From: Henner Zeller <h.zeller@acm.org>
Date: Thu, 21 Jan 2021 20:20:53 +0000 (-0800)
Subject: Fix digit-formatting calculation for small numbers.
X-Git-Tag: working-ls180~34^2~1
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7d014902ec579eccd04446131fea4772dd715daf;p=yosys.git

Fix digit-formatting calculation for small numbers.

Calling log10() on zero causes a non-sensical value to be calculated. On some
compile options, I've observed yosys crashing with an illegal
instruction (SIGILL).

To make it safe, fix the calculation to do a range check; wrap it a
decimal_digits() function, and use it where the previous ceil(log10(n)) call
was used. As a side, it also improves readability.

Signed-off-by: Henner Zeller <h.zeller@acm.org>
---

diff --git a/frontends/aiger/aigerparse.cc b/frontends/aiger/aigerparse.cc
index 07e3cd6e0..2d7c2187e 100644
--- a/frontends/aiger/aigerparse.cc
+++ b/frontends/aiger/aigerparse.cc
@@ -55,6 +55,10 @@ inline int32_t from_big_endian(int32_t i32) {
 #define log_debug2(...) ;
 //#define log_debug2(...) log_debug(__VA_ARGS__)
 
+static int decimal_digits(unsigned n) {
+	return n > 1 ? ceil(log10(n)) : 1;
+}
+
 struct ConstEvalAig
 {
 	RTLIL::Module *module;
@@ -515,7 +519,7 @@ void AigerReader::parse_aiger_ascii()
 	unsigned l1, l2, l3;
 
 	// Parse inputs
-	int digits = ceil(log10(I));
+	int digits = decimal_digits(I);
 	for (unsigned i = 1; i <= I; ++i, ++line_count) {
 		if (!(f >> l1))
 			log_error("Line %u cannot be interpreted as an input!\n", line_count);
@@ -537,7 +541,7 @@ void AigerReader::parse_aiger_ascii()
 		clk_wire->port_input = true;
 		clk_wire->port_output = false;
 	}
-	digits = ceil(log10(L));
+	digits = decimal_digits(L);
 	for (unsigned i = 0; i < L; ++i, ++line_count) {
 		if (!(f >> l1 >> l2))
 			log_error("Line %u cannot be interpreted as a latch!\n", line_count);
@@ -575,7 +579,7 @@ void AigerReader::parse_aiger_ascii()
 	}
 
 	// Parse outputs
-	digits = ceil(log10(O));
+	digits = decimal_digits(O);
 	for (unsigned i = 0; i < O; ++i, ++line_count) {
 		if (!(f >> l1))
 			log_error("Line %u cannot be interpreted as an output!\n", line_count);
@@ -643,7 +647,7 @@ void AigerReader::parse_aiger_binary()
 	std::string line;
 
 	// Parse inputs
-	int digits = ceil(log10(I));
+	int digits = decimal_digits(I);
 	for (unsigned i = 1; i <= I; ++i) {
 		log_debug2("%d is an input\n", i);
 		RTLIL::Wire *wire = module->addWire(stringf("$i%0*d", digits, i));
@@ -662,7 +666,7 @@ void AigerReader::parse_aiger_binary()
 		clk_wire->port_input = true;
 		clk_wire->port_output = false;
 	}
-	digits = ceil(log10(L));
+	digits = decimal_digits(L);
 	l1 = (I+1) * 2;
 	for (unsigned i = 0; i < L; ++i, ++line_count, l1 += 2) {
 		if (!(f >> l2))
@@ -700,7 +704,7 @@ void AigerReader::parse_aiger_binary()
 	}
 
 	// Parse outputs
-	digits = ceil(log10(O));
+	digits = decimal_digits(O);
 	for (unsigned i = 0; i < O; ++i, ++line_count) {
 		if (!(f >> l1))
 			log_error("Line %u cannot be interpreted as an output!\n", line_count);