Merge branch 'feature/unused-var'

libsrc/_wasm/unistd/mkdir.c

@@ -5,6 +5,7 @@
 extern int __max_preopen_fd;
 
 int mkdir(const char *fn, mode_t mode) {
+  (void)mode;
   size_t fnlen = strlen(fn);
   for (int base_fd = 3; base_fd < __max_preopen_fd; ++base_fd) {
     Prestat prestat;
@@ -29,7 +30,6 @@ int mkdir(const char *fn, mode_t mode) {
       fnlen2 = fnlen - 1;
     }
 
-    Filestat fs;
     uint32_t result = path_create_directory(base_fd, fn2, fnlen2);
     if (result == 0)
       return 0;

libsrc/crt0/_start.c

@@ -39,6 +39,7 @@ static void start2(int argc, char *argv[], char *env[]) {
 }
 
 void _start(void) {
+  (void)start2;  // Avoid warning: unused function 'start2'
 #if defined(__x86_64__)
   __asm("mov (%rsp), %rdi\n"
         "lea 8(%rsp), %rsi\n"

libsrc/stdlib/getrandom.c

@@ -4,6 +4,7 @@
 #include "../_wasm/wasi.h"
 
 ssize_t getrandom(void *buf, size_t buflen, unsigned int flags) {
+  (void)flags;
   random_get(buf, buflen);
   return buflen;
 }

src/cc/backend/codegen.c

@@ -10,6 +10,7 @@
 
 #include "arch_config.h"
 #include "ast.h"
+#include "cc_misc.h"  // is_function_omitted
 #include "fe_misc.h"  // curfunc, curscope
 #include "ir.h"
 #include "optimize.h"
@@ -874,8 +875,8 @@ bool gen_defun(Function *func) {
     return false;
 
   VarInfo *funcvi = scope_find(global_scope, func->name, NULL);
-  if (funcvi != NULL && satisfy_inline_criteria(funcvi, funcvi->storage)) {
-    // Omit inline function: func->extra preserves the value (NULL).
+  if (is_function_omitted(funcvi)) {
+    // Omit function: func->extra preserves the value (NULL).
     return false;
   }
 

src/cc/backend/codegen_expr.c

@@ -563,14 +563,20 @@ static VReg *gen_comma(Expr *expr) {
 static VReg *gen_assign_sub(Expr *lhs, Expr *rhs) {
   VReg *src = gen_expr(rhs);
   if (lhs->kind == EX_VAR) {
+    const VarInfo *varinfo = scope_find(lhs->var.scope, lhs->var.name, NULL);
+    assert(varinfo != NULL);
     if (is_prim_type(lhs->type) && !is_global_scope(lhs->var.scope)) {
-      const VarInfo *varinfo = scope_find(lhs->var.scope, lhs->var.name, NULL);
       if (is_local_storage(varinfo)) {
         assert(varinfo->local.vreg != NULL);
         new_ir_mov(varinfo->local.vreg, src, is_unsigned(rhs->type) ? IRF_UNSIGNED : 0);
         return src;
       }
     }
+
+    if ((varinfo->storage & (VS_STATIC | VS_USED)) == VS_STATIC) {
+      // Can be omitted.
+      return src;
+    }
   }
 
   VReg *dst = gen_lval(lhs);

src/cc/backend/emit_util.c

@@ -410,7 +410,10 @@ void emit_code(Vector *decls) {
   emit_comment(NULL);
   for (int i = 0; i < global_scope->vars->len; ++i) {
     VarInfo *varinfo = global_scope->vars->data[i];
-    if ((varinfo->storage & (VS_EXTERN | VS_ENUM_MEMBER)) || varinfo->type->kind == TY_FUNC)
+    int storage = varinfo->storage;
+    if (varinfo->type->kind == TY_FUNC ||
+        (storage & (VS_EXTERN | VS_ENUM_MEMBER)) ||
+        (storage & (VS_STATIC | VS_USED)) == VS_STATIC)  // Static variable but not used.
       continue;
     emit_varinfo(varinfo, varinfo->global.init);
   }

src/cc/cc1.c

@@ -47,30 +47,10 @@ static void compile1(FILE *ifp, const char *filename, Vector *decls) {
   parse(decls);
 }
 
