From 30907da717ec3c75090b83406f66720f24ed8c6f Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Thu, 6 Jun 2024 23:13:11 -0400
Subject: [PATCH 1/9] This actually took me like a week

---
 calyx-frontend/src/attribute.rs               |  4 +++
 calyx-opt/src/analysis/promotion_analysis.rs  |  2 +-
 calyx-opt/src/passes/static_promotion.rs      |  8 ++++-
 .../src/passes/top_down_compile_control.rs    | 12 ++++++--
 temp/Makefile                                 |  4 +++
 temp/test.futil                               | 29 +++++++++++++++++++
 6 files changed, 54 insertions(+), 5 deletions(-)
 create mode 100644 temp/Makefile
 create mode 100644 temp/test.futil

diff --git a/calyx-frontend/src/attribute.rs b/calyx-frontend/src/attribute.rs
index 79e5c76042..3ffe749ef5 100644
--- a/calyx-frontend/src/attribute.rs
+++ b/calyx-frontend/src/attribute.rs
@@ -69,7 +69,11 @@ pub enum BoolAttr {
     #[strum(serialize = "promoted")]
     /// denotes a static component or control promoted from dynamic
     Promoted,
+    #[strum(serialize = "fast")]
+    /// https://github.com/calyxir/calyx/issues/1828
+    Fast,
 }
+
 impl From<BoolAttr> for Attribute {
     fn from(attr: BoolAttr) -> Self {
         Attribute::Bool(attr)
diff --git a/calyx-opt/src/analysis/promotion_analysis.rs b/calyx-opt/src/analysis/promotion_analysis.rs
index 938ba31aca..adbfd9fa8b 100644
--- a/calyx-opt/src/analysis/promotion_analysis.rs
+++ b/calyx-opt/src/analysis/promotion_analysis.rs
@@ -1,4 +1,4 @@
-use calyx_ir::{self as ir};
+use calyx_ir::{self as ir, BoolAttr};
 use std::collections::HashMap;
 use std::rc::Rc;
 
diff --git a/calyx-opt/src/passes/static_promotion.rs b/calyx-opt/src/passes/static_promotion.rs
index b13c116955..00a64c323c 100644
--- a/calyx-opt/src/passes/static_promotion.rs
+++ b/calyx-opt/src/passes/static_promotion.rs
@@ -5,7 +5,7 @@ use crate::traversal::{
     Action, ConstructVisitor, Named, Order, ParseVal, PassOpt, VisResult,
     Visitor,
 };
-use calyx_ir::{self as ir, LibrarySignatures};
+use calyx_ir::{self as ir, BoolAttr, LibrarySignatures};
 use calyx_utils::CalyxResult;
 use ir::GetAttributes;
 use itertools::Itertools;
@@ -490,6 +490,12 @@ impl Visitor for StaticPromotion {
             })
         };
         self.inference_analysis.fixup_ctrl(&mut new_ctrl);
+
+        // this might be part of a larger issue where passes remove some attributes they shouldn't
+        if s.get_attributes().has(BoolAttr::Fast) {
+            new_ctrl.get_mut_attributes().insert(BoolAttr::Fast, 1);
+        }
+
         Ok(Action::change(new_ctrl))
     }
 
diff --git a/calyx-opt/src/passes/top_down_compile_control.rs b/calyx-opt/src/passes/top_down_compile_control.rs
index 872604233a..6525ce7ccf 100644
--- a/calyx-opt/src/passes/top_down_compile_control.rs
+++ b/calyx-opt/src/passes/top_down_compile_control.rs
@@ -3,7 +3,9 @@ use crate::passes;
 use crate::traversal::{
     Action, ConstructVisitor, Named, ParseVal, PassOpt, VisResult, Visitor,
 };
-use calyx_ir::{self as ir, GetAttributes, LibrarySignatures, Printer, RRC};
+use calyx_ir::{
+    self as ir, BoolAttr, GetAttributes, LibrarySignatures, Printer, RRC,
+};
 use calyx_ir::{build_assignments, guard, structure, Id};
 use calyx_utils::Error;
 use calyx_utils::{CalyxResult, OutputFile};
@@ -495,7 +497,7 @@ impl Schedule<'_, '_> {
             // NOTE: We explicilty do not add `not_done` to the guard.
             // See explanation in [ir::TopDownCompileControl] to understand
             // why.
-            if early_transitions {
+            if early_transitions || con.has_attribute(BoolAttr::Fast) {
                 for (st, g) in &prev_states {
                     let early_go = build_assignments!(self.builder;
                         group["go"] = g ? signal_on["out"];
@@ -1130,7 +1132,11 @@ impl Visitor for TopDownCompileControl {
         let mut builder = ir::Builder::new(comp, sigs);
         let mut sch = Schedule::from(&mut builder);
         // Add assignments for the final states
-        sch.calculate_states(&control.borrow(), self.early_transitions)?;
+        sch.calculate_states(
+            &control.borrow(),
+            self.early_transitions
+                || control.borrow().has_attribute(BoolAttr::Fast),
+        )?;
         let comp_group =
             sch.realize_schedule(self.dump_fsm, &mut self.fsm_groups);
         if let Some(json_out_file) = &self.dump_fsm_json {
diff --git a/temp/Makefile b/temp/Makefile
new file mode 100644
index 0000000000..7e2fc24542
--- /dev/null
+++ b/temp/Makefile
@@ -0,0 +1,4 @@
+.PHONY: run
+run:
+	cd .. && cargo build
+	calyx-pass -e ../target/debug/calyx -c main -b tdcc test.futil
diff --git a/temp/test.futil b/temp/test.futil
new file mode 100644
index 0000000000..88c70a80e7
--- /dev/null
+++ b/temp/test.futil
@@ -0,0 +1,29 @@
+import "primitives/core.futil";
+import "primitives/memories/comb.futil";
+
+component main(@go go: 1) -> (@done done: 1) {
+  cells {
+    @external(1) in_mem = comb_mem_d1(32, 1, 32);
+    @external(1) out_mem = comb_mem_d1(32, 1, 32);
+    i0 = std_reg(32);
+  }
+  wires {
+    group d1 {
+      in_mem.addr0 = 32'd0;
+      i0.in = in_mem.read_data;
+      i0.write_en = 1'b1;
+      d1[done] = i0.done;
+    }
+    static<1> group s2 {
+      in_mem.addr0 = 32'd0;
+      out_mem.write_data = i0.out;
+      out_mem.write_en = 1'b1;
+    }
+  }
+  control {
+    @fast seq {
+      d1;
+      s2;
+    }
+  }
+}

