Revert "Remove wide mux inference"

This reverts commit 738fdfe8f5.

CHANGELOG

@@ -22,6 +22,7 @@ Yosys 0.8 .. Yosys 0.8-dev
     - Added "synth_ice40 -abc9" (experimental)
     - Added "synth -abc9" (experimental)
     - "synth_xilinx" to now infer hard shift registers, using new "shregmap -tech xilinx"
+    - "synth_xilinx" to now infer wide multiplexers
 
 
 Yosys 0.7 .. Yosys 0.8

techlibs/xilinx/Makefile.inc

@@ -30,6 +30,7 @@ $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/drams_map.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/arith_map.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/ff_map.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/lut_map.v))
+$(eval $(call add_share_file,share/xilinx,techlibs/xilinx/mux_map.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_xc7.box))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_xc7.lut))
 

techlibs/xilinx/cells_map.v

@@ -154,3 +154,123 @@ module \$__XILINX_SHREG_ (input C, input D, input [31:0] L, input E, output Q, o
     end
   endgenerate
 endmodule
+
+module \$__XILINX_SHIFTX (A, B, Y);
+  parameter A_SIGNED = 0;
+  parameter B_SIGNED = 0;
+  parameter A_WIDTH = 1;
+  parameter B_WIDTH = 1;
+  parameter Y_WIDTH = 1;
+
+  input [A_WIDTH-1:0] A;
+  input [B_WIDTH-1:0] B;
+  output [Y_WIDTH-1:0] Y;
+
+  parameter [A_WIDTH-1:0] _TECHMAP_CONSTMSK_A_ = 0;
+  parameter [A_WIDTH-1:0] _TECHMAP_CONSTVAL_A_ = 0;
+  parameter [B_WIDTH-1:0] _TECHMAP_CONSTMSK_B_ = 0;
+  parameter [B_WIDTH-1:0] _TECHMAP_CONSTVAL_B_ = 0;
+
+  function integer compute_num_leading_X_in_A;
+    integer i, c;
+  begin
+    compute_num_leading_X_in_A = 0;
+    c = 1;
+    for (i = A_WIDTH-1; i >= 0; i=i-1) begin
+      if (!_TECHMAP_CONSTMSK_A_[i] || _TECHMAP_CONSTVAL_A_[i] !== 1'bx)
+        c = 0;
+      compute_num_leading_X_in_A = compute_num_leading_X_in_A + c;
+    end
+  end
+  endfunction
+  localparam num_leading_X_in_A = compute_num_leading_X_in_A();
+
+  generate
+    genvar i, j;
+    // Bit-blast
+    if (Y_WIDTH > 1) begin
+      for (i = 0; i < Y_WIDTH; i++)
+        \$__XILINX_SHIFTX  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(A_WIDTH-Y_WIDTH+1), .B_WIDTH(B_WIDTH), .Y_WIDTH(1'd1)) bitblast (.A(A[A_WIDTH-Y_WIDTH+i:i]), .B(B), .Y(Y[i]));
+    end
+    // If the LSB of B is constant zero (and Y_WIDTH is 1) then
+    //   we can optimise by removing every other entry from A
+    //   and popping the constant zero from B
+    else if (_TECHMAP_CONSTMSK_B_[0] && !_TECHMAP_CONSTVAL_B_[0]) begin
+      wire [(A_WIDTH+1)/2-1:0] A_i;
+      for (i = 0; i < (A_WIDTH+1)/2; i++)
+        assign A_i[i] = A[i*2];
+      \$__XILINX_SHIFTX  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH((A_WIDTH+1'd1)/2'd2), .B_WIDTH(B_WIDTH-1'd1), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(A_i), .B(B[B_WIDTH-1:1]), .Y(Y));
+    end
+    // Trim off any leading 1'bx -es in A, and resize B accordingly
+    else if (num_leading_X_in_A > 0) begin
+      localparam A_WIDTH_new = A_WIDTH - num_leading_X_in_A;
+      localparam B_WIDTH_new = $clog2(A_WIDTH_new);
+      \$__XILINX_SHIFTX  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(A_WIDTH_new), .B_WIDTH(B_WIDTH_new), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(A[A_WIDTH_new-1:0]), .B(B[B_WIDTH_new-1:0]), .Y(Y));
+    end
+    else if (B_WIDTH < 3 || A_WIDTH <= 4) begin
+      \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(A_WIDTH), .B_WIDTH(B_WIDTH), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(A), .B(B), .Y(Y));
+    end