-static bool parse_fopt(const char *optarg, bool value) {
-  static const struct {
-    const char *flag_name;
-    off_t flag_offset;
-  } kFlagTable[] = {
-    {"common", offsetof(CcFlags, common)},
-  };
-
-  for (size_t i = 0; i < ARRAY_SIZE(kFlagTable); ++i) {
-    if (strcmp(optarg, kFlagTable[i].flag_name) == 0) {
-      size_t len = strlen(kFlagTable[i].flag_name);
-      if (optarg[len] != '\0')
-        continue;
-      bool *p = (bool*)((char*)&cc_flags + kFlagTable[i].flag_offset);
-      *p = value;
-      return true;
-    }
-  }
-  return false;
-}
-
 int main(int argc, char *argv[]) {
   enum {
     OPT_FNO = 128,
+    OPT_WNO,
     OPT_SSA,
   };
 
@@ -80,8 +60,9 @@ int main(int argc, char *argv[]) {
     {"O", optional_argument},  // Optimization level
 
     // Sub command
-    {"fno-", required_argument, OPT_FNO},
-    {"f", required_argument},
+    {"fno-", optional_argument, OPT_FNO},
+    {"f", optional_argument},
+    {"Wno-", optional_argument, OPT_WNO},
     {"W", required_argument},
 
     // Feature flag.
@@ -120,16 +101,38 @@ int main(int argc, char *argv[]) {
 
     case 'f':
     case OPT_FNO:
+      if (optarg == NULL) {
+        fprintf(stderr, "Warning: missing argument for -f\n");
+        break;
+      }
       if (!parse_fopt(optarg, opt == 'f')) {
         // Silently ignored.
         // fprintf(stderr, "Warning: unknown option for -f: %s\n", optarg);
       }
       break;
 
     case 'W':
+      if (optarg != NULL) {
+        if (strcmp(optarg, "error") == 0) {
+          cc_flags.warn_as_error = true;
+          break;
+        }
+        if (strcmp(optarg, "all") == 0) {
+          // Assume all members are bool.
+          for (bool *p = (bool*)&cc_flags.warn; p < (bool*)(&cc_flags.warn + 1); ++p)
+            *p = true;
+          break;
+        }
+      }
+      // Fallthrough
+    case OPT_WNO:
+      if (optarg == NULL) {
+        fprintf(stderr, "Warning: missing argument for -W\n");
+        break;
+      }
       if (strcmp(optarg, "error") == 0) {
         cc_flags.warn_as_error = true;
-      } else {
+      } else if (!parse_wopt(optarg, opt == 'W')) {
         // Silently ignored.
         // fprintf(stderr, "Warning: unknown option for -W: %s\n", optarg);
       }

src/cc/frontend/cc_misc.c

@@ -5,10 +5,17 @@
 #include <inttypes.h>  // PRId64
 
 #include "ast.h"
+#include "fe_misc.h"
 #include "type.h"
 #include "util.h"
 #include "var.h"
 
+bool is_function_omitted(const VarInfo *funcvi) {
+  assert(funcvi != NULL);
+  return (satisfy_inline_criteria(funcvi, funcvi->storage) ||
+      (funcvi->storage & (VS_STATIC | VS_USED)) == VS_STATIC);  // Static function but not used.
+}
+
 static void eval_initial_value(Expr *expr, Expr **pvar, int64_t *poffset) {
   switch (expr->kind) {
   case EX_FIXNUM:

src/cc/frontend/cc_misc.h

@@ -1,10 +1,14 @@
 #pragma once
 
+#include <stdbool.h>
 #include <stdint.h>
 
 typedef struct Expr Expr;
 typedef struct Initializer Initializer;
 typedef struct Type Type;
+typedef struct VarInfo VarInfo;
+
+bool is_function_omitted(const VarInfo *funcvi);
 
 typedef struct {
   void (*emit_align)(void *ud, int align);