added priority circuit to attempt to remove delay due to rippling in pmpadrdec

wally-pipelined/src/mmu/pmpadrdec.sv

@@ -34,9 +34,10 @@ module pmpadrdec (
   input  logic [7:0]       PMPCfg,
   input  logic [`XLEN-1:0] PMPAdr,
   input  logic             PAgePMPAdrIn,
-  input  logic             NoLowerMatchIn,
+//  input  logic             NoLowerMatchIn,
+  input  logic             FirstMatch,
   output logic             PAgePMPAdrOut,
-  output logic             NoLowerMatchOut,
+//  output logic             NoLowerMatchOut,
   output logic             Match, Active, 
   output logic             L, X, W, R
 );
@@ -47,7 +48,7 @@ module pmpadrdec (
 
   logic TORMatch, NAMatch;
   logic PAltPMPAdr;
-  logic FirstMatch;
+//  logic FirstMatch;
   logic [`PA_BITS-1:0] CurrentAdrFull;
   logic [1:0] AdrMode;
 
@@ -87,8 +88,8 @@ module pmpadrdec (
                  (AdrMode == NA4 || AdrMode == NAPOT) ? NAMatch :
                  0;
 
-  assign FirstMatch =      NoLowerMatchIn & Match;
+//  assign FirstMatch =      NoLowerMatchIn & Match;
-  assign NoLowerMatchOut = NoLowerMatchIn & ~Match;
+//  assign NoLowerMatchOut = NoLowerMatchIn & ~Match;
   assign L = PMPCfg[7] & FirstMatch;
   assign X = PMPCfg[2] & FirstMatch;
   assign W = PMPCfg[1] & FirstMatch;

wally-pipelined/src/mmu/pmpchecker.sv

@@ -55,7 +55,7 @@ module pmpchecker (
   // Bit i is high when the address falls in PMP region i
   logic                    EnforcePMP;
   logic [7:0]              PMPCfg[`PMP_ENTRIES-1:0];
-  logic [`PMP_ENTRIES-1:0] Match;      // PMP Entry matches
+  logic [`PMP_ENTRIES-1:0] Match, FirstMatch;      // PMP Entry matches
   logic [`PMP_ENTRIES-1:0] Active;     // PMP register i is non-null
   logic [`PMP_ENTRIES-1:0] L, X, W, R; // PMP matches and has flag set
   // verilator lint_off UNOPTFLAT
@@ -70,9 +70,11 @@ module pmpchecker (
     .PMPAdr(PMPADDR_ARRAY_REGW),
     .PAgePMPAdrIn({PAgePMPAdr[`PMP_ENTRIES-2:0], 1'b1}),
     .PAgePMPAdrOut(PAgePMPAdr),
-    .NoLowerMatchIn({NoLowerMatch[`PMP_ENTRIES-2:0], 1'b1}),
+//    .NoLowerMatchIn({NoLowerMatch[`PMP_ENTRIES-2:0], 1'b1}),
-    .NoLowerMatchOut(NoLowerMatch),
+//    .NoLowerMatchOut(NoLowerMatch),
-    .Match, .Active, .L, .X, .W, .R);
+    .FirstMatch, .Match, .Active, .L, .X, .W, .R);
+
+  prioritycircuit #(`PMP_ENTRIES) pmppriority(.a(Match), .y(FirstMatch)); // Take the ripple gates/signals out of the pmpadrdec and into another unit. *** seems like it won't actually help since there still needs to be a ripple of some kind with this logic.
 
   // Only enforce PMP checking for S and U modes when at least one PMP is active or in Machine mode when L bit is set in selected region
   assign EnforcePMP = (PrivilegeModeW == `M_MODE) ? |L : |Active; 

wally-pipelined/src/mmu/prioritycircuit.sv

@@ -1,5 +1,5 @@
 ///////////////////////////////////////////
-// tlbpriority.sv
+// prioritycircuit.sv
 //
 // Written: tfleming@hmc.edu & jtorrey@hmc.edu 7 April 2021
 // Modified: Teo Ene 15 Apr 2021:
@@ -30,7 +30,7 @@
 
 `include "wally-config.vh"
 
-module tlbpriority #(parameter ENTRIES = 8) (
+module prioritycircuit #(parameter ENTRIES = 8) (
   input  logic  [ENTRIES-1:0] a,
   output logic  [ENTRIES-1:0] y
 );

wally-pipelined/src/mmu/tlblru.sv

@@ -39,7 +39,7 @@ module tlblru #(parameter TLB_ENTRIES = 8) (
   logic                AllUsed;  // High if the next access causes all RU bits to be 1
 
   // Find the first line not recently used
-  tlbpriority #(TLB_ENTRIES) nru(~RUBits, WriteLines);
+  prioritycircuit #(TLB_ENTRIES) nru(~RUBits, WriteLines);
 
   // Track recently used lines, updating on a CAM Hit or TLB write
   assign WriteEnables = WriteLines & {(TLB_ENTRIES){TLBWrite}};