From d7dafc48726b549c6c3089eef8fbbdaf428bfb44 Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Fri, 7 Jun 2024 00:25:46 -0400
Subject: [PATCH 2/9] Add well-formed check for @fast

---
 calyx-opt/src/analysis/promotion_analysis.rs  |  2 +-
 calyx-opt/src/passes/well_formed.rs           | 39 +++++++++++++++++++
 runt.toml                                     | 23 +++++++++--
 temp/test.futil                               |  1 -
 temp/test2.futil                              | 28 +++++++++++++
 .../as_least_as_fast/dynamic_static.futil     | 28 +++++++++++++
 .../as_least_as_fast/static_dynamic.futil     | 28 +++++++++++++
 .../fast-attr/semantic_preservation/.gitkeep  |  0
 .../semantic_preservation/README.txt          |  1 +
 9 files changed, 145 insertions(+), 5 deletions(-)
 create mode 100644 temp/test2.futil
 create mode 100644 tests/correctness/fast-attr/as_least_as_fast/dynamic_static.futil
 create mode 100644 tests/correctness/fast-attr/as_least_as_fast/static_dynamic.futil
 create mode 100644 tests/correctness/fast-attr/semantic_preservation/.gitkeep
 create mode 100644 tests/correctness/fast-attr/semantic_preservation/README.txt

diff --git a/calyx-opt/src/analysis/promotion_analysis.rs b/calyx-opt/src/analysis/promotion_analysis.rs
index adbfd9fa8b..938ba31aca 100644
--- a/calyx-opt/src/analysis/promotion_analysis.rs
+++ b/calyx-opt/src/analysis/promotion_analysis.rs
@@ -1,4 +1,4 @@
-use calyx_ir::{self as ir, BoolAttr};
+use calyx_ir::{self as ir};
 use std::collections::HashMap;
 use std::rc::Rc;
 
diff --git a/calyx-opt/src/passes/well_formed.rs b/calyx-opt/src/passes/well_formed.rs
index ddc9ba06e5..168d3e10dc 100644
--- a/calyx-opt/src/passes/well_formed.rs
+++ b/calyx-opt/src/passes/well_formed.rs
@@ -3,6 +3,7 @@ use calyx_ir::{
     self as ir, CellType, Component, GetAttributes, LibrarySignatures,
     RESERVED_NAMES,
 };
+use calyx_ir::{BoolAttr, Seq};
 use calyx_utils::{CalyxResult, Error, WithPos};
 use ir::Nothing;
 use ir::StaticTiming;
@@ -203,6 +204,30 @@ fn same_type(proto_out: &CellType, proto_in: &CellType) -> CalyxResult<()> {
     }
 }
 
+/// Confirms (in agreement with [this discussion](https://github.com/calyxir/calyx/issues/1828))
+/// that the `@fast` sequence `seq` is composed of alternating static-dynamic controls.
+fn check_fast_seq_invariant(seq: &Seq) -> CalyxResult<()> {
+    if seq.stmts.is_empty() {
+        return Ok(());
+    }
+    let mut last_is_static = seq
+        .stmts
+        .first()
+        .expect("non-empty already asserted")
+        .is_static();
+    for stmt in seq.stmts.iter().skip(1) {
+        if stmt.is_static() == last_is_static {
+            return Err(
+                Error::malformed_control(
+                    "`seq` marked `@fast` does not contain alternating static-dynamic control children (see #1828)"
+                )
+            );
+        }
+        last_is_static = stmt.is_static();
+    }
+    Ok(())
+}
+
 impl Visitor for WellFormed {
     fn start(
         &mut self,
@@ -680,6 +705,20 @@ impl Visitor for WellFormed {
         Ok(Action::Continue)
     }
 
+    fn start_seq(
+        &mut self,
+        s: &mut calyx_ir::Seq,
+        _comp: &mut Component,
+        _sigs: &LibrarySignatures,
+        _comps: &[calyx_ir::Component],
+    ) -> VisResult {
+        if s.attributes.has(BoolAttr::Fast) {
+            check_fast_seq_invariant(s)?;
+        }
+
+        Ok(Action::Continue)
+    }
+
     fn finish_if(
         &mut self,
         s: &mut ir::If,
diff --git a/runt.toml b/runt.toml
index 9b1fda3484..09bd73e520 100644
--- a/runt.toml
+++ b/runt.toml
@@ -233,9 +233,7 @@ timeout = 120
 
