Adds val, and optionally stack_trace & nn_module_stack metadata back to SymInt compute nodes that we CSE, with a hook on `graph.create_node()`. Not sure if there's other metadata we want to populate here?
Pull Request resolved: https://github.com/pytorch/pytorch/pull/134516
Approved by: https://github.com/ezyang
Adds val, and optionally stack_trace & nn_module_stack metadata back to SymInt compute nodes that we CSE, with a hook on `graph.create_node()`. Not sure if there's other metadata we want to populate here?
Pull Request resolved: https://github.com/pytorch/pytorch/pull/134516
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: Some symbols (unbacked symints?) can have upper bound that is `sys.maxsize - 1` but our code for runtime assertions assumes that such upper bounds would come in as `sympy.oo` (like backed symints?) in order to drop them. So we weren't dropping them, which this PR fixes.
Test Plan: added test
Differential Revision: D61352056
Pull Request resolved: https://github.com/pytorch/pytorch/pull/133627
Approved by: https://github.com/SherlockNoMad
Some sympy Functions aren't supported by sympy_interp(); we can't turn them into FX nodes, so currently the runtime asserts CSE pass avoids CSE'ing on any expression containing a sympy Function. https://github.com/pytorch/pytorch/pull/132325 started tracking unsupported functions, so we switch the check to that to be more precise. We also check for and skip unsupported functions when adding asserts - previously we only did the check for CSE, and not adding new expressions.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/132457
Approved by: https://github.com/avikchaudhuri
original PR: https://github.com/pytorch/pytorch/pull/128599 (re-created after revert + poisoned diff train)
Summary:
This PR adds deduplication and CSE for runtime asserts. Existing size computation in the graph is CSE'd along with added runtime asserts, and redundant asserts are removed. Shape calls on intermediate tensors are also turned into compute on input sizes if possible, allowing intermediate tensors to be freed earlier. For example:
```
z = torch.cat([x, x], dim=0) # 2*s0
w = z.repeat(y.shape[0]) # 2*s0*s1
_w = w.shape[0]
s0 = x.shape[0]
s1 = y.shape[0]
_w0 = 2 * s0
_w = _w0 * s1
```
Additionally, constrain_range calls are deduplicated. Single-symbol bound checks for unbacked symbols (e.g. u0 >= 0, u0 <= 5) and sym_constrain_range.default calls are also removed, since they accumulate range info in the ShapeEnv, and are replaced with two _assert_scalar.default calls that check the min/max bounds. For example:
```
torch.sym_constrain_range_for_size(n, min=2, max=16)
torch.sym_constrain_range(n, min=4, max=20)
torch._check(n >= 0)
torch._check(n >= 3)
torch._check(n <= 14)
torch.sym_constrain_range_for_size(n)
torch._check(n >= 4)
torch._check(n <= 14)
```
Test Plan:
contbuild & OSS CI, see 940e4477ab
Original Phabricator Test Plan:
Imported from GitHub, without a `Test Plan:` line.
Differential Revision: D59543603
Pull Request resolved: https://github.com/pytorch/pytorch/pull/130380
Approved by: https://github.com/izaitsevfb
This PR adds deduplication and CSE for runtime asserts. Existing size computation in the graph is CSE'd along with added runtime asserts, and redundant asserts are removed. Shape calls on intermediate tensors are also turned into compute on input sizes if possible, allowing intermediate tensors to be freed earlier. For example:
```
z = torch.cat([x, x], dim=0) # 2*s0
w = z.repeat(y.shape[0]) # 2*s0*s1
_w = w.shape[0]
# something with _w ...
# turns into ->
s0 = x.shape[0]
s1 = y.shape[0]
_w0 = 2 * s0
_w = _w0 * s1
```
Additionally, constrain_range calls are deduplicated. Single-symbol bound checks for unbacked symbols (e.g. u0 >= 0, u0 <= 5) and sym_constrain_range.default calls are also removed, since they accumulate range info in the ShapeEnv, and are replaced with two _assert_scalar.default calls that check the min/max bounds. For example:
```
torch.sym_constrain_range_for_size(n, min=2, max=16)
torch.sym_constrain_range(n, min=4, max=20)
torch._check(n >= 0)
torch._check(n >= 3)
torch._check(n <= 14)
# turns into
torch.sym_constrain_range_for_size(n)
torch._check(n >= 4)
torch._check(n <= 14)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/128599
Approved by: https://github.com/ezyang
This PR adds deduplication and CSE for runtime asserts. Existing size computation in the graph is CSE'd along with added runtime asserts, and redundant asserts are removed. Shape calls on intermediate tensors are also turned into compute on input sizes if possible, allowing intermediate tensors to be freed earlier. For example:
```
z = torch.cat([x, x], dim=0) # 2*s0
w = z.repeat(y.shape[0]) # 2*s0*s1
_w = w.shape[0]
