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[FIRRTL][LowerLayers] Lower layers does not update HPs of non-local annotations
Given this firrtl IR:
FIRRTL version 4.0.0
circuit Top: %[[ {"class": "circt.test", "target": "~Top|Top/foo:Foo>w"} ]]
layer A, bind:
public module Top:
inst foo of Foo
inst bar of Foo
module Foo:
layerblock A:
wire w : UInt<8>
invalidate w
compiling with firtool -parse-only test.fir
gives the following IR:
module {
firrtl.circuit "Top" {
hw.hierpath private @nla [@Top::@sym, @Foo]
firrtl.layer @A bind {
}
firrtl.module @Top() attributes {convention = #firrtl<convention scalarized>} {
firrtl.instance foo sym @sym interesting_name @Foo()
firrtl.instance bar interesting_name @Foo()
}
firrtl.module private @Foo() {
firrtl.layerblock @A {
%w = firrtl.wire interesting_name {annotations = [{circt.nonlocal = @nla, class = "circt.test"}]} : !firrtl.uint<8>
%invalid_ui8 = firrtl.invalidvalue : !firrtl.uint<8>
firrtl.matchingconnect %w, %invalid_ui8 : !firrtl.uint<8>
}
}
}
}
After LowerLayers runs we get this IR:
// -----// IR Dump After LowerLayers (firrtl-lower-layers) //----- //
firrtl.circuit "Top" {
sv.verbatim "`ifndef layers_Top_A\0A`define layers_Top_A" {output_file = #hw.output_file<"layers_Top_A.sv", excludeFromFileList>}
hw.hierpath private @nla [@Top::@sym, @Foo]
firrtl.module @Top() attributes {convention = #firrtl<convention scalarized>} {
firrtl.instance foo sym @sym @Foo()
firrtl.instance bar @Foo()
}
firrtl.module private @Foo_A() {
%w = firrtl.wire {annotations = [{circt.nonlocal = @nla, class = "circt.test"}]} : !firrtl.uint<8>
%c0_ui8 = firrtl.constant 0 : !firrtl.uint<8>
firrtl.matchingconnect %w, %c0_ui8 : !firrtl.uint<8>
}
firrtl.module private @Foo() {
firrtl.instance a {lowerToBind, output_file = #hw.output_file<"layers_Top_A.sv", excludeFromFileList>} @Foo_A()
}
sv.verbatim "`endif // layers_Top_A" {output_file = #hw.output_file<"layers_Top_A.sv", excludeFromFileList>}
}
This issue is that the non-local annotation on wire w
is not updated when the wire is moved in to a module Foo_A
, and corresponding hierpath operation still points to @Foo
. I.e.
hw.hierpath private @nla [@Top::@sym, @Foo]
should be
hw.hierpath private @nla [@Top::@sym, @Foo::@a_sym, @Foo_A]
and the instance of Foo_A
needs a new symbol a_sym
.
Note that we can't just modify the original HierpathOp, since it may have other users which were not moved, so we must create a new Hierpath op.
This currently does not trigger a verifier error, which has a tracking issue here: https://github.com/llvm/circt/issues/4896 A similar issue was tackled here: https://github.com/llvm/circt/issues/6717