Turns out codegen'ing a nested step graph break is significantly more complicated than first thought. The optimized function should actually do:
- call graph/load values/do side effects etc.
- call into the leaf's resume function, but skipped (this essentially step graph break function for just the leaf function)
- call into all the other resume functions, traced.
This PR also adds `torch._dynamo.step_unsupported()`, which can be used for internal testing purposes to better test step graph break handling.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/162737
Approved by: https://github.com/Lucaskabela
ghstack dependencies: #160601
This is needed because if we codegen cells for nested frames AFTER side effects, then reconstruction could get messed up. From below:
>The added test case demonstrates the reconstruction failure if we kept cell codegen at the original place (only happens with nested graph breaks since we reconstruct nested frame cells from VariableTracker rather than directly using LOAD_CLOSURE).
>At a high level, what happened before this change was that side_effects was pruning the cells (I don't recall exactly why this happens), and because cells were codegen'd after the side effects were applied, we were unable to properly reconstruct the cell. The error I was seeing was a list/tuple IndexError.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160601
Approved by: https://github.com/mlazos
Nested continuation function code objects are now unique w.r.t. stack trace below (and including) the current code object.
Without this change, e.g. in the added test, `f3` would be recompiled on the second graph break.
Followup: we can skip guards on continuation functions.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/159786
Approved by: https://github.com/anijain2305
ghstack dependencies: #159329, #159678, #159817, #160138
Fix comments to reflect that we no longer codegen cells to be sent to resume function as inputs - they are instead codegen'd after the unsupported instruction in order to build resume functions that are closures.
Also simplify some codegen.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160138
Approved by: https://github.com/anijain2305
ghstack dependencies: #159329, #159678, #159817
We are refactoring dynamo code for convert frame so that we can have modularized pieces sharable between different compiler frontends (e.g. torch.compile, precompile and torch.export).
This PR adds a new helper function compile_frame() which takes a bytecode and a transform function and return compiled bytecode + output graph as DynamoOutput type.
Differential Revision: [D80430802](https://our.internmc.facebook.com/intern/diff/D80430802/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/160855
Approved by: https://github.com/tugsbayasgalan
ghstack dependencies: #160814, #160815
This should prevent bad resume function prologues from slipping by. In particular, graph breaks in resume function prologues will now hard error.
Implementation details:
- The resume function prologue is surrounded by `LOAD_CONST arg, STORE_FAST __is_tracing_resume_prologue` instructions. The first sequence has `arg=True` and the second sequence has `arg=False`.
- InstructionTranslator will know when it is tracing a resume function prologue when it detects `STORE_FAST __is_tracing_resume_prologue`. The top of stack will be True to mark the start of the prologue, False to mark the end.
- When `convert_frame.py` detects that an error occurred while the InstructionTranslator was tracing a resume function prologue, we will wrap the exception and hard error
Pull Request resolved: https://github.com/pytorch/pytorch/pull/154564
Approved by: https://github.com/jansel
ghstack dependencies: #154283, #154289, #154782, #156762, #155166
This should prevent bad resume function prologues from slipping by. In particular, graph breaks in resume function prologues will now hard error.
Implementation details:
- The resume function prologue is surrounded by `LOAD_CONST arg, STORE_FAST __is_tracing_resume_prologue` instructions. The first sequence has `arg=True` and the second sequence has `arg=False`.
- InstructionTranslator will know when it is tracing a resume function prologue when it detects `STORE_FAST __is_tracing_resume_prologue`. The top of stack will be True to mark the start of the prologue, False to mark the end.
- When `convert_frame.py` detects that an error occurred while the InstructionTranslator was tracing a resume function prologue, we will wrap the exception and hard error
Pull Request resolved: https://github.com/pytorch/pytorch/pull/154564
Approved by: https://github.com/jansel
ghstack dependencies: #154283, #154289, #154782, #155166
This should prevent bad resume function prologues from slipping by. In particular, graph breaks in resume function prologues will now hard error.
Implementation details:
- The resume function prologue is surrounded by `LOAD_CONST arg, STORE_FAST __is_tracing_resume_prologue` instructions. The first sequence has `arg=True` and the second sequence has `arg=False`.
- InstructionTranslator will know when it is tracing a resume function prologue when it detects `STORE_FAST __is_tracing_resume_prologue`. The top of stack will be True to mark the start of the prologue, False to mark the end.
