(WIP) Batched autodiff #2181
(WIP) Batched autodiff #2181
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This still requires changes in the tblgenerated derivative files. For example, createForwardModeTangent in MulFOpFwdDerivative could be altered like this:
```
LogicalResult createForwardModeTangent(Operation *op0, OpBuilder &builder, MGradientUtils *gutils) const
{
auto op = cast<arith::MulFOp>(op0);
if (gutils->width != 1) {
auto newop = gutils->getNewFromOriginal(op0);
for (auto res : newop->getResults()) {
res.setType(mlir::RankedTensorType::get({gutils->width}, res.getType()));
}
}
gutils->eraseIfUnused(op);
if (gutils->isConstantInstruction(op))
return success();
mlir::Value res = nullptr;
if (!gutils->isConstantValue(op->getOperand(0)))
{
auto dif = gutils->invertPointerM(op->getOperand(0), builder);
{
mlir::Value itmp = ({
// Computing MulFOp
auto fwdarg_0 = dif;
dif.dump();
// TODO: gutils->makeBatched(...)
auto fwdarg_1 = gutils->getNewFromOriginal(op->getOperand(1));
builder.create<arith::MulFOp>(op.getLoc(), fwdarg_0, fwdarg_1);
});
itmp.dump();
if (!res)
res = itmp;
else
{
auto operandType = cast<AutoDiffTypeInterface>(res.getType());
res = operandType.createAddOp(builder, op.getLoc(), res, itmp);
}
}
}
if (!gutils->isConstantValue(op->getOperand(1)))
{
auto dif = gutils->invertPointerM(op->getOperand(1), builder);
{
mlir::Value itmp = ({
// Computing MulFOp
auto fwdarg_0 = dif;
dif.dump();
auto fwdarg_1 = gutils->getNewFromOriginal(op->getOperand(0));
builder.create<arith::MulFOp>(op.getLoc(), fwdarg_0, fwdarg_1);
});
if (!res)
res = itmp;
else
{
auto operandType = cast<AutoDiffTypeInterface>(res.getType());
res = operandType.createAddOp(builder, op.getLoc(), res, itmp);
}
}
}
assert(res);
gutils->setDiffe(op->getResult(0), res, builder);
return success();
}
```
| @@ -27,7 +27,11 @@ getFunctionTypeForClone(mlir::FunctionType FTy, DerivativeMode mode, | |||
| for (auto &&[Ty, returnPrimal, returnShadow, activity] : llvm::zip( | |||
| FTy.getResults(), returnPrimals, returnShadows, ReturnActivity)) { | |||
| if (returnPrimal) { | |||
| RetTypes.push_back(Ty); | |||
| if (width != 1) { | |||
| RetTypes.push_back(mlir::RankedTensorType::get({width}, Ty)); | |||
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This shouldn’t need changing since the primal is always unmodified, only Derivatives are changed (and we should be pushing the getshadow types for those below)
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Oh, then I'm confused of what batched autodiff is.
How should my testcase change?
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Nvm, it clicked. It's just the shadow that's batched 😅
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so here's an example from llvm vector mode for example: https://github.com/EnzymeAD/Enzyme/blob/main/enzyme/test/Enzyme/ForwardModeVector/add.ll
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tho perhaps mul will be more illustrative, https://github.com/EnzymeAD/Enzyme/blob/main/enzyme/test/Enzyme/ForwardModeVector/mul.ll (and obviously feel free to look at any/all of the other examples
|
I haven't yet fully made the changes in enzyme-tblgen.cpp, and either way this just works for the simple test case. mlir::Value itmp = ({
// Computing MulFOp
auto fwdarg_0 = dif;
auto fwdarg_1 = gutils->getNewFromOriginal(op->getOperand(1));
if (gutils->width != 1)
{
fwdarg_1 = builder.create<tensor::SplatOp>(
op.getLoc(),
mlir::RankedTensorType::get({gutils->width},
fwdarg_1.getType()),
fwdarg_1);
}
builder.create<arith::MulFOp>(op.getLoc(), fwdarg_0, fwdarg_1);
});But this is the MLIR code that is generated for this simple test: func.func private @fwddiffe2square(%arg0: f64, %arg1: tensor<2xf64>) -> tensor<2xf64> {
%splat = tensor.splat %arg0 : tensor<2xf64>
%0 = arith.mulf %arg1, %splat : tensor<2xf64>
%splat_0 = tensor.splat %arg0 : tensor<2xf64>
%1 = arith.mulf %arg1, %splat_0 : tensor<2xf64>
%2 = arith.addf %0, %1 : tensor<2xf64>
%3 = arith.mulf %arg0, %arg0 : f64
return %2 : tensor<2xf64>
} |
Added some type conversions to tensor types if
width != 1. The simple test case seems correct now.TODO: