Merge pull request #4028 from povik/cmp2softlogic

synth_lattice: Optionally do constant comparisons in soft logic

techlibs/common/Makefile.inc

@@ -34,3 +34,4 @@ $(eval $(call add_share_file,share,techlibs/common/abc9_model.v))
 $(eval $(call add_share_file,share,techlibs/common/abc9_map.v))
 $(eval $(call add_share_file,share,techlibs/common/abc9_unmap.v))
 $(eval $(call add_share_file,share,techlibs/common/cmp2lcu.v))
+$(eval $(call add_share_file,share,techlibs/common/cmp2softlogic.v))

techlibs/common/cmp2softlogic.v

@@ -0,0 +1,117 @@
+module constgtge(C, A, B, Y);
+parameter A_WIDTH = 0;
+parameter B_WIDTH = 0;
+
+(* force_downto *)
+input [A_WIDTH-1:0] A;
+(* force_downto *)
+input [B_WIDTH-1:0] B;
+output Y;
+input C;
+
+wire [A_WIDTH:0] ch;
+genvar n;
+generate
+	if (B_WIDTH > A_WIDTH) begin
+		// Fail
+	end else begin
+		assign ch[0] = C;
+		for (n = 0; n < A_WIDTH; n = n + 1) begin
+			if (n < B_WIDTH) begin
+				assign ch[n + 1] = B[n] ? (ch[n] && A[n]) : (ch[n] || A[n]);
+			end else begin
+				assign ch[n + 1] = ch[n] || A[n];
+			end
+		end
+		assign Y = ch[A_WIDTH];
+	end
+endgenerate
+endmodule
+
+module constltle(C, A, B, Y);
+parameter A_WIDTH = 0;
+parameter B_WIDTH = 0;
+
+(* force_downto *)
+input [A_WIDTH-1:0] A;
+(* force_downto *)
+input [B_WIDTH-1:0] B;
+output Y;
+input C;
+
+wire [A_WIDTH:0] ch;
+genvar n;
+generate
+	if (B_WIDTH > A_WIDTH) begin
+		// Fail
+	end else begin
+		assign ch[0] = C;
+		for (n = 0; n < A_WIDTH; n = n + 1) begin
+			if (n < B_WIDTH) begin
+				assign ch[n + 1] = !B[n] ? (ch[n] && !A[n]) : (ch[n] || !A[n]);
+			end else begin
+				assign ch[n + 1] = ch[n] && !A[n];
+			end
+		end
+		assign Y = ch[A_WIDTH];
+	end
+endgenerate
+endmodule
+
+(* techmap_celltype = "$ge $gt $le $lt" *)
+module _map_const_cmp_(A, B, Y);
+parameter A_WIDTH = 0;
+parameter B_WIDTH = 0;
+parameter Y_WIDTH = 0;
+parameter A_SIGNED = 0;
+parameter B_SIGNED = 0;
+
+(* force_downto *)
+input [A_WIDTH-1:0] A;
+(* force_downto *)
+input [B_WIDTH-1:0] B;
+(* force_downto *)
+output [Y_WIDTH-1:0] Y;
+
+parameter _TECHMAP_CELLTYPE_ = "";
+
+parameter _TECHMAP_CONSTMSK_A_ = 0;
+parameter _TECHMAP_CONSTVAL_A_ = 0;
+parameter _TECHMAP_CONSTMSK_B_ = 0;
+parameter _TECHMAP_CONSTVAL_B_ = 0;
+
+wire [1023:0] _TECHMAP_DO_ = "opt -fast;";
+
+wire [A_WIDTH:0] ch;
+
+genvar n;
+generate
+	if (Y_WIDTH != 1 || A_SIGNED || B_SIGNED)
+		wire _TECHMAP_FAIL_ = 1;
+	else if (&_TECHMAP_CONSTMSK_A_) begin
+		if (A_WIDTH > B_WIDTH)
+			wire _TECHMAP_FAIL_ = 1;
+		else if (_TECHMAP_CELLTYPE_ == "$lt" || _TECHMAP_CELLTYPE_ == "$le")
+			constgtge #(.A_WIDTH(B_WIDTH), .B_WIDTH(A_WIDTH))
+				_TECHMAP_REPLACE_(.A(B), .B(A), .Y(Y),
+					.C(_TECHMAP_CELLTYPE_ == "$lt"));
+		else
+			constltle #(.A_WIDTH(B_WIDTH), .B_WIDTH(A_WIDTH))
+				_TECHMAP_REPLACE_(.A(B), .B(A), .Y(Y),
+					.C(_TECHMAP_CELLTYPE_ == "$gt"));
+	end else if (&_TECHMAP_CONSTMSK_B_) begin
+		if (B_WIDTH > A_WIDTH)
+			wire _TECHMAP_FAIL_ = 1;
+		else if (_TECHMAP_CELLTYPE_ == "$lt" || _TECHMAP_CELLTYPE_ == "$le")
+			constltle #(.A_WIDTH(A_WIDTH), .B_WIDTH(B_WIDTH))
+				_TECHMAP_REPLACE_(.A(A), .B(B), .Y(Y),
+					.C(_TECHMAP_CELLTYPE_ == "$le"));
+		else
+			constgtge #(.A_WIDTH(A_WIDTH), .B_WIDTH(B_WIDTH))
+				_TECHMAP_REPLACE_(.A(A), .B(B), .Y(Y),
+					.C(_TECHMAP_CELLTYPE_ == "$ge"));
+	end else
+		wire _TECHMAP_FAIL_ = 1;
+endgenerate
+
+endmodule

techlibs/lattice/synth_lattice.cc

@@ -127,6 +127,10 @@ struct SynthLatticePass : public ScriptPass
 		log("        read/write collision\" (same result as setting the no_rw_check\n");
 		log("        attribute on all memories).\n");
 		log("\n");
+		log("    -cmp2softlogic\n");
+		log("        implement constant comparisons in soft logic, do not involve\n");
+		log("        hard carry chains\n");
+		log("\n");
 		log("\n");
 		log("The following commands are executed by this synthesis command:\n");
 		help_script();
@@ -135,6 +139,7 @@ struct SynthLatticePass : public ScriptPass
 
 	string top_opt, edif_file, json_file, family;
 	bool noccu2, nodffe, nobram, nolutram, nowidelut, asyncprld, flatten, dff, retime, abc2, abc9, iopad, nodsp, no_rw_check, have_dsp;
+	bool cmp2softlogic;
 	string postfix, arith_map, brams_map, dsp_map;
 
 	void clear_flags() override
@@ -162,6 +167,7 @@ struct SynthLatticePass : public ScriptPass
 		brams_map = "";
 		dsp_map = "";
 		have_dsp = false;
+		cmp2softlogic = false;
 	}
 
 	void execute(std::vector<std::string> args, RTLIL::Design *design) override
@@ -263,6 +269,10 @@ struct SynthLatticePass : public ScriptPass
 				no_rw_check = true;
 				continue;
 			}
+			if (args[argidx] == "-cmp2softlogic") {
+				cmp2softlogic = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
@@ -343,6 +353,8 @@ struct SynthLatticePass : public ScriptPass
 			run("peepopt");
 			run("opt_clean");
 			run("share");
+			if (cmp2softlogic)
+				run("techmap -map +/cmp2softlogic.v");
 			run("techmap -map +/cmp2lut.v -D LUT_WIDTH=4");
 			run("opt_expr");
 			run("opt_clean");