From bf8ca989d603b52d4be8c6460a2685d469a4edac Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Sun, 28 Jul 2024 00:58:00 +0200
Subject: [PATCH] Add `--show-backtrace` option to disable backtrace for even
 smaller binary.

---
 lib/std/core/builtin.c3          |  2 +-
 lib/std/core/env.c3              |  1 +
 releasenotes.md                  |  1 +
 src/build/build.h                | 10 ++++++++++
 src/build/build_internal.h       |  5 +++++
 src/build/build_options.c        | 10 ++++++++--
 src/build/builder.c              |  4 ++++
 src/build/project.c              |  6 ++++++
 src/compiler/compiler.c          |  1 +
 src/compiler/semantic_analyser.c |  2 +-
 10 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/lib/std/core/builtin.c3 b/lib/std/core/builtin.c3
index ef74bbb2a..9fef9518a 100644
--- a/lib/std/core/builtin.c3
+++ b/lib/std/core/builtin.c3
@@ -683,7 +683,7 @@ fn void install_signal_handler(CInt signal, SignalFunction func) @local
 }
 
 // Clean this up
-fn void install_signal_handlers() @init(101) @local
+fn void install_signal_handlers() @init(101) @local @if(env::BACKTRACE)
 {
 	install_signal_handler(libc::SIGBUS, &sig_bus_error);
 	install_signal_handler(libc::SIGSEGV, &sig_segmentation_fault);
diff --git a/lib/std/core/env.c3 b/lib/std/core/env.c3
index 79118e13d..e9e9c8fa1 100644
--- a/lib/std/core/env.c3
+++ b/lib/std/core/env.c3
@@ -128,6 +128,7 @@ const bool F128_SUPPORT = $$PLATFORM_F128_SUPPORTED;
 const REGISTER_SIZE = $$REGISTER_SIZE;
 const bool COMPILER_SAFE_MODE = $$COMPILER_SAFE_MODE;
 const bool DEBUG_SYMBOLS = $$DEBUG_SYMBOLS;
+const bool BACKTRACE = $$BACKTRACE;
 const usz LLVM_VERSION = $$LLVM_VERSION;
 const bool BENCHMARKING = $$BENCHMARKING;
 const bool TESTING = $$TESTING;
diff --git a/releasenotes.md b/releasenotes.md
index db69e43e4..1077baeec 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -14,6 +14,7 @@
 - Don't generate .o files on `compile` and `compile-run` if there is no `main`.
 - c3c init-lib does not create the directory with the .c3l suffix #1253
 - Permit foreach values to be optional.
+- Add `--show-backtrace` option to disable backtrace for even smaller binary.
 
 ### Fixes
 - Broken WASM library code.
diff --git a/src/build/build.h b/src/build/build.h
index f06e97d04..62c8e0ff3 100644
--- a/src/build/build.h
+++ b/src/build/build.h
@@ -192,6 +192,13 @@ typedef enum
 	USE_STDLIB_ON = 1
 } UseStdlib;
 
+typedef enum
+{
+	SHOW_BACKTRACE_NOT_SET = -1,
+	SHOW_BACKTRACE_OFF = 0,
+	SHOW_BACKTRACE_ON = 1
+} ShowBacktrace;
+
 typedef enum
 {
 	SIZE_OPTIMIZATION_NOT_SET = -1,
@@ -383,6 +390,7 @@ typedef struct BuildOptions_
 	DiagnosticsSeverity severity[DIAG_END_SENTINEL];
 	OptimizationSetting optsetting;
 	DebugInfo debug_info_override;
+	ShowBacktrace show_backtrace;
 	ArchOsTarget arch_os_target_override;
 	SafetyLevel safety_level;
 	PanicLevel panic_level;
@@ -529,6 +537,7 @@ typedef struct
 	UseStdlib use_stdlib;
 	EmitStdlib emit_stdlib;
 	LinkLibc link_libc;
+	ShowBacktrace show_backtrace;
 	StripUnused strip_unused;
 	DebugInfo debug_info;
 	MergeFunctions merge_functions;
@@ -603,6 +612,7 @@ static BuildTarget default_build_target = {
 		.optsize = SIZE_OPTIMIZATION_NOT_SET,
 		.arch_os_target = ARCH_OS_TARGET_DEFAULT,
 		.debug_info = DEBUG_INFO_NOT_SET,
+		.show_backtrace = SHOW_BACKTRACE_NOT_SET,
 		.use_stdlib = USE_STDLIB_NOT_SET,
 		.link_libc = LINK_LIBC_NOT_SET,
 		.emit_stdlib = EMIT_STDLIB_NOT_SET,
diff --git a/src/build/build_internal.h b/src/build/build_internal.h
index f0bdeaeeb..1853dbc83 100644
--- a/src/build/build_internal.h
+++ b/src/build/build_internal.h
@@ -81,6 +81,11 @@ static const char *optlevels[4] = {
 	[OPTIMIZATION_AGGRESSIVE] = "max",
 };
 