 [[tests]]
 name = "correctness static timing one-hot encoding"
-paths = [
-  "tests/correctness/static-interface/*.futil",
-]
+paths = ["tests/correctness/static-interface/*.futil"]
 cmd = """
 fud exec --from calyx --to jq \
          --through verilog \
@@ -334,6 +332,25 @@ fud exec --from calyx --to jq \
          {} -q
 """
 
+# todo: need to test that removing @fast (e.g. using sed) causes >= cycles
+#
+# Copilot said:
+#   # Replace 'command1' and 'command2' with your actual commands
+#   [[ $(command1) -le $(command2) ]] && echo "true" || echo "false"
+#
+# [[tests]]
+# name = "correctness: @fast improves speed"
+# paths = ["tests/correctness/fast-attr/at_least_as_fast/*.futil"]
+# cmd = """
+# fud exec --from calyx --to jq \
+#          --through dat \
+#          --through verilog \
+#          -s verilog.data {}.data \
+#          -s calyx.flags "-d static-promotion" \
+#          -s jq.expr ".cycles" \
+#          {} -q
+# """
+
 [[tests]]
 name = "[frontend] tcam testing"
 paths = ["tests/correctness/tcam/*.futil"]
diff --git a/temp/test.futil b/temp/test.futil
index 88c70a80e7..ab6e0a01ef 100644
--- a/temp/test.futil
+++ b/temp/test.futil
@@ -15,7 +15,6 @@ component main(@go go: 1) -> (@done done: 1) {
       d1[done] = i0.done;
     }
     static<1> group s2 {
-      in_mem.addr0 = 32'd0;
       out_mem.write_data = i0.out;
       out_mem.write_en = 1'b1;
     }
diff --git a/temp/test2.futil b/temp/test2.futil
new file mode 100644
index 0000000000..e7e55d245e
--- /dev/null
+++ b/temp/test2.futil
@@ -0,0 +1,28 @@
+import "primitives/core.futil";
+import "primitives/memories/comb.futil";
+
+component main(@go go: 1) -> (@done done: 1) {
+  cells {
+    @external(1) in_mem = comb_mem_d1(32, 1, 32);
+    @external(1) out_mem = comb_mem_d1(32, 1, 32);
+    i0 = std_reg(32);
+  }
+  wires {
+    static<1> group s1 {
+      in_mem.addr0 = 32'd0;
+      i0.in = in_mem.read_data;
+      i0.write_en = 1'b1;
+    }
+    group d2 {
+      out_mem.write_data = i0.out;
+      out_mem.write_en = 1'b1;
+      d2[done] = out_mem.done;
+    }
+  }
+  control {
+    @fast seq {
+      s1;
+      d2;
+    }
+  }
+}
diff --git a/tests/correctness/fast-attr/as_least_as_fast/dynamic_static.futil b/tests/correctness/fast-attr/as_least_as_fast/dynamic_static.futil
new file mode 100644
index 0000000000..ab6e0a01ef
--- /dev/null
+++ b/tests/correctness/fast-attr/as_least_as_fast/dynamic_static.futil
@@ -0,0 +1,28 @@
+import "primitives/core.futil";
+import "primitives/memories/comb.futil";
+
+component main(@go go: 1) -> (@done done: 1) {
+  cells {
+    @external(1) in_mem = comb_mem_d1(32, 1, 32);
+    @external(1) out_mem = comb_mem_d1(32, 1, 32);
+    i0 = std_reg(32);
+  }
+  wires {
+    group d1 {
+      in_mem.addr0 = 32'd0;
+      i0.in = in_mem.read_data;
+      i0.write_en = 1'b1;
+      d1[done] = i0.done;
+    }
+    static<1> group s2 {
+      out_mem.write_data = i0.out;
+      out_mem.write_en = 1'b1;
+    }
+  }
+  control {
+    @fast seq {
+      d1;
+      s2;
+    }
+  }
+}
diff --git a/tests/correctness/fast-attr/as_least_as_fast/static_dynamic.futil b/tests/correctness/fast-attr/as_least_as_fast/static_dynamic.futil
new file mode 100644
index 0000000000..e7e55d245e
--- /dev/null
+++ b/tests/correctness/fast-attr/as_least_as_fast/static_dynamic.futil
@@ -0,0 +1,28 @@
+import "primitives/core.futil";
+import "primitives/memories/comb.futil";
+
+component main(@go go: 1) -> (@done done: 1) {
+  cells {
+    @external(1) in_mem = comb_mem_d1(32, 1, 32);
+    @external(1) out_mem = comb_mem_d1(32, 1, 32);
+    i0 = std_reg(32);
+  }
+  wires {
+    static<1> group s1 {
+      in_mem.addr0 = 32'd0;
+      i0.in = in_mem.read_data;
+      i0.write_en = 1'b1;
+    }
+    group d2 {
+      out_mem.write_data = i0.out;
+      out_mem.write_en = 1'b1;
+      d2[done] = out_mem.done;
+    }
+  }
+  control {
+    @fast seq {
+      s1;
+      d2;
+    }
+  }
+}
diff --git a/tests/correctness/fast-attr/semantic_preservation/.gitkeep b/tests/correctness/fast-attr/semantic_preservation/.gitkeep
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tests/correctness/fast-attr/semantic_preservation/README.txt b/tests/correctness/fast-attr/semantic_preservation/README.txt
new file mode 100644
index 0000000000..707588bd03
--- /dev/null
+++ b/tests/correctness/fast-attr/semantic_preservation/README.txt
@@ -0,0 +1 @@
+TODO: tests that using `@fast` does not change the function of the program

