[FIRRTL] DropConst pass #5152
[FIRRTL] DropConst pass #5152
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If you move the when op checking to a verifier, then you could probably re-write this very generically:
op->walk([](op){
if (op.isa<ConstCast>())
....
for (region : op.getRegion)
for (block : region.getBlocks)
for (blarg : block.getArguments)
blarg.setType(updateType(blarg.getType));
for (result : op.getResult())
result.setType(updateType(result.getType());
We need to start thinking about how enumeration types and const are going to work.
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Didn't review this as closely as before. I think you can merge this, or if you want to increase your commit count, split it up into 3 commits for DropConst pass, const drop type changes + SubAccess::inferReturnType, connect verifier.
Do we properly handle the error detection in this case?
module Foo:
input i : UInt<4>
output c : const UInt<8>[16]
; It is an error to use a non-const index to drive a value to a const
c[i] <= UInt<8>(10)
Would be nice if we didn't walk the subaccess chain twice in the connect verifier, but we can iterate on it. We have also talked about moving the flow verification on to the module, as it might be faster to do it as a dataflow pass. We could do something similar with the const correctness verification.
I believe these tests cover the subaccess cases: circt/test/Dialect/FIRRTL/connect-errors.mlir Line 614 in 71ed710 circt/test/Dialect/FIRRTL/connect-errors.mlir Line 626 in 71ed710 |
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Updated to disallow any assignment to a subaccess that drops const |
Builds on #5151.
Added DropConst pass that checks const usage in when blocks, then drops all
const modifiers from types.