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https://github.com/frida/tinycc
synced 2024-12-24 22:16:49 +03:00
Fix some code suppression fallout
Some more subtle issues with code suppression: - outputting asms but not their operand setup is broken - but global asms must always be output - statement expressions are transparent to code suppression - vtop can't be transformed from VT_CMP/VT_JMP when nocode_wanted Also remove .exe files from tests2 if they don't fail.
This commit is contained in:
parent
559ee1e940
commit
42e2a67f23
32
tccasm.c
32
tccasm.c
@ -32,7 +32,7 @@ ST_FUNC int asm_get_local_label_name(TCCState *s1, unsigned int n)
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}
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ST_FUNC void asm_expr(TCCState *s1, ExprValue *pe);
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static int tcc_assemble_internal(TCCState *s1, int do_preprocess);
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static int tcc_assemble_internal(TCCState *s1, int do_preprocess, int global);
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static Sym sym_dot;
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/* Return a symbol we can use inside the assembler, having name NAME.
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@ -462,7 +462,7 @@ static void pop_section(TCCState *s1)
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use_section1(s1, prev);
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}
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static void asm_parse_directive(TCCState *s1)
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static void asm_parse_directive(TCCState *s1, int global)
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{
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int n, offset, v, size, tok1;
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Section *sec;
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@ -644,7 +644,8 @@ static void asm_parse_directive(TCCState *s1)
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save_parse_state(&saved_parse_state);
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begin_macro(init_str, 1);
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while (repeat-- > 0) {
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tcc_assemble_internal(s1, (parse_flags & PARSE_FLAG_PREPROCESS));
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tcc_assemble_internal(s1, (parse_flags & PARSE_FLAG_PREPROCESS),
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global);
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macro_ptr = init_str->str;
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}
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end_macro();
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@ -913,14 +914,10 @@ static void asm_parse_directive(TCCState *s1)
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/* assemble a file */
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static int tcc_assemble_internal(TCCState *s1, int do_preprocess)
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static int tcc_assemble_internal(TCCState *s1, int do_preprocess, int global)
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{
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int saved_nocode_wanted;
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int opcode;
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saved_nocode_wanted = nocode_wanted;
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nocode_wanted = 0;
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/* XXX: undefine C labels */
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ch = file->buf_ptr[0];
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@ -940,7 +937,7 @@ static int tcc_assemble_internal(TCCState *s1, int do_preprocess)
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while (tok != TOK_LINEFEED)
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next();
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} else if (tok >= TOK_ASMDIR_FIRST && tok <= TOK_ASMDIR_LAST) {
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asm_parse_directive(s1);
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asm_parse_directive(s1, global);
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} else if (tok == TOK_PPNUM) {
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Sym *sym;
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const char *p;
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@ -964,7 +961,7 @@ static int tcc_assemble_internal(TCCState *s1, int do_preprocess)
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/* handle "extern void vide(void); __asm__("vide: ret");" as
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"__asm__("globl vide\nvide: ret");" */
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Sym *sym = sym_find(opcode);
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if (sym && (sym->type.t & VT_EXTERN) && saved_nocode_wanted) {
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if (sym && (sym->type.t & VT_EXTERN) && global) {
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sym = label_find(opcode);
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if (!sym) {
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sym = label_push(&s1->asm_labels, opcode, 0);
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@ -993,7 +990,6 @@ static int tcc_assemble_internal(TCCState *s1, int do_preprocess)
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asm_free_labels(s1);
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nocode_wanted = saved_nocode_wanted;
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return 0;
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}
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@ -1017,7 +1013,7 @@ ST_FUNC int tcc_assemble(TCCState *s1, int do_preprocess)
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ELFW(ST_INFO)(STB_LOCAL, STT_FILE), 0,
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SHN_ABS, file->filename);
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ret = tcc_assemble_internal(s1, do_preprocess);
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ret = tcc_assemble_internal(s1, do_preprocess, 1);
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cur_text_section->data_offset = ind;
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@ -1032,7 +1028,7 @@ ST_FUNC int tcc_assemble(TCCState *s1, int do_preprocess)
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/* assemble the string 'str' in the current C compilation unit without
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C preprocessing. NOTE: str is modified by modifying the '\0' at the
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end */
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static void tcc_assemble_inline(TCCState *s1, char *str, int len)
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static void tcc_assemble_inline(TCCState *s1, char *str, int len, int global)
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{
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int saved_parse_flags;
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const int *saved_macro_ptr;
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@ -1044,7 +1040,7 @@ static void tcc_assemble_inline(TCCState *s1, char *str, int len)
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memcpy(file->buffer, str, len);
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macro_ptr = NULL;
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tcc_assemble_internal(s1, 0);
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tcc_assemble_internal(s1, 0, global);
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tcc_close();
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parse_flags = saved_parse_flags;
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@ -1277,7 +1273,7 @@ ST_FUNC void asm_instr(void)
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clobber_regs, out_reg);
