WIP: adding ExecuteToUnitInterface::is_no_longer_speculative_prediction

crates/cpu/src/rename_execute_retire.rs

@@ -203,6 +203,16 @@ pub struct UnitMOpCantCauseCancel<C: PhantomConstGet<CpuConfig>> {
     pub config: C,
 }
 
+/// This tells the Unit that if [`Self::if_cant_cause_cancel_id`] can no longer cause a cancel
+/// (either via [`UnitMOpCantCauseCancel`] or [`UnitFinishCauseCancel`] without a cancel),
+/// then [`Self::then_no_longer_speculative_id`] will no longer be speculative.
+#[hdl(no_static)]
+pub struct UnitMOpIsNoLongerSpeculativePrediction<C: PhantomConstGet<CpuConfig>> {
+    pub if_cant_cause_cancel_id: MOpId,
+    pub then_no_longer_speculative_id: MOpId,
+    pub config: C,
+}
+
 /// Interface from the Rename/Execute/Retire control logic to a single Unit.
 ///
 /// ## State diagram for a single &micro;Op in a Unit
@@ -223,6 +233,8 @@ pub struct ExecuteToUnitInterface<C: PhantomConstGet<CpuConfig>> {
     pub inputs_ready: HdlOption<UnitInputsReady<C>>,
     /// if [`Self::unit_outputs_ready`] is `false`, then this is always [`HdlNone`]
     pub is_no_longer_speculative: HdlOption<UnitMOpIsNoLongerSpeculative<C>>,
+    /// if [`Self::unit_outputs_ready`] is `false`, then this is always [`HdlNone`]
+    pub is_no_longer_speculative_prediction: HdlOption<UnitMOpIsNoLongerSpeculativePrediction<C>>,
     /// this uses [`Self::unit_outputs_ready`] as a shared ready flag
     #[hdl(flip)]
     pub cant_cause_cancel: HdlOption<UnitMOpCantCauseCancel<C>>,
@@ -1263,31 +1275,62 @@ impl<C: PhantomConstCpuConfig> RenameExecuteRetireState<C> {
     fn get_unit_mop_is_no_longer_speculative(
         &self,
         unit_index: usize,
-    ) -> SimValue<HdlOption<UnitMOpIsNoLongerSpeculative<C>>> {
+    ) -> Option<SimValue<UnitMOpIsNoLongerSpeculative<C>>> {
-        let ret_ty = HdlOption[UnitMOpIsNoLongerSpeculative[self.config]];
         if self.is_canceling() {
-            let retval = #[hdl(sim)]
+            return None;
-            ret_ty.HdlNone();
-            return retval; // separate variable to work around rust-analyzer parse error
         }
         for rob in self.rob.renamed() {
             if rob.unit_index == unit_index
                 && !rob.is_speculative
                 && let Some(_) = rob.mop_in_unit_state.without_speculative()
             {
-                let retval = #[hdl(sim)]
+                return Some(
-                ret_ty.HdlSome(
                     #[hdl(sim)]
                     UnitMOpIsNoLongerSpeculative::<_> {
                         id: &rob.mop.id,
                         config: self.config,
                     },
                 );
-                return retval; // separate variable to work around rust-analyzer parse error
             }
         }
-        #[hdl(sim)]
+        None
-        ret_ty.HdlNone()
+    }
+    #[hdl]
+    fn get_unit_mop_is_no_longer_speculative_prediction(
+        &self,
+        unit_index: usize,
+    ) -> Option<SimValue<UnitMOpIsNoLongerSpeculativePrediction<C>>> {
+        if self.is_canceling() {
+            return None;
+        }
+        let mut renamed_iter = self.rob.renamed();
+        let if_cant_cause_cancel_id = loop {
+            let Some(renamed) = renamed_iter.next() else {
+                return None;
+            };
+            if renamed.can_cause_cancel() {
+                if renamed.unit_index != unit_index {
+                    return None;
+                }
+                break &renamed.mop.id;
+            }
+        };
+        for renamed in renamed_iter {
+            if renamed.unit_index == unit_index {
+                return Some(
+                    #[hdl(sim)]