From 0ecda0c311684c40ef16afbbc6b39e2a0738bc9e Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Mon, 10 Jun 2024 12:07:37 -0400
Subject: [PATCH 3/9] Prevent  from cascading

---
 .../src/passes/top_down_compile_control.rs    | 24 ++++++++++++-------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/calyx-opt/src/passes/top_down_compile_control.rs b/calyx-opt/src/passes/top_down_compile_control.rs
index 6525ce7ccf..e2c2f783ef 100644
--- a/calyx-opt/src/passes/top_down_compile_control.rs
+++ b/calyx-opt/src/passes/top_down_compile_control.rs
@@ -462,6 +462,8 @@ impl Schedule<'_, '_> {
         preds: Vec<PredEdge>,
         // True if early_transitions are allowed
         early_transitions: bool,
+        // True if the `@fast` attribute has successfully been applied to the parent of this control
+        has_fast_guarantee: bool,
     ) -> CalyxResult<Vec<PredEdge>> {
         match con {
         // See explanation of FSM states generated in [ir::TopDownCompileControl].
@@ -497,7 +499,7 @@ impl Schedule<'_, '_> {
             // NOTE: We explicilty do not add `not_done` to the guard.
             // See explanation in [ir::TopDownCompileControl] to understand
             // why.
-            if early_transitions || con.has_attribute(BoolAttr::Fast) {
+            if early_transitions || has_fast_guarantee {
                 for (st, g) in &prev_states {
                     let early_go = build_assignments!(self.builder;
                         group["go"] = g ? signal_on["out"];
@@ -544,9 +546,13 @@ impl Schedule<'_, '_> {
         early_transitions: bool,
     ) -> CalyxResult<Vec<PredEdge>> {
         let mut prev = preds;
-        for stmt in &seq.stmts {
-            prev =
-                self.calculate_states_recur(stmt, prev, early_transitions)?;
+        for (i, stmt) in seq.stmts.iter().enumerate() {
+            prev = self.calculate_states_recur(
+                stmt,
+                prev,
+                early_transitions,
+                i > 0 && seq.get_attributes().has(BoolAttr::Fast),
+            )?;
         }
         Ok(prev)
     }
@@ -579,6 +585,7 @@ impl Schedule<'_, '_> {
             &if_stmt.tbranch,
             tru_transitions,
             early_transitions,
+            false,
         )?;
         // Previous states transitioning into false branch need the conditional
         // to be false.
@@ -596,6 +603,7 @@ impl Schedule<'_, '_> {
                 &if_stmt.fbranch,
                 fal_transitions,
                 early_transitions,
+                false,
             )?
         };
 
@@ -638,6 +646,7 @@ impl Schedule<'_, '_> {
             &while_stmt.body,
             transitions,
             early_transitions,
+            false,
         )?;
 
         // Step 3: The final out edges from the while come from:
@@ -742,6 +751,7 @@ impl Schedule<'_, '_> {
             con,
             vec![first_state],
             early_transitions,
+            false,
         )?;
         self.add_nxt_transition(prev);
         Ok(())
@@ -1132,11 +1142,7 @@ impl Visitor for TopDownCompileControl {
         let mut builder = ir::Builder::new(comp, sigs);
         let mut sch = Schedule::from(&mut builder);
         // Add assignments for the final states
-        sch.calculate_states(
-            &control.borrow(),
-            self.early_transitions
-                || control.borrow().has_attribute(BoolAttr::Fast),
-        )?;
+        sch.calculate_states(&control.borrow(), self.early_transitions)?;
         let comp_group =
             sch.realize_schedule(self.dump_fsm, &mut self.fsm_groups);
         if let Some(json_out_file) = &self.dump_fsm_json {

From 70e25d6b16040577fa5a320ccd7211db6a56368d Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Mon, 10 Jun 2024 12:11:58 -0400
Subject: [PATCH 4/9] Forgot to remove these

---
 runt.toml                                     | 19 -------------
 .../as_least_as_fast/dynamic_static.futil     | 28 -------------------
 .../as_least_as_fast/static_dynamic.futil     | 28 -------------------
 .../fast-attr/semantic_preservation/.gitkeep  |  0
 .../semantic_preservation/README.txt          |  1 -
 5 files changed, 76 deletions(-)
 delete mode 100644 tests/correctness/fast-attr/as_least_as_fast/dynamic_static.futil
 delete mode 100644 tests/correctness/fast-attr/as_least_as_fast/static_dynamic.futil
 delete mode 100644 tests/correctness/fast-attr/semantic_preservation/.gitkeep
 delete mode 100644 tests/correctness/fast-attr/semantic_preservation/README.txt

diff --git a/runt.toml b/runt.toml
index e14ca3a6ab..7b1e5c4080 100644
--- a/runt.toml
+++ b/runt.toml
@@ -332,25 +332,6 @@ fud exec --from calyx --to jq \
          {} -q
 """
 
