History

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.

Michael Matz committed 9 years ago

Commit 42e2a671 parent 559ee1e8 files · +138 −20Browse files

Unified · Split

8 files
  1. tccasm.c +16 −16
  2. tccgen.c +16 −3
  3. tests/tcctest.c +32 −0
  4. tests/tests2/85-asm-outside-function.c +2 −0
  5. tests/tests2/85-asm-outside-function.expect +1 −0
  6. tests/tests2/88_codeopt.c +68 −0
  7. tests/tests2/88_codeopt.expect +2 −0
  8. tests/tests2/Makefile +1 −1
tccasm.c+16−16
@@ -32,7 +32,7 @@ ST_FUNC int asm_get_local_label_name(TCCState *s1, unsigned int n) · 31 unmodified lines
3232 }
3333
3434 ST_FUNC void asm_expr(TCCState *s1, ExprValue *pe);
35−static int tcc_assemble_internal(TCCState *s1, int do_preprocess);
35+static int tcc_assemble_internal(TCCState *s1, int do_preprocess, int global);
3636 static Sym sym_dot;
3737
3838 /* Return a symbol we can use inside the assembler, having name NAME.
@@ -462,7 +462,7 @@ static void pop_section(TCCState *s1) · 423 unmodified lines
462462 use_section1(s1, prev);
463463 }
464464
465−static void asm_parse_directive(TCCState *s1)
465+static void asm_parse_directive(TCCState *s1, int global)
466466 {
467467 int n, offset, v, size, tok1;
468468 Section *sec;
@@ -644,7 +644,8 @@ static void asm_parse_directive(TCCState *s1) · 175 unmodified lines
644644 save_parse_state(&saved_parse_state);
645645 begin_macro(init_str, 1);
646646 while (repeat-- > 0) {
647− tcc_assemble_internal(s1, (parse_flags & PARSE_FLAG_PREPROCESS));
647+ tcc_assemble_internal(s1, (parse_flags & PARSE_FLAG_PREPROCESS),
648+ global);
648649 macro_ptr = init_str->str;
649650 }
650651 end_macro();
@@ -913,14 +914,10 @@ static void asm_parse_directive(TCCState *s1) · 262 unmodified lines
913914
914915
915916 /* assemble a file */
916−static int tcc_assemble_internal(TCCState *s1, int do_preprocess)
917+static int tcc_assemble_internal(TCCState *s1, int do_preprocess, int global)
917918 {
918− int saved_nocode_wanted;
919919 int opcode;
920920
921− saved_nocode_wanted = nocode_wanted;
922− nocode_wanted = 0;
923−
924921 /* XXX: undefine C labels */
925922
926923 ch = file->buf_ptr[0];
@@ -940,7 +937,7 @@ static int tcc_assemble_internal(TCCState *s1, int do_preprocess) · 13 unmodified lines
940937 while (tok != TOK_LINEFEED)
941938 next();
942939 } else if (tok >= TOK_ASMDIR_FIRST && tok <= TOK_ASMDIR_LAST) {
943− asm_parse_directive(s1);
940+ asm_parse_directive(s1, global);
944941 } else if (tok == TOK_PPNUM) {
945942 Sym *sym;
946943 const char *p;
@@ -964,7 +961,7 @@ static int tcc_assemble_internal(TCCState *s1, int do_preprocess) · 17 unmodified lines
964961 /* handle "extern void vide(void); __asm__("vide: ret");" as
965962 "__asm__("globl vide\nvide: ret");" */
966963 Sym *sym = sym_find(opcode);
967− if (sym && (sym->type.t & VT_EXTERN) && saved_nocode_wanted) {
964+ if (sym && (sym->type.t & VT_EXTERN) && global) {
968965 sym = label_find(opcode);
969966 if (!sym) {
970967 sym = label_push(&s1->asm_labels, opcode, 0);
@@ -993,7 +990,6 @@ static int tcc_assemble_internal(TCCState *s1, int do_preprocess) · 22 unmodified lines
993990
994991 asm_free_labels(s1);
995992
996− nocode_wanted = saved_nocode_wanted;
997993 return 0;
998994 }
999995
@@ -1017,7 +1013,7 @@ ST_FUNC int tcc_assemble(TCCState *s1, int do_preprocess) · 17 unmodified lines
10171013 ELFW(ST_INFO)(STB_LOCAL, STT_FILE), 0,
10181014 SHN_ABS, file->filename);
10191015
1020− ret = tcc_assemble_internal(s1, do_preprocess);
1016+ ret = tcc_assemble_internal(s1, do_preprocess, 1);
10211017
