verilog: fix handling of nested ifdef directives

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

1 files changed, 38 insertions, 11 deletions

diff --git a/frontends/verilog/preproc.cc b/frontends/verilog/preproc.cc
index de707593f..84966e501 100644
--- a/frontends/verilog/preproc.cc
+++ b/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;
 		}