af7169b4a
Denys Vlasenko
2019-10-25
Subject
clang/llvm 9 fix - do not eliminate a store to a fake "const"
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Commit Diff GitHub →
coreutils/test.c +1 -1include/libbb.h +21 -1libbb/appletlib.c +1 -1libbb/lineedit.c +1 -1shell/ash.c +3 -3
coreutils/test.c+1 -1
| @@ -411,7 +411,7 @@ extern struct test_statics *const test_ptr_to_statics; | |
| #define leaving (S.leaving ) | |
| #define INIT_S() do { \ | |
| - | (*(struct test_statics**)&test_ptr_to_statics) = xzalloc(sizeof(S)); \ |
| + | (*(struct test_statics**)not_const_pp(&test_ptr_to_statics)) = xzalloc(sizeof(S)); \ |
| barrier(); \ | |
| } while (0) | |
| #define DEINIT_S() do { \ | |
include/libbb.h+21 -1
| @@ -2153,12 +2153,32 @@ struct globals; | |
| * Magic prevents ptr_to_globals from going into rodata. | |
| * If you want to assign a value, use SET_PTR_TO_GLOBALS(x) */ | |
| extern struct globals *const ptr_to_globals; | |
| + | |
| + | #if defined(__clang_major__) && __clang_major__ >= 9 |
| + | /* Clang/llvm drops assignment to "constant" storage. Silently. |
| + | * Needs serious convincing to not eliminate the store. |
| + | */ |
| + | static ALWAYS_INLINE void* not_const_pp(const void *p) |
| + | { |
| + | void *pp; |
| + | __asm__ __volatile__( |
| + | "# forget that p points to const" |
| + | : /*outputs*/ "=r" (pp) |
| + | : /*inputs*/ "0" (p) |
| + | ); |
| + | return pp; |
| + | } |
| + | #else |
| + | static ALWAYS_INLINE void* not_const_pp(const void *p) { return (void*)p; } |
| + | #endif |
| + | |
| /* At least gcc 3.4.6 on mipsel system needs optimization barrier */ | |
| #define barrier() __asm__ __volatile__("":::"memory") | |
| #define SET_PTR_TO_GLOBALS(x) do { \ | |
| - | (*(struct globals**)&ptr_to_globals) = (void*)(x); \ |
| + | (*(struct globals**)not_const_pp(&ptr_to_globals)) = (void*)(x); \ |
| barrier(); \ | |
| } while (0) | |
| + | |
| #define FREE_PTR_TO_GLOBALS() do { \ | |
| if (ENABLE_FEATURE_CLEAN_UP) { \ | |
| free(ptr_to_globals); \ | |
libbb/appletlib.c+1 -1
| @@ -304,7 +304,7 @@ void lbb_prepare(const char *applet | |
| IF_FEATURE_INDIVIDUAL(, char **argv)) | |
| { | |
| #ifdef __GLIBC__ | |
| - | (*(int **)&bb_errno) = __errno_location(); |
| + | (*(int **)not_const_pp(&bb_errno)) = __errno_location(); |
| barrier(); | |
| #endif | |
| applet_name = applet; | |
libbb/lineedit.c+1 -1
| @@ -203,7 +203,7 @@ extern struct lineedit_statics *const lineedit_ptr_to_statics; | |
| #define delbuf (S.delbuf ) | |
| #define INIT_S() do { \ | |
| - | (*(struct lineedit_statics**)&lineedit_ptr_to_statics) = xzalloc(sizeof(S)); \ |
| + | (*(struct lineedit_statics**)not_const_pp(&lineedit_ptr_to_statics)) = xzalloc(sizeof(S)); \ |
| barrier(); \ | |
| cmdedit_termw = 80; \ | |
| IF_USERNAME_OR_HOMEDIR(home_pwd_buf = (char*)null_str;) \ | |
shell/ash.c+3 -3
| @@ -489,7 +489,7 @@ extern struct globals_misc *BB_GLOBAL_CONST ash_ptr_to_globals_misc; | |
| #define random_gen (G_misc.random_gen ) | |
| #define backgndpid (G_misc.backgndpid ) | |
| #define INIT_G_misc() do { \ | |
| - | (*(struct globals_misc**)&ash_ptr_to_globals_misc) = xzalloc(sizeof(G_misc)); \ |
| + | (*(struct globals_misc**)not_const_pp(&ash_ptr_to_globals_misc)) = xzalloc(sizeof(G_misc)); \ |
| barrier(); \ | |
| curdir = nullstr; \ | |
| physdir = nullstr; \ | |
| @@ -1542,7 +1542,7 @@ extern struct globals_memstack *BB_GLOBAL_CONST ash_ptr_to_globals_memstack; | |
| #define g_stacknleft (G_memstack.g_stacknleft) | |
| #define stackbase (G_memstack.stackbase ) | |
| #define INIT_G_memstack() do { \ | |
| - | (*(struct globals_memstack**)&ash_ptr_to_globals_memstack) = xzalloc(sizeof(G_memstack)); \ |
| + | (*(struct globals_memstack**)not_const_pp(&ash_ptr_to_globals_memstack)) = xzalloc(sizeof(G_memstack)); \ |
| barrier(); \ | |
| g_stackp = &stackbase; \ | |
| g_stacknxt = stackbase.space; \ | |
| @@ -2165,7 +2165,7 @@ extern struct globals_var *BB_GLOBAL_CONST ash_ptr_to_globals_var; | |
| #endif | |
| #define INIT_G_var() do { \ | |
| unsigned i; \ | |
| - | (*(struct globals_var**)&ash_ptr_to_globals_var) = xzalloc(sizeof(G_var)); \ |
| + | (*(struct globals_var**)not_const_pp(&ash_ptr_to_globals_var)) = xzalloc(sizeof(G_var)); \ |
| barrier(); \ | |
| for (i = 0; i < ARRAY_SIZE(varinit_data); i++) { \ | |
| varinit[i].flags = varinit_data[i].flags; \ | |