Merge pull request #290 from stnolting/fix_xreduce_sim_issues

🧪 try to fix *_reduce_f functions usage for gate-level simulation

CHANGELOG.md

@@ -33,6 +33,7 @@ The version number is globally defined by the `hw_version_c` constant in the mai
 
 | Date (*dd.mm.yyyy*) | Version | Comment |
 |:----------:|:-------:|:--------|
+| 19.03.2022 | 1.6.9.4 | :test_tube: change usage of VHDL `*_reduce_f` functions for signals that might effect gate-level simulations; [PR #290](https://github.com/stnolting/neorv32/pull/290) |
 | 19.03.2022 | 1.6.9.3 | :bug: fixed minor bug in **FPU** - incorrect/missing reset (even if reset to `'-'`) of some registers |
 | 18.03.2022 | 1.6.9.2 | fixed minor bug in **TRNG** hand shake (that marked the same RND value as valid for several times); minor optimization of **processor's reset generator** |
 | 14.03.2022 | 1.6.9.1 | `mtval` CSR is set to zero for software breakpoints (`[c.]ebreak` instruction(s)) - this is permitted by the RISC-V machine ISA spec. v1.12; [PR #289](https://github.com/stnolting/neorv32/pull/289) |

rtl/core/neorv32_cpu_bus.vhd

@@ -486,9 +486,9 @@ begin
   end process pmp_check_permission;
 
   -- final PMP access fault signals --
-  if_pmp_fault <= or_reduce_f(pmp.if_fault) when (PMP_NUM_REGIONS > 0) else '0';
-  ld_pmp_fault <= or_reduce_f(pmp.ld_fault) when (PMP_NUM_REGIONS > 0) else '0';
-  st_pmp_fault <= or_reduce_f(pmp.st_fault) when (PMP_NUM_REGIONS > 0) else '0';
+  if_pmp_fault <= '1' when (or_reduce_f(pmp.if_fault) = '1') and (PMP_NUM_REGIONS > 0) else '0';
+  ld_pmp_fault <= '1' when (or_reduce_f(pmp.ld_fault) = '1') and (PMP_NUM_REGIONS > 0) else '0';
+  st_pmp_fault <= '1' when (or_reduce_f(pmp.st_fault) = '1') and (PMP_NUM_REGIONS > 0) else '0';
 
 
 end neorv32_cpu_bus_rtl;

rtl/core/neorv32_cpu_control.vhd

@@ -902,8 +902,16 @@ begin
     end if;
 
     -- register/uimm5 checks --
-    decode_aux.rs1_zero <= not or_reduce_f(execute_engine.i_reg(instr_rs1_msb_c downto instr_rs1_lsb_c));
-    decode_aux.rd_zero  <= not or_reduce_f(execute_engine.i_reg(instr_rd_msb_c  downto instr_rd_lsb_c));
+    if (execute_engine.i_reg(instr_rs1_msb_c downto instr_rs1_lsb_c) = "00000") then
+      decode_aux.rs1_zero <= '1';
+    else
+      decode_aux.rs1_zero <= '0';
+    end if;
+    if (execute_engine.i_reg(instr_rd_msb_c downto instr_rd_lsb_c) = "00000") then
+      decode_aux.rd_zero <= '1';
+    else
+      decode_aux.rd_zero <= '0';
+    end if;
   end process decode_helper;
 
 
@@ -1667,8 +1675,9 @@ begin
   end process trap_controller;
 
   -- any exception/interrupt? --
-  trap_ctrl.exc_fire <= or_reduce_f(trap_ctrl.exc_buf); -- sync. exceptions CANNOT be masked
-  trap_ctrl.irq_fire <= (or_reduce_f(trap_ctrl.irq_buf) and csr.mstatus_mie and trap_ctrl.db_irq_en) or trap_ctrl.db_irq_fire; -- interrupts CAN be masked (but not the DEBUG halt IRQ)
+  trap_ctrl.exc_fire <= '1' when (or_reduce_f(trap_ctrl.exc_buf) = '1') else '0'; -- sync. exceptions CANNOT be masked
+  trap_ctrl.irq_fire <= '1' when ((or_reduce_f(trap_ctrl.irq_buf) = '1') and (csr.mstatus_mie = '1') and (trap_ctrl.db_irq_en = '1')) or -- interrupts CAN be masked
+                                 (trap_ctrl.db_irq_fire = '1') else '0'; -- but not the DEBUG halt IRQ
 
