic_shapes:
1) unsupported by the export solver, meaning the solver doesn't know how to provide useful fixes for those functions
2) unsupported by the sympy interpreter - meaning we can't reify them into FX nodes because the functions aren't present in PythonReferenceAnalysis
This splits the current call into a call for each version, with the Export solver the only user of 1). For 1), we enumerate the functions in _sympy/functions.py, and subtract the functions we know we can support. For 2) there's only 3 functions we've seen pop up in test cases.
cc jgong5 mingfeima XiaobingSuper sanchitintel ashokei jingxu10
Differential Revision: D61863394
Pulled By: pianpwk
Pull Request resolved: https://github.com/pytorch/pytorch/pull/134598
Approved by: https://github.com/angelayi
There's 2 concepts of unsupported sympy.Functions in symbolic_shapes:
1) unsupported by the export solver, meaning the solver doesn't know how to provide useful fixes for those functions
2) unsupported by the sympy interpreter - meaning we can't reify them into FX nodes because the functions aren't present in PythonReferenceAnalysis
This splits the current call into a call for each version, with the Export solver the only user of 1). For 1), we enumerate the functions in _sympy/functions.py, and subtract the functions we know we can support. For 2) there's only 3 functions we've seen pop up in test cases.
Differential Revision: D61677956
Pull Request resolved: https://github.com/pytorch/pytorch/pull/134271
Approved by: https://github.com/avikchaudhuri
Summary: Fixes https://github.com/pytorch/pytorch/issues/134133
Test Plan:
Tested on the small repro in the linked issue with different lengths N (replacing 100), recording N vs. time taken in nanoseconds:
10 127268319
20 220839662
30 325463125
40 429259441
50 553136055
60 670799769
70 999170514
80 899014103
90 997168902
100 1168202035
110 1388556619
120 1457488235
130 1609816470
140 2177889877
150 1917560313
160 2121096113
170 2428502334
180 4117450755
190 4003068224
So N ~ 200 takes ~5s. Previously even smaller N would go for >1 min.
Didn't add a perf test because ezyang is planning to build a benchmark.
Also tested on https://www.internalfb.com/diff/D61560171, which now gets past the stuck point.
Differential Revision: D61619660
Pull Request resolved: https://github.com/pytorch/pytorch/pull/134150
Approved by: https://github.com/ezyang
Sympy's implementation of Min/Max displays asymptotically bad behavior on `TORCH_COMPILE_CPROFILE=1 python torchrec/distributed/tests/test_pt2_multiprocess.py TestPt2Train.test_compile_multiprocess`. Evidence profile:
On this test case, we spend 42% of all time compiling the network on ShapeEnv.replace, which in turn spends all of its time in xreplace.
The problem appears to be find_localzeros call. By vendoring the implementations of Min/Max, we can potentially reduce the cost of this operation.
The implementation is copy-pasted sympy/functions/elementary/miscellaneous.py but with some adjustments:
* I deleted logic related to differentatiation, evalf and heaviside, as it's not relevant to PyTorch reasoning
* There's some massaging to appease PyTorch's linters, including a lot of noqa and type: ignore (which I could potentially refactor away with substantive changes, but that's better as its own change)
* I deleted the second loop iteration for is_connected, as an attempt at initial optimization (this also simplifies the port, since I can omit some code). I'll comment at that point what the exact difference is.
Before this change, the test in question takes 100s with 40 features; post this change, afterwards, it takes only 69s.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/133319
Approved by: https://github.com/Skylion007
------
The opposite of #130836. Pin `sympy >= 1.13.0` for Python >= 3.9 and `sympy == 1.12.1` for Python 3.8.
- #130836
See the PR description of #130836 for more details.