- When `convert_frame.py` detects that an error occurred while the InstructionTranslator was tracing a resume function prologue, we will wrap the exception and hard error
Pull Request resolved: https://github.com/pytorch/pytorch/pull/154564
Approved by: https://github.com/jansel
ghstack dependencies: #154283, #154289, #154782, #155166
Old: ~pack resume function stack + locals into a list: we need to be able to pass frame stack+locals in lists to hand off to nested functions in the future, so we implement this part first.~
We are no longer doing this right now since GraphModule/guard variable naming gets messed up. Going forward, our approach will be to keep the top frame unpacked, but pack the rest of the contents of other frames in a list.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/151056
Approved by: https://github.com/jansel
Old: ~pack resume function stack + locals into a list: we need to be able to pass frame stack+locals in lists to hand off to nested functions in the future, so we implement this part first.~
We are no longer doing this right now since GraphModule/guard variable naming gets messed up. Going forward, our approach will be to keep the top frame unpacked, but pack the rest of the contents of other frames in a list.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/151056
Approved by: https://github.com/jansel
Implements https://github.com/pytorch/pytorch/issues/93753 - move frame local guard accessors to C++.
Before, we used dict accessors on a Python dict representing the frame's fastlocals that we manually build. We move this accessor to C++ and additionally use the fastlocal index whenever possible.
Some implementation notes:
- `FrameLocalsMapping` is now initialized as a C++ vector of `PyObject`s. We do not just use the frame's localsplus/fastlocals buffer because we also unbox cells.
- `FrameLocalsMapping` can still be converted into a Python dict representing the frame's fastlocals, but it is done lazily.
- We update `LeafGuard`, `GuardAccessor`, and `GuardManager`'s `check_nopybind` methods to accept `FrameLocalsMapping`. By default, we convert the `FrameLocalsMapping` to a Python dict and run the original `check_nopybind` on it, but in some cases, conversion is not needed.
- We add a new guard accessor `FrameLocalsGuardAccessor`, which is similar to `DictGetItemGuardAccessor` but has special handling for `FrameLocalsMapping`. We create a separate class to emphasize different use cases, but we could probably combine these two (can do in a follow up)
dynamo_guard_eval.py microbenchmark update:
- 713.2us -> 630.0us (3.10)
- 598.8us -> 530.7us (3.12)
Other followups:
- Add `FrameLocalsMapping` version for `check_verbose_nopybind` in order to match behavior between `check_nopybind` and `check_verbose_nopybind`. This can prevent difficult debugging situations where guards fail (`check_nopybind` returns false) but no guard error message is generated (`check_verbose_nopybind` succeeds).
- Rewrite the `SHAPE_ENV` guard into C++ - it is a fairly common guard that results in `FrameLocalsMapping` needing to convert to a dict
Pull Request resolved: https://github.com/pytorch/pytorch/pull/140063
Approved by: https://github.com/jansel
ghstack dependencies: #142117, #142430
Prior to this patch, we are using `ConstantVariable.create` to create VT
for frozenset objects, and intended yet failed to predicate that on all
itmes being literals (see https://github.com/pytorch/pytorch/pull/140984#discussion_r1847393736).
The code was from https://github.com/pytorch/torchdynamo/commit/7c03434 and
the original goal was to help DBR quantization, but as the new test in
this patch shows, it could lead to silent incorrectness.
Upon a closer look, this exposes some subtleties in how Dynamo handles
`ConstantVariable` and `LOAD_CONST`, so this patch both fixes the
aforementioned issue and documents, enforces, and makes explicit the
invariants around `ConstantVariable` and `LOAD_CONST` -- only immutable
objects are supported.
Specifically, this patch:
1. refine the checks for wrapping a `frozenset` object, document why we
can't just wrap its items directly due to lack of `Sourcec` for set
items, and use a safe workaround (`SourcelessBuilder`) to ensure
soundness while keeping the DBR quantization support.
2. Adds more types to `common_constant_types`, thereby making
`ConstantVariable.is_base_literal` more lenient, and strictly checks
this property in the constructor of `ConstantVariable`.
3. Change relevant uses of `create_instruction("LOAD_CONST", ...)` to
`create_load_const` which checks `is_safe_constant`, and makes
developer overrides explicit by using `create_load_const_unchecked`
when needed.
4. In a few places, use more specific `VariableTracker`, e.g.,
`TypingVariable` rather than `ConstantVariable`, and
`FrozensetVariable` rather than `SetVariable`.
(2) and (3) are mainly to future-proof Dynamo against bugs like (1).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/141504
Approved by: https://github.com/jansel
* Automatically applies ruff rule 401. Turns loops into equivalent list comprehensions which are faster and do not leak the scope of the loop variables.
* list comprehensions not only often have better typing, but are 50+% faster than for loops on overhead. They also preserve length information etc and are better for the interpreter to optimize.
* Manually went back and made mypy happy after the change.
* Also fixed style lints in files covered by flake8 but not by pyfmt
Pull Request resolved: https://github.com/pytorch/pytorch/pull/140980
Approved by: https://github.com/justinchuby, https://github.com/malfet
This PR implements tracing of with contexts with TorchFunction modes which have the default enter/exit behavior (ie pushing/popping the mode)
Typically the bytecode for a context manager looks like this during a graph break:
1. graph call
2. enter context
3. unsupported code
4. exit context
5. resume call
resume fn structure:
1. enter context
2. jump
...
