Move from +/shiftx2mux.v into +/techmap.v; cleanup

techlibs/common/Makefile.inc

@@ -30,4 +30,3 @@ $(eval $(call add_share_file,share,techlibs/common/cmp2lut.v))
 $(eval $(call add_share_file,share,techlibs/common/cells.lib))
 $(eval $(call add_share_file,share,techlibs/common/mul2dsp.v))
 $(eval $(call add_share_file,share,techlibs/common/dummy.box))
-$(eval $(call add_share_file,share,techlibs/common/shiftx2mux.v))

techlibs/common/shiftx2mux.v

@@ -1,38 +0,0 @@
-(* techmap_celltype = /*"$shift*/ "$shiftx" *)
-module _80_shift_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;
-        localparam CLOG2_Y_WIDTH = $clog2(Y_WIDTH);
-
-        if (B_WIDTH <= CLOG2_Y_WIDTH+1)
-            wire _TECHMAP_FAIL_ = 1;
-        // In order to perform this optimisation, this $shiftx must
-        //   only shift in units of Y_WIDTH, which we check by ensuring
-        //   that the appropriate LSBs of B are zero
-        else if (_TECHMAP_CONSTMSK_B_[CLOG2_Y_WIDTH-1:0] == {CLOG2_Y_WIDTH{1'b1}} && _TECHMAP_CONSTVAL_B_[CLOG2_Y_WIDTH-1:0] != {CLOG2_Y_WIDTH{1'b0}})
-            wire _TECHMAP_FAIL_ = 1;
-        else begin
-            // Halve the size of $shiftx by $mux-ing A according to 
-            //   the LSB of B, after discarding the zeroed bits
-            wire [(A_WIDTH+Y_WIDTH)/2-1:0] AA;
-            for (i = 0; i < (A_WIDTH/Y_WIDTH); i=i+2)
-                assign AA[(i/2)*Y_WIDTH +: Y_WIDTH] = B[CLOG2_Y_WIDTH] ? A[(i+1)*Y_WIDTH +: Y_WIDTH] : A[(i+0)*Y_WIDTH +: Y_WIDTH];
-            $shiftx #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH((A_WIDTH+Y_WIDTH)/2'd2), .B_WIDTH(B_WIDTH-1), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(AA), .B({B[B_WIDTH-1:CLOG2_Y_WIDTH+1], {CLOG2_Y_WIDTH{1'b0}}}), .Y(Y));
-        end
-    endgenerate
-endmodule
-
-

techlibs/common/techmap.v

@@ -129,12 +129,46 @@ module _90_shift_shiftx (A, B, Y);
 	input [B_WIDTH-1:0] B;
 	output [Y_WIDTH-1:0] Y;
 
+	parameter _TECHMAP_CELLTYPE_ = "";
+	parameter [B_WIDTH-1:0] _TECHMAP_CONSTMSK_B_ = 0;
+	parameter [B_WIDTH-1:0] _TECHMAP_CONSTVAL_B_ = 0;
+
+	localparam extbit = _TECHMAP_CELLTYPE_ == "$shift" ? 1'b0 : 1'bx;
+
+	generate
+`ifndef NO_LSB_FIRST_SHIFT_SHIFTX
+		// If $shift/$shiftx only shifts in units of Y_WIDTH
+		//   (a common pattern created by pmux2shiftx)
+		//   which is checked by ensuring that all that
+		//   the appropriate LSBs of B are constant zero,
+		//   then we can decompose LSB first instead of
+		//   MSB first
+		localparam CLOG2_Y_WIDTH = $clog2(Y_WIDTH);
+		if (B_WIDTH > CLOG2_Y_WIDTH+1 &&
+			_TECHMAP_CONSTMSK_B_[CLOG2_Y_WIDTH-1:0] == {CLOG2_Y_WIDTH{1'b1}} &&
+			_TECHMAP_CONSTVAL_B_[CLOG2_Y_WIDTH-1:0] == {CLOG2_Y_WIDTH{1'b0}}) begin
+			// Halve the size of $shift/$shiftx by $mux-ing A according to
+			//   the LSB of B, after discarding the zeroed bits
+			localparam len = 2**(B_WIDTH-1);
+			wire [len-1:0] T, F;
+			genvar i;
+			for (i = 0; i < A_WIDTH; i=i+Y_WIDTH*2) begin
+				assign F[i/2 +: Y_WIDTH] = A[i +: Y_WIDTH];
+				assign T[i/2 +: Y_WIDTH] = (i + Y_WIDTH < A_WIDTH) ? A[i+Y_WIDTH +: Y_WIDTH] : {Y_WIDTH{extbit}};
+			end
+			wire [len-1:0] AA = B[CLOG2_Y_WIDTH] ? T : F;
+			wire [B_WIDTH-2:0] BB = {B[B_WIDTH-1:CLOG2_Y_WIDTH+1], {CLOG2_Y_WIDTH{1'b0}}};
+			if (_TECHMAP_CELLTYPE_ == "$shift")
+				$shift #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(len), .B_WIDTH(B_WIDTH-1), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(AA), .B(BB), .Y(Y));
+			else
+				$shiftx #(.A_SIGNED(A_SIGNED), .B_SIGNED(B_SIGNED), .A_WIDTH(len), .B_WIDTH(B_WIDTH-1), .Y_WIDTH(Y_WIDTH)) _TECHMAP_REPLACE_ (.A(AA), .B(BB), .Y(Y));
+		end
+		else
+`endif
+		begin
 			localparam BB_WIDTH = `MIN($clog2(`MAX(A_WIDTH, Y_WIDTH)) + (B_SIGNED ? 2 : 1), B_WIDTH);
 			localparam WIDTH = `MAX(A_WIDTH, Y_WIDTH) + (B_SIGNED ? 2**(BB_WIDTH-1) : 0);
 
-	parameter _TECHMAP_CELLTYPE_ = "";
-	localparam extbit = _TECHMAP_CELLTYPE_ == "$shift" ? 1'b0 : 1'bx;
-
 			wire [1023:0] _TECHMAP_DO_00_ = "proc;;";
 			wire [1023:0] _TECHMAP_DO_01_ = "CONSTMAP; opt_muxtree; opt_expr -mux_undef -mux_bool -fine;;;";
 
@@ -168,8 +202,9 @@ module _90_shift_shiftx (A, B, Y);
 							buffer = {WIDTH{extbit}};
 					end
 			end
-
 			assign Y = buffer;
+		end
+	endgenerate
 endmodule
 
 

tests/techmap/shiftx2mux.ys

@@ -74,13 +74,13 @@ design -save gold
 
 
 design -load gold
-techmap
+techmap -D NO_LSB_FIRST_SHIFT_SHIFTX
 abc -lut 6
 select -assert-min 17 t:$lut
 
 
 design -load gold
-techmap -map +/shiftx2mux.v -map +/techmap.v
+techmap
 abc -lut 6
 select -assert-count 16 t:$lut
 
@@ -92,13 +92,13 @@ sat -verify -prove-asserts -show-ports miter
 
 
 design -load gold
-techmap
+techmap -D NO_LSB_FIRST_SHIFT_SHIFTX
 abc9 -lut 6
 select -assert-min 17 t:$lut
 
 
 design -load gold
-techmap -map +/shiftx2mux.v -map +/techmap.v
+techmap
 abc9 -lut 6
 select -assert-count 16 t:$lut