`sympy` 1.13.0 introduces some breaking changes which break our tests. More specifically:
- Ref [Backwards compatibility breaks and deprecations](https://github.com/sympy/sympy/wiki/release-notes-for-1.13.0#backwards-compatibility-breaks-and-deprecations)
> BREAKING CHANGE: Float and Integer/Rational no longer compare equal with a == b. From now on Float(2.0) != Integer(2). Previously expressions involving Float would compare unequal e.g. x*2.0 != x*2 but an individual Float would compare equal to an Integer. In SymPy 1.7 a Float will always compare unequal to an Integer even if they have the same "value". Use sympy.numbers.int_valued(number) to test if a number is a concrete number with no decimal part. ([#25614](https://github.com/sympy/sympy/pull/25614) by [@smichr](https://github.com/smichr))
`sympy >= 1.13.0` is required to enable Python 3.13 support. This should be part of #130689.
- #130689
Pull Request resolved: https://github.com/pytorch/pytorch/pull/130895
Approved by: https://github.com/ezyang
**Summary**
Inductor currently uses modulo and division to compute indices into certain multi-dimensional tensors, such as those arising from row padding. This PR matches on that indexing pattern, replacing it with an N-D block pointer. This should be more efficient than computing indices with division and modulo, and it can easily map to DMAs on non-GPU hardware targets.
Because the 1D block size needs to map to an integer block shape in ND, we need to know that the ND block size evenly divides the size of the iteration range. This PR only generates ND block pointers when it can guarantee that the iteration order and number of elements loaded are unchanged. This means that the number of elements in a slice of the iteration range must either be:
- Powers of 2. Since Triton block sizes are powers of 2, any integer power of 2 either divides the block size, or is greater than the block size. In the latter case, `CielDiv(x, y)` rounds up to 1.
- Multiples of the maximum block size. Since block sizes are powers of 2, the maximum block size is a multiple of every possible block size.
Note that a *slice* of the iteration range does not include the leading dimension. Thus we can support arbitrary leading dimensions like `(5,8)`.
Feature proposal and discussion: https://github.com/pytorch/pytorch/issues/125077
Example kernel:
```
triton.jit
def triton_(in_ptr0, out_ptr0, xnumel, XBLOCK : tl.constexpr):
xnumel = 4096
xoffset = tl.program_id(0) * XBLOCK
xindex = xoffset + tl.arange(0, XBLOCK)[:]
xmask = xindex < xnumel
tmp0 = tl.reshape(tl.load(tl.make_block_ptr(in_ptr0, shape=[32, 16, 8], strides=[1024, 32, 1], block_shape=[32 * (32 <= ((127 + XBLOCK) // 128)) + ((127 + XBLOCK) // 128) * (((127 + XBLOCK) // 128) < 32), 16 * (16 <= ((7 + XBLOCK) // 8)) + ((7 + XBLOCK) // 8) * (((7 + XBLOCK) // 8) < 16), 8 * (8 <= XBLOCK) + XBLOCK * (XBLOCK < 8)], order=[0, 1, 2], offsets=[(xoffset // 128), (xoffset // 8) % 16, xoffset % 8]), boundary_check=[0, 1, 2]), [XBLOCK])
tmp1 = tmp0 + tmp0
tl.store(tl.make_block_ptr(out_ptr0, shape=[4096], strides=[1], block_shape=[XBLOCK], order=[0], offsets=[xoffset]), tl.broadcast_to(tmp1, [XBLOCK]).to(tl.float32))
''', device_str='cuda')
```
**Test Plan**
This PR adds a new CI test script to cover this feature. The tests can be grouped into a few main categories:
- Can we generate strided block pointers for the appropriate shapes?
- Powers of 2
- Non-power of 2, but multiple of the maximum block size
- Arbitrary leading dimensions, with power of 2 inner dimensions
- Weird strides and offsets
- Reductions
- Symbolic shapes that are multiples of the maximum block size (wasn't able to trace this through dynamo)
- Broadcasts (some variables are missing from the indexing expression)
- Do we still compile other cases correctly, even if we don't expect to be able to generate block pointers?
