[Gemmini] Fuse linalg.matmul and linalg.transpose when lowering to Gemmini DIalect #300
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| /*bScaleFactor = */ scale1, /*dScaleFactor = */ scale1, /*act = */ 0, | ||
| /*accScale = */ scale1, /*bertScale = */ scale0); | ||
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| // llvm::outs() << " has " |
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Clear the comments here.
| // If this matmul operation is followed by a transpose operation, do fusion. | ||
| // We should make sure that the result of this matmul op only has one user. | ||
| Operation* fuseOp = *output0.user_begin(); | ||
| int output0Use = 0; |
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There is a serious error in logic here.I would suggest writing the pattern inside the canonicalizer of the gemmini.tile_matmul op.What you should be determining is whether there is only one user of gemmini.tile_matmul and it is linalg.transpose.bTranspose is a attribute, so let it be the opposite.You shouldn't be judging the number of linalg.transpose, it's completely wrong to do so.A pass is based on a greedy algorithm, so this pass will continue to match against the pattern.
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Hi, thanks for your suggestions. I agree that it is indeed possible to do the match during gemmini.tile_matmul lowering. However, I still don’t understand why there is a problem with greedy matching here. Can you give an example here? Maybe I’m not that familiar with it yet.
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%1 = gemmini.tile_matmul {transepose = false}
.....
%4 = linalg.transpose %1
.....
%7 = linalg.transpose %4
.....
use(%7)
first
%1 = gemmini.tile_matmul {transepose = true}
.....
%7 = linalg.transpose %1
.....
use(%7)
second
%1 = gemmini.tile_matmul {transepose = false}
.....
use(%1)
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%1 = gemmini.tile_matmul {transepose = false}
.....
%4 = linalg.transpose %1
.....
%7 = linalg.transpose %1
I'm not sure if this happens in the model not sure if it does.
So for this fuse pattern, you should make sure that there is only one op that uses gemmini.tile_matmul and that op is linalg.transpose.
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| if (output0Use) { | ||
| // llvm::outs() << "Fuse linalg.matmul and linalg.transpose. \n"; |
| /*bScaleFactor = */ scale1, /*dScaleFactor = */ scale1, /*act = */0, | ||
| /*accScale = */ scale1, /*bertScale = */ scale0, | ||
| /*repeatingBias = */ false, /*aTranspose = */ true, | ||
| /*bTranspose = */ true); |
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bTranspose is an attribute.Obviously the method to create gemmini.tile_matmul here just write one.
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For C = AB, C = C^T, we use this formula : C^T = (AB)^T = B^T A^T.
So, we change the position of input0 and input1, and set aTranspose and bTranspose true.
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If so, the reasoning is the same, you just need to make aTranspose the opposite of bTransepose as before.
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Regarding the conclusion that transpose is not supported, it is recommended that you write a C program to test it. The table is an indication of whether or not to transpose A and B. In this case, it is transpose C. |
As transposer is provied by Gemmini Arch, we can benefit from it when a matmul opearation is followed by a transpose operation. In this PR, we try to fuse
linalg.matmulandlinalg.transposewhen lowering to Gemmini DIalect. And we make sure that the result of this matmul operation only has one user.However, when we use WS dataflow, A_transpose and B_transpose is not supported simultaneously. You can check this in https://github.com/ucb-bar/gemmini.
So we can compile succefully now, but may get incorrect result finally.