-# todo: need to test that removing @fast (e.g. using sed) causes >= cycles
-#
-# Copilot said:
-#   # Replace 'command1' and 'command2' with your actual commands
-#   [[ $(command1) -le $(command2) ]] && echo "true" || echo "false"
-#
-# [[tests]]
-# name = "correctness: @fast improves speed"
-# paths = ["tests/correctness/fast-attr/at_least_as_fast/*.futil"]
-# cmd = """
-# fud exec --from calyx --to jq \
-#          --through dat \
-#          --through verilog \
-#          -s verilog.data {}.data \
-#          -s calyx.flags "-d static-promotion" \
-#          -s jq.expr ".cycles" \
-#          {} -q
-# """
-
 [[tests]]
 name = "[frontend] tcam testing"
 paths = ["tests/correctness/tcam/*.futil"]
diff --git a/tests/correctness/fast-attr/as_least_as_fast/dynamic_static.futil b/tests/correctness/fast-attr/as_least_as_fast/dynamic_static.futil
deleted file mode 100644
index ab6e0a01ef..0000000000
--- a/tests/correctness/fast-attr/as_least_as_fast/dynamic_static.futil
+++ /dev/null
@@ -1,28 +0,0 @@
-import "primitives/core.futil";
-import "primitives/memories/comb.futil";
-
-component main(@go go: 1) -> (@done done: 1) {
-  cells {
-    @external(1) in_mem = comb_mem_d1(32, 1, 32);
-    @external(1) out_mem = comb_mem_d1(32, 1, 32);
-    i0 = std_reg(32);
-  }
-  wires {
-    group d1 {
-      in_mem.addr0 = 32'd0;
-      i0.in = in_mem.read_data;
-      i0.write_en = 1'b1;
-      d1[done] = i0.done;
-    }
-    static<1> group s2 {
-      out_mem.write_data = i0.out;
-      out_mem.write_en = 1'b1;
-    }
-  }
-  control {
-    @fast seq {
-      d1;
-      s2;
-    }
-  }
-}
diff --git a/tests/correctness/fast-attr/as_least_as_fast/static_dynamic.futil b/tests/correctness/fast-attr/as_least_as_fast/static_dynamic.futil
deleted file mode 100644
index e7e55d245e..0000000000
--- a/tests/correctness/fast-attr/as_least_as_fast/static_dynamic.futil
+++ /dev/null
@@ -1,28 +0,0 @@
-import "primitives/core.futil";
-import "primitives/memories/comb.futil";
-
-component main(@go go: 1) -> (@done done: 1) {
-  cells {
-    @external(1) in_mem = comb_mem_d1(32, 1, 32);
-    @external(1) out_mem = comb_mem_d1(32, 1, 32);
-    i0 = std_reg(32);
-  }
-  wires {
-    static<1> group s1 {
-      in_mem.addr0 = 32'd0;
-      i0.in = in_mem.read_data;
-      i0.write_en = 1'b1;
-    }
-    group d2 {
-      out_mem.write_data = i0.out;
-      out_mem.write_en = 1'b1;
-      d2[done] = out_mem.done;
-    }
-  }
-  control {
-    @fast seq {
-      s1;
-      d2;
-    }
-  }
-}
diff --git a/tests/correctness/fast-attr/semantic_preservation/.gitkeep b/tests/correctness/fast-attr/semantic_preservation/.gitkeep
deleted file mode 100644
index e69de29bb2..0000000000
diff --git a/tests/correctness/fast-attr/semantic_preservation/README.txt b/tests/correctness/fast-attr/semantic_preservation/README.txt
deleted file mode 100644
index 707588bd03..0000000000
--- a/tests/correctness/fast-attr/semantic_preservation/README.txt
+++ /dev/null
@@ -1 +0,0 @@
-TODO: tests that using `@fast` does not change the function of the program

From 2ee19f793f1addef11211956b1ccf0bac0cfa367 Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Mon, 10 Jun 2024 13:11:37 -0400
Subject: [PATCH 5/9] Add basic tests

---
 runt.toml                                     | 26 +++++++++++
 temp/Makefile                                 |  4 --
 temp/test.futil                               | 28 -----------
 temp/test2.futil                              | 28 -----------
 .../fast-attr/invalid/invalid.expect          |  9 ++++
 .../fast-attr/invalid/invalid.futil           | 46 +++++++++++++++++++
 .../fast-attr/invalid/invalid.futil.data      | 12 +++++
 .../fast-attr/valid/fast6inc.expect           |  5 ++
 .../fast-attr/valid/fast6inc.futil            | 46 +++++++++++++++++++
 .../fast-attr/valid/fast6inc.futil.data       | 12 +++++
 10 files changed, 156 insertions(+), 60 deletions(-)
 delete mode 100644 temp/Makefile
 delete mode 100644 temp/test.futil
 delete mode 100644 temp/test2.futil
 create mode 100644 tests/correctness/fast-attr/invalid/invalid.expect
 create mode 100644 tests/correctness/fast-attr/invalid/invalid.futil
 create mode 100644 tests/correctness/fast-attr/invalid/invalid.futil.data
 create mode 100644 tests/correctness/fast-attr/valid/fast6inc.expect
 create mode 100644 tests/correctness/fast-attr/valid/fast6inc.futil
 create mode 100644 tests/correctness/fast-attr/valid/fast6inc.futil.data

diff --git a/runt.toml b/runt.toml
index 7b1e5c4080..4afad75fa8 100644
--- a/runt.toml
+++ b/runt.toml
@@ -388,6 +388,32 @@ fud e --from systolic --to jq \
 """
 expect_dir = "tests/correctness/systolic/mmult-expect"
 
