util: Make m5 commands return a bool instead of calling usage.

By delegating actually calling usage() elsewhere, we can remove a dependency
from the commands themselves, and also make testing easier since we won't
exit() every time we call a command with bad arguments.

Change-Id: I6b8e2cb77ce0456b16673f10349362cc53218bba
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27565
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

util/m5/src/command.cc

@@ -52,6 +52,5 @@ Command::run(const DispatchTable &dt, Args &args)
     if (num_args < cmd.minArgs || num_args > cmd.maxArgs)
         return false;
 
-    cmd.func(dt, args);
-    return true;
+    return cmd.func(dt, args);
 }

util/m5/src/command.hh

@@ -46,7 +46,7 @@ class Command
     // The maximum number of arguments the command can handle.
     const int maxArgs;
 
-    using FuncType = void (*)(const DispatchTable &dt, Args &args);
+    using FuncType = bool (*)(const DispatchTable &dt, Args &args);
     // A function which processes command line arguments and passes them to
     // the underlying function through the dispatch table.
     FuncType func;

util/m5/src/command.test.cc

@@ -40,18 +40,20 @@ class DispatchTable {};
 
 DispatchTable dt;
 
-void
+bool
 do_test1(const DispatchTable &dt, Args &args)
 {
     ran_test1 = true;
+    return true;
 }
 
 bool ran_test2 = false;
 
-void
+bool
 do_test2(const DispatchTable &dt, Args &args)
 {
     ran_test2 = true;
+    return true;
 }
 
 TEST(CommandTest, OneCommandNoArgs)

util/m5/src/command/addsymbol.cc

@@ -29,20 +29,21 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_add_symbol(const DispatchTable &dt, Args &args)
 {
     uint64_t addr;
     if (!args.pop(addr))
-        usage();
+        return false;
     const std::string &symbol = args.pop();
 
     (*dt.m5_add_symbol)(addr, symbol.c_str());
+
+    return true;
 }
 
 Command add_symbol = {

util/m5/src/command/checkpoint.cc

@@ -29,19 +29,19 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_checkpoint(const DispatchTable &dt, Args &args)
 {
     uint64_t ns_delay, ns_period;
     if (!args.pop(ns_delay, 0) || !args.pop(ns_period, 0))
-        usage();
+        return false;
 
     (*dt.m5_checkpoint)(ns_delay, ns_period);
+    return true;
 }
 
 Command checkpoint = {

util/m5/src/command/dumpresetstats.cc

@@ -29,19 +29,20 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_dump_reset_stats(const DispatchTable &dt, Args &args)
 {
     uint64_t ns_delay, ns_period;
     if (!args.pop(ns_delay, 0) || !args.pop(ns_period, 0))
-        usage();
+        return false;
 
     (*dt.m5_dump_reset_stats)(ns_delay, ns_period);
+
+    return true;
 }
 
 Command dump_reset_stats = {

util/m5/src/command/dumpstats.cc

@@ -29,19 +29,20 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_dump_stats(const DispatchTable &dt, Args &args)
 {
     uint64_t ns_delay, ns_period;
     if (!args.pop(ns_delay, 0) || !args.pop(ns_period, 0))
-        usage();
+        return false;
 
     (*dt.m5_dump_stats)(ns_delay, ns_period);
+
+    return true;
 }
 
 Command dump_stats = {

util/m5/src/command/exit.cc

@@ -29,19 +29,20 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_exit(const DispatchTable &dt, Args &args)
 {
     uint64_t ns_delay;
     if (!args.pop(ns_delay, 0))
-        usage();
+        return false;
 
     (*dt.m5_exit)(ns_delay);
+
+    return true;
 }
 
 Command exit_cmd = {

util/m5/src/command/fail.cc

@@ -29,19 +29,20 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_fail(const DispatchTable &dt, Args &args)
 {
     uint64_t ns_delay, code;
     if (!args.pop(code) || !args.pop(ns_delay, 0))
-        usage();
+        return false;
 
     (*dt.m5_fail)(ns_delay, code);
+
+    return true;
 }
 
 Command fail_cmd = {

util/m5/src/command/initparam.cc

@@ -31,19 +31,21 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_initparam(const DispatchTable &dt, Args &args)
 {
     uint64_t key_str[2];
     if (!args.pop(key_str, 2))
-        usage();
+        return false;
+
     uint64_t val = (*dt.m5_init_param)(key_str[0], key_str[1]);
     std::cout << val;
+
+    return true;
 }
 
 Command init_param = {

util/m5/src/command/loadsymbol.cc

@@ -29,15 +29,15 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_loadsymbol(const DispatchTable &dt, Args &args)
 {
     (*dt.m5_load_symbol)();
+    return true;
 }
 
 Command load_symbol = {

util/m5/src/command/readfile.cc

@@ -32,7 +32,6 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
@@ -62,13 +61,15 @@ read_file(const DispatchTable &dt, std::ostream &os)
     return offset;
 }
 
-void
+bool
 do_read_file(const DispatchTable &dt, Args &args)
 {
     if (args.size() > 0)
-        usage();
+        return false;
 
     read_file(dt, std::cout);
+
+    return true;
 }
 
 Command read_file_cmd = {

util/m5/src/command/resetstats.cc

@@ -29,19 +29,20 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
-void
+bool
 do_reset_stats(const DispatchTable &dt, Args &args)
 {
     uint64_t ns_delay, ns_period;
     if (!args.pop(ns_delay, 0) || !args.pop(ns_period, 0))
-        usage();
+        return false;
 
     (*dt.m5_reset_stats)(ns_delay, ns_period);
+
+    return true;
 }
 
 Command reset_stats = {

util/m5/src/command/sum.cc

@@ -31,22 +31,23 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
 
 // For testing purposes.
-void
+bool
 do_sum(const DispatchTable &dt, Args &args)
 {
     uint64_t a, b, c, d, e, f;
     if (!args.pop(a) || !args.pop(b) || !args.pop(c, 0) ||
             !args.pop(d, 0) || !args.pop(e, 0) || !args.pop(f, 0))
-        usage();
+        return false;
 
     unsigned sum = (*dt.m5_sum)(a, b, c, d, e, f);
     std::cout << "Sum is " << sum << "." << std::endl;
+
+    return true;
 }
 
 Command sum = {

util/m5/src/command/writefile.cc

@@ -33,7 +33,6 @@
 #include "args.hh"
 #include "command.hh"
 #include "dispatch_table.hh"
-#include "usage.hh"
 
 namespace
 {
@@ -75,13 +74,15 @@ write_file(const DispatchTable &dt, const std::string &filename,
     std::cerr << "Wrote " << offset << " bytes." << std::endl;
 }
 
-void
+bool
 do_write_file(const DispatchTable &dt, Args &args)
 {
     const std::string &filename = args.pop();
     const std::string &host_filename = args.pop(filename);
 
     write_file(dt, filename, host_filename);
+
+    return true;
 }
 
 Command write_file_cmd = {