+    else if (B_WIDTH == 3) begin
+      localparam a_width0 = 2 ** 2;
+      localparam a_widthN = A_WIDTH - a_width0;
+      wire T0, T1;
+      \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_width0), .B_WIDTH(2),                .Y_WIDTH(Y_WIDTH)) fpga_soft_mux      (.A(A[a_width0-1:0]),       .B(B[2-1:0]),                .Y(T0));
+      if (a_widthN > 1)
+        \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_soft_mux_last (.A(A[A_WIDTH-1:a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T1));
+      else
+        assign T1 = A[A_WIDTH-1];
+      MUXF7 fpga_hard_mux (.I0(T0), .I1(T1), .S(B[B_WIDTH-1]), .O(Y));
+    end
+    else if (B_WIDTH == 4) begin
+      localparam a_width0 = 2 ** 2;
+      localparam num_mux8 = A_WIDTH / a_width0;
+      localparam a_widthN = A_WIDTH - num_mux8*a_width0;
+      wire [4-1:0] T;
+      wire T0, T1;
+      for (i = 0; i < 4; i++)
+        if (i < num_mux8)
+          \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_width0), .B_WIDTH(2),                .Y_WIDTH(Y_WIDTH)) fpga_soft_mux      (.A(A[i*a_width0+:a_width0]), .B(B[2-1:0]),                .Y(T[i]));
+        else if (i == num_mux8 && a_widthN > 0) begin
+          if (a_widthN > 1)
+            \$shiftx  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_soft_mux_last (.A(A[A_WIDTH-1:i*a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T[i]));
+          else
+            assign T[i] = A[A_WIDTH-1];
+        end
+        else
+          assign T[i] = 1'bx;
+      MUXF7 fpga_hard_mux_0 (.I0(T[0]), .I1(T[1]), .S(B[2]), .O(T0));
+      MUXF7 fpga_hard_mux_1 (.I0(T[2]), .I1(T[3]), .S(B[2]), .O(T1));
+      MUXF8 fpga_hard_mux_2 (.I0(T0),   .I1(T1),   .S(B[3]), .O(Y));
+    end
+    else begin
+      localparam a_width0 = 2 ** 4;
+      localparam num_mux16 = A_WIDTH / a_width0;
+      localparam a_widthN = A_WIDTH - num_mux16*a_width0;
+      wire [(2**(B_WIDTH-4))-1:0] T;
+      for (i = 0; i < 2 ** (B_WIDTH-4); i++)
+        if (i < num_mux16)
+          \$__XILINX_SHIFTX  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_width0), .B_WIDTH(4),                .Y_WIDTH(Y_WIDTH)) fpga_soft_mux      (.A(A[i*a_width0+:a_width0]), .B(B[4-1:0]),                .Y(T[i]));
+        else if (i == num_mux16 && a_widthN > 0) begin
+          if (a_widthN > 1)
+            \$__XILINX_SHIFTX  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(a_widthN), .B_WIDTH($clog2(a_widthN)), .Y_WIDTH(Y_WIDTH)) fpga_soft_mux_last (.A(A[A_WIDTH-1:i*a_width0]), .B(B[$clog2(a_widthN)-1:0]), .Y(T[i]));
+          else
+            assign T[i] = A[A_WIDTH-1];
+        end
+        else
+          assign T[i] = 1'bx;
+      \$__XILINX_SHIFTX  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(2**(B_WIDTH-4)), .B_WIDTH(B_WIDTH-4), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(T), .B(B[B_WIDTH-1:4]), .Y(Y));
+    end
+  endgenerate
+endmodule
+
+module \$_MUX8_ (A, B, C, D, E, F, G, H, S, T, U, Y);
+input A, B, C, D, E, F, G, H, S, T, U;
+output Y;
+  \$__XILINX_SHIFTX  #(.A_SIGNED(0), .B_SIGNED(0), .A_WIDTH(8), .B_WIDTH(3), .Y_WIDTH(1)) _TECHMAP_REPLACE_ (.A({H,G,F,E,D,C,B,A}), .B({U,T,S}), .Y(Y));
+endmodule
+
+module \$_MUX16_ (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, S, T, U, V, Y);
+input A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, S, T, U, V;
+output Y;
+  \$__XILINX_SHIFTX  #(.A_SIGNED(0), .B_SIGNED(0), .A_WIDTH(16), .B_WIDTH(4), .Y_WIDTH(1)) _TECHMAP_REPLACE_ (.A({P,O,N,M,L,K,J,I,H,G,F,E,D,C,B,A}), .B({V,U,T,S}), .Y(Y));
+endmodule