+[[tests]]
+name = "[correctness] `@fast` attribute should not change program behavior"
+paths = ["tests/correctness/fast-attr/valid/*.futil"]
+cmd = """
+fud exec --from calyx --to jq \
+         --through dat \
+         --through icarus-verilog \
+         -s calyx.flags "-p validate -p compile -p lower" \
+         -s verilog.data {}.data \
+         -s jq.expr ".memories" \
+         {} -q
+"""
+
+[[tests]]
+name = "[correctness] `@fast` attribute should reject unoptimizable sequences"
+paths = ["tests/correctness/fast-attr/invalid/*.futil"]
+cmd = """
+fud exec --from calyx --to jq \
+         --through dat \
+         --through icarus-verilog \
+         -s calyx.flags "-p validate -p compile -p lower" \
+         -s verilog.data {}.data \
+         -s jq.expr ".memories" \
+         {} -q
+"""
+
 [[tests]]
 name = "[frontend] systolic array relu static correctness"
 paths = ["tests/correctness/systolic/relu-inputs/*.data"]
diff --git a/temp/Makefile b/temp/Makefile
deleted file mode 100644
index 7e2fc24542..0000000000
--- a/temp/Makefile
+++ /dev/null
@@ -1,4 +0,0 @@
-.PHONY: run
-run:
-	cd .. && cargo build
-	calyx-pass -e ../target/debug/calyx -c main -b tdcc test.futil
diff --git a/temp/test.futil b/temp/test.futil
deleted file mode 100644
index ab6e0a01ef..0000000000
--- a/temp/test.futil
+++ /dev/null
@@ -1,28 +0,0 @@
-import "primitives/core.futil";
-import "primitives/memories/comb.futil";
-
-component main(@go go: 1) -> (@done done: 1) {
-  cells {
-    @external(1) in_mem = comb_mem_d1(32, 1, 32);
-    @external(1) out_mem = comb_mem_d1(32, 1, 32);
-    i0 = std_reg(32);
-  }
-  wires {
-    group d1 {
-      in_mem.addr0 = 32'd0;
-      i0.in = in_mem.read_data;
-      i0.write_en = 1'b1;
-      d1[done] = i0.done;
-    }
-    static<1> group s2 {
-      out_mem.write_data = i0.out;
-      out_mem.write_en = 1'b1;
-    }
-  }
-  control {
-    @fast seq {
-      d1;
-      s2;
-    }
-  }
-}
diff --git a/temp/test2.futil b/temp/test2.futil
deleted file mode 100644
index e7e55d245e..0000000000
--- a/temp/test2.futil
+++ /dev/null
@@ -1,28 +0,0 @@
-import "primitives/core.futil";
-import "primitives/memories/comb.futil";
-
-component main(@go go: 1) -> (@done done: 1) {
-  cells {
-    @external(1) in_mem = comb_mem_d1(32, 1, 32);
-    @external(1) out_mem = comb_mem_d1(32, 1, 32);
-    i0 = std_reg(32);
-  }
-  wires {
-    static<1> group s1 {
-      in_mem.addr0 = 32'd0;
-      i0.in = in_mem.read_data;
-      i0.write_en = 1'b1;
-    }
-    group d2 {
-      out_mem.write_data = i0.out;
-      out_mem.write_en = 1'b1;
-      d2[done] = out_mem.done;
-    }
-  }
-  control {
-    @fast seq {
-      s1;
-      d2;
-    }
-  }
-}
diff --git a/tests/correctness/fast-attr/invalid/invalid.expect b/tests/correctness/fast-attr/invalid/invalid.expect
new file mode 100644
index 0000000000..9108f31eb7
--- /dev/null
+++ b/tests/correctness/fast-attr/invalid/invalid.expect
@@ -0,0 +1,9 @@
+---CODE---
+255
+---STDERR---
+[fud] ERROR: `/Users/ethan/Documents/GitHub/calyx/target/debug/calyx -l /Users/ethan/Documents/GitHub/calyx -b verilog --disable-verify -p validate -p compile -p lower' failed:
+=====STDERR=====
+Error: Malformed Control: `seq` marked `@fast` does not contain alternating static-dynamic control children (see #1828)
+
+=====STDOUT=====
+
diff --git a/tests/correctness/fast-attr/invalid/invalid.futil b/tests/correctness/fast-attr/invalid/invalid.futil
new file mode 100644
index 0000000000..bedbd75fc8
--- /dev/null
+++ b/tests/correctness/fast-attr/invalid/invalid.futil
@@ -0,0 +1,46 @@
+import "primitives/core.futil";
+import "primitives/memories/comb.futil";
+
+component main(@go go: 1) -> (@done done: 1) {
+    cells {
+        @external m = comb_mem_d1(32, 1, 32);
+        i0 = std_reg(32);
+        add = std_add(32);
+    }
+    wires {
+        static<1> group init {
+            i0.in = 32'd0;
+            i0.write_en = 1'b1;
+        }
+        group dyn_inc {
+            add.left = i0.out;
+            add.right = 32'd1;
+            i0.in = add.out;
+            i0.write_en = 1'b1;
+            dyn_inc[done] = i0.done;
+        }
+        static<1> group static_inc {
+            add.left = i0.out;
+            add.right = 32'd1;
+            i0.in = add.out;
+            i0.write_en = 1'b1;
+        }
+        group write {
+            m.write_data = i0.out;
+            m.write_en = 1'b1;
+            write[done] = m.done;
+        }
+    }
+    control {
+        @fast seq {
+            init;
+            dyn_inc;
+            dyn_inc;
+            dyn_inc;
+            static_inc;
+            static_inc;
+            static_inc;
+            write;
+        }
+    }
+}
diff --git a/tests/correctness/fast-attr/invalid/invalid.futil.data b/tests/correctness/fast-attr/invalid/invalid.futil.data
new file mode 100644
index 0000000000..478b067a84
--- /dev/null
+++ b/tests/correctness/fast-attr/invalid/invalid.futil.data
@@ -0,0 +1,12 @@
+{
+    "m": {
+        "data": [
+            0
+        ],
+        "format": {
+            "numeric_type": "bitnum",
+            "is_signed": false,
+            "width": 32
+        }
+    }
+}
diff --git a/tests/correctness/fast-attr/valid/fast6inc.expect b/tests/correctness/fast-attr/valid/fast6inc.expect
new file mode 100644
index 0000000000..91474f14fb
--- /dev/null
+++ b/tests/correctness/fast-attr/valid/fast6inc.expect
@@ -0,0 +1,5 @@
+{
+  "m": [
+    6
+  ]
+}
diff --git a/tests/correctness/fast-attr/valid/fast6inc.futil b/tests/correctness/fast-attr/valid/fast6inc.futil
new file mode 100644
index 0000000000..4579d81e5c
--- /dev/null
+++ b/tests/correctness/fast-attr/valid/fast6inc.futil
@@ -0,0 +1,46 @@
+import "primitives/core.futil";
+import "primitives/memories/comb.futil";
+
+component main(@go go: 1) -> (@done done: 1) {
+    cells {
+        @external m = comb_mem_d1(32, 1, 32);
+        i0 = std_reg(32);
+        add = std_add(32);
+    }
+    wires {
+        static<1> group init {
+            i0.in = 32'd0;
+            i0.write_en = 1'b1;
+        }
+        group dyn_inc {
+            add.left = i0.out;
+            add.right = 32'd1;
+            i0.in = add.out;
+            i0.write_en = 1'b1;
+            dyn_inc[done] = i0.done;
+        }
+        static<1> group static_inc {
+            add.left = i0.out;
+            add.right = 32'd1;
+            i0.in = add.out;
+            i0.write_en = 1'b1;
+        }
+        group write {
+            m.write_data = i0.out;
+            m.write_en = 1'b1;
+            write[done] = m.done;
+        }
+    }
+    control {
+        @fast seq {
+            init;
+            dyn_inc;
+            static_inc;
+            dyn_inc;
+            static_inc;
+            dyn_inc;
+            static_inc;
+            write;
+        }
+    }
+}
diff --git a/tests/correctness/fast-attr/valid/fast6inc.futil.data b/tests/correctness/fast-attr/valid/fast6inc.futil.data
new file mode 100644
index 0000000000..478b067a84
--- /dev/null
+++ b/tests/correctness/fast-attr/valid/fast6inc.futil.data
@@ -0,0 +1,12 @@
+{
+    "m": {
+        "data": [
+            0
+        ],
+        "format": {
+            "numeric_type": "bitnum",
+            "is_signed": false,
+            "width": 32
+        }
+    }
+}