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/* assemble the string with tcc internal assembler */
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tcc_assemble_inline(tcc_state, astr1.data, astr1.size - 1);
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tcc_assemble_inline(tcc_state, astr1.data, astr1.size - 1, 0);
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/* restore the current C token */
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next();
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@ -1299,7 +1295,10 @@ ST_FUNC void asm_instr(void)
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ST_FUNC void asm_global_instr(void)
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{
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CString astr;
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int saved_nocode_wanted = nocode_wanted;
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/* Global asm blocks are always emitted. */
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nocode_wanted = 0;
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next();
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parse_asm_str(&astr);
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skip(')');
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@ -1315,7 +1314,7 @@ ST_FUNC void asm_global_instr(void)
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ind = cur_text_section->data_offset;
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/* assemble the string with tcc internal assembler */
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tcc_assemble_inline(tcc_state, astr.data, astr.size - 1);
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tcc_assemble_inline(tcc_state, astr.data, astr.size - 1, 1);
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cur_text_section->data_offset = ind;
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@ -1323,5 +1322,6 @@ ST_FUNC void asm_global_instr(void)
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next();
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cstr_free(&astr);
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nocode_wanted = saved_nocode_wanted;
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}
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#endif /* CONFIG_TCC_ASM */
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19
tccgen.c
19
tccgen.c
@ -575,8 +575,16 @@ static void vsetc(CType *type, int r, CValue *vc)
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tcc_error("memory full (vstack)");
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/* cannot let cpu flags if other instruction are generated. Also
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avoid leaving VT_JMP anywhere except on the top of the stack
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because it would complicate the code generator. */
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if (vtop >= vstack) {
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because it would complicate the code generator.
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Don't do this when nocode_wanted. vtop might come from
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!nocode_wanted regions (see 88_codeopt.c) and transforming
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it to a register without actually generating code is wrong
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as their value might still be used for real. All values
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we push under nocode_wanted will eventually be popped
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again, so that the VT_CMP/VT_JMP value will be in vtop
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when code is unsuppressed again. */
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if (vtop >= vstack && !nocode_wanted) {
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v = vtop->r & VT_VALMASK;
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if (v == VT_CMP || (v & ~1) == VT_JMP)
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gv(RC_INT);
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@ -4367,13 +4375,18 @@ ST_FUNC void unary(void)
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gen_cast(&type);
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}
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} else if (tok == '{') {
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int saved_nocode_wanted = nocode_wanted;
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if (const_wanted)
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tcc_error("expected constant");
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/* save all registers */
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save_regs(0);
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/* statement expression : we do not accept break/continue
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inside as GCC does */
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inside as GCC does. We do retain the nocode_wanted state,
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as statement expressions can't ever be entered from the
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outside, so any reactivation of code emission (from labels
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or loop heads) can be disabled again after the end of it. */
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block(NULL, NULL, 1);
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nocode_wanted = saved_nocode_wanted;
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skip(')');
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} else {
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gexpr();
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@ -1404,6 +1404,15 @@ void optimize_out(void)
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if (defined_function() && 0)
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refer_to_undefined();
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if (0) {
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(void)sizeof( ({
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do { } while (0);
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0;
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}) );
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undefined_function();
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}
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/* Leave the "if(1)return; printf()" in this order and last in the function */
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if (1)
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return;
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printf ("oor:%d\n", undefined_function());
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@ -3251,6 +3260,28 @@ void trace_console(long len, long len2)
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}
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#endif
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}
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void test_asm_dead_code(void)
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{
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long rdi;
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/* Try to make sure that xdi contains a zero, and hence will
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lead to a segfault if the next asm is evaluated without
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arguments being set up. */
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asm volatile ("" : "=D" (rdi) : "0" (0));
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(void)sizeof (({
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int var;
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/* This shouldn't trigger a segfault, either the argument