+                    UnitMOpIsNoLongerSpeculativePrediction::<_> {
+                        if_cant_cause_cancel_id,
+                        then_no_longer_speculative_id: &renamed.mop.id,
+                        config: self.config,
+                    },
+                );
+            }
+            if renamed.can_cause_cancel() {
+                break;
+            }
+        }
+        None
     }
     #[hdl]
     fn unit_output_ready(&mut self, output_ready: SimValue<UnitOutputReady<C>>) {
@@ -1618,21 +1661,8 @@ impl<C: PhantomConstCpuConfig> RenameExecuteRetireState<C> {
             };
         }
         for renamed in self.rob.renamed_mut() {
-            let can_cause_cancel = match renamed.mop_in_unit_state {
-                MOpInUnitState::NotYetEnqueued => true,
-                MOpInUnitState::InputsNotReadySpeculative { can_cause_cancel } => can_cause_cancel,
-                MOpInUnitState::InputsReady {
-                    speculative: _,
-                    can_cause_cancel,
-                } => can_cause_cancel,
-                MOpInUnitState::OutputReady {
-                    speculative: _,
-                    can_cause_cancel,
-                } => can_cause_cancel,
-                MOpInUnitState::FinishedAndOrCausedCancel => renamed.caused_cancel.is_some(),
-            };
             renamed.is_speculative = false;
-            if can_cause_cancel {
+            if renamed.can_cause_cancel() {
                 break;
             }
         }
@@ -1719,6 +1749,7 @@ async fn rename_execute_retire_run(
                 enqueue,
                 inputs_ready,
                 is_no_longer_speculative,
+                is_no_longer_speculative_prediction,
                 cant_cause_cancel: _,
                 output_ready: _,
                 finish_cause_cancel: _,
@@ -1747,6 +1778,11 @@ async fn rename_execute_retire_run(
                 state.get_unit_mop_is_no_longer_speculative(unit_index),
             )
             .await;
+            sim.write(
+                is_no_longer_speculative_prediction,
+                state.get_unit_mop_is_no_longer_speculative_prediction(unit_index),
+            )
+            .await;
             sim.write(unit_outputs_ready, !is_canceling).await;
         }
         sim.wait_for_clock_edge(cd.clk).await;
@@ -1767,6 +1803,7 @@ async fn rename_execute_retire_run(
                 enqueue,
                 inputs_ready,
                 is_no_longer_speculative,
+                is_no_longer_speculative_prediction: _, // no action necessary
                 cant_cause_cancel,
                 output_ready,
                 finish_cause_cancel,
@@ -1959,6 +1996,7 @@ pub fn rename_execute_retire(config: PhantomConst<CpuConfig>) {
                             enqueue,
                             inputs_ready,
                             is_no_longer_speculative,
+                            is_no_longer_speculative_prediction,
                             cant_cause_cancel: _,
                             output_ready: _,
                             finish_cause_cancel: _,
@@ -1992,6 +2030,12 @@ pub fn rename_execute_retire(config: PhantomConst<CpuConfig>) {
                             (is_no_longer_speculative.ty()).HdlNone(),
                         )
                         .await;
+                        sim.write(
+                            is_no_longer_speculative_prediction,
+                            #[hdl(sim)]
+                            (is_no_longer_speculative_prediction.ty()).HdlNone(),
+                        )
+                        .await;
                         sim.write(unit_outputs_ready, false).await;
                     }
                 },

