Nix expr: Expose Mono's profiler

Dist/launch-scripts.nix

@@ -12,7 +12,17 @@
 , debugDotnetHostCrashes
 , initConfig # pretend this is JSON; the following env. vars will be substituted by the wrapper script (if surrounded by double-percent e.g. `%%BIZHAWK_DATA_HOME%%`): `BIZHAWK_DATA_HOME`
 , isManualLocalBuild # i.e. dotnet build in nix-shell; skips everything involving BIZHAWK_DATA_HOME, such as copying Assets and initConfig
+, profileManagedCalls
 }: let
+	/**
+	 * you can make use of the call duration data by seeing which methods it's spending the longest in: `mprof-report --reports=call --method-sort=self output/*.flame.mlpd` (really you'd want to sort by self/count but that's not an option)
+	 *
+	 * the other useful profiling mode is allocations: `nix-shell --argstr profileManagedCalls " --profile=log:alloc,nocalls,output=%t.alloc.mlpd"`
+	 * you can make use of the allocation data by listing which types had the most instances allocated: `mprof-report --reports=alloc --alloc-sort=count output/*.alloc.mlpd`
+	 */
+	monoProfilerFlag = if builtins.isString profileManagedCalls
+		then profileManagedCalls
+		else if profileManagedCalls then " --profile=log:noalloc,calls,zip,output=%t.flame.mlpd" else "";
 	hawkVersion = bizhawkAssemblies.hawkSourceInfo.version;
 	commentLineIf = b: lib.optionalString b "# ";
 	/**
@@ -79,7 +89,8 @@
 		else
 			export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$ldLibPath"
 		fi
-		${if bizhawkAssemblies.hawkSourceInfo.hasAssemblyResolveHandler then "" else ''export MONO_PATH="$BIZHAWK_HOME/dll/nlua:$BIZHAWK_HOME/dll"
+		${if profileManagedCalls == false then "" else ''printf "Will write profiling results to %s/*.mlpd\n" "$PWD"
+		''}${if bizhawkAssemblies.hawkSourceInfo.hasAssemblyResolveHandler then "" else ''export MONO_PATH="$BIZHAWK_HOME/dll/nlua:$BIZHAWK_HOME/dll"
 		''}${lib.optionalString (!debugPInvokes) "# "}export MONO_LOG_LEVEL=debug MONO_LOG_MASK=dll # pass `--arg debugPInvokes true` to nix-build to enable
 		${lib.optionalString debugDotnetHostCrashes "# "}export MONO_CRASH_NOFILE=1 # pass `--arg debugDotnetHostCrashes true` to nix-build to disable
 		if [ "$1" = '--mono-no-redirect' ]; then
@@ -88,7 +99,8 @@
 		fi
 		printf "(capturing output in %s/EmuHawkMono_last*.txt)\n" "$PWD" >&2
 		exec '${redirectOutputToFiles}' EmuHawkMono_laststdout.txt EmuHawkMono_laststderr.txt \
-			'${lib.getBin bizhawkAssemblies.mono}/bin/mono' "$mainAppPath" --config=config.json "$@"
+			'${lib.getBin bizhawkAssemblies.mono}/bin/mono'${monoProfilerFlag} \
+				"$mainAppPath" --config=config.json "$@"
 	'';
 in {
 	inherit emuhawk;
@@ -108,9 +120,11 @@ in {
 		export BIZHAWK_DATA_HOME="$BIZHAWK_DATA_HOME/emuhawk-monort-${hawkVersion}"
 		cd "$BIZHAWK_DATA_HOME"
 
-		export MONO_PATH="$BIZHAWK_HOME/dll"
+		${if profileManagedCalls == false then "" else ''printf "Will write profiling results to %s/*.mlpd\n" "$PWD"
+		''}export MONO_PATH="$BIZHAWK_HOME/dll"
 		${lib.optionalString (!debugPInvokes) "# "}export MONO_LOG_LEVEL=debug MONO_LOG_MASK=dll # pass `--arg debugPInvokes true` to nix-build to enable
-		exec '${lib.getBin bizhawkAssemblies.mono}/bin/mono' "$BIZHAWK_HOME/DiscoHawk.exe" "$@"
+		exec '${lib.getBin bizhawkAssemblies.mono}/bin/mono'${monoProfilerFlag} \
+			"$BIZHAWK_HOME/DiscoHawk.exe" "$@"
 	'';
 	emuhawkNonNixOS = writeShellScript "emuhawk-mono-wrapper-non-nixos" ''exec '${nixGL}/bin/nixGL' '${emuhawk}' "$@"'';
 }

default.nix

@@ -68,6 +68,7 @@ in {
 , extraDotnetBuildFlags ? "" # currently passed to EVERY `dotnet build` and `dotnet test` invocation (and does not replace the flags for parallel compilation added by default)
 , forNixOS ? true
 , initConfig ? {} # forwarded to Dist/launch-scripts.nix (see docs there)
+, profileManagedCalls ? false # forwarded to Dist/launch-scripts.nix
 }: let
 	isVersionAtLeast = lib.flip lib.versionAtLeast; # I stand by this being the more useful param order w.r.t. currying
 	replaceDotWithUnderscore = s: lib.replaceStrings [ "." ] [ "_" ] s;
@@ -99,7 +100,7 @@ in {
 		inherit lib
 			writeShellScript writeText
 			bizhawkAssemblies nixGL
-			debugPInvokes debugDotnetHostCrashes initConfig isManualLocalBuild;
+			debugPInvokes debugDotnetHostCrashes initConfig isManualLocalBuild profileManagedCalls;
 		mkfifo = coreutils;
 		mktemp = coreutils;
 	};

shell.nix

@@ -9,11 +9,15 @@
 , debugDotnetHostCrashes ? false # forwarded to Dist/launch-scripts.nix
 , debugPInvokes ? false # forwarded to Dist/launch-scripts.nix
 , forNixOS ? true
+, profileManagedCalls ? false # forwarded to Dist/launch-scripts.nix
 , useKate ? false
 , useNanoAndCola ? false
 , useVSCode ? false
 }: let
-	avail = import ./. { inherit debugDotnetHostCrashes debugPInvokes forNixOS system; };
+	avail = import ./. {
+		inherit forNixOS system
+			debugDotnetHostCrashes debugPInvokes profileManagedCalls;
+	};
 	f = drv: mkShell {
 		packages = [ git powershell ]
 			++ lib.optionals useNanoAndCola [ git-cola nano ]