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// SPDX-License-Identifier: Apache-2.0
package firrtl
package passes
import firrtl.Mappers._
import firrtl.ir._
import Utils.throwInternalError
import firrtl.options.Dependency
/** Remove [[firrtl.ir.ValidIf ValidIf]] and replace [[firrtl.ir.IsInvalid IsInvalid]] with a connection to zero */
object RemoveValidIf extends Pass {
val UIntZero = Utils.zero
val SIntZero = SIntLiteral(BigInt(0), IntWidth(1))
val ClockZero = DoPrim(PrimOps.AsClock, Seq(UIntZero), Seq.empty, ClockType)
val FixedZero = FixedLiteral(BigInt(0), IntWidth(1), IntWidth(0))
val AsyncZero = DoPrim(PrimOps.AsAsyncReset, Seq(UIntZero), Nil, AsyncResetType)
/** Returns an [[firrtl.ir.Expression Expression]] equal to zero for a given [[firrtl.ir.GroundType GroundType]]
* @note Accepts [[firrtl.ir.Type Type]] but dyanmically expects [[firrtl.ir.GroundType GroundType]]
*/
def getGroundZero(tpe: Type): Expression = tpe match {
case g: GroundType => Utils.getGroundZero(g)
case other => throwInternalError(s"Unexpected type $other")
}
override def prerequisites = firrtl.stage.Forms.LowForm
override def optionalPrerequisiteOf =
Seq(Dependency[SystemVerilogEmitter], Dependency[VerilogEmitter])
override def invalidates(a: Transform): Boolean = a match {
case _: firrtl.transforms.ConstantPropagation => true // switching out the validifs allows for more constant prop
case _ => false
}
// Recursive. Removes ValidIfs
private def onExp(e: Expression): Expression = {
e.map(onExp) match {
case ValidIf(_, value, _) => value
case x => x
}
}
// Recursive. Replaces IsInvalid with connecting zero
private def onStmt(s: Statement): Statement = s.map(onStmt).map(onExp) match {
case invalid @ IsInvalid(info, loc) =>
loc.tpe match {
case _: AnalogType => EmptyStmt
case tpe => Connect(info, loc, getGroundZero(tpe))
}
case other => other
}
private def onModule(m: DefModule): DefModule = {
m match {
case m: Module => Module(m.info, m.name, m.ports, onStmt(m.body))
case m: ExtModule => m
}
}
def run(c: Circuit): Circuit = Circuit(c.info, c.modules.map(onModule), c.main)
}
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