Compiler: control global data initialization with $force-initializers

* no longer force global data initialization unless specified in recipe.txt

Author: chqrlie

common/build_target.c2

@@ -104,6 +104,7 @@ public type Target struct @(opaque) {
     Kind kind;
 
     bool disable_asserts;
+    bool force_initializers;
     bool no_libc;
     BackEndKind backend;
     bool backend_no_build;
@@ -172,6 +173,10 @@ public fn bool Target.hasAsserts(const Target* t) { return !t.disable_asserts; }
 
 public type Visitor fn void (void* arg, u32 name, Kind kind);
 
+public fn void Target.enableForceInitializers(Target* t) { t.force_initializers = true; }
+
+public fn bool Target.hasForceInitializers(const Target* t) { return t.force_initializers; }
+
 public fn void Target.visitLibs(const Target* t, Visitor visitor, void* arg) {
     t.libs.visit(visitor, arg);
 }

compiler/c2recipe_parser.c2

@@ -44,6 +44,7 @@ type Kind enum u8 {
     Warnings,
     Backend,
     DisableAsserts,
+    ForceInitializers,
     NoLibc,
     Config,
     Export,
@@ -66,6 +67,7 @@ const char*[] kind_names = {
     "$warnings",
     "$backend",
     "$disable-asserts",
+    "$force-initializers",
     "$nolibc",
     "$config",
     "$export",
@@ -182,7 +184,6 @@ fn void Parser.error(Parser* p, const char* format @(printf_format), ...) @(nore
 
     char[256] locstr;
     p.sm.loc2str(p.token.loc, locstr, elemsof(locstr));
-
     if (color.useColor()) {
         fprintf(stderr, "%s: %serror:%s %s\n", locstr, color.Red.str(), color.Normal.str(), msg);
     } else {
@@ -418,6 +419,9 @@ fn void Parser.lex_option(Parser* p, Token* result) {
     case "disable-asserts":
         result.kind = Kind.DisableAsserts;
         break;
+    case "force-initializers":
+        result.kind = Kind.ForceInitializers;
+        break;
     case "nolibc":
         result.kind = Kind.NoLibc;
         break;
@@ -477,6 +481,7 @@ fn void Parser.parseTop(Parser* p) {
         case Warnings:
         case Backend:
         case DisableAsserts:
+        case ForceInitializers:
         case NoLibc:
             p.error("must be inside target");
             break;
@@ -728,6 +733,11 @@ fn void Parser.parseTarget(Parser* p) {
             p.consumeToken();
             p.target.disableAsserts();
             break;
+        case ForceInitializers:
+            if (files_started) p.error("$force-initializers must come before files");
+            p.consumeToken();
+            p.target.enableForceInitializers();
+            break;
         case NoLibc:
             if (files_started) p.error("$nolibc must come before files");
             p.consumeToken();

compiler/compiler_generate.c2

@@ -74,6 +74,7 @@ fn void Compiler.generate(Compiler* c, const char* target_name, const char* outp
                              c.mainFunc,
                              &asm_files,
                              c.target.hasAsserts(),
+                             c.target.hasForceInitializers(),
                              c.target.getFastBuild() | c.opts.fast_build,
                              c.opts.asan, c.opts.msan, c.opts.ubsan,
                              c.opts.test_mode, c.opts.trace_calls);

generator/c/c_generator.c2

@@ -74,6 +74,7 @@ type Generator struct {
     const build_file.Info* build_info;
     const target_info.Info* targetInfo;
     bool enable_asserts;
+    bool force_initializers;
     bool fast_build;
     bool asan;
     bool msan;
@@ -613,13 +614,16 @@ fn bool Generator.emitGlobalVarDecl(Generator* gen, string_buffer.Buf* out, Decl
         // generate definition to c file
         if (!d.isExported() && !emit_header) out.add("static ");
         gen.emitGlobalVarDeclCommon(out, d);
-        out.add(" = ");
         Expr* ie = vd.getInit();
         if (ie) {
+            out.add(" = ");
             gen.emitConstExpr(out, ie, Assignment);
         } else {
             // auto-initialize (only required for embedded targets)
-            gen.emitAutoInit(out, d.getType());
+            if (gen.force_initializers) {
+                out.add(" = ");
+                gen.emitAutoInit(out, d.getType());
+            }
         }
         out.add(";\n");
     }
@@ -1293,6 +1297,7 @@ public fn void generate(string_pool.Pool* astPool,
                         Decl* mainFunc,
                         string_list.List* asm_files,
                         bool enable_asserts,
+                        bool force_initializers,
                         bool fast_build, bool asan, bool msan, bool ubsan,
                         bool test_mode, bool trace_calls)
 {
@@ -1307,6 +1312,7 @@ public fn void generate(string_pool.Pool* astPool,
     gen.init(astPool, target, kind, output_dir, dir, diags, sm, build_info, mainFunc);
     gen.auxPool = auxPool;
     gen.enable_asserts = enable_asserts;
+    gen.force_initializers = force_initializers;
     gen.fast_build = fast_build;
     gen.asan = asan;
     gen.msan = msan;

test/c_generator/attributes/exported_not_static.c2t

@@ -20,9 +20,9 @@ public fn i32 main(i32 argc, const i8** argv)
 
 // @expect{atleast, cgen/build.c}
 
-static int32_t file1_a = 0;
-int32_t file1_b = 0;
-static int32_t file1_c = 0;
+static int32_t file1_a;
+int32_t file1_b;
+static int32_t file1_c;
 
 static void file1_f(void);
 void file1_g(void);

test/c_generator/constants/string_literals.c2t

@@ -35,7 +35,7 @@ static const char test1_BBB[4] = "bbb";
 static char test1_ddd[4] = "ddd";
 static char test1_eee[4] = "eee";
 static const char* test1_fff = "fff";
-static const char* test1_ggg = NULL;
-static char test1_hhh[3] = { };
-static char* test1_iii = NULL;
+static const char* test1_ggg;
+static char test1_hhh[3];
+static char* test1_iii;
 

test/c_generator/functions/struct_functions/global.c2t

@@ -25,7 +25,7 @@ struct test_Type_ {
   int32_t member;
 };
 
-static test_Type test_t = { };
+static test_Type test_t;
 
 static void test_Type_init(test_Type* _arg0)
 {

test/c_generator/module/static_single_module.c2t

@@ -17,8 +17,8 @@ public i32 y2;
 
 // @expect{atleast, cgen/build.c}
 
-static int32_t test1_x1 = 0;
-int32_t test1_y1 = 0;
+static int32_t test1_x1;
+int32_t test1_y1;
 
 // test2 symbols are not generated, because they are unused
 

test/c_generator/module/variable_fast_build.c2t

@@ -13,8 +13,8 @@ public char[] y2 = { 1, 2, 3, 4 }
 // @expect{atleast, cgen/test1.c}
 #include "test1.h"
 
-static int32_t test1_x1 = 0;
-int32_t test1_y1 = 0;
+static int32_t test1_x1;
+int32_t test1_y1;
 char test1_y2[4] = { 1, 2, 3, 4 };
 
 // @expect{atleast, cgen/test1.h}

test/c_generator/stmts/local_array_decl.c2t

@@ -20,7 +20,7 @@ public fn i32 main() {
 
 #define test_Size 20
 
-static int32_t test_board[20][20] = { };
+static int32_t test_board[20][20];
 
 static void test_func1(void);