   -- debug mode (entry) interrupts --
   trap_ctrl.db_irq_en   <= '0' when (CPU_EXTENSION_RISCV_DEBUG = true) and ((debug_ctrl.running = '1') or (csr.dcsr_step = '1')) else '1'; -- no interrupts when IN debug mode or IN single-step mode
@@ -2659,7 +2668,11 @@ begin
       if (HPM_NUM_CNTS /= 0) then
         for i in 0 to HPM_NUM_CNTS-1 loop
           -- do not increment if CPU is in debug mode --
-          hpmcnt_trigger(i) <= or_reduce_f(cnt_event and csr.mhpmevent(i)(cnt_event'left downto 0)) and (not debug_ctrl.running);
+          if (or_reduce_f(cnt_event and csr.mhpmevent(i)(cnt_event'left downto 0)) = '1') and (debug_ctrl.running = '0') then
+            hpmcnt_trigger(i) <= '1';
+          else
+            hpmcnt_trigger(i) <= '0';
+          end if;
         end loop; -- i
       end if;
     end if;

rtl/core/neorv32_cpu_cp_bitmanip.vhd

@@ -470,7 +470,7 @@ begin
   clmul.rs2 <= bit_rev_f(rs2_reg) when (cmd_buf(op_clmulr_c) = '1') else rs2_reg;
 
   -- multiplier busy? --
-  clmul.busy <= or_reduce_f(clmul.cnt);
+  clmul.busy <= '1' when (or_reduce_f(clmul.cnt) = '1') else '0';
 
 
   -- Operation Results ----------------------------------------------------------------------
@@ -522,7 +522,7 @@ begin
   -- single-bit instructions --
   res_int(op_bclr_c) <= rs1_reg and (not one_hot_core);
   res_int(op_bext_c)(data_width_c-1 downto 1) <= (others => '0');
-  res_int(op_bext_c)(0) <= or_reduce_f(rs1_reg and one_hot_core);
+  res_int(op_bext_c)(0) <= '1' when (or_reduce_f(rs1_reg and one_hot_core) = '1') else '0';
   res_int(op_binv_c) <= rs1_reg xor one_hot_core;
   res_int(op_bset_c) <= rs1_reg or one_hot_core;
 

rtl/core/neorv32_cpu_cp_fpu.vhd

@@ -312,9 +312,18 @@ begin
   begin
     for i in 0 to 1 loop -- for rs1 and rs2 inputs
       -- check for all-zero/all-one --
-      op_m_all_zero_v := not or_reduce_f(op_data(i)(22 downto 00));
-      op_e_all_zero_v := not or_reduce_f(op_data(i)(30 downto 23));
-      op_e_all_one_v  := and_reduce_f(op_data(i)(30 downto 23));
+      op_m_all_zero_v := '0';
+      op_e_all_zero_v := '0';
+      op_e_all_one_v  := '0';
+      if (or_reduce_f(op_data(i)(22 downto 00)) = '0') then
+        op_m_all_zero_v := '1';
+      end if;
+      if (or_reduce_f(op_data(i)(30 downto 23)) = '0') then
+        op_e_all_zero_v := '1';
+      end if;
+      if (and_reduce_f(op_data(i)(30 downto 23)) = '1') then
+        op_e_all_one_v  := '1';
+      end if;
 