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registers need to be set up and the asm emitted despite
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this being in an unevaluated context, or both the argument
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setup _and_ the asm emission need to be suppressed. The latter
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is better. Disabling asm code gen when suppression is on
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also fixes the above trace_console bug, but that came earlier
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than asm suppression. */
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asm volatile ("movl $0,(%0)" : : "D" (&var) : "memory");
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var;
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}));
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}
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void asm_test(void)
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{
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char buf[128];
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@ -3334,6 +3365,7 @@ void asm_test(void)
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printf ("regvar=%x\n", regvar);
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test_high_clobbers();
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trace_console(8, 8);
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test_asm_dead_code();
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return;
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label1:
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goto label2;
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@ -1,7 +1,9 @@
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extern int printf (const char *, ...);
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extern void vide(void);
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__asm__("vide: ret");
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int main() {
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vide();
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printf ("okay\n");
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return 0;
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}
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@ -0,0 +1 @@
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okay
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68
tests/tests2/88_codeopt.c
Normal file
68
tests/tests2/88_codeopt.c
Normal file
@ -0,0 +1,68 @@
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/* Check some way in where code suppression caused various
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miscompilations. */
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extern int printf (const char *, ...);
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typedef unsigned long size_t;
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size_t _brk_start, _brk_end;
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void * extend_brk(size_t size, size_t align)
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{
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size_t mask = align - 1;
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void *ret = 0;
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do {
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if (__builtin_expect(!!(_brk_start == 0), 0))
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do {
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printf("wrong1\n");
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} while (0);
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} while (0);
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_brk_end = (_brk_end + mask) & ~mask;
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ret = (void *)_brk_end;
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_brk_end += size;
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return ret;
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}
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static void get_args (int a, int b)
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{
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if (a != 1)
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printf("wrong2\n");
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else
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printf("okay\n");
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}
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void bla(void)
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{
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int __ret = 42;
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({
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if (__builtin_expect(!!(0), 0)) {
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if (__builtin_expect(!!__ret, 0))
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printf("wrong3\n");
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int x = !!(__ret);
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}
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__ret;
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});
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get_args(!!__ret, sizeof(__ret));
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}
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_Bool chk(unsigned long addr, unsigned long limit, unsigned long size)
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{
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_Bool ret;
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/* This just needs to compile, no runtime test. (And it doesn't compile
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only with certain internal checking added that's not committed). */
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if (0)
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ret = 0 != (!!(addr > limit - size));
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}
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int main()
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{
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void *r;
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_brk_start = 1024;
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_brk_end = 1024;
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r = extend_brk (4096, 16);
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if (!r)
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printf("wrong4\n");
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else
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printf("okay\n");
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bla();
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return 0;
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}
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2
tests/tests2/88_codeopt.expect
Normal file
2
tests/tests2/88_codeopt.expect
Normal file
@ -0,0 +1,2 @@
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okay
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okay
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@ -59,7 +59,7 @@ all test: $(filter-out $(SKIP),$(TESTS))
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$(TCC) $< -o ./$*.exe $(FILTER) 2>&1 && \
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./$*.exe $(ARGS) >$*.output 2>&1 || true; \
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fi
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@diff -Nbu $(SRC)/$*.expect $*.output && rm -f $*.output
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@diff -Nbu $(SRC)/$*.expect $*.output && rm -f $*.output $*.exe
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# automatically generate .expect files with gcc:
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%.expect : %.c
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