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[TIR][Schedule] Derive Nonnegative Bounds from Shape Var #15210

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This PR enhance the arithmetic analysis used in compute-at to further help symbolic bound simplification.

Previously, when a variable n appears in the shape of an input buffer T.Buffer((n * 32), "float32"), we could safely assume that n is nonnegative as it is part of the shape. This could help us simplify some bounds during scheduling as well as lowering.

For example, for integers n and bx where bx has a symbolic bound [0, 32 * n), if n is nonnegative, we could simplify the following expressions to True:

0 <= floordiv(bx, n) < 32
0 <= floormod(bx, n) < n

This PR depends on #15193 to provide an interface that hints analyzer.

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@junrushao junrushao marked this pull request as ready for review July 3, 2023 03:51
This PR enhance the arithmetic analysis used in compute-at to further
help symbolic bound simplification.

Previously, when a variable `n` appears in the shape of an input buffer
`T.Buffer((n * 32), "float32")`, we could safely assume that `n` is
nonnegative as it is part of the shape. This could help us simplify some
bounds during scheduling as well as lowering.

For example, for integers `n` and `bx` where `bx` has a symbolic bound
`[0, 32 * n)`, if `n` is nonnegative, we could simplify the following
expressions to True:

```
0 <= floordiv(bx, n) < 32
0 <= floormod(bx, n) < n
```

This PR depends on apache#15193 to provide an interface that hints analyzer.
@junrushao junrushao force-pushed the feature/2023-07-02/compute-at-symbolic-bound branch from 1052628 to 17faf25 Compare July 3, 2023 05:14
@tqchen tqchen merged commit 03ef29e into apache:main Jul 3, 2023
junrushao added a commit to junrushao/tvm that referenced this pull request Jul 4, 2023
This PR enhances Decode-GEMV rule with the following changes:
- Normalize the GEMV iter domain to S-R-C via transform-block-layout.
  This would help with further analysis and scheduling, in cases for
  example, when there was no spatial loop in the original reduction
  block.
- Get rid of the ad hoc iter type analysis, including the logic calling
  into a TVM packed func `tir.schedule.GetLoopIterType` using
  `tvm._ffi.get_global_func`.
- Split out the logic for two separate cases of scheduling, where the
  innermost dimension is spatial or reduction.
- Introduces `suggest_threads_per_block` to guess the threads to be
  allocated each threadblock. This helps avoid the previous case where
  dlight allocates 256 threads for a workload whose degree of parallelism
  is only 128.
- Misc improvements.

This rest of the changes are split out to separate PRs that are already
merged to main.
- [x] Pass the hints to arithmetic analyzer that shape variables should
be positive ones (apache#15210)
- [x] Eliminate unnecessary block predicate generation - should be
provable via affine analysis (apache#15193)
- [x] Shrink local memory allocation if only one element `X[threadIdx.x]`
is used (apache#15207)
junrushao added a commit to junrushao/tvm that referenced this pull request Jul 4, 2023
This PR enhances Decode-GEMV rule with the following changes:
- Normalize the GEMV iter domain to S-R-C via transform-block-layout.
  This would help with further analysis and scheduling, in cases for
  example, when there was no spatial loop in the original reduction
  block.
- Get rid of the ad hoc iter type analysis, including the logic calling
  into a TVM packed func `tir.schedule.GetLoopIterType` using
  `tvm._ffi.get_global_func`.
- Split out the logic for two separate cases of scheduling, where the
  innermost dimension is spatial or reduction.
- Introduces `suggest_threads_per_block` to guess the threads to be
  allocated each threadblock. This helps avoid the previous case where
  dlight allocates 256 threads for a workload whose degree of parallelism
  is only 128.
- Misc improvements.

This rest of the changes are split out to separate PRs that are already
merged to main.
- [x] Pass the hints to arithmetic analyzer that shape variables should
be positive ones (apache#15210)
- [x] Eliminate unnecessary block predicate generation - should be
provable via affine analysis (apache#15193)
- [x] Shrink local memory allocation if only one element `X[threadIdx.x]`
is used (apache#15207)
junrushao added a commit to junrushao/tvm that referenced this pull request Jul 4, 2023
This PR enhances Decode-GEMV rule with the following changes:
- Normalize the GEMV iter domain to S-R-C via transform-block-layout.
  This would help with further analysis and scheduling, in cases for
  example, when there was no spatial loop in the original reduction
  block.
- Get rid of the ad hoc iter type analysis, including the logic calling
  into a TVM packed func `tir.schedule.GetLoopIterType` using
  `tvm._ffi.get_global_func`.
- Split out the logic for two separate cases of scheduling, where the
  innermost dimension is spatial or reduction.
- Introduces `suggest_threads_per_block` to guess the threads to be
  allocated each threadblock. This helps avoid the previous case where
  dlight allocates 256 threads for a workload whose degree of parallelism
  is only 128.
- Misc improvements.

This rest of the changes are split out to separate PRs that are already
merged to main.
- [x] Pass the hints to arithmetic analyzer that shape variables should
be positive ones (apache#15210)
- [x] Eliminate unnecessary block predicate generation - should be
provable via affine analysis (apache#15193)
- [x] Shrink local memory allocation if only one element `X[threadIdx.x]`
is used (apache#15207)
junrushao added a commit to junrushao/tvm that referenced this pull request Jul 4, 2023
This PR enhances Decode-GEMV rule with the following changes:
- Normalize the GEMV iter domain to S-R-C via transform-block-layout.
  This would help with further analysis and scheduling, in cases for
  example, when there was no spatial loop in the original reduction
  block.
- Get rid of the ad hoc iter type analysis, including the logic calling
  into a TVM packed func `tir.schedule.GetLoopIterType` using
  `tvm._ffi.get_global_func`.
- Split out the logic for two separate cases of scheduling, where the
  innermost dimension is spatial or reduction.
- Introduces `suggest_threads_per_block` to guess the threads to be
  allocated each threadblock. This helps avoid the previous case where
  dlight allocates 256 threads for a workload whose degree of parallelism
  is only 128.
- Misc improvements.

This rest of the changes are split out to separate PRs that are already
merged to main.
- [x] Pass the hints to arithmetic analyzer that shape variables should
be positive ones (apache#15210)
- [x] Eliminate unnecessary block predicate generation - should be
provable via affine analysis (apache#15193)
- [x] Shrink local memory allocation if only one element `X[threadIdx.x]`
is used (apache#15207)
junrushao added a commit to junrushao/tvm that referenced this pull request Jul 5, 2023
This PR enhances Decode-GEMV rule with the following changes:
- Normalize the GEMV iter domain to S-R-C via transform-block-layout.
  This would help with further analysis and scheduling, in cases for
  example, when there was no spatial loop in the original reduction
  block.
- Get rid of the ad hoc iter type analysis, including the logic calling
  into a TVM packed func `tir.schedule.GetLoopIterType` using
  `tvm._ffi.get_global_func`.
- Split out the logic for two separate cases of scheduling, where the
  innermost dimension is spatial or reduction.
- Introduces `suggest_threads_per_block` to guess the threads to be
  allocated each threadblock. This helps avoid the previous case where
  dlight allocates 256 threads for a workload whose degree of parallelism
  is only 128.
- Misc improvements.

This rest of the changes are split out to separate PRs that are already
merged to main.
- [x] Pass the hints to arithmetic analyzer that shape variables should
be positive ones (apache#15210)
- [x] Eliminate unnecessary block predicate generation - should be
provable via affine analysis (apache#15193)
- [x] Shrink local memory allocation if only one element `X[threadIdx.x]`
is used (apache#15207)
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4 participants