+static const char *backtrace_levels[2] = {
+	[SHOW_BACKTRACE_OFF] = "off",
+	[SHOW_BACKTRACE_ON] = "on",
+};
+
 static const char *reloc_models[5] = {
 	[RELOC_NONE] = "none",
 	[RELOC_SMALL_PIC] = "pic",
diff --git a/src/build/build_options.c b/src/build/build_options.c
index 7d4f530d5..793a53614 100644
--- a/src/build/build_options.c
+++ b/src/build/build_options.c
@@ -99,9 +99,9 @@ static void usage(void)
 	PRINTF("  -O2                        - Unsafe, high optimization, emit debug info.");
 	PRINTF("  -O3                        - Unsafe, high optimization, single module, emit debug info.");
 	PRINTF("  -O4                        - Unsafe, highest optimization, relaxed maths, single module, emit debug info, no panic messages.");
-	PRINTF("  -O5                        - Unsafe, highest optimization, fast maths, single module, emit debug info, no panic messages.");
+	PRINTF("  -O5                        - Unsafe, highest optimization, fast maths, single module, emit debug info, no panic messages, no backtrace.");
 	PRINTF("  -Os                        - Unsafe, high optimization, small code, single module, no debug info, no panic messages.");
-	PRINTF("  -Oz                        - Unsafe, high optimization, tiny code, single module, no debug info, no panic messages.");
+	PRINTF("  -Oz                        - Unsafe, high optimization, tiny code, single module, no debug info, no panic messages, no backtrace.");
 	PRINTF("  -D <name>                  - Add feature flag <name>.");
 	PRINTF("  -U <name>                  - Remove feature flag <name>.");
 	PRINTF("  --trust=<option>           - Trust level: none (default), include ($include allowed), full ($exec / exec allowed).");
@@ -123,6 +123,7 @@ static void usage(void)
 	PRINTF("  --optlevel=<option>        - Code optimization level: none, less, more, max.");
 	PRINTF("  --optsize=<option>         - Code size optimization: none, small, tiny.");
 	PRINTF("  --single-module=<yes|no>   - Compile all modules together, enables more inlining.");
+	PRINTF("  --show-backtrace=<yes|no>  - Show detailed backtrace on segfaults.");
 	PRINTF("");
 	PRINTF("  -g                         - Emit debug info.");
 	PRINTF("  -g0                        - Emit no debug info.");
@@ -684,6 +685,11 @@ static void parse_option(BuildOptions *options)
 				options->safety_level = (SafetyLevel)parse_multi_option(argopt, 2, on_off);
 				return;
 			}
+			if ((argopt = match_argopt("show-backtrace")))
+			{
+				options->show_backtrace = (ShowBacktrace) parse_multi_option(argopt, 2, on_off);
+				return;
+			}
 			if ((argopt = match_argopt("panic-msg")))
 			{
 				options->panic_level = (PanicLevel)parse_multi_option(argopt, 2, on_off);
diff --git a/src/build/builder.c b/src/build/builder.c
index b4540e9dc..7ff633bb0 100644
--- a/src/build/builder.c
+++ b/src/build/builder.c
@@ -105,6 +105,7 @@ void update_build_target_with_opt_level(BuildTarget *target, OptimizationSetting
 	AutoVectorization vectorization = VECTORIZATION_OFF;
 	AutoVectorization slp_vectorization = VECTORIZATION_OFF;
 	MergeFunctions merge_functions = MERGE_FUNCTIONS_OFF;
+	ShowBacktrace show_backtrace = SHOW_BACKTRACE_ON;
 	bool single_module = false;
 	FpOpt fp_opt = FP_STRICT;
 	switch (level)
@@ -172,6 +173,7 @@ void update_build_target_with_opt_level(BuildTarget *target, OptimizationSetting
 			optsize = SIZE_OPTIMIZATION_TINY;
 			panic_level = PANIC_OFF;
 			safety_level = SAFETY_OFF;
+			show_backtrace = SHOW_BACKTRACE_OFF;
 			single_module = true;
 			slp_vectorization = VECTORIZATION_ON;
 			vectorization = VECTORIZATION_OFF;
@@ -182,6 +184,7 @@ void update_build_target_with_opt_level(BuildTarget *target, OptimizationSetting
 	}
 	if (target->optsize == SIZE_OPTIMIZATION_NOT_SET) target->optsize = optsize;
 	if (target->optlevel == OPTIMIZATION_NOT_SET) target->optlevel = optlevel;
+	if (target->show_backtrace == SHOW_BACKTRACE_NOT_SET) target->show_backtrace = show_backtrace;
 	if (target->feature.safe_mode == SAFETY_NOT_SET) target->feature.safe_mode = safety_level;
 	if (target->feature.panic_level == PANIC_NOT_SET) target->feature.panic_level = panic_level;
 	if (target->debug_info == DEBUG_INFO_NOT_SET) target->debug_info = debug;
@@ -281,6 +284,7 @@ static void update_build_target_from_options(BuildTarget *target, BuildOptions *
 	if (options->strip_unused != STRIP_UNUSED_NOT_SET) target->strip_unused = options->strip_unused;
 	if (options->memory_environment != MEMORY_ENV_NOT_SET) target->memory_environment = options->memory_environment;
 	if (options->debug_info_override != DEBUG_INFO_NOT_SET) target->debug_info = options->debug_info_override;
+	if (options->show_backtrace != SHOW_BACKTRACE_NOT_SET) target->show_backtrace = options->show_backtrace;
 	if (options->arch_os_target_override != ARCH_OS_TARGET_DEFAULT) target->arch_os_target = options->arch_os_target_override;
 	if (options->reloc_model != RELOC_DEFAULT) target->reloc_model = options->reloc_model;
 	if (options->symtab_size) target->symtab_size = options->symtab_size;
diff --git a/src/build/project.c b/src/build/project.c
index 9306360bb..623a9df04 100644
--- a/src/build/project.c
+++ b/src/build/project.c
@@ -41,6 +41,7 @@ const char *project_default_keys[][2] = {
 		{"panic-msg", "Turn panic message output on or off."},
 		{"reloc", "Relocation model: none, pic, PIC, pie, PIE."},
 		{"safe", "Set safety (contracts, runtime bounds checking, null pointer checks etc) on or off."},
+		{"show-backtrace", "Print backtrace on signals."},
 		{"script-dir", "The directory where 'exec' is run."},
 		{"single-module", "Compile all modules together, enables more inlining."},
 		{"soft-float", "Output soft-float functions."},
@@ -107,6 +108,7 @@ const char* project_target_keys[][2] = {
 		{"safe", "Set safety (contracts, runtime bounds checking, null pointer checks etc) on or off."},
 		{"script-dir", "The directory where 'exec' is run."},
 		{"single-module", "Compile all modules together, enables more inlining."},
+		{"show-backtrace", "Print backtrace on signals."},
 		{"soft-float", "Output soft-float functions."},
 		{"sources", "Additional paths to project sources for the target."},
 		{"sources-override", "Paths to project sources for this target, overriding global settings."},
@@ -208,6 +210,7 @@ static void load_into_build_target(JSONObject *json, const char *target_name, Bu
 			[DEBUG_INFO_NONE] = "none",
 			[DEBUG_INFO_LINE_TABLES] = "line-tables"
 	};
+
 	DebugInfo info = GET_SETTING(DebugInfo, "debug-info", debug_infos, "one of 'full' 'line-table' or 'none'.");
 	if (info > -1) target->debug_info = info;
 