10221018 cur_text_section->data_offset = ind;
10231019
@@ -1032,7 +1028,7 @@ ST_FUNC int tcc_assemble(TCCState *s1, int do_preprocess) · 8 unmodified lines
10321028 /* assemble the string 'str' in the current C compilation unit without
10331029 C preprocessing. NOTE: str is modified by modifying the '\0' at the
10341030 end */
1035−static void tcc_assemble_inline(TCCState *s1, char *str, int len)
1031+static void tcc_assemble_inline(TCCState *s1, char *str, int len, int global)
10361032 {
10371033 int saved_parse_flags;
10381034 const int *saved_macro_ptr;
@@ -1044,7 +1040,7 @@ static void tcc_assemble_inline(TCCState *s1, char *str, int len) · 5 unmodified lines
10441040 memcpy(file->buffer, str, len);
10451041
10461042 macro_ptr = NULL;
1047− tcc_assemble_internal(s1, 0);
1043+ tcc_assemble_internal(s1, 0, global);
10481044 tcc_close();
10491045
10501046 parse_flags = saved_parse_flags;
@@ -1277,7 +1273,7 @@ ST_FUNC void asm_instr(void) · 226 unmodified lines
12771273 clobber_regs, out_reg);
12781274
12791275 /* assemble the string with tcc internal assembler */
1280− tcc_assemble_inline(tcc_state, astr1.data, astr1.size - 1);
1276+ tcc_assemble_inline(tcc_state, astr1.data, astr1.size - 1, 0);
12811277
12821278 /* restore the current C token */
12831279 next();
@@ -1299,7 +1295,10 @@ ST_FUNC void asm_instr(void) · 15 unmodified lines
12991295 ST_FUNC void asm_global_instr(void)
13001296 {
13011297 CString astr;
1298+ int saved_nocode_wanted = nocode_wanted;
13021299
1300+ /* Global asm blocks are always emitted. */
1301+ nocode_wanted = 0;
13031302 next();
13041303 parse_asm_str(&astr);
13051304 skip(')');
@@ -1315,7 +1314,7 @@ ST_FUNC void asm_global_instr(void) · 9 unmodified lines
13151314 ind = cur_text_section->data_offset;
13161315
13171316 /* assemble the string with tcc internal assembler */
1318− tcc_assemble_inline(tcc_state, astr.data, astr.size - 1);
1317+ tcc_assemble_inline(tcc_state, astr.data, astr.size - 1, 1);
13191318
13201319 cur_text_section->data_offset = ind;
13211320
@@ -1323,5 +1322,6 @@ ST_FUNC void asm_global_instr(void) · 1 unmodified line
13231322 next();
13241323
13251324 cstr_free(&astr);
1325+ nocode_wanted = saved_nocode_wanted;
13261326 }
13271327 #endif /* CONFIG_TCC_ASM */
tccgen.c+16−3
@@ -575,8 +575,16 @@ static void vsetc(CType *type, int r, CValue *vc) · 574 unmodified lines
575575 tcc_error("memory full (vstack)");
576576 /* cannot let cpu flags if other instruction are generated. Also
577577 avoid leaving VT_JMP anywhere except on the top of the stack
578− because it would complicate the code generator. */
579− if (vtop >= vstack) {
578+ because it would complicate the code generator.
579+
580+ Don't do this when nocode_wanted. vtop might come from
581+ !nocode_wanted regions (see 88_codeopt.c) and transforming
582+ it to a register without actually generating code is wrong
583+ as their value might still be used for real. All values
584+ we push under nocode_wanted will eventually be popped
585+ again, so that the VT_CMP/VT_JMP value will be in vtop
586+ when code is unsuppressed again. */
587+ if (vtop >= vstack && !nocode_wanted) {
580588 v = vtop->r & VT_VALMASK;
581589 if (v == VT_CMP || (v & ~1) == VT_JMP)
582590 gv(RC_INT);
@@ -4367,13 +4375,18 @@ ST_FUNC void unary(void) · 3784 unmodified lines
43674375 gen_cast(&type);
43684376 }
43694377 } else if (tok == '{') {
4378+ int saved_nocode_wanted = nocode_wanted;
43704379 if (const_wanted)
43714380 tcc_error("expected constant");
43724381 /* save all registers */
43734382 save_regs(0);