crates/cpu/src/rename_execute_retire/reorder_buffer.rs

@@ -173,6 +173,21 @@ impl<C: PhantomConstCpuConfig> RobEntry<C> {
             }
         }
     }
+    pub(crate) fn can_cause_cancel(&self) -> bool {
+        match self.mop_in_unit_state {
+            MOpInUnitState::NotYetEnqueued => true,
+            MOpInUnitState::InputsNotReadySpeculative { can_cause_cancel } => can_cause_cancel,
+            MOpInUnitState::InputsReady {
+                speculative: _,
+                can_cause_cancel,
+            } => can_cause_cancel,
+            MOpInUnitState::OutputReady {
+                speculative: _,
+                can_cause_cancel,
+            } => can_cause_cancel,
+            MOpInUnitState::FinishedAndOrCausedCancel => self.caused_cancel.is_some(),
+        }
+    }
 }
 
 #[hdl]

crates/cpu/src/test/decode_and_run_single_insn.rs

@@ -204,6 +204,7 @@ fn connect_to_unit_nop<C: Type + PhantomConstGet<CpuConfig>>(
         enqueue,
         inputs_ready,
         is_no_longer_speculative,
+        is_no_longer_speculative_prediction,
         cant_cause_cancel: _,
         output_ready: _,
         finish_cause_cancel: _,
@@ -218,6 +219,10 @@ fn connect_to_unit_nop<C: Type + PhantomConstGet<CpuConfig>>(
         is_no_longer_speculative,
         is_no_longer_speculative.ty().HdlNone(),
     );
+    connect(
+        is_no_longer_speculative_prediction,
+        is_no_longer_speculative_prediction.ty().HdlNone(),
+    );
     connect(unit_outputs_ready, false);
     connect(cancel_all.data, HdlNone());
 }
@@ -506,6 +511,7 @@ impl<C: PhantomConstCpuConfig, MaxMOpCount: Size> DecodeAndRunSingleInsnState<C,
                         enqueue,
                         inputs_ready,
                         is_no_longer_speculative,
+                        is_no_longer_speculative_prediction,
                         cant_cause_cancel: _, // we don't track if it can cause a cancel
                         output_ready,
                         finish_cause_cancel,
@@ -513,6 +519,10 @@ impl<C: PhantomConstCpuConfig, MaxMOpCount: Size> DecodeAndRunSingleInsnState<C,
                         cancel_all,
                         config: _,
                     } = to_unit;
+                    connect(
+                        is_no_longer_speculative_prediction,
+                        is_no_longer_speculative_prediction.ty().HdlNone(),
+                    );
                     connect(unit_outputs_ready, true);
                     connect(cancel_all.data, HdlNone());
                     #[hdl]

crates/cpu/src/unit/alu_branch.rs

@@ -1260,6 +1260,7 @@ pub fn alu_branch(
         enqueue,
         inputs_ready,
         is_no_longer_speculative: _, // we don't care about being speculative for these instructions
+        is_no_longer_speculative_prediction: _,
         cant_cause_cancel,
         output_ready,
         finish_cause_cancel,

crates/cpu/src/unit/load_store.rs

@@ -988,6 +988,7 @@ async fn load_store_impl(
                 enqueue,
                 inputs_ready: _,
                 is_no_longer_speculative: _,
+                is_no_longer_speculative_prediction: _,
                 cant_cause_cancel,
                 output_ready,
                 finish_cause_cancel,
@@ -1042,6 +1043,7 @@ async fn load_store_impl(
                 enqueue,
                 inputs_ready,
                 is_no_longer_speculative,
+                is_no_longer_speculative_prediction,
                 cant_cause_cancel,
                 output_ready,
                 finish_cause_cancel,
@@ -1066,6 +1068,15 @@ async fn load_store_impl(
             {
                 state.from_execute_is_no_longer_speculative(is_no_longer_speculative);
             }
+            #[hdl(sim)]
+            if let HdlSome(is_no_longer_speculative_prediction) = sim
+                .read_past(is_no_longer_speculative_prediction, cd.clk)
+                .await
+            {
+                state.from_execute_is_no_longer_speculative_prediction(
+                    is_no_longer_speculative_prediction,
+                );
+            }
             if sim.read_past_bool(unit_outputs_ready, cd.clk).await {
                 #[hdl(sim)]
                 if let HdlSome(cant_cause_cancel) = sim.read_past(cant_cause_cancel, cd.clk).await {
@@ -1221,6 +1232,7 @@ pub fn load_store(
                         enqueue,
                         inputs_ready: _,
                         is_no_longer_speculative: _,
+                        is_no_longer_speculative_prediction: _,
                         cant_cause_cancel,
                         output_ready,
                         finish_cause_cancel,

