diff options
| -rw-r--r-- | compiler.c | 28 | ||||
| -rw-r--r-- | tests/03_bugs/03_switch_fallthrough_miscompilation | 16 |
2 files changed, 24 insertions, 20 deletions
@@ -2292,7 +2292,7 @@ static void uc_compiler_compile_switch(uc_compiler *compiler) { uc_chunk *chunk = uc_compiler_current_chunk(compiler); - size_t i, first_jmp, skip_jmp, next_jmp, default_jmp = 0; + size_t i, first_jmp, skip_jmp, next_jmp, default_off = 0; bool in_case = false; uc_jmplist jmps = {}; uc_patchlist p = {}; @@ -2317,7 +2317,7 @@ uc_compiler_compile_switch(uc_compiler *compiler) !uc_compiler_parse_check(compiler, TK_EOF)) { /* handle `default:` */ if (uc_compiler_parse_match(compiler, TK_DEFAULT)) { - if (default_jmp) { + if (default_off) { uc_compiler_syntax_error(compiler, compiler->parser->prev.pos, "more than one switch default case"); @@ -2326,9 +2326,8 @@ uc_compiler_compile_switch(uc_compiler *compiler) uc_compiler_parse_consume(compiler, TK_COLON); - /* jump over default case, can only be reached by fallthrough or - * conditional jump after last failed case condition */ - default_jmp = uc_compiler_emit_jmp(compiler, 0, 0); + /* remember address of default branch */ + default_off = chunk->count; in_case = true; } @@ -2385,29 +2384,19 @@ uc_compiler_compile_switch(uc_compiler *compiler) if (i + 2 < jmps.count) uc_compiler_set_jmpaddr(compiler, next_jmp, jmps.entries[i + 2] + 5); /* case was last in switch, jump to default */ - else if (default_jmp) - uc_compiler_set_jmpaddr(compiler, next_jmp, default_jmp + 5); + else if (default_off) + uc_compiler_set_jmpaddr(compiler, next_jmp, default_off); /* if no default, jump to end */ else uc_compiler_set_jmpaddr(compiler, next_jmp, chunk->count); } - /* if we have a default case, set target for the skip jump */ - if (default_jmp) { - /* if we have cases, jump to the first one */ - if (jmps.count) - uc_compiler_set_jmpaddr(compiler, default_jmp, jmps.entries[0] + 5); - /* ... otherwise turn jump into no-op */ - else - uc_compiler_set_jmpaddr(compiler, default_jmp, default_jmp + 5); - } - /* if we have cases, patch initial jump after the first case condition */ if (jmps.count) uc_compiler_set_jmpaddr(compiler, first_jmp, jmps.entries[0] + 5); /* ... otherwise jump into default */ - else if (default_jmp) - uc_compiler_set_jmpaddr(compiler, first_jmp, default_jmp + 5); + else if (default_off) + uc_compiler_set_jmpaddr(compiler, first_jmp, default_off); /* ... otherwise if no defualt, turn into no-op */ else uc_compiler_set_jmpaddr(compiler, first_jmp, first_jmp + 5); @@ -2417,7 +2406,6 @@ uc_compiler_compile_switch(uc_compiler *compiler) uc_compiler_leave_scope(compiler); uc_compiler_backpatch(compiler, chunk->count, 0); - } static void diff --git a/tests/03_bugs/03_switch_fallthrough_miscompilation b/tests/03_bugs/03_switch_fallthrough_miscompilation new file mode 100644 index 0000000..3e6410e --- /dev/null +++ b/tests/03_bugs/03_switch_fallthrough_miscompilation @@ -0,0 +1,16 @@ +When falling through from a matched switch case into the default case, +the compiler incorrectly emitted bytecode that led to an endless loop. + +-- Expect stdout -- +1 +-- End -- + +-- Testcase -- +{% + switch (1) { + case 1: + default: + print("1\n"); + } +%} +-- End -- |