@@ -233,6 +236,9 @@ static void load_into_build_target(JSONObject *json, const char *target_name, Bu
 	// Safety level
 	target->feature.safe_mode = (SafetyLevel)get_valid_bool(PROJECT_JSON, target_name, json, "safe", target->feature.safe_mode);
 
+	// Backtrace
+	target->show_backtrace = (ShowBacktrace) get_valid_bool(PROJECT_JSON, target_name, json, "show-backtrace", target->show_backtrace);
+
 	// Panic level
 	target->feature.panic_level = (PanicLevel)get_valid_bool(PROJECT_JSON, target_name, json, "panic-msg",
 	                                                          target->feature.panic_level);
diff --git a/src/compiler/compiler.c b/src/compiler/compiler.c
index e1aefb642..97f8d2fc5 100644
--- a/src/compiler/compiler.c
+++ b/src/compiler/compiler.c
@@ -1109,6 +1109,7 @@ void compile()
 	setup_int_define("COMPILER_SIZE_OPT_LEVEL", (uint64_t)active_target.optsize, type_int);
 	setup_bool_define("COMPILER_SAFE_MODE", safe_mode_enabled());
 	setup_bool_define("DEBUG_SYMBOLS", active_target.debug_info == DEBUG_INFO_FULL);
+	setup_bool_define("BACKTRACE", active_target.show_backtrace != SHOW_BACKTRACE_OFF);
 	setup_int_define("LLVM_VERSION", llvm_version_major, type_int);
 	setup_bool_define("BENCHMARKING", active_target.benchmarking);
 	setup_int_define("JMP_BUF_SIZE", jump_buffer_size(), type_int);
diff --git a/src/compiler/semantic_analyser.c b/src/compiler/semantic_analyser.c
index 15a56f9db..c6a24f7b3 100644
--- a/src/compiler/semantic_analyser.c
+++ b/src/compiler/semantic_analyser.c
@@ -260,7 +260,7 @@ static void sema_analyze_to_stage(AnalysisStage stage)
 
 static void assign_panicfn(void)
 {
-	if (!active_target.panicfn && no_stdlib())
+	if (active_target.feature.panic_level == PANIC_OFF || (!active_target.panicfn && no_stdlib()))
 	{
 		global_context.panic_var = NULL;
 		global_context.panicf = NULL;