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 07e3cd6e0aad0eb7672dec50ede179e8753d8070..2d7c2187e2f3fb1e8ebe71a6d1cae8077713d7d3 100644 (file)
--- 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);