crates/cpu/tests/load_store_unit.rs

@@ -2149,6 +2149,7 @@ async fn load_store_tester_impl<C: PhantomConstCpuConfig>(
                 enqueue,
                 inputs_ready,
                 is_no_longer_speculative,
+                is_no_longer_speculative_prediction,
                 cant_cause_cancel: _,
                 output_ready: _,
                 finish_cause_cancel: _,
@@ -2168,6 +2169,11 @@ async fn load_store_tester_impl<C: PhantomConstCpuConfig>(
                     state.to_load_store_is_no_longer_speculative(),
                 )
                 .await;
+                sim.write(
+                    is_no_longer_speculative_prediction,
+                    state.to_load_store_is_no_longer_speculative_prediction(),
+                )
+                .await;
             } else {
                 sim.write(enqueue.data, enqueue.ty().data.HdlNone()).await;
                 sim.write(inputs_ready, inputs_ready.ty().HdlNone()).await;
@@ -2176,6 +2182,11 @@ async fn load_store_tester_impl<C: PhantomConstCpuConfig>(
                     is_no_longer_speculative.ty().HdlNone(),
                 )
                 .await;
+                sim.write(
+                    is_no_longer_speculative_prediction,
+                    is_no_longer_speculative_prediction.ty().HdlNone(),
+                )
+                .await;
             }
             sim.write(cancel_all.data, state.to_load_store_cancel_all())
                 .await;
@@ -2190,6 +2201,7 @@ async fn load_store_tester_impl<C: PhantomConstCpuConfig>(
                 enqueue,
                 inputs_ready,
                 is_no_longer_speculative,
+                is_no_longer_speculative_prediction,
                 cant_cause_cancel,
                 output_ready,
                 finish_cause_cancel,
@@ -2213,6 +2225,15 @@ async fn load_store_tester_impl<C: PhantomConstCpuConfig>(
             {
                 state.handle_to_load_store_is_no_longer_speculative(is_no_longer_speculative);
             }
+            #[hdl(sim)]
+            if let HdlSome(is_no_longer_speculative_prediction) = sim
+                .read_past(is_no_longer_speculative_prediction, cd.clk)
+                .await
+            {
+                state.handle_to_load_store_is_no_longer_speculative_prediction(
+                    is_no_longer_speculative_prediction,
+                );
+            }
             if sim.read_past_bool(unit_outputs_ready, cd.clk).await {
                 #[hdl(sim)]
                 if let HdlSome(cant_cause_cancel) = sim.read_past(cant_cause_cancel, cd.clk).await {
@@ -2293,6 +2314,7 @@ fn load_store_tester(config: PhantomConst<CpuConfig>) {
                         enqueue,
                         inputs_ready,
                         is_no_longer_speculative,
+                        is_no_longer_speculative_prediction,
                         cant_cause_cancel: _,
                         output_ready: _,
                         finish_cause_cancel: _,
@@ -2318,6 +2340,11 @@ fn load_store_tester(config: PhantomConst<CpuConfig>) {
                         is_no_longer_speculative.ty().HdlNone(),
                     )
                     .await;
+                    sim.write(
+                        is_no_longer_speculative_prediction,
+                        is_no_longer_speculative_prediction.ty().HdlNone(),
+                    )
+                    .await;
                     sim.write(unit_outputs_ready, false).await;
                     sim.write(cancel_all.data, HdlNone()).await;
                     sim.write(test_passed, false).await;