From f7dff29c6ce959968cb489fcbee2d3ebde0784d0 Mon Sep 17 00:00:00 2001
From: Zoltan Varga <vargaz@gmail.com>
Date: Thu, 18 Apr 2019 16:41:47 -0400
Subject: [PATCH] [aot] Add a depfile= argument which causes the AOT compiler
 to write out a gcc style dep file listing the dependencies between the output
 file and all referenced assemblies. (#14124)

* [aot] Add a depfile= argument which causes the AOT compiler to write out a gcc style dep file listing the dependencies between the output file and all referenced assemblies.

* Add a manpage entry.

* Update after comments.
---
 man/mono.1               |  3 +++
 mono/mini/aot-compiler.c | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/man/mono.1 b/man/mono.1
index e783173c932..cf27efc72a9 100644
--- a/man/mono.1
+++ b/man/mono.1
@@ -267,6 +267,9 @@ Print the architecture the AOT in this copy of Mono targets and quit.
 Generates all required wrappers, so that it is possible to run --interpreter without
 any code generation at runtime.  This option only makes sense with \fBmscorlib.dll\fR.
 Embedders can set
+.TP
+.I depfile=[filename]
+Outputs a gcc -M style dependency file.
 
 .nf
 mono_jit_set_aot_mode (MONO_AOT_MODE_INTERP);
diff --git a/mono/mini/aot-compiler.c b/mono/mini/aot-compiler.c
index 886d715c30f..d03c43f2694 100644
--- a/mono/mini/aot-compiler.c
+++ b/mono/mini/aot-compiler.c
@@ -234,6 +234,7 @@ typedef struct MonoAotOptions {
 	gboolean profile_only;
 	gboolean no_opt;
 	char *clangxx;
+	char *depfile;
 } MonoAotOptions;
 
 typedef enum {
@@ -8029,6 +8030,8 @@ mono_aot_parse_options (const char *aot_options, MonoAotOptions *opts)
 			opts->no_opt = TRUE;
 		} else if (str_begins_with (arg, "clangxx=")) {
 			opts->clangxx = g_strdup (arg + strlen ("clangxx="));
+		} else if (str_begins_with (arg, "depfile=")) {
+			opts->depfile = g_strdup (arg + strlen ("depfile="));
 		} else if (str_begins_with (arg, "help") || str_begins_with (arg, "?")) {
 			printf ("Supported options for --aot:\n");
 			printf ("    asmonly\n");
@@ -8076,6 +8079,7 @@ mono_aot_parse_options (const char *aot_options, MonoAotOptions *opts)
 			printf ("    llvmopts=\n");
 			printf ("    llvmllc=\n");
 			printf ("    clangxx=\n");
+			printf ("    depfile=\n");
 			printf ("    help/?\n");
 			exit (0);
 		} else {
@@ -13588,6 +13592,32 @@ print_stats (MonoAotCompile *acfg)
 		mono_dedup_log_stats (acfg);
 }
 
+static void
+create_depfile (MonoAotCompile *acfg)
+{
+	FILE *depfile;
+
+	// FIXME: Support other configurations
+	g_assert (acfg->aot_opts.llvm_only && acfg->aot_opts.asm_only && acfg->aot_opts.llvm_outfile);
+
+	depfile = fopen (acfg->aot_opts.depfile, "w");
+	g_assert (depfile);
+
+	int ntargets = 1;
+	char **targets = g_new0 (char*, ntargets);
+	targets [0] = acfg->aot_opts.llvm_outfile;
+	for (int tindex = 0; tindex < ntargets; ++tindex) {
+		fprintf (depfile, "%s: ", targets [tindex]);
+		for (int i = 0; i < acfg->image_table->len; i++) {
+			MonoImage *image = (MonoImage*)g_ptr_array_index (acfg->image_table, i);
+			fprintf (depfile, " %s", image->filename);
+		}
+		fprintf (depfile, "\n");
+	}
+	g_free (targets);
+	fclose (depfile);
+}
+
 static int
 emit_aot_image (MonoAotCompile *acfg)
 {
@@ -13810,6 +13840,9 @@ emit_aot_image (MonoAotCompile *acfg)
 
 	aot_printf (acfg, "JIT time: %d ms, Generation time: %d ms, Assembly+Link time: %d ms.\n", acfg->stats.jit_time / 1000, acfg->stats.gen_time / 1000, acfg->stats.link_time / 1000);
 
+	if (acfg->aot_opts.depfile)
+		create_depfile (acfg);
+
 	if (acfg->aot_opts.dump_json)
 		aot_dump (acfg);
 
-- 
2.11.4.GIT