       -- check special cases --
       op_is_zero_v   := op_e_all_zero_v and      op_m_all_zero_v;  -- zero
@@ -1351,7 +1360,11 @@ begin
           sreg.lower <= mantissa_i(45 downto 23);
           sreg.ext_g <= mantissa_i(22);
           sreg.ext_r <= mantissa_i(21);
-          sreg.ext_s <= or_reduce_f(mantissa_i(20 downto 0));
+          if (or_reduce_f(mantissa_i(20 downto 0)) = '1') then
+            sreg.ext_s <= '1';
+          else
+            sreg.ext_s <= '0';
+          end if;
           -- check for special cases --
           if ((ctrl.class(fp_class_snan_c)       or ctrl.class(fp_class_qnan_c)       or -- NaN
                ctrl.class(fp_class_neg_zero_c)   or ctrl.class(fp_class_pos_zero_c)   or -- zero
@@ -1466,10 +1479,10 @@ begin
   end process ctrl_engine;
 
   -- stop shifting when normalized --
-  sreg.done <= (not or_reduce_f(sreg.upper(sreg.upper'left downto 1))) and sreg.upper(0); -- input is zero, hidden one is set
+  sreg.done <= '1' when (or_reduce_f(sreg.upper(sreg.upper'left downto 1)) = '0') and (sreg.upper(0) = '1') else '0'; -- input is zero, hidden one is set
 
   -- all-zero including hidden bit --
-  sreg.zero <= not or_reduce_f(sreg.upper);
+  sreg.zero <= '1' when (or_reduce_f(sreg.upper) = '0') else '0';
 
   -- result --
   result_o(31)           <= ctrl.res_sgn;
@@ -1708,7 +1721,9 @@ begin
 
         when S_NORMALIZE_BUSY => -- running normalization cycle
         -- ------------------------------------------------------------
-          sreg.ext_s <= sreg.ext_s or or_reduce_f(sreg.mant(sreg.mant'left-2 downto 0)); -- sticky bit
+          if (or_reduce_f(sreg.mant(sreg.mant'left-2 downto 0)) = '1') then
+            sreg.ext_s <= '1'; -- sticky bit
+          end if;
           if (or_reduce_f(ctrl.cnt(ctrl.cnt'left-1 downto 0)) = '0') then
             if (ctrl.unsign = '0') then -- signed conversion
               ctrl.over <= ctrl.over or sreg.int(sreg.int'left); -- update overrun flag again to check for numerical overflow into sign bit

rtl/core/neorv32_cpu_cp_muldiv.vhd

@@ -91,6 +91,7 @@ architecture neorv32_cpu_cp_muldiv_rtl of neorv32_cpu_cp_muldiv is
   signal rs2_is_signed : std_ulogic;
   signal div_res_corr  : std_ulogic;
   signal out_en        : std_ulogic;
+  signal rs2_zero      : std_ulogic;
 
   -- divider core --
   signal remainder        : std_ulogic_vector(data_width_c-1 downto 0);
@@ -152,7 +153,7 @@ begin
         when DIV_PREPROCESS =>
           -- check relevant input signs for result sign compensation --
           if (cp_op = cp_op_div_c) then -- signed div operation
-            div_res_corr <= (rs1_i(rs1_i'left) xor rs2_i(rs2_i'left)) and or_reduce_f(rs2_i); -- different signs AND rs2 not zero
+            div_res_corr <= (rs1_i(rs1_i'left) xor rs2_i(rs2_i'left)) and (not rs2_zero); -- different signs AND rs2 not zero
           elsif (cp_op = cp_op_rem_c) then -- signed rem operation
             div_res_corr <= rs1_i(rs1_i'left);
           else
@@ -183,6 +184,9 @@ begin
     end if;
   end process coprocessor_ctrl;
 