- Unsupported static shapes
- Unsupported symbolic shapes
- Mixing and matching these cases:
- Pointwise and reduction in the same kernel
- Sanity check the test harness
- Do we raise an exception if the expected number of block pointers and the actual number are different?
**Follow-ups**
There are a few important cases which this PR can't handle. I'm hoping these can be deferred to follow-up PRs:
- Handle non-divisible shapes
- Change the tiling algorithm to generate a 2D (X,Y) blocking, if doing so enables block pointers to be emitted.
- Pad unsupported loads up to the nearest divisible size, then mask/slice out the extra elements? This is probably the best solution, but I'm not yet sure how to go about it in triton.
- Take advantage of this analysis when `triton.use_block_ptr=False`. I'm guessing we can still avoid `%` and `/` without requiring block pointers. Maybe we could compute block indices with arange and broadcast instead?
Differential Revision: D56739375
Pull Request resolved: https://github.com/pytorch/pytorch/pull/127342
Approved by: https://github.com/jansel, https://github.com/shunting314
In a previous life, we used sympy.oo to represent the lower/upper bounds of integer ranges. Later, we changed this to be sys.maxsize - 1 for a few reasons: (1) sometimes we do tests on a value being exactly sys.maxsize, and we wanted to avoid a data dependent guard in this case, (2) sympy.oo corresponds to floating point infinity, so you get incorrect types for value ranges with oo, and (3) you can do slightly better reasoning if you assume that input sizes fall within representable 64-bit integer range.
After working in the sys.maxsize regime for a bit, I've concluded that this was actually a bad idea. Specifically, the problem is that you end up with sys.maxsize in your upper bound, and then whenever you do any sort of size-increasing computation like size * 2, you end up with 2 * sys.maxsize, and you end up doing a ton of arbitrary precision int computation that is totally unnecessary. A symbolic bound is better.
But especially after #126905, we can't go back to using sympy.oo, because that advertises that it's not an integer, and now your ValueRanges is typed incorrectly. So what do we do? We define a new numeric constant `int_oo`, which is like `sympy.oo` but it advertises `is_integer`. **test/test_sympy_utils.py** describes some basic properties of the number, and **torch/utils/_sympy/numbers.py** has the actual implementation.
The rest of the changes of the PR are working out the implications of this change. I'll give more commentary as inline comments.
Fixes https://github.com/pytorch/pytorch/issues/127396
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/127693
Approved by: https://github.com/lezcano
ghstack dependencies: #126905
In a previous life, we used sympy.oo to represent the lower/upper bounds of integer ranges. Later, we changed this to be sys.maxsize - 1 for a few reasons: (1) sometimes we do tests on a value being exactly sys.maxsize, and we wanted to avoid a data dependent guard in this case, (2) sympy.oo corresponds to floating point infinity, so you get incorrect types for value ranges with oo, and (3) you can do slightly better reasoning if you assume that input sizes fall within representable 64-bit integer range.
After working in the sys.maxsize regime for a bit, I've concluded that this was actually a bad idea. Specifically, the problem is that you end up with sys.maxsize in your upper bound, and then whenever you do any sort of size-increasing computation like size * 2, you end up with 2 * sys.maxsize, and you end up doing a ton of arbitrary precision int computation that is totally unnecessary. A symbolic bound is better.
But especially after #126905, we can't go back to using sympy.oo, because that advertises that it's not an integer, and now your ValueRanges is typed incorrectly. So what do we do? We define a new numeric constant `int_oo`, which is like `sympy.oo` but it advertises `is_integer`. **test/test_sympy_utils.py** describes some basic properties of the number, and **torch/utils/_sympy/numbers.py** has the actual implementation.
The rest of the changes of the PR are working out the implications of this change. I'll give more commentary as inline comments.
Fixes https://github.com/pytorch/pytorch/issues/127396
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/127693
Approved by: https://github.com/lezcano
ghstack dependencies: #126905
At a high level, the idea behind this PR is:
* Make it clearer what the promotion and int/float rules for various Sympy operations are. Operators that previously were polymorphic over int/float are now split into separate operators for clarity. We never do mixed int/float addition/multiplication etc in sympy, instead, we always promote to the appropriate operator. (However, equality is currently not done correctly.)