# something with _w ...
# turns into ->
s0 = x.shape[0]
s1 = y.shape[0]
_w0 = 2 * s0
_w = _w0 * s1
```
Additionally, constrain_range calls are deduplicated. Single-symbol bound checks for unbacked symbols (e.g. u0 >= 0, u0 <= 5) and sym_constrain_range.default calls are also removed, since they accumulate range info in the ShapeEnv, and are replaced with two _assert_scalar.default calls that check the min/max bounds. For example:
```
torch.sym_constrain_range_for_size(n, min=2, max=16)
torch.sym_constrain_range(n, min=4, max=20)
torch._check(n >= 0)
torch._check(n >= 3)
torch._check(n <= 14)
# turns into
torch.sym_constrain_range_for_size(n)
torch._check(n >= 4)
torch._check(n <= 14)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/128599
Approved by: https://github.com/ezyang
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
With the current state of export's dynamic shapes, we struggle with guards and constraints that are beyond the current dynamic shapes language, expressed with dims and derived dims. While we can compile and guarantee correctness for guards within the current language (e.g. min/max ranges, linear relationships, integer divisibility) we struggle to dynamically compile guards which extend beyond that.
For these "complex" guards, we typically do either of the following: 1) raise a constraint violation error, along the lines of "not all values of <symbol> in the specified range satisfy <guard>", with or without suggested fixes, 2) specialize to the provided static values and suggest removing dynamism, or 3) fail compilation due to some arbitrary unsupported case. Previous [work](https://github.com/pytorch/pytorch/pull/124949) went towards resolving this by disabling forced specializations, instead allowing the user to fail at runtime with incorrect inputs.
In this PR, relying on [hybrid backed-unbacked symints](https://github.com/pytorch/pytorch/issues/121749), [deferred runtime asserts](https://github.com/pytorch/pytorch/blob/main/torch/fx/passes/runtime_assert.py), and the function [_is_supported_equivalence()](d7de4c9d80/torch/fx/experimental/symbolic_shapes.py (L1824)), we add a flag `_allow_complex_guards_as_runtime_asserts` which allows the user to compile exported programs containing these guards and maintain dynamism, while adding correctness checks as runtime assertions in the graph.
Hybrid backed-unbacked symints allow us to easily bypass "implicit" guards emitted from computation - guards that we ~expect to be true. Popular examples revolve around reshapes:
```
# reshape
def forward(self, x, y): # x: [s0, s1], y: [s2]
return x.reshape([-1]) + y # guard s0 * s1 = s2
This leads to the following exported program
class GraphModule(torch.nn.Module):
def forward(self, x: "f32[s0, s1]", y: "f32[s2]"):
sym_size_int: "Sym(s2)" = torch.ops.aten.sym_size.int(y, 0)
mul: "Sym(-s2)" = -1 * sym_size_int; sym_size_int = None
sym_size_int_1: "Sym(s0)" = torch.ops.aten.sym_size.int(x, 0)
sym_size_int_2: "Sym(s1)" = torch.ops.aten.sym_size.int(x, 1)
mul_1: "Sym(s0*s1)" = sym_size_int_1 * sym_size_int_2; sym_size_int_1 = sym_size_int_2 = None
add: "Sym(s0*s1 - s2)" = mul + mul_1; mul = mul_1 = None
eq: "Sym(Eq(s0*s1 - s2, 0))" = add == 0; add = None
_assert_scalar = torch.ops.aten._assert_scalar.default(eq, "Runtime assertion failed for expression Eq(s0*s1 - s2, 0) on node 'eq'"); eq = None
view: "f32[s0*s1]" = torch.ops.aten.view.default(x, [-1]); x = None
add_1: "f32[s0*s1]" = torch.ops.aten.add.Tensor(view, y); view = y = None
return (add_1,)
```
Another case is symbol divisibility:
```
def forward(self, x): # x: [s0, s1]
return x.reshape([-1, x.shape[0] - 1]) # Eq(Mod(s0 * s1, s0 - 1), 0)
```
Applying deferred runtime asserts also helps dynamic compilation for "explicit" complex guards that typically cause problems for export. For example we can generate runtime asserts for not-equal guards, and complex conditions like the following:
```
class Foo(torch.nn.Module):
def forward(self, x, y):
# check that negation of first guard also shows up as runtime assertion
if x.shape[0] == y.shape[0]: # False
return x + y
elif x.shape[0] == y.shape[0] ** 3: # False
return x + 2, y + 3
elif x.shape[0] ** 2 == y.shape[0] * 3: # True
return x * 2.0, y * 3.0
```
For the above graph we will generate 3 runtime assertions: the negation of the first 2, and the 3rd condition as a guard.
One additional benefit here over the current state of exported programs is that this adds further correctness guarantees - previously with explicit complex guards, if compilation succeeded, the guards would be ignored at runtime, treated as given.
As shown above, the runtime asserts appear as math ops in the graph, generated by the sympy interpreter, resulting in an _assert_scalar call. There is an option to avoid adding these asserts into the graph, by setting `TORCH_DYNAMO_DO_NOT_EMIT_RUNTIME_ASSERTS=1`. This results in the "original" computation graph, with dynamism, and any incorrect inputs will fail on ops during runtime. Further work could go into prettifying the printer, so the majority of the graph isn't guard-related.