From 53e567f56e23956bdf3023f91689f544e99592d6 Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Mon, 10 Jun 2024 15:37:24 -0400
Subject: [PATCH 6/9] There has to be a better way

---
 tests/correctness/fast-attr/invalid/invalid.expect | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/correctness/fast-attr/invalid/invalid.expect b/tests/correctness/fast-attr/invalid/invalid.expect
index 9108f31eb7..44bcbc349b 100644
--- a/tests/correctness/fast-attr/invalid/invalid.expect
+++ b/tests/correctness/fast-attr/invalid/invalid.expect
@@ -1,7 +1,7 @@
 ---CODE---
 255
 ---STDERR---
-[fud] ERROR: `/Users/ethan/Documents/GitHub/calyx/target/debug/calyx -l /Users/ethan/Documents/GitHub/calyx -b verilog --disable-verify -p validate -p compile -p lower' failed:
+[fud] ERROR: `/home/calyx/target/debug/calyx -l /home/calyx -b verilog --disable-verify -p validate -p compile -p lower' failed:
 =====STDERR=====
 Error: Malformed Control: `seq` marked `@fast` does not contain alternating static-dynamic control children (see #1828)
 

From 7b6c8375830b261b84c3523c0c6fce7395459dab Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Sat, 15 Jun 2024 19:19:18 -0400
Subject: [PATCH 7/9] Implement Rachit and Caleb's reviews

---
 runt.toml                                     |  8 ++---
 .../fast-attr/valid/fast6inc.expect           |  9 +++--
 tools/cache/cache.futil                       | 34 +++++++++++++++++++
 3 files changed, 44 insertions(+), 7 deletions(-)
 create mode 100644 tools/cache/cache.futil

diff --git a/runt.toml b/runt.toml
index 4afad75fa8..e9d91739e6 100644
--- a/runt.toml
+++ b/runt.toml
@@ -395,9 +395,9 @@ cmd = """
 fud exec --from calyx --to jq \
          --through dat \
          --through icarus-verilog \
-         -s calyx.flags "-p validate -p compile -p lower" \
+         -s calyx.flags "-p validate -p compile -p lower -d static-promotion" \
          -s verilog.data {}.data \
-         -s jq.expr ".memories" \
+         -s jq.expr "." \
          {} -q
 """
 
