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Refactor tensor_new.cpp to use TensorOptions instead of DispatchKey#54034

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Refactor tensor_new.cpp to use TensorOptions instead of DispatchKey#54034
ezyang wants to merge 7 commits intogh/ezyang/949/basefrom
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@ezyang ezyang commented Mar 15, 2021

Stack from ghstack:

Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical. Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions. The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key(); it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time). See also #53124. But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about construction of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?

  • Sources (things that used to PRODUCE DispatchKey)
    • Most top level functions take a DispatchKey as their argument. I
      use the new function dispatchKeyToTensorOptions to convert it into
      a TensorOptions
    • typeIdWithDefault now produces a TensorOptions (probably could do
      with a rename, though I didn't)
  • Sinks (things that used to CONSUME DispatchKey)
    • Previously, the function options() was typically used to convert the
      DispatchKey into a TensorOptions. Now its replacement build_options
      just takes a TensorOptions and sets some extra fields on it.
      Irritatingly, I can't just replace
      build_options(options, scalar_type, device) with
      options.dtype(scalar_type).device(device) because the semantics
      are slightly different: if device is nullopt, we should preserve
      the usage of the device specified in options (what options.device()
      does is overwrite the device unconditionally; e.g., if device is
      nullopt, unset device from options)
    • The other major sink for DispatchKey was internal_new_from_data,
      but it turns out it only really extracts the device type from
      the dispatch key. Now it just pulls out the device from
      TensorOptions.
  • To actually do the translation of DispatchKey to TensorOptions, I
    introduce new functions dispatchKeyToLayout (replicating
    layout_from_backend--there are still a few uses of this function
    so I couldn't delete it) and dispatchKeyToDeviceType (replacing
    computeDeviceType)
  • In all internal functions, whenever DispatchKey is taken as an argument,
    I instead take TensorOptions as an argument, and pass it along.
  • Anywhere legacyExtractDispatchKey(other.key_set()) equality was
    previously used, I now do other.options().type_equal(), which
    is the intended BC for doing "backend to backend" comparisons
  • There are a few places in the sparse constructors where we allocated
    a tensor for values, and then read out the dispatch key from the
    result to allocate the keys. As best as I can tell, this is totally
    equivalent to just passing in the options to both values and indices
    (the only difference is dtype, which is captured via a separate
    argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all. I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet. I can delete:

  • backendToCPU
  • backendToXPU
  • backendToCUDA
  • backendToHIP
  • backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang ezyang@fb.com

Differential Revision: D27109509

Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

[ghstack-poisoned]
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facebook-github-bot commented Mar 15, 2021

💊 CI failures summary and remediations

As of commit a48b54a (more details on the Dr. CI page):


  • 1/1 failures introduced in this PR

🕵️ 1 new failure recognized by patterns

The following CI failures do not appear to be due to upstream breakages:

See GitHub Actions build clang-tidy (1/1)

Step: "Add annotations" (full log | diagnosis details | 🔁 rerun)

2021-03-18T16:25:47.3819241Z update-alternatives: error: no alternatives for nsight-sys
2021-03-18T16:25:47.3641658Z Setting up x11proto-damage-dev (1:2018.4-4) ...
2021-03-18T16:25:47.3642543Z Setting up cuda-nvjpeg-10-2 (10.2.89-1) ...
2021-03-18T16:25:47.3643460Z Setting up libxcb-dri3-dev:amd64 (1.13-2~ubuntu18.04) ...
2021-03-18T16:25:47.3644343Z Setting up libcublas10 (10.2.3.254-1) ...
2021-03-18T16:25:47.3645131Z Setting up libcublas-dev (10.2.3.254-1) ...
2021-03-18T16:25:47.3645951Z Setting up cuda-cufft-10-2 (10.2.89-1) ...
2021-03-18T16:25:47.3646868Z Setting up cuda-nsight-compute-10-2 (10.2.89-1) ...
2021-03-18T16:25:47.3647900Z Setting up nsight-systems-2020.4.3 (2020.4.3.7-10543b6) ...
2021-03-18T16:25:47.3725774Z update-alternatives: using /opt/nvidia/nsight-systems/2020.4.3/target-linux-x64/nsys to provide /usr/local/bin/nsys (nsys) in auto mode
2021-03-18T16:25:47.3813115Z update-alternatives: error: alternative path /opt/nvidia/nsight-systems/2020.4.3/host-linux-x64/nsight-sys doesn't exist
2021-03-18T16:25:47.3819241Z update-alternatives: error: no alternatives for nsight-sys
2021-03-18T16:25:47.3876172Z update-alternatives: using /opt/nvidia/nsight-systems/2020.4.3/host-linux-x64/nsys-ui to provide /usr/local/bin/nsys-ui (nsys-ui) in auto mode
2021-03-18T16:25:47.3912851Z Setting up libxcb-shape0-dev:amd64 (1.13-2~ubuntu18.04) ...
2021-03-18T16:25:47.3936232Z Setting up cuda-cusparse-10-2 (10.2.89-1) ...
2021-03-18T16:25:47.4003838Z Setting up cuda-cuobjdump-10-2 (10.2.89-1) ...
2021-03-18T16:25:47.4027566Z Setting up libxcb-glx0-dev:amd64 (1.13-2~ubuntu18.04) ...
2021-03-18T16:25:47.4049401Z Setting up libgles2:amd64 (1.0.0-2ubuntu2.3) ...
2021-03-18T16:25:47.4070486Z Setting up libglu1-mesa:amd64 (9.0.0-2.1build1) ...
2021-03-18T16:25:47.4090571Z Setting up libegl-mesa0:amd64 (20.0.8-0ubuntu1~18.04.1) ...
2021-03-18T16:25:47.4162420Z Setting up cuda-sanitizer-api-10-2 (10.2.89-1) ...
2021-03-18T16:25:47.4228243Z Setting up cuda-nvjpeg-dev-10-2 (10.2.89-1) ...