* Enforce strict typing on ValueRanges: if you have a ValueRange for a float, the lower and upper MUST be floats, and so forth for integers.
The story begins in **torch/utils/_sympy/functions.py**. Here, I make some changes to how we represent certain operations in sympy expressions:
* FloorDiv now only supports integer inputs; to do float floor division, do a truediv and then a trunc. Additionally, we remove the divide out addition by gcd optimization, because sympy gcd is over fields and is willing to generate rationals (but rationals are bad for ValueRange strict typing).
* ModularIndexing, LShift, RShift now assert they are given integer inputs.
* Mod only supports integer inputs; eventually we will support FloatMod (left for later work, when we build out Sympy support for floating operations). Unfortunately, I couldn't assert integer inputs here, because of a bad interaction with sympy's inequality solver that is used by the offline solver
* TrueDiv is split into FloatTrueDiv and IntTrueDiv. This allows for us to eventually generate accurate code for Python semantics IntTrueDiv, which is written in a special way to preserve precision when the inputs are >= 2**53 beyond what first coercing the integer to floats and then doing true division.
* Trunc is split to TruncToFloat and TruncToInt.
* Round is updated to return a float, not an int, making it consistent with the round op handler in Inductor. To get Python-style conversion to int, we call TruncToInt on the result.
* RoundDecimal updated to consistently only ever return a float
* Add ToFloat for explicit coercion to float (required so we can enforce strict ValueRanges typing)
In **torch/__init__.py**, we modify SymInt and SymFloat to appropriately call into new bindings that route to these refined sympy operations. Also, we modify `torch.sym_min` and `torch.sym_max` to have promotion semantics (if one argument is a float, the return result is always a float), making them inconsistent with builtins.min/max, but possible to do type analysis without runtime information.
We also need to introduce some new op handlers in **torch/_inductor/ops_handler.py**:
* `to_int` for truncation to int64, directly corresponding to TruncToInt; this can be implemented by trunc and dtype, but with a dedicated handler it is more convenient for roundtripping in Sympy
* `int_truediv` for Python-style integer true division, which has higher precision than casting to floats and then running `truediv`
These changes have consequences. First, we need to make some administrative changes:
* Actually wire up these Sympy functions from SymInt/SymFloat in **torch/fx/experimental/sym_node.py**, including the new promotion rules (promote2)
* Add support for new Sympy functions in **torch/utils/_sympy/interp.py**, **torch/utils/_sympy/reference.py**
* In particular, in torch.utils._sympy.reference, we have a strong preference to NOT do nontrivial compute, instead, everything in ops handler should map to a singular sympy function
* TODO: I chose to roundtrip mod back to our Mod function, but I think I'm going to have to deal with the C/Python inconsistency this to fix tests here
* Add printer support for the Sympy functions in **torch/_inductor/codegen/common.py**, **torch/_inductor/codegen/cpp_utils.py**, **torch/_inductor/codegen/triton.py**. `int_truediv` and mixed precision equality is currently not implemented soundly, so we will lose precision in codegen for large values. TODO: The additions here are not exhaustive yet
* Update ValueRanges logic to use new sympy functions in **torch/utils/_sympy/value_ranges.py**. In general, we prefer to use the new Sympy function rather than try to roll things by hand, which is what was done previously for many VR analysis functions.
