add support for speculative loads

crates/cpu/src/rename_execute_retire/unit.mermaid

@@ -0,0 +1,41 @@
+%% SPDX-License-Identifier: LGPL-3.0-or-later
+%% See Notices.txt for copyright information
+stateDiagram-v2
+    direction LR
+
+    state "Inputs not ready<br/>Speculative<br/>Can cause cancel" as inr_s_c
+    state "Inputs not ready<br/>Speculative" as inr_s
+    state "Inputs ready<br/>Speculative<br/>Can cause cancel" as ir_s_c
+    state "Inputs ready<br/>Speculative" as ir_s
+    state "Inputs ready<br/>Can cause cancel" as ir_c
+    state "Inputs ready" as ir
+    state "Output ready<br/>Speculative<br/>Can cause cancel" as or_s_c
+    state "Output ready<br/>Can cause cancel" as or_c
+    state "Output ready<br/>Speculative" as or_s
+    state "Output ready" as or
+
+    [*] --> inr_s_c: Enqueue
+
+    inr_s_c --> inr_s: Can't cause cancel
+    ir_s_c --> ir_s: Can't cause cancel
+    ir_c --> ir: Can't cause cancel
+    or_s_c --> or_s: Can't cause cancel
+    or_c --> or: Can't cause cancel
+
+    ir_s_c --> ir_c: No longer speculative
+    ir_s --> ir: No longer speculative
+    or_s_c --> or_c: No longer speculative
+    or_s --> or: No longer speculative
+
+    inr_s_c --> ir_s_c: Inputs ready
+    inr_s --> ir_s: Inputs ready
+
+    ir_s_c --> or_s_c: Output Ready
+    ir_c --> or_c: Output Ready
+    ir_s --> or_s: Output Ready
+    ir --> or: Output Ready
+
+    or_s_c --> [*]: Finish
+    or_c --> [*]: Finish
+    or_s --> [*]: Finish
+    or --> [*]: Finish