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…spatchKey"

Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

[ghstack-poisoned]
ezyang added a commit that referenced this pull request Mar 15, 2021
Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

ghstack-source-id: 798965d
Pull Request resolved: #54034
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ezyang commented Mar 16, 2021

Apparently I broke torch.DoubleTensor(torch.DoubleTensor([0.0])). Whacky!

toString(dispatch_key), " (got ", toString(legacyExtractDispatchKey(other.key_set())), ")");
Tensor new_with_tensor(c10::TensorOptions options, at::ScalarType scalar_type, const Tensor& other) {
TORCH_CHECK_TYPE(other.options().type_equal(options), "expected ",
options, " (got ", other.options(), ")");
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This isn't right, because other.options() also includes dtype

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a) I'm not sure which thing isn't right here b) regardless, is it worth putting in a comment?

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This comment is out of date; the code is updated!

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ezyang commented Mar 16, 2021

There are a few places in the sparse constructors where we allocated
a tensor for values, and then read out the dispatch key from the
result to allocate the keys. As best as I can tell, this is totally
equivalent to just passing in the options to both values and indices
(the only difference is dtype, which is captured via a separate
argument)

The CUDA failures suggest I was wrong here.

…spatchKey"

Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

[ghstack-poisoned]
ezyang added a commit that referenced this pull request Mar 16, 2021
Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

ghstack-source-id: b1ecfa7
Pull Request resolved: #54034
@ezyang ezyang requested a review from smessmer March 16, 2021 18:17
@ezyang ezyang requested a review from bhosmer March 16, 2021 18:44
…spatchKey"

Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

[ghstack-poisoned]
ezyang added 3 commits March 17, 2021 07:55
…spatchKey"

Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

Differential Revision: [D27109509](https://our.internmc.facebook.com/intern/diff/D27109509)

[ghstack-poisoned]
…spatchKey"

Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

Differential Revision: [D27109509](https://our.internmc.facebook.com/intern/diff/D27109509)

[ghstack-poisoned]
…spatchKey"

Fixes #53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also #53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to #53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

Differential Revision: [D27109509](https://our.internmc.facebook.com/intern/diff/D27109509)

[ghstack-poisoned]
@ezyang
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ezyang commented Mar 18, 2021

This needs reviews!

@ezyang ezyang requested a review from anjali411 March 18, 2021 17:10
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Nice cleanup - one nontrivial thing inline (if I'm reading the code right)

c10::DispatchKey typeIdWithDefault(PythonArgs& r, int64_t device_idx, c10::DispatchKey dispatch_key) {
auto device_type = r.isNone(device_idx) ? computeDeviceType(dispatch_key) : r.device(device_idx).type();
return backendToDispatchKey(backendToBackendOfDeviceType(dispatchKeyToBackend(dispatch_key), device_type));
c10::TensorOptions typeIdWithDefault(PythonArgs& r, int64_t device_idx, c10::DispatchKey dispatch_key) {
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This really is overdue for a rename but yeah there's no obvious upgrade. What about just optionsWithDefaultDevice or something?

auto options = dispatchKeyToTensorOptions(dispatch_key);
if (!r.isNone(device_idx)) {
// TODO: This line doesn't seem to be exercised at all in tests
options = options.device(r.device(device_idx).type());
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Doesn't this still have the problem you described in the "janky" note? Index gets scraped off in the same way as before I think.

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Yes, I think you're right. It's too bad I can't tell if it matters or not cuz it's not exercised by tests LOL

toString(dispatch_key), " (got ", toString(legacyExtractDispatchKey(other.key_set())), ")");
Tensor new_with_tensor(c10::TensorOptions options, at::ScalarType scalar_type, const Tensor& other) {
TORCH_CHECK_TYPE(other.options().type_equal(options), "expected ",
options, " (got ", other.options(), ")");
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a) I'm not sure which thing isn't right here b) regardless, is it worth putting in a comment?