techlibs/xilinx/mux_map.v

@@ -0,0 +1,52 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *                2019  Eddie Hung    <eddie@fpgeh.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+module \$shiftx (A, B, Y);
+  parameter A_SIGNED = 0;
+  parameter B_SIGNED = 0;
+  parameter A_WIDTH = 1;
+  parameter B_WIDTH = 1;
+  parameter Y_WIDTH = 1;
+
+  input [A_WIDTH-1:0] A;
+  input [B_WIDTH-1:0] B;
+  output [Y_WIDTH-1:0] Y;
+
+  parameter [B_WIDTH-1:0] _TECHMAP_CONSTMSK_B_ = 0;
+  parameter [B_WIDTH-1:0] _TECHMAP_CONSTVAL_B_ = 0;
+
+  generate
+    genvar i, j;
+    // TODO: Check if this opt still necessary
+    if (B_SIGNED) begin
+      if (_TECHMAP_CONSTMSK_B_[B_WIDTH-1] && _TECHMAP_CONSTVAL_B_[B_WIDTH-1] == 1'b0)
+        // Optimisation to remove B_SIGNED if sign bit of B is constant-0
+        \$__XILINX_SHIFTX  #(.A_SIGNED(A_SIGNED), .B_SIGNED(0), .A_WIDTH(A_WIDTH), .B_WIDTH(B_WIDTH-1'd1), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(A), .B(B[B_WIDTH-2:0]), .Y(Y));
+      else
+        wire _TECHMAP_FAIL_ = 1;
+    end
+    else if (B_WIDTH < 3 || A_WIDTH <= 4) begin
+      wire _TECHMAP_FAIL_ = 1;
+    end
+    else begin
+        \$__XILINX_SHIFTX  #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(A_WIDTH), .B_WIDTH(B_WIDTH), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(A), .B(B), .Y(Y));
+    end
+  endgenerate
+endmodule

techlibs/xilinx/synth_xilinx.cc

@@ -72,6 +72,9 @@ struct SynthXilinxPass : public ScriptPass
 		log("    -nosrl\n");
 		log("        disable inference of shift registers\n");
 		log("\n");
+		log("    -nomux\n");
+		log("        disable inference of wide multiplexers\n");
+		log("\n");
 		log("    -run <from_label>:<to_label>\n");
 		log("        only run the commands between the labels (see below). an empty\n");
 		log("        from label is synonymous to 'begin', and empty to label is\n");
@@ -93,7 +96,7 @@ struct SynthXilinxPass : public ScriptPass
 	}
 
 	std::string top_opt, edif_file, blif_file, abc, arch;
-	bool flatten, retime, vpr, nocarry, nobram, nodram, nosrl;
+	bool flatten, retime, vpr, nocarry, nobram, nodram, nosrl, nomux;
 
 	void clear_flags() YS_OVERRIDE
 	{
@@ -108,6 +111,7 @@ struct SynthXilinxPass : public ScriptPass
 		nobram = false;
 		nodram = false;
 		nosrl = false;
+		nomux = false;
 		arch = "xc7";
 	}
 
@@ -171,6 +175,10 @@ struct SynthXilinxPass : public ScriptPass
 				nosrl = true;
 				continue;
 			}
+			if (args[argidx] == "-nomux") {
+				nomux = true;
+				continue;
+			}
 			if (args[argidx] == "-abc9") {
 				abc = "abc9";
 				continue;
@@ -219,11 +227,15 @@ struct SynthXilinxPass : public ScriptPass
 		if (check_label("coarse")) {
 			run("synth -run coarse");
 
+			//if (!nomux || help_mode)
+			//	run("muxpack", "(skip if '-nomux')");
+
 			// shregmap -tech xilinx can cope with $shiftx and $mux
 			//   cells for identifying variable-length shift registers,
 			//   so attempt to convert $pmux-es to the former
-			if (!nosrl || help_mode)
+			// Also: wide multiplexer inference benefits from this too
-				run("pmux2shiftx", "(skip if '-nosrl')");
+			if (!(nosrl && nomux) || help_mode)
+				run("pmux2shiftx", "(skip if '-nosrl' and '-nomux')");
 
 			// Run a number of peephole optimisations, including one
 			//   that optimises $mul cells driving $shiftx's B input
@@ -261,6 +273,10 @@ struct SynthXilinxPass : public ScriptPass
 			}
 
 			std::string techmap_files = " -map +/techmap.v";
+			if (help_mode)
+				techmap_files += " [-map +/xilinx/mux_map.v]";
+			else if (!nomux)
+				techmap_files += " -map +/xilinx/mux_map.v";
 			if (help_mode)
 				techmap_files += " [-map +/xilinx/arith_map.v]";
 			else if (!nocarry) {
@@ -275,6 +291,8 @@ struct SynthXilinxPass : public ScriptPass
 		}
 
 		if (check_label("map_cells")) {
+			if (!nomux || help_mode)
+				run("muxcover -mux8 -mux16", "(skip if '-nomux')");
 			run("techmap -map +/techmap.v -map +/xilinx/cells_map.v");
 			run("clean");
 		}