Write execution logs to a named log file (#409)

This patch adds a --log argument to spike. If not given, the behaviour
is unchanged: messages logging execution of instructions and (if
commit logging is enabled) commits go to stderr.

If --log=P is given, Spike now writes these messages to a log file at
the path P. This is nice, because they are no longer tangled up with
other errors and warnings.

The code is mostly plumbing: passing a FILE* object through to the
functions that were using stderr. I've written a simple "log_file_t"
class, which opens a log file if necessary and yields it or stderr.

1 files changed, 1 insertions, 1 deletions

diff --git a/spike_main/spike-log-parser.cc b/spike_main/spike-log-parser.cc
index 5de6220..d174afc 100644
--- a/spike_main/spike-log-parser.cc
+++ b/spike_main/spike-log-parser.cc
@@ -27,7 +27,7 @@ int main(int argc, char** argv)
   parser.option(0, "isa", 1, [&](const char* s){isa = s;});
   parser.parse(argv);
 
-  processor_t p(isa, DEFAULT_PRIV, DEFAULT_VARCH, 0, 0);
+  processor_t p(isa, DEFAULT_PRIV, DEFAULT_VARCH, 0, 0, false, nullptr);
   if (extension) {
     p.register_extension(extension());
   }