+  -- rs2 zero? --
+  rs2_zero <= '1' when (or_reduce_f(rs2_i) = '0') else '0';
+
   -- co-processor command --
   cp_op <= ctrl_i(ctrl_ir_funct3_2_c downto ctrl_ir_funct3_0_c);
 

rtl/core/neorv32_cpu_cp_shifter.vhd

@@ -119,7 +119,7 @@ begin
   -- shift control/output --
   serial_shifter_ctrl:
   if (FAST_SHIFT_EN = false) generate
-    shifter.done <= not or_reduce_f(shifter.cnt(shifter.cnt'left downto 1));
+    shifter.done <= '1' when (or_reduce_f(shifter.cnt(shifter.cnt'left downto 1)) = '0') else '0';
     valid_o      <= shifter.busy and shifter.done;
     res_o        <= shifter.sreg when (shifter.busy = '0') and (shifter.busy_ff = '1') else (others => '0');
   end generate;

rtl/core/neorv32_cpu_regfile.vhd

@@ -116,7 +116,7 @@ begin
     end process rf_access;
 
     -- writing to x0? --
-    rd_is_x0 <= not or_reduce_f(ctrl_i(ctrl_rf_rd_adr4_c downto ctrl_rf_rd_adr0_c));
+    rd_is_x0 <= '1' when (ctrl_i(ctrl_rf_rd_adr4_c downto ctrl_rf_rd_adr0_c) = "00000") else '0';
   end generate;
 
   reg_file_rv32e: -- embedded register file with 16 registers
@@ -133,7 +133,7 @@ begin
     end process rf_access;
 
     -- writing to x0? --
-    rd_is_x0 <= not or_reduce_f(ctrl_i(ctrl_rf_rd_adr3_c downto ctrl_rf_rd_adr0_c));
+    rd_is_x0 <= '1' when (ctrl_i(ctrl_rf_rd_adr3_c downto ctrl_rf_rd_adr0_c) = "0000") else '0';
   end generate;
 
   -- access addresses --

rtl/core/neorv32_icache.vhd

@@ -545,7 +545,7 @@ begin
   end process comparator;
 
   -- global hit --
-  hit_o <= or_reduce_f(hit);
+  hit_o <= '1' when (or_reduce_f(hit) = '1') else '0';
 
 
 	-- Cache Data Memory ----------------------------------------------------------------------

rtl/core/neorv32_package.vhd

@@ -65,7 +65,7 @@ package neorv32_package is
   -- Architecture Constants (do not modify!) ------------------------------------------------
   -- -------------------------------------------------------------------------------------------
   constant data_width_c : natural := 32; -- native data path width - do not change!
-  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01060903"; -- no touchy!
+  constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01060904"; -- no touchy!
   constant archid_c     : natural := 19; -- official NEORV32 architecture ID - hands off!
 
   -- Check if we're inside the Matrix -------------------------------------------------------

rtl/core/neorv32_slink.vhd

@@ -8,7 +8,7 @@
 -- # ********************************************************************************************* #
 -- # BSD 3-Clause License                                                                          #
 -- #                                                                                               #
--- # Copyright (c) 2021, Stephan Nolting. All rights reserved.                                     #
+-- # Copyright (c) 2022, Stephan Nolting. All rights reserved.                                     #
 -- #                                                                                               #
 -- # Redistribution and use in source and binary forms, with or without modification, are          #
 -- # permitted provided that the following conditions are met:                                     #
@@ -208,7 +208,9 @@ begin
           end if;
           ack_write <= '1';
         else -- TX links
-          ack_write <= or_reduce_f(link_sel and tx_fifo_free);
+          if (or_reduce_f(link_sel and tx_fifo_free) = '1') then
+            ack_write <= '1';
+          end if;
         end if;
       end if;
 
@@ -243,8 +245,10 @@ begin
               data_o <= (others => '0');
           end case;
         else -- RX links
-          data_o   <= rx_fifo_rdata(to_integer(unsigned(addr(4 downto 2))));
-          ack_read <= or_reduce_f(link_sel and rx_fifo_avail);
+          data_o <= rx_fifo_rdata(to_integer(unsigned(addr(4 downto 2))));
+          if (or_reduce_f(link_sel and rx_fifo_avail) = '1') then
+            ack_read <= '1';
+          end if;
         end if;
       end if;
     end if;
@@ -328,8 +332,14 @@ begin
   irq_generator: process(clk_i)
   begin
     if rising_edge(clk_i) then
-      irq_rx_o <= or_reduce_f(rx_irq.set);
-      irq_tx_o <= or_reduce_f(tx_irq.set);
+      irq_rx_o <= '0';
+      irq_tx_o <= '0';
+      if (or_reduce_f(rx_irq.set) = '1') then
+        irq_rx_o <= '1';
+      end if;
+      if (or_reduce_f(tx_irq.set) = '1') then
+        irq_tx_o <= '1';
+      end if;
     end if;
   end process irq_generator;
 

