From 6c632200d544133c3b0cb1adfb907eafe75961ae Mon Sep 17 00:00:00 2001
From: Hansung Kim <hansung_kim@berkeley.edu>
Date: Wed, 3 Apr 2024 15:29:51 -0700
Subject: [PATCH] Divide by per-breakdown cycle for avg stall cycles

---
 hw/rtl/core/VX_core.sv     | 16 ++++++++--------
 hw/rtl/core/VX_operands.sv |  3 +++
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/hw/rtl/core/VX_core.sv b/hw/rtl/core/VX_core.sv
index 45426053..0c9a7ac1 100644
--- a/hw/rtl/core/VX_core.sv
+++ b/hw/rtl/core/VX_core.sv
@@ -436,31 +436,31 @@ module VX_core import VX_gpu_pkg::*; #(
                      pipeline_perf_if.scb_stalls, `ISSUE_WIDTH);
             $display("issue scoreboard: stalls by operand hazard: alu %d (%2.2f cycles per issue)",
                      scrb_alu_per_core,
-                     $itor(scrb_alu_per_core) / $itor(dispatch_fires_total));
+                     $itor(scrb_alu_per_core) / $itor(pipeline_perf_if.dispatch_fires[`EX_ALU]));
             $display("issue scoreboard: stalls by operand hazard: fpu %d (%2.2f cycles per issue)",
                      scrb_fpu_per_core,
-                     $itor(scrb_fpu_per_core) / $itor(dispatch_fires_total));
+                     $itor(scrb_fpu_per_core) / $itor(pipeline_perf_if.dispatch_fires[`EX_FPU]));
             $display("issue scoreboard: stalls by operand hazard: lsu %d (%2.2f cycles per issue)",
                      scrb_lsu_per_core,
-                     $itor(scrb_lsu_per_core) / $itor(dispatch_fires_total));
+                     $itor(scrb_lsu_per_core) / $itor(pipeline_perf_if.dispatch_fires[`EX_LSU]));
             $display("issue scoreboard: stalls by operand hazard: sfu %d (%2.2f cycles per issue)",
                      scrb_sfu_per_core,
-                     $itor(scrb_sfu_per_core) / $itor(dispatch_fires_total));
+                     $itor(scrb_sfu_per_core) / $itor(pipeline_perf_if.dispatch_fires[`EX_SFU]));
             $display("issue scoreboard: sfu stalls: %d (scrs=%f, wctl=%f)",pipeline_perf_if.units_uses[`EX_SFU],
                      $itor(scrb_csrs_per_core) / $itor(sfu_tot) * 100.0,
                      $itor(scrb_wctl_per_core) / $itor(sfu_tot) * 100.0);
             $display("issue dispatch: stalls by FU busy: alu %d (%2.2f cycles per issue)",
                      pipeline_perf_if.dispatch_stalls[`EX_ALU],
-                     $itor(pipeline_perf_if.dispatch_stalls[`EX_ALU]) / $itor(dispatch_fires_total));
+                     $itor(pipeline_perf_if.dispatch_stalls[`EX_ALU]) / $itor(pipeline_perf_if.dispatch_fires[`EX_ALU]));
             $display("issue dispatch: stalls by FU busy: fpu %d (%2.2f cycles per issue)",
                      pipeline_perf_if.dispatch_stalls[`EX_FPU],
-                     $itor(pipeline_perf_if.dispatch_stalls[`EX_FPU]) / $itor(dispatch_fires_total));
+                     $itor(pipeline_perf_if.dispatch_stalls[`EX_FPU]) / $itor(pipeline_perf_if.dispatch_fires[`EX_FPU]));
             $display("issue dispatch: stalls by FU busy: lsu %d (%2.2f cycles per issue)",
                      pipeline_perf_if.dispatch_stalls[`EX_LSU],
-                     $itor(pipeline_perf_if.dispatch_stalls[`EX_LSU]) / $itor(dispatch_fires_total));
+                     $itor(pipeline_perf_if.dispatch_stalls[`EX_LSU]) / $itor(pipeline_perf_if.dispatch_fires[`EX_LSU]));
             $display("issue dispatch: stalls by FU busy: sfu %d (%2.2f cycles per issue)",
                      pipeline_perf_if.dispatch_stalls[`EX_SFU],
-                     $itor(pipeline_perf_if.dispatch_stalls[`EX_SFU]) / $itor(dispatch_fires_total));
+                     $itor(pipeline_perf_if.dispatch_stalls[`EX_SFU]) / $itor(pipeline_perf_if.dispatch_fires[`EX_SFU]));
             $display("issue dispatch: fires: total %d",
                      dispatch_fires_total);
             $display("issue dispatch: fires: alu %d",
diff --git a/hw/rtl/core/VX_operands.sv b/hw/rtl/core/VX_operands.sv
index 3747502f..28f1edf1 100644
--- a/hw/rtl/core/VX_operands.sv
+++ b/hw/rtl/core/VX_operands.sv
@@ -197,6 +197,9 @@ module VX_operands import VX_gpu_pkg::*; #(
         assign stg_valid_in = scoreboard_if[i].valid && data_ready;
         assign scoreboard_if[i].ready = stg_ready_in && data_ready;        
 
+        // NOTE(hansung): toggle_buffer is 1-reg pipe without flow, halving
+        // throughput.  Wouldn't this cap overall IPC?  Or OK as long as
+        // ISSUE_WIDTH > 1?
         VX_toggle_buffer #(
             .DATAW (DATAW)
         ) staging_buffer (