[PATCH] D70897: [Matrix] Add forward shape propagation and first shape aware lowerings.

[LuoYuanke via Phabricator via llvm-commits]

LuoYuanke added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/LowerMatrixIntrinsics.cpp:365
+        if (OpShape != ShapeMap.end())
+          setShapeInfo(Inst, OpShape->second);
+        continue;
----------------
fhahn wrote:
> LuoYuanke wrote:
> > It seems only store instruction is propagated with the shape information. Why? Take below pseudo code for example. Are v2 and v3 propagated with the shape information?   
> > ```
> > v1 = matrix_columnwise_load(..., m, n)
> > v2 = max(v1, 0)
> > v3 = v1 / v2
> > store v3, ptr
> > ```
> This patch mostly adds the infrastructure for the propagation and only uses it for store instructions. So in the example, the shape is not propagated by this patch.
> 
> Additional support for loads (D70900), binary operators (D70898) and back-propagation (D70899) are added in follow-up commits, to make reviewing them more manageable. The whole patch series is linked in Phabricator (see the 'stack' section).
> 
> Please note that we could propagate shape information to more instructions, e.g. phis or selects. That can be added as follow-up as well, it is just a matter of priorities (we found loads/stores/binary operators to be by far the most common operations in matrix expressions). Any help with covering more cases would be very welcome :)
Thank you for reply. Do you propagate the shape information recursively? If the matrix is stored to memory, does the propagation break? Can we get the shape information when reload the matrix from memory?

```
v1 = matrix_multipy(..., m, n, k)
store v1, ptr *
v2 = load ptr*
```
How do we pass the shape information across function and return shape from function? Do you plan to have matrix as first class type?

```
v1 = matrix_multipy(..., m, n, k)
v2 = call foo(v1)
```


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  https://reviews.llvm.org/D70897/new/

https://reviews.llvm.org/D70897