adding option to par-to-seq that doesn't attempt to establish total o…

…rder

calyx-opt/src/passes/par_to_seq.rs

@@ -1,11 +1,14 @@
 use crate::analysis;
-use crate::traversal::{Action, Named, VisResult, Visitor};
+use crate::traversal::{
+    Action, ConstructVisitor, Named, ParseVal, PassOpt, VisResult, Visitor,
+};
 use calyx_ir::{self as ir, LibrarySignatures};
+use calyx_utils::CalyxResult;
 
-#[derive(Default)]
 /// Transforms all `par` into `seq`. Uses [analysis::ControlOrder] to get a
 /// sequentialization of `par` such that the program still computes the same
-/// value. When there is no such sequentialization, errors out.
+/// value. When there is no such sequentialization, errors out unless the
+/// `always_sequentialize` option is true.
 ///
 ///
 /// # Example
@@ -21,7 +24,11 @@ use calyx_ir::{self as ir, LibrarySignatures};
 /// ```
 ///
 /// To remove uneccessarily nested `par` blocks, run collapse-control.
-pub struct ParToSeq;
+pub struct ParToSeq {
+    /// sequentializes without checking
+    /// NOTE: does not guarantee correctness on shared reads and writes
+    always_sequentialize: bool,
+}
 
 impl Named for ParToSeq {
     fn name() -> &'static str {
@@ -31,6 +38,32 @@ impl Named for ParToSeq {
     fn description() -> &'static str {
         "Transform `par` blocks to `seq`"
     }
+
+    fn opts() -> Vec<crate::traversal::PassOpt> {
+        vec![PassOpt::new(
+            "always-sequentialize",
+            "Sequentializes the program without attempting to preserve dataflow dependencies.",
+            ParseVal::Bool(false),
+            PassOpt::parse_bool,
+        )]
+    }
+}
+
+impl ConstructVisitor for ParToSeq {
+    fn from(ctx: &ir::Context) -> CalyxResult<Self>
+    where
+        Self: Sized + Named,
+    {
+        let opts = Self::get_opts(ctx);
+
+        Ok(ParToSeq {
+            always_sequentialize: opts[&"always-sequentialize"].bool(),
+        })
+    }
+
+    fn clear_data(&mut self) {
+        /* All data can be transferred between components */
+    }
 }
 
 impl Visitor for ParToSeq {
@@ -42,9 +75,14 @@ impl Visitor for ParToSeq {
         _c: &LibrarySignatures,
         _comps: &[ir::Component],
     ) -> VisResult {
-        let total_order =
-            analysis::ControlOrder::<true>::get_total_order(s.stmts.drain(..))?;
-        let par = ir::Control::seq(total_order);
+        let par = if self.always_sequentialize {
+            ir::Control::seq(s.stmts.drain(..).collect())
+        } else {
+            let total_order = analysis::ControlOrder::<true>::get_total_order(
+                s.stmts.drain(..),
+            )?;
+            ir::Control::seq(total_order)
+        };
         Ok(Action::change(par))
     }
 }