// tensor should go to CUDA, so we have to get the information in somehow.
//
// This code is kind of jank. For one, the dtype in options is silently ignored
// by internal_new_from_data. Also, in classic janky code style, it used to
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This is a choice we're making in adopting the new scheme though, right? The relevant subset of stuff carried by an options argument will be context-dependent.

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Not... really? Previously the code accepted DispatchKey, but ignored everything besides the Device associated with that DispatchKey. Options is a bigger type, but the mismatch in size was always there in the code.

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ezyang commented Mar 19, 2021

Gonna see if I can land this stack ready to go (if it lands, I'll fix these in follow up), otherwise I'll address these comments

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@ezyang merged this pull request in e0aebe2.

@facebook-github-bot facebook-github-bot deleted the gh/ezyang/949/head branch March 23, 2021 14:16
laurentdupin pushed a commit to laurentdupin/pytorch that referenced this pull request Apr 24, 2026
…ytorch#54034)

Summary:
Pull Request resolved: pytorch#54034

Fixes pytorch#53544

I had to touch a bunch of lines but the refactoring was fairly
mechanical.  Here's how it works.

The basic concept behind this PR is that tensor_new.cpp was previously
abusing DispatchKey when it actually meant TensorOptions.  The provided
DispatchKey argument to most of the constructor functions typically
comes from torch::tensors::get_default_dispatch_key();  it doesn't
really make sense for people to set the default dispatch key, but
this got grandfathered in due to the old API set_default_tensor_type
(where the "Type" concept got refactored into "DispatchKey" concept
over time).  See also pytorch#53124.  But the upshot is that, semantically,
what we refer to as the default dispatch key really is more like
torch.set_default_tensor_type(torch.Tensor) versus
torch.set_default_tensor_type(torch.cuda.Tensor): clearly the user
wants to do something about *construction* of the tensor, and
TensorOptions captures that exactly.

So, how exactly to translate from one to the other?
- Sources (things that used to PRODUCE DispatchKey)
  - Most top level functions take a DispatchKey as their argument.  I
    use the new function dispatchKeyToTensorOptions to convert it into
    a TensorOptions
  - typeIdWithDefault now produces a TensorOptions (probably could do
    with a rename, though I didn't)
- Sinks (things that used to CONSUME DispatchKey)
  - Previously, the function options() was typically used to convert the
    DispatchKey into a TensorOptions.  Now its replacement build_options
    just takes a TensorOptions and sets some extra fields on it.
    Irritatingly, I can't just replace
    `build_options(options, scalar_type, device)` with
    `options.dtype(scalar_type).device(device)` because the semantics
    are slightly different: if device is nullopt, we should preserve
    the usage of the device specified in options (what options.device()
    does is overwrite the device unconditionally; e.g., if device is
    nullopt, unset device from options)
  - The other major sink for DispatchKey was `internal_new_from_data`,
    but it turns out it only really extracts the device type from
    the dispatch key.  Now it just pulls out the device from
    TensorOptions.
- To actually do the translation of DispatchKey to TensorOptions, I
  introduce new functions dispatchKeyToLayout (replicating
  layout_from_backend--there are still a few uses of this function
  so I couldn't delete it) and dispatchKeyToDeviceType (replacing
  computeDeviceType)
- In all internal functions, whenever DispatchKey is taken as an argument,
  I instead take TensorOptions as an argument, and pass it along.
- Anywhere `legacyExtractDispatchKey(other.key_set())` equality was
  previously used, I now do `other.options().type_equal()`, which
  is the intended BC for doing "backend to backend" comparisons
- There are a few places in the sparse constructors where we allocated
  a tensor for values, and then read out the dispatch key from the
  result to allocate the keys.  As best as I can tell, this is totally
  equivalent to just passing in the options to both values and indices
  (the only difference is dtype, which is captured via a separate
  argument)

This refactor doesn't really go far enough: for example, there are now
functions that take both TensorOptions and ScalarType, when really
the TensorOptions can capture this all.  I kept it solely just
s/DispatchKey/TensorOptions/ to reduce the number of possible bugs;
also, a lot of this will be mooted by a proper fix to pytorch#53124.

Even with this limited refactor, the payoff is sweet.  I can delete:

- backendToCPU
- backendToXPU
- backendToCUDA
- backendToHIP
- backendToBackendOfDeviceType

The reason I can do this is because I can simply overwrite layout in TensorOptions
to do the conversion, rather than having to type out each backend case
explicitly.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

Test Plan: Imported from OSS

Reviewed By: bhosmer

Differential Revision: D27109509

Pulled By: ezyang

fbshipit-source-id: 91d16cfbc390127770362ac04fb43f7e070077e9
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