Revert "sras: lock SRAS if there is too much calls"

This reverts commit 071fc948.

src/frontend/sras.sv

@@ -16,8 +16,7 @@
 // segmented return address stack
 module sras #(
     parameter int unsigned DEPTH = 2,
-    parameter int unsigned SpecDepth = 16,
-    parameter int unsigned SZ_OVF = 16
+    parameter int unsigned SpecDepth = 16
 )(
     input  logic             clk_i,
     input  logic             rst_ni,
@@ -35,7 +34,6 @@ module sras #(
     logic [$clog2(SpecDepth)-1:0] ptr_backup_d, ptr_backup_q;
     logic [SpecDepth-1:0][$clog2(DEPTH)-1:0] tos_d, tos_q;
     ariane_pkg::ras_t [SpecDepth-1:0][DEPTH-1:0] stack_d, stack_q;
-    logic [SpecDepth-1:0][SZ_OVF-1:0] ovf_counter_d, ovf_counter_q;
 
     assign ptr_spec_d = (bad_spec_i) ? ptr_backup_q : (begin_spec_i) ? ptr_spec_q + 1'b1 : ptr_spec_q;
     assign ptr_backup_d = (valid_spec_i) ? ptr_backup_q + 1'b1 : ptr_backup_q;
@@ -50,51 +48,26 @@ module sras #(
     assign pp_plus_one = tos_q[ptr_spec_q] + 1'b1;
     assign prev_minus_one = previous_tos - 1'b1;
 
-    logic overflow;
-    assign overflow = |ovf_counter_q[ptr_spec_q];
-
     always_comb begin
         tos_d = tos_q;
-        ovf_counter_d = ovf_counter_q;
 
         if (flush_i) begin
             tos_d = '0;
-            ovf_counter_d = '0;
-        end else if (!bad_spec_i) begin
-            if (push_i && !pop_i) begin
-                if (overflow) begin
-                    ovf_counter_d[ptr_spec_d] = ovf_counter_q[ptr_spec_q] + 1'b1;
-                end else begin
-                    if (prev_plus_one == '0 || pp_plus_one == '0) begin
-                        ovf_counter_d[ptr_spec_d] = ovf_counter_q[ptr_spec_q] + 1'b1;
-                        ovf_counter_d[ptr_spec_q] = ovf_counter_q[ptr_spec_q] + 1'b1;
-                    end else begin
-                        tos_d[ptr_spec_d] = prev_plus_one;
-                        tos_d[ptr_spec_q] = pp_plus_one;
-                    end
-                end
-            end else if (!push_i && pop_i) begin
-                if (ovf_counter_q[ptr_spec_q] != '0) begin
-                    ovf_counter_d[ptr_spec_d] = ovf_counter_q[ptr_spec_q] - 1'b1;
-                end else begin
-                    tos_d[ptr_spec_d] = prev_minus_one;
-                end
-            end else if (!bad_spec_i && begin_spec_i) begin
-                tos_d[ptr_spec_d] = tos_q[ptr_spec_q];
-                ovf_counter_d[ptr_spec_d] = ovf_counter_q[ptr_spec_q];
-            end
+        end else if (push_i && !pop_i) begin
+            tos_d[ptr_spec_d] = prev_plus_one;
+            tos_d[ptr_spec_q] = pp_plus_one;
+        end else if (!push_i && pop_i) begin
+            tos_d[ptr_spec_d] = prev_minus_one;
+        end else if (!bad_spec_i && begin_spec_i) begin
+            tos_d[ptr_spec_d] = tos_q[ptr_spec_q];
         end
     end
 
-    logic can_pop, can_push;
-    assign can_pop = pop_i && ovf_counter_d[ptr_spec_q][SZ_OVF-1:1] == '0 && !bad_spec_i;
-    assign can_push = push_i && ovf_counter_d[ptr_spec_q] == '0 && !bad_spec_i;
-
     assign data_o = stack_q[previous_tos_addr][previous_tos];
 
     ariane_pkg::ras_t to_push;
-    assign to_push.ra = (can_push) ? data_i : 0;
-    assign to_push.valid = can_push;
+    assign to_push.ra = (push_i) ? data_i : 0;
+    assign to_push.valid = push_i;
 
     ariane_pkg::ras_t [DEPTH-1:0] new_stack, prev_stack;
 
@@ -105,11 +78,11 @@ module sras #(
             new_stack = stack_q[ptr_spec_q];
         end
 
-        if (can_pop) begin
+        if (pop_i) begin
             new_stack[previous_tos] = to_push;
         end
 
-        if (can_push) begin
+        if (push_i) begin
             new_stack[prev_plus_one] = to_push;
         end
     end
@@ -117,7 +90,7 @@ module sras #(
     always_comb begin
         prev_stack = stack_q[ptr_spec_q];
 
-        if (can_push) begin
+        if (push_i) begin
             prev_stack[pp_plus_one] = to_push;
         end
     end
@@ -131,17 +104,15 @@ module sras #(
 
     always_ff @(posedge clk_i or negedge rst_ni) begin
         if (~rst_ni) begin
-            stack_q       <= '0;
-            ptr_spec_q    <= '0;
-            ptr_backup_q  <= '0;
-            tos_q         <= '0;
-            ovf_counter_q <= '0;
+            stack_q      <= '0;
+            ptr_spec_q   <= '0;
+            ptr_backup_q <= '0;
+            tos_q        <= '0;
         end else begin
-            stack_q       <= stack_d;
-            ptr_spec_q    <= ptr_spec_d;
-            ptr_backup_q  <= ptr_backup_d;
-            tos_q         <= tos_d;
-            ovf_counter_q <= ovf_counter_d;
+            stack_q      <= stack_d;
+            ptr_spec_q   <= ptr_spec_d;
+            ptr_backup_q <= ptr_backup_d;
+            tos_q        <= tos_d;
         end
     end