rtl/core/neorv32_top.vhd

@@ -424,7 +424,11 @@ begin
       -- keep internal reset active for at least <ext_rstn_sync'size> clock cycles --
       ext_rstn_sync <= ext_rstn_sync(ext_rstn_sync'left-1 downto 0) & '1';
       -- beautified external reset signal --
-      ext_rstn <= and_reduce_f(ext_rstn_sync);
+      if (and_reduce_f(ext_rstn_sync) = '1') then
+        ext_rstn <= '1';
+      else
+        ext_rstn <= '0';
+      end if;
       -- system reset: can also be triggered by watchdog and debug module --
       sys_rstn <= ext_rstn and wdt_rstn and dci_ndmrstn;
     end if;
@@ -436,15 +440,19 @@ begin
   clock_generator: process(sys_rstn, clk_i)
   begin
     if (sys_rstn = '0') then
-      clk_gen_en_ff <= '-';
-      clk_div_ff    <= (others => '-');
+      clk_gen_en_ff <= '0'; -- reset required
       clk_div       <= (others => '0'); -- reset required
+      clk_div_ff    <= (others => '-');
     elsif rising_edge(clk_i) then
-      clk_gen_en_ff <= or_reduce_f(clk_gen_en);
-      clk_div_ff    <= clk_div;
-      if (clk_gen_en_ff = '1') then -- actual clock generator
+      if (or_reduce_f(clk_gen_en) = '0') then
+        clk_gen_en_ff <= '0';
+      else
+        clk_gen_en_ff <= '1';
+      end if;
+      if (clk_gen_en_ff = '1') then
         clk_div <= std_ulogic_vector(unsigned(clk_div) + 1);
       end if;
+      clk_div_ff <= clk_div;
     end if;
   end process clock_generator;
 
@@ -944,8 +952,8 @@ begin
   -- IO Access? -----------------------------------------------------------------------------
   -- -------------------------------------------------------------------------------------------
   io_acc  <= '1' when (p_bus.addr(data_width_c-1 downto index_size_f(io_size_c)) = io_base_c(data_width_c-1 downto index_size_f(io_size_c))) else '0';
-  io_rden <= io_acc and p_bus.re;
-  io_wren <= io_acc and p_bus.we and and_reduce_f(p_bus.ben); -- only full-word write accesses are allowed (reduces HW complexity)
+  io_rden <= '1' when (io_acc = '1') and (p_bus.re = '1') else '0';
+  io_wren <= '1' when (io_acc = '1') and (p_bus.we = '1') and (p_bus.ben = "1111") else '0'; -- only full-word write accesses are allowed (reduces HW complexity)
 
 
   -- Custom Functions Subsystem (CFS) -------------------------------------------------------

rtl/core/neorv32_xirq.vhd

@@ -10,7 +10,7 @@
 -- # ********************************************************************************************* #
 -- # BSD 3-Clause License                                                                          #
 -- #                                                                                               #
--- # Copyright (c) 2021, Stephan Nolting. All rights reserved.                                     #
+-- # Copyright (c) 2022, Stephan Nolting. All rights reserved.                                     #
 -- #                                                                                               #
 -- # Redistribution and use in source and binary forms, with or without modification, are          #
 -- # permitted provided that the following conditions are met:                                     #
@@ -186,7 +186,7 @@ begin
   end process irq_buffer;
 
   -- anyone firing? --
-  irq_fire <= or_reduce_f(irq_buf);
+  irq_fire <= '1' when (or_reduce_f(irq_buf) = '1') else '0';
 
 
   -- IRQ Priority Encoder -----------------------------------------------------