In **torch/fx/experimental/symbolic_shapes.py** we need to make some symbolic reasoning adjustments:
* Avoid generation of rational subexpressions by removing simplification of `x // y` into `floor(x / y)`. This simplification then triggers an addition simplification rule `(x + y) / c --> x / c + y / c` which is bad because x / c is a rational number now
* `_assert_bound_is_rational` is no more, we no longer generate rational bounds
* Don't intersect non-int value ranges with the `int_range`
* Support more sympy Functions for guard SYMPY_INTERP
* Assert the type of value range is consistent with the variable type
The new asserts uncovered necessary bug fixes:
* **torch/_inductor/codegen/cpp.py**, **torch/_inductor/select_algorithm.py**, **torch/_inductor/sizevars.py** - Ensure Wild/Symbol manually allocated in Inductor is marked `is_integer` so it's accepted to build expressions
* **torch/_inductor/utils.py** - make sure you actually pass in sympy.Expr to these functions
* **torch/_inductor/ir.py** - make_contiguous_strides_for takes int/SymInt, not sympy.Expr!
* **torch/export/dynamic_shapes.py** - don't use infinity to represent int ranges, instead use sys.maxsize - 1
Because of the removal of some symbolic reasoning that produced rationals, some of our symbolic reasoning has gotten worse and we are unable to simplify some guards. Check the TODO at **test/test_proxy_tensor.py**
**Reland notes.** This requires this internal fbcode diff https://www.internalfb.com/phabricator/paste/view/P1403322587 but I cannot prepare the diff codev due to https://fb.workplace.com/groups/osssupport/posts/26343544518600814/
It also requires this Executorch PR https://github.com/pytorch/executorch/pull/3911 but the ET PR can be landed prior to this landing.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/126905
Approved by: https://github.com/xadupre, https://github.com/lezcano
At a high level, the idea behind this PR is:
* Make it clearer what the promotion and int/float rules for various Sympy operations are. Operators that previously were polymorphic over int/float are now split into separate operators for clarity. We never do mixed int/float addition/multiplication etc in sympy, instead, we always promote to the appropriate operator. (However, equality is currently not done correctly.)
* Enforce strict typing on ValueRanges: if you have a ValueRange for a float, the lower and upper MUST be floats, and so forth for integers.
The story begins in **torch/utils/_sympy/functions.py**. Here, I make some changes to how we represent certain operations in sympy expressions:
* FloorDiv now only supports integer inputs; to do float floor division, do a truediv and then a trunc. Additionally, we remove the divide out addition by gcd optimization, because sympy gcd is over fields and is willing to generate rationals (but rationals are bad for ValueRange strict typing).
* ModularIndexing, LShift, RShift now assert they are given integer inputs.
* Mod only supports integer inputs; eventually we will support FloatMod (left for later work, when we build out Sympy support for floating operations). Unfortunately, I couldn't assert integer inputs here, because of a bad interaction with sympy's inequality solver that is used by the offline solver
* TrueDiv is split into FloatTrueDiv and IntTrueDiv. This allows for us to eventually generate accurate code for Python semantics IntTrueDiv, which is written in a special way to preserve precision when the inputs are >= 2**53 beyond what first coercing the integer to floats and then doing true division.
* Trunc is split to TruncToFloat and TruncToInt.
* Round is updated to return a float, not an int, making it consistent with the round op handler in Inductor. To get Python-style conversion to int, we call TruncToInt on the result.
* RoundDecimal updated to consistently only ever return a float
* Add ToFloat for explicit coercion to float (required so we can enforce strict ValueRanges typing)
In **torch/__init__.py**, we modify SymInt and SymFloat to appropriately call into new bindings that route to these refined sympy operations. Also, we modify `torch.sym_min` and `torch.sym_max` to have promotion semantics (if one argument is a float, the return result is always a float), making them inconsistent with builtins.min/max, but possible to do type analysis without runtime information.