3. exit context
The issue with torch function modes is that side effects will replay any mutations to the torch function stack performed during tracing. So, we do not need to enter and exit around the unsupported code in the original function (doing so would result in a duplicate torch function mode entry during execution of the unsupported code), and we don't need to enter again in the resume function (the mode that was pushed from the side effects bytecode would still be on the stack).
So for torch function modes the structure of our output code is this:
1. graph call
2. mutate tf mode stack to replay mutations
4. unsupported code
5. on exception restore stack
6. resume function
Then our resume fn looks like this:
1. no-op enter torch function mode
2. jump
3. exit tf mode
To implement the no-op enter of the torch function mode I added torch function mode in polyfill which no-op enters, but normally exits. This is needed because we still want to trace the with context in the resume function, and exit properly (the exit instructions will still be in the function, so we need to generate instructions to set up the context).
Separately from the bytecode, dynamo also tracks contexts on the block stack, which is how the SETUP_* instructions are implemented. Naturally at a graph break, we exit these block stacks to properly reset the contexts entirely, so that we can re-enter around the unsupported code soundly. However once again, in the torch function mode case, in the event of a graph we do not want to perform any exit side effects because we want to preserve the state of the mode stack as is so that we will properly update the stack with bytecode mentioned in the first section. If we exited here, dynamo would pop the mode off of the symbolic stack, and not update the true python torch function mode stack with the suffix bytecode. All in all, for torch function modes we enter exactly once, update the global torch function mode stack with side effects bytecode, re-read this stack when compiling the resume function, and exit exactly once in the resume function. This matches the semantics of eager exactly.
Approved by: https://github.com/williamwen42
ghstack dependencies: #134732, #133137, #135443, #135444
Pull Request resolved: https://github.com/pytorch/pytorch/pull/137114
Approved by: https://github.com/yanboliang
This PR implements tracing of with contexts with TorchFunction modes which have the default enter/exit behavior (ie pushing/popping the mode)
Typically the bytecode for a context manager looks like this during a graph break:
1. graph call
2. enter context
3. unsupported code
4. exit context
5. resume call
resume fn structure:
1. enter context
2. jump
...
3. exit context
The issue with torch function modes is that side effects will replay any mutations to the torch function stack performed during tracing. So, we do not need to enter and exit around the unsupported code in the original function (doing so would result in a duplicate torch function mode entry during execution of the unsupported code), and we don't need to enter again in the resume function (the mode that was pushed from the side effects bytecode would still be on the stack).
So for torch function modes the structure of our output code is this:
1. graph call
2. mutate tf mode stack to replay mutations
4. unsupported code
5. on exception restore stack
6. resume function
Then our resume fn looks like this:
1. no-op enter torch function mode
2. jump
3. exit tf mode
To implement the no-op enter of the torch function mode I added torch function mode in polyfill which no-op enters, but normally exits. This is needed because we still want to trace the with context in the resume function, and exit properly (the exit instructions will still be in the function, so we need to generate instructions to set up the context).
Separately from the bytecode, dynamo also tracks contexts on the block stack, which is how the SETUP_* instructions are implemented. Naturally at a graph break, we exit these block stacks to properly reset the contexts entirely, so that we can re-enter around the unsupported code soundly. However once again, in the torch function mode case, in the event of a graph we do not want to perform any exit side effects because we want to preserve the state of the mode stack as is so that we will properly update the stack with bytecode mentioned in the first section. If we exited here, dynamo would pop the mode off of the symbolic stack, and not update the true python torch function mode stack with the suffix bytecode. All in all, for torch function modes we enter exactly once, update the global torch function mode stack with side effects bytecode, re-read this stack when compiling the resume function, and exit exactly once in the resume function. This matches the semantics of eager exactly.
Approved by: https://github.com/williamwen42
ghstack dependencies: #134732, #133137, #135443, #135444
Pull Request resolved: https://github.com/pytorch/pytorch/pull/137114
Approved by: https://github.com/yanboliang
This reverts commit 7743149b2b.
Reverts
* https://github.com/pytorch/pytorch/pull/135503
* https://github.com/pytorch/pytorch/pull/135502
* https://github.com/pytorch/pytorch/pull/135422
This passes this test. Earlier, the getitem would stay like a getitem in the Fx graph. But now the fake tensor propagations fails saying that .item is called. It seems that torch function is not getting triggered while fake tensor propagation.
```
import torch
from torch.nn.attention.flex_attention import BlockMask, _mask_mod_signature, _score_mod_signature, flex_attention
from torch._inductor.lowering import make_pointwise, register_lowering
from torch._inductor.virtualized import ops
from torch.nn.attention.flex_attention import create_block_mask
torch.set_default_device('cuda')
flex_attention = torch.compile(flex_attention, dynamic=False)
prefix_lengths = torch.arange(8)
def prefix_lm(b, h, q, kv):
return prefix_lengths[b] >= kv
mask = create_block_mask(prefix_lm, 8, None, 512, 512, _compile=True)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/136590
Approved by: https://github.com/Chillee
