Compiler: improve target architecture handling

* simplify target triplet parsing and unparsing
* add --target command line option for testing

Author: chqrlie

common/target_info.c2

@@ -18,7 +18,7 @@ module target_info;
 import console;
 
 import c_errno local;
-import stdio;
+import stdio local;
 import stdlib local;
 import string local;
 import sys_utsname;
@@ -142,45 +142,27 @@ fn void Info.init(Info* info) {
         break;
     }
 
-    stdio.sprintf(info.triple, "%s-%s-%s-%s",
-        arch_names[info.arch],
-        vendor_names[info.vendor],
-        system_names[info.sys],
-        abi_names[info.abi]);
+    snprintf(info.triple, elemsof(info.triple), "%s-%s-%s-%s",
+             arch_names[info.arch],
+             vendor_names[info.vendor],
+             system_names[info.sys],
+             abi_names[info.abi]);
 }
 
 public fn bool Info.fromString(Info* info, const char* triple) {
     // expect format: <arch><sub>-<vendor>-<sys>-<abi>
     // TODO support sub for ARM
-    // Note: very ugly way to split string
     char[32] arch_str;
     char[32] vendor_str;
     char[32] sys_str;
     char[32] abi_str;
-    char*[4] matches = { arch_str, vendor_str, sys_str, abi_str };
-
-    i32 match = 0;
-    const char* start = triple;
-    const char* cp = start;
-    while (*cp) {
-        if (*cp == '-') {
-            u32 len = cast<u32>(cp - start);
-            strncpy(matches[match], start, len);
-            matches[match][len] = 0;
-            start = cp + 1;
-            match++;
-            if (match == 5) return false;
-        }
-        cp++;
-    }
-    if (cp != start) {
-        u32 len = cast<u32>(cp - start);
-        // TODO check len
-        strncpy(matches[match], start, len);
-        matches[match][len] = 0;
-        match++;
-    }
-    if (match != 4) return false;
+    u32 pos = 0;
+
+    // split the triple string into 4 components
+    if (sscanf(triple, "%31[^-]-%31[^-]-%31[^-]-%31[^-]%n",
+               arch_str, vendor_str, sys_str, abi_str, &pos) != 4
+    ||  triple[pos] != '\0')
+        return false;
 
     info.arch = str2arch(arch_str);
     if (info.arch == Arch.Unknown) {
@@ -203,7 +185,6 @@ public fn bool Info.fromString(Info* info, const char* triple) {
 
 public fn const char* Info.str(const Info* info) {
     return info.triple;
-
 }
 
 public fn const char* Info.getSystemName(const Info* info) {

compiler/compiler.c2

@@ -81,6 +81,7 @@ public type Options struct {
     bool msan;
     bool ubsan;
     u32 libdir; // from environment varible C2_LIBDIR, into auxPool
+    char *target_triple;
 }
 
 public fn void build(string_pool.Pool* auxPool,
@@ -244,6 +245,8 @@ fn void Compiler.build(Compiler* c,
     c.is_image = target.getKind() == build_target.Kind.Image;
     c.libdirs.init(c.auxPool);
 
+    const char* target_str = opts.target_triple;
+
     const char* output_base = constants.output_dir;
     if (c.build_info) {
         const char* output_dir2 = c.build_info.getOutputDir();
@@ -261,15 +264,7 @@ fn void Compiler.build(Compiler* c,
         for (u32 i=0; i<dirs.length(); i++) {
             c.libdirs.add(dirs.get_idx(i));
         }
-        const char* target_str = c.build_info.getTarget();
-        if (target_str) {
-            if (!c.targetInfo.fromString(target_str)) {
-                console.error("invalid target triple: %s", target_str);
-                stdlib.exit(-1);
-            }
-        } else {
-            c.targetInfo.getNative();
-        }
+        target_str = c.build_info.getTarget();
     } else {
         if (c.is_image) {
             // TODO src loc
@@ -279,6 +274,14 @@ fn void Compiler.build(Compiler* c,
         if (c.opts.libdir) c.libdirs.add(c.opts.libdir);
         c.targetInfo.getNative();
     }
+    if (target_str) {
+        if (!c.targetInfo.fromString(target_str)) {
+            console.error("invalid target triple: %s", target_str);
+            stdlib.exit(-1);
+        }
+    } else {
+        c.targetInfo.getNative();
+    }
     console.debug("triple: %s", c.targetInfo.str());
 
     c.addGlobalDefine("SYSTEM", c.targetInfo.getSystemName());

compiler/main.c2

@@ -198,6 +198,7 @@ const char[] Usage_help =
     "  --noplugins       do not use plugins\n"
     "  --showlibs        print available libraries\n"
     "  --showplugins     print available plugins\n"
+    "  --target triple   cross compile for a specified architecture\n"
     "  --targets         show available targets in recipe\n"
     "  --test            test mode (do not check for main() function)\n"
     "  --trace-calls     generate code that traces function calls\n"
@@ -242,6 +243,11 @@ fn i32 parse_long_opt(i32 i, i32 argc, char** argv, compiler.Options* comp_opts,
     case "showplugins":
         opts.show_plugins = true;
         break;
+    case "target":
+        if (i==argc-1) missing_arg(arg);
+        i++;
+        comp_opts.target_triple = argv[i];
+        break;
     case "targets":
         opts.show_targets = true;
         break;