We also need to introduce some new op handlers in **torch/_inductor/ops_handler.py**:
* `to_int` for truncation to int64, directly corresponding to TruncToInt; this can be implemented by trunc and dtype, but with a dedicated handler it is more convenient for roundtripping in Sympy
* `int_truediv` for Python-style integer true division, which has higher precision than casting to floats and then running `truediv`
These changes have consequences. First, we need to make some administrative changes:
* Actually wire up these Sympy functions from SymInt/SymFloat in **torch/fx/experimental/sym_node.py**, including the new promotion rules (promote2)
* Add support for new Sympy functions in **torch/utils/_sympy/interp.py**, **torch/utils/_sympy/reference.py**
* In particular, in torch.utils._sympy.reference, we have a strong preference to NOT do nontrivial compute, instead, everything in ops handler should map to a singular sympy function
* TODO: I chose to roundtrip mod back to our Mod function, but I think I'm going to have to deal with the C/Python inconsistency this to fix tests here
* Add printer support for the Sympy functions in **torch/_inductor/codegen/common.py**, **torch/_inductor/codegen/cpp_utils.py**, **torch/_inductor/codegen/triton.py**. `int_truediv` and mixed precision equality is currently not implemented soundly, so we will lose precision in codegen for large values. TODO: The additions here are not exhaustive yet
* Update ValueRanges logic to use new sympy functions in **torch/utils/_sympy/value_ranges.py**. In general, we prefer to use the new Sympy function rather than try to roll things by hand, which is what was done previously for many VR analysis functions.
In **torch/fx/experimental/symbolic_shapes.py** we need to make some symbolic reasoning adjustments:
* Avoid generation of rational subexpressions by removing simplification of `x // y` into `floor(x / y)`. This simplification then triggers an addition simplification rule `(x + y) / c --> x / c + y / c` which is bad because x / c is a rational number now
* `_assert_bound_is_rational` is no more, we no longer generate rational bounds
* Don't intersect non-int value ranges with the `int_range`
* Support more sympy Functions for guard SYMPY_INTERP
* Assert the type of value range is consistent with the variable type
The new asserts uncovered necessary bug fixes:
* **torch/_inductor/codegen/cpp.py**, **torch/_inductor/select_algorithm.py**, **torch/_inductor/sizevars.py** - Ensure Wild/Symbol manually allocated in Inductor is marked `is_integer` so it's accepted to build expressions
* **torch/_inductor/utils.py** - make sure you actually pass in sympy.Expr to these functions
* **torch/_inductor/ir.py** - make_contiguous_strides_for takes int/SymInt, not sympy.Expr!
* **torch/export/dynamic_shapes.py** - don't use infinity to represent int ranges, instead use sys.maxsize - 1
Because of the removal of some symbolic reasoning that produced rationals, some of our symbolic reasoning has gotten worse and we are unable to simplify some guards. Check the TODO at **test/test_proxy_tensor.py**
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/126905
Approved by: https://github.com/xadupre, https://github.com/lezcano
At a high level, the idea behind this PR is:
* Make it clearer what the promotion and int/float rules for various Sympy operations are. Operators that previously were polymorphic over int/float are now split into separate operators for clarity. We never do mixed int/float addition/multiplication etc in sympy, instead, we always promote to the appropriate operator. (However, equality is currently not done correctly.)
* Enforce strict typing on ValueRanges: if you have a ValueRange for a float, the lower and upper MUST be floats, and so forth for integers.
The story begins in **torch/utils/_sympy/functions.py**. Here, I make some changes to how we represent certain operations in sympy expressions:
* FloorDiv now only supports integer inputs; to do float floor division, do a truediv and then a trunc. Additionally, we remove the divide out addition by gcd optimization, because sympy gcd is over fields and is willing to generate rationals (but rationals are bad for ValueRange strict typing).
* ModularIndexing, LShift, RShift now assert they are given integer inputs.
* Mod only supports integer inputs; eventually we will support FloatMod (left for later work, when we build out Sympy support for floating operations). Unfortunately, I couldn't assert integer inputs here, because of a bad interaction with sympy's inequality solver that is used by the offline solver
* TrueDiv is split into FloatTrueDiv and IntTrueDiv. This allows for us to eventually generate accurate code for Python semantics IntTrueDiv, which is written in a special way to preserve precision when the inputs are >= 2**53 beyond what first coercing the integer to floats and then doing true division.
* Trunc is split to TruncToFloat and TruncToInt.