Ideally this PR would subsume and remove the recently added [_disable_forced_specializations](https://github.com/pytorch/pytorch/pull/124949) flag, but that flag still handles one additional case of specialization: single-variable equalities where the symbol is solvable for a concrete value: see this [PR](https://github.com/pytorch/pytorch/pull/126925)
This PR doesn't change any behavior around data-dependent errors/unbacked symints yet, that could be further work.
NOTE: will take naming change suggestions for the flag :)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/127129
Approved by: https://github.com/avikchaudhuri
The padded dense -> jagged conversion op has the signature:
```
_fbgemm_dense_to_jagged_forward(Tensor dense, Tensor[] offsets, SymInt? total_L=None) -> Tensor
```
when `total_L` is not specified, the meta registration has a data-dependent output shape (based on `offsets[0][-1]`). Returning an unbacked SymInt here should work in theory, but traceable wrapper subclass support is missing in later code to handle deferred runtime asserts. This PR fixes this.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/126198
Approved by: https://github.com/ezyang
```
python test/test_fx.py -k test_public_api_surface
```
was failing with a complaint about infinite recursion. Fixed that and then marked the two API changes from #123681 as private (for `get_example_value`) and backward compatible (for `insert_deferred_runtime_asserts`).
Fixes#104012
Pull Request resolved: https://github.com/pytorch/pytorch/pull/125706
Approved by: https://github.com/BoyuanFeng
Fixes [internal error](https://fb.workplace.com/groups/1075192433118967/permalink/1416709435633930/).
The issue is that the asserting nodes added in the `insert_deferred_runtime_assertion` pass do not contain metadata that the ExportedProgram requires the graph to have. One solution to fix this is to retrace the entire module, or another solution is to manually add back this metadata.
This diff implements the latter solution (manually add back the metadata) through hooking into fx.graph's `create_node` function, and adding export-specific metadata for every node that is created. The reason I did this is so that the `insert_deferred_runtime_assertion` does not have to know about what metadata export wants.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/125414
Approved by: https://github.com/zhxchen17, https://github.com/BoyuanFeng
This completely subsumes https://github.com/pytorch/pytorch/pull/120816
This makes use of the unbacked binding machinery to teach Inductor how to generate deferred runtime asserts directly. There is some back story about why I did it this way, let me explain.
Previously, our strategy for generating runtime asserts was that Dynamo would insert them into the FX graph after finishing tracing, and we would attempt to code generate them based on the FX graph. This is a good strategy for export, where we immediately export the graph. However, this strategy was afflicted by problems in eager, where we reuse the same ShapeEnv as before. In particular, on subsequent graph passes, we would immediately turn all of these assertions into noops, because when we evaluated their expressions, we would see that because we had a deferred runtime assert in the ShapeEnv, we know "oh, of course this expression is True" already. Oops!
So, with this PR, we take the attitude that as long as the ShapeEnv sticks around, the ShapeEnv's list of deferred runtime asserts is the source of truth, and we don't put anything in the graph. So we just need to decide when to actually generate asserts, and the place I picked was Inductor lowering, since we already have an AssertScalar buffer concept, and so I just need to insert them at this point. AssertScalar also uses raw sympy.Expr rather than SymInt/Bool, so it is easier to prevent unrestricted simplification at this point.
There are a few things jumbled together in this PR. I can split them if you want, but some of the changes are before I changed my strategy, but they're useful changes anyway.
**torch/_dynamo/output_graph.py** and **torch/_inductor/lowering.py** - Here, we stop putting deferred runtime asserts in the graph. I also have to make sure we don't DCE unused symbol arguments; we're going to get some goofy graph arguments this way, will be good to restore that optimization eventually. We also just disable codegen for `_assert_scalar` entirely; we assume that ShapeEnv will be good enough to capture all of these.
**torch/_inductor/codegen/wrapper.py** and **torch/_inductor/ir.py** - Add a way to codegen sizevars without forcing simplification
**torch/_inductor/graph.py** - The main logic. Our strategy is to interpose in the same place we are testing that unbacked SymInts are properly showing up in lowered code. The logic is directly analogous to the logic in the existing insert deferred runtime asserts FX pass, but it's simpler because sympy expressions can be directly stored on inductor IR nodes.
**torch/fx/experimental/symbolic_shapes.py** - For extra safety, we have a way of freezing runtime asserts, so that if you try to add more we error. This prevents us from adding runtime asserts after we've done lowering. There's a funny interaction with backwards which there's a comment for in graph.py
**torch/fx/passes/runtime_assert.py** - This is not really needed in this PR, but I rewrote the runtime assert logic to use unbacked_bindings rather than inferring it by looking for unbacked SymInts. Now, keypaths are translated into FX node acessors. Unfortunately, I couldn't delete the old inference code, because you still need it to find backed SymInts from arguments (as this pass may be used on graphs which don't explicitly bind all their shape variables as argments). There are some new tests exercising this.
TODO: I think we need to generate asserts for replacements too. This is a preexisting problem that the old FX pass had too.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/124874
Approved by: https://github.com/jansel
ghstack dependencies: #124864