43744383 /* statement expression : we do not accept break/continue
4375− inside as GCC does */
4384+ inside as GCC does. We do retain the nocode_wanted state,
4385+ as statement expressions can't ever be entered from the
4386+ outside, so any reactivation of code emission (from labels
4387+ or loop heads) can be disabled again after the end of it. */
43764388 block(NULL, NULL, 1);
4389+ nocode_wanted = saved_nocode_wanted;
43774390 skip(')');
43784391 } else {
43794392 gexpr();
tests/tcctest.c+32−0
@@ -1404,6 +1404,15 @@ void optimize_out(void) · 1403 unmodified lines
14041404 if (defined_function() && 0)
14051405 refer_to_undefined();
14061406
1407+ if (0) {
1408+ (void)sizeof( ({
1409+ do { } while (0);
1410+ 0;
1411+ }) );
1412+ undefined_function();
1413+ }
1414+
1415+ /* Leave the "if(1)return; printf()" in this order and last in the function */
14071416 if (1)
14081417 return;
14091418 printf ("oor:%d\n", undefined_function());
@@ -3251,6 +3260,28 @@ void trace_console(long len, long len2) · 1841 unmodified lines
32513260 }
32523261 #endif
32533262 }
3263+
3264+void test_asm_dead_code(void)
3265+{
3266+ long rdi;
3267+ /* Try to make sure that xdi contains a zero, and hence will
3268+ lead to a segfault if the next asm is evaluated without
3269+ arguments being set up. */
3270+ asm volatile ("" : "=D" (rdi) : "0" (0));
3271+ (void)sizeof (({
3272+ int var;
3273+ /* This shouldn't trigger a segfault, either the argument
3274+ registers need to be set up and the asm emitted despite
3275+ this being in an unevaluated context, or both the argument
3276+ setup _and_ the asm emission need to be suppressed. The latter
3277+ is better. Disabling asm code gen when suppression is on
3278+ also fixes the above trace_console bug, but that came earlier
3279+ than asm suppression. */
3280+ asm volatile ("movl $0,(%0)" : : "D" (&var) : "memory");
3281+ var;
3282+ }));
3283+}
3284+
32543285 void asm_test(void)
32553286 {
32563287 char buf[128];
@@ -3334,6 +3365,7 @@ void asm_test(void) · 77 unmodified lines
33343365 printf ("regvar=%x\n", regvar);
33353366 test_high_clobbers();
33363367 trace_console(8, 8);
3368+ test_asm_dead_code();
33373369 return;
33383370 label1:
33393371 goto label2;
tests/tests2/85-asm-outside-function.c+2−0
@@ -1,7 +1,9 @@
1+extern int printf (const char *, ...);
12 extern void vide(void);
23 __asm__("vide: ret");
34
45 int main() {
56 vide();
7+ printf ("okay\n");
68 return 0;
79 }
tests/tests2/85-asm-outside-function.expect+1−0
@@ -0,0 +1 @@
1+okay
tests/tests2/88_codeopt.c+68−0
@@ -0,0 +1,68 @@
1+/* Check some way in where code suppression caused various
2+ miscompilations. */
3+extern int printf (const char *, ...);
4+typedef unsigned long size_t;
5+
6+size_t _brk_start, _brk_end;
7+void * extend_brk(size_t size, size_t align)
8+{
9+ size_t mask = align - 1;
10+ void *ret = 0;
11+
12+ do {
13+ if (__builtin_expect(!!(_brk_start == 0), 0))
14+ do {
15+ printf("wrong1\n");
16+ } while (0);
17+ } while (0);
18+ _brk_end = (_brk_end + mask) & ~mask;
19+ ret = (void *)_brk_end;
20+ _brk_end += size;
21+
22+ return ret;
23+}
24+
25+static void get_args (int a, int b)
26+{
27+ if (a != 1)
28+ printf("wrong2\n");
29+ else
30+ printf("okay\n");
31+}
32+
33+void bla(void)
34+{
35+ int __ret = 42;
36+ ({
37+ if (__builtin_expect(!!(0), 0)) {
38+ if (__builtin_expect(!!__ret, 0))
39+ printf("wrong3\n");
40+ int x = !!(__ret);
41+ }
42+ __ret;
43+ });
44+ get_args(!!__ret, sizeof(__ret));
45+}
46+
47+_Bool chk(unsigned long addr, unsigned long limit, unsigned long size)
48