verilog: fix handling of nested ifdef directives

- track depth so we know whether to consider higher-level elsifs
- error on unmatched endif/elsif/else

frontends/verilog/preproc.cc

@@ -727,7 +727,8 @@ frontend_verilog_preproc(std::istream                 &f,
 
 	std::vector<std::string> filename_stack;
 	int ifdef_fail_level = 0;
-	bool in_elseif = false;
+	int ifdef_pass_level = 0;
+	bool ifdef_already_satisfied = false;
 
 	output_code.clear();
 	input_buffer.clear();
@@ -743,42 +744,68 @@ frontend_verilog_preproc(std::istream                 &f,
 		if (tok == "`endif") {
 			if (ifdef_fail_level > 0)
 				ifdef_fail_level--;
-			if (ifdef_fail_level == 0)
-				in_elseif = false;
+			else if (ifdef_pass_level > 0)
+				ifdef_already_satisfied = --ifdef_pass_level;
+			else
+				log_error("Found %s outside of macro conditional branch!\n", tok.c_str());
 			continue;
 		}
 
 		if (tok == "`else") {
-			if (ifdef_fail_level == 0)
+			if (ifdef_fail_level == 0) {
+				if (ifdef_pass_level == 0)
+					log_error("Found %s outside of macro conditional branch!\n", tok.c_str());
+				log_assert(ifdef_already_satisfied);
 				ifdef_fail_level = 1;
-			else if (ifdef_fail_level == 1 && !in_elseif)
+			} else if (ifdef_fail_level == 1 && !ifdef_already_satisfied) {
 				ifdef_fail_level = 0;
+				ifdef_pass_level++;
+				ifdef_already_satisfied = true;
+			}
 			continue;
 		}
 
 		if (tok == "`elsif") {
 			skip_spaces();
 			std::string name = next_token(true);
-			if (ifdef_fail_level == 0)
-				ifdef_fail_level = 1, in_elseif = true;
-			else if (ifdef_fail_level == 1 && defines.find(name))
-				ifdef_fail_level = 0, in_elseif = true;
+			if (ifdef_fail_level == 0) {
+				if (ifdef_pass_level == 0)
+					log_error("Found %s outside of macro conditional branch!\n", tok.c_str());
+				log_assert(ifdef_already_satisfied);
+				ifdef_fail_level = 1;
+			} else if (ifdef_fail_level == 1 && !ifdef_already_satisfied && defines.find(name)) {
+				ifdef_fail_level = 0;
+				ifdef_pass_level++;
+				ifdef_already_satisfied = true;
+			}
 			continue;
 		}
 
 		if (tok == "`ifdef") {
 			skip_spaces();
 			std::string name = next_token(true);
-			if (ifdef_fail_level > 0 || !defines.find(name))
+			if (ifdef_fail_level > 0 || !defines.find(name)) {
 				ifdef_fail_level++;
+			} else {
+				ifdef_pass_level++;
+				ifdef_already_satisfied = true;
+			}
+			if (ifdef_fail_level == 1)
+				ifdef_already_satisfied = false;
 			continue;
 		}
 
 		if (tok == "`ifndef") {
 			skip_spaces();
 			std::string name = next_token(true);
-			if (ifdef_fail_level > 0 || defines.find(name))
+			if (ifdef_fail_level > 0 || defines.find(name)) {
 				ifdef_fail_level++;
+			} else {
+				ifdef_pass_level++;
+				ifdef_already_satisfied = true;
+			}
+			if (ifdef_fail_level == 1)
+				ifdef_already_satisfied = false;
 			continue;
 		}
 

tests/simple/ifdef_1.v

@@ -0,0 +1,88 @@
+module top(o1, o2, o3, o4);
+
+`define FAIL input wire not_a_port;
+
+`ifdef COND_1
+	`FAIL
+`elsif COND_2
+	`FAIL
+`elsif COND_3
+	`FAIL
+`elsif COND_4
+	`FAIL
+`else
+
+	`define COND_4
+	output wire o4;
+
+	`ifdef COND_1
+		`FAIL
+	`elsif COND_2
+		`FAIL
+	`elsif COND_3
+		`FAIL
+	`elsif COND_4
+
+		`define COND_3
+		output wire o3;
+
+		`ifdef COND_1
+			`FAIL
+		`elsif COND_2
+			`FAIL
+		`elsif COND_3
+
+			`define COND_2
+			output wire o2;
+
+			`ifdef COND_1
+				`FAIL
+			`elsif COND_2
+
+				`define COND_1
+				output wire o1;
+
+				`ifdef COND_1
+
+					`ifdef COND_1
+					`elsif COND_2
+						`FAIL
+					`elsif COND_3
+						`FAIL
+					`elsif COND_4
+						`FAIL
+					`else
+						`FAIL
+					`endif
+
+				`elsif COND_2
+					`FAIL
+				`elsif COND_3
+					`FAIL
+				`elsif COND_4
+					`FAIL
+				`else
+					`FAIL
+				`endif
+
+			`elsif COND_3
+				`FAIL
+			`elsif COND_4
+				`FAIL
+			`else
+				`FAIL
+			`endif
+
+		`elsif COND_4
+			`FAIL
+		`else
+			`FAIL
+		`endif
+
+	`else
+		`FAIL
+	`endif
+
+`endif
+
+endmodule

tests/simple/ifdef_2.v

@@ -0,0 +1,21 @@
+module top(o1, o2, o3);
+
+output wire o1;
+
+`define COND_1
+`define COND_2
+`define COND_3
+
+`ifdef COND_1
+	output wire o2;
+`elsif COND_2
+	input wire dne1;
+`elsif COND_3
+	input wire dne2;
+`else
+	input wire dne3;
+`endif
+
+output wire o3;
+
+endmodule

tests/verilog/include_self.v

@@ -0,0 +1,30 @@
+`ifdef GUARD_5
+module top;
+	wire x;
+endmodule
+
+`elsif GUARD_4
+`define GUARD_5
+`include "include_self.v"
+
+`elsif GUARD_3
+`define GUARD_4
+`include "include_self.v"
+
+`elsif GUARD_2
+`define GUARD_3
+`include "include_self.v"
+
+`elsif GUARD_1
+`define GUARD_2
+`include "include_self.v"
+
+`elsif GUARD_0
+`define GUARD_1
+`include "include_self.v"
+
+`else
+`define GUARD_0
+`include "include_self.v"
+
+`endif

tests/verilog/include_self.ys

@@ -0,0 +1,2 @@
+read_verilog include_self.v
+select -assert-count 1 top/x

tests/verilog/unmatched_else.ys

@@ -0,0 +1,6 @@
+logger -expect error "Found `else outside of macro conditional branch!" 1
+read_verilog <<EOT
+module top;
+`else
+endmodule
+EOT

tests/verilog/unmatched_elsif.ys

@@ -0,0 +1,6 @@
+logger -expect error "Found `elsif outside of macro conditional branch!" 1
+read_verilog <<EOT
+module top;
+`elsif
+endmodule
+EOT

tests/verilog/unmatched_endif.ys

@@ -0,0 +1,6 @@
+logger -expect error "Found `endif outside of macro conditional branch!" 1
+read_verilog <<EOT
+module top;
+`endif
+endmodule
+EOT