* Round is updated to return a float, not an int, making it consistent with the round op handler in Inductor. To get Python-style conversion to int, we call TruncToInt on the result.
* RoundDecimal updated to consistently only ever return a float
* Add ToFloat for explicit coercion to float (required so we can enforce strict ValueRanges typing)
In **torch/__init__.py**, we modify SymInt and SymFloat to appropriately call into new bindings that route to these refined sympy operations. Also, we modify `torch.sym_min` and `torch.sym_max` to have promotion semantics (if one argument is a float, the return result is always a float), making them inconsistent with builtins.min/max, but possible to do type analysis without runtime information.
We also need to introduce some new op handlers in **torch/_inductor/ops_handler.py**:
* `to_int` for truncation to int64, directly corresponding to TruncToInt; this can be implemented by trunc and dtype, but with a dedicated handler it is more convenient for roundtripping in Sympy
* `int_truediv` for Python-style integer true division, which has higher precision than casting to floats and then running `truediv`
These changes have consequences. First, we need to make some administrative changes:
* Actually wire up these Sympy functions from SymInt/SymFloat in **torch/fx/experimental/sym_node.py**, including the new promotion rules (promote2)
* Add support for new Sympy functions in **torch/utils/_sympy/interp.py**, **torch/utils/_sympy/reference.py**
* In particular, in torch.utils._sympy.reference, we have a strong preference to NOT do nontrivial compute, instead, everything in ops handler should map to a singular sympy function
* TODO: I chose to roundtrip mod back to our Mod function, but I think I'm going to have to deal with the C/Python inconsistency this to fix tests here
* Add printer support for the Sympy functions in **torch/_inductor/codegen/common.py**, **torch/_inductor/codegen/cpp_utils.py**, **torch/_inductor/codegen/triton.py**. `int_truediv` and mixed precision equality is currently not implemented soundly, so we will lose precision in codegen for large values. TODO: The additions here are not exhaustive yet
* Update ValueRanges logic to use new sympy functions in **torch/utils/_sympy/value_ranges.py**. In general, we prefer to use the new Sympy function rather than try to roll things by hand, which is what was done previously for many VR analysis functions.
In **torch/fx/experimental/symbolic_shapes.py** we need to make some symbolic reasoning adjustments:
* Avoid generation of rational subexpressions by removing simplification of `x // y` into `floor(x / y)`. This simplification then triggers an addition simplification rule `(x + y) / c --> x / c + y / c` which is bad because x / c is a rational number now
* `_assert_bound_is_rational` is no more, we no longer generate rational bounds
* Don't intersect non-int value ranges with the `int_range`
* Support more sympy Functions for guard SYMPY_INTERP
* Assert the type of value range is consistent with the variable type
The new asserts uncovered necessary bug fixes:
* **torch/_inductor/codegen/cpp.py**, **torch/_inductor/select_algorithm.py**, **torch/_inductor/sizevars.py** - Ensure Wild/Symbol manually allocated in Inductor is marked `is_integer` so it's accepted to build expressions
* **torch/_inductor/utils.py** - make sure you actually pass in sympy.Expr to these functions
* **torch/_inductor/ir.py** - make_contiguous_strides_for takes int/SymInt, not sympy.Expr!
* **torch/export/dynamic_shapes.py** - don't use infinity to represent int ranges, instead use sys.maxsize - 1
Because of the removal of some symbolic reasoning that produced rationals, some of our symbolic reasoning has gotten worse and we are unable to simplify some guards. Check the TODO at **test/test_proxy_tensor.py**
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/126905
Approved by: https://github.com/xadupre, https://github.com/lezcano
Sympy simplifications don't obey floating point semantics, so don't
use Sympy for this. Keep them as is, only evaluate with the reference
implementations when all arguments are known.
This may end up getting subsumed by some other changes later, but I
wanted to understand if this was easy and it seems to be easy.
This doesn't actually depend on the earlier diffs on the stack and I can detach it.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/122823
Approved by: https://github.com/lezcano
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