@@ -408,9 +408,9 @@ cmd = """
 fud exec --from calyx --to jq \
          --through dat \
          --through icarus-verilog \
-         -s calyx.flags "-p validate -p compile -p lower" \
+         -s calyx.flags "-p validate -p compile -p lower -d static-promotion" \
          -s verilog.data {}.data \
-         -s jq.expr ".memories" \
+         -s jq.expr "." \
          {} -q
 """
 
diff --git a/tests/correctness/fast-attr/valid/fast6inc.expect b/tests/correctness/fast-attr/valid/fast6inc.expect
index 91474f14fb..b9f64f9677 100644
--- a/tests/correctness/fast-attr/valid/fast6inc.expect
+++ b/tests/correctness/fast-attr/valid/fast6inc.expect
@@ -1,5 +1,8 @@
 {
-  "m": [
-    6
-  ]
+  "cycles": 9,
+  "memories": {
+    "m": [
+      6
+    ]
+  }
 }
diff --git a/tools/cache/cache.futil b/tools/cache/cache.futil
new file mode 100644
index 0000000000..2be1efd52e
--- /dev/null
+++ b/tools/cache/cache.futil
@@ -0,0 +1,34 @@
+// This file was generated
+import "primitives/core.futil";
+import "primitives/memories/seq.futil";
+
+// dummy main
+component main() -> () {
+  cells {}
+  wires {}
+  control {}
+}
+
+$define ADDRESS_WIDTH 16
+$define EXTRA_BITS 2
+
+$define L1_TAG_BITS 8
+$define L1_INDEX_BITS 6
+$define L1_BLOCKS_PER_SET 4
+$define L1_BLOCK_SIZE 4
+
+// entry = [ valid bit | dirty bit | tag bits | block bits ]
+$define L1_ENTRY_BITS EXTRA_BITS + L1_TAG_BITS + L1_INDEX_BITS + L1_BLOCKS_PER_SET * L1_BLOCK_SIZE * 8
+$define L1_NUM_ENTRIES 2 ^ L1_INDEX_BITS 
+
+component cache_level_L1(@go(1) read_go: 1, @go(2) write_go: 1) -> (
+  @done(1) read_done: 1,
+  @done(2) write_done: 1
+) {
+  cells {
+    entries = seq_mem_d1($L1_ENTRY_BITS, $L1_NUM_ENTRIES, $L1_INDEX_BITS);
+  }
+  wires {}
+  control {} 
+}
+

From 0b9344781bfb6fdd86c07933cff5d0e756880889 Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Sun, 16 Jun 2024 18:06:16 -0400
Subject: [PATCH 8/9] Oops

---
 tests/correctness/fast-attr/invalid/invalid.expect | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/correctness/fast-attr/invalid/invalid.expect b/tests/correctness/fast-attr/invalid/invalid.expect
index 44bcbc349b..d39716899f 100644
--- a/tests/correctness/fast-attr/invalid/invalid.expect
+++ b/tests/correctness/fast-attr/invalid/invalid.expect
@@ -1,7 +1,7 @@
 ---CODE---
 255
 ---STDERR---
-[fud] ERROR: `/home/calyx/target/debug/calyx -l /home/calyx -b verilog --disable-verify -p validate -p compile -p lower' failed:
+[fud] ERROR: `/home/calyx/target/debug/calyx -l /home/calyx -b verilog --disable-verify -p validate -p compile -p lower -d static-promotion' failed:
 =====STDERR=====
 Error: Malformed Control: `seq` marked `@fast` does not contain alternating static-dynamic control children (see #1828)
 

From 648728d15748b8f9652f9bb7736a81f1837fe516 Mon Sep 17 00:00:00 2001
From: Ethan Uppal <113849268+ethanuppal@users.noreply.github.com>
Date: Mon, 5 Aug 2024 20:01:13 -0400
Subject: [PATCH 9/9] Remove erroneous file

---
 tools/cache/cache.futil | 34 ----------------------------------
 1 file changed, 34 deletions(-)
 delete mode 100644 tools/cache/cache.futil

diff --git a/tools/cache/cache.futil b/tools/cache/cache.futil
deleted file mode 100644
index 2be1efd52e..0000000000
--- a/tools/cache/cache.futil
+++ /dev/null
@@ -1,34 +0,0 @@
-// This file was generated
-import "primitives/core.futil";
-import "primitives/memories/seq.futil";
-
-// dummy main
-component main() -> () {
-  cells {}
-  wires {}
-  control {}
-}
-
-$define ADDRESS_WIDTH 16
-$define EXTRA_BITS 2
-
-$define L1_TAG_BITS 8
-$define L1_INDEX_BITS 6
-$define L1_BLOCKS_PER_SET 4
-$define L1_BLOCK_SIZE 4
-
-// entry = [ valid bit | dirty bit | tag bits | block bits ]
-$define L1_ENTRY_BITS EXTRA_BITS + L1_TAG_BITS + L1_INDEX_BITS + L1_BLOCKS_PER_SET * L1_BLOCK_SIZE * 8
-$define L1_NUM_ENTRIES 2 ^ L1_INDEX_BITS 
-
-component cache_level_L1(@go(1) read_go: 1, @go(2) write_go: 1) -> (
-  @done(1) read_done: 1,
-  @done(2) write_done: 1
-) {
-  cells {
-    entries = seq_mem_d1($L1_ENTRY_BITS, $L1_NUM_ENTRIES, $L1_INDEX_BITS);
-  }
-  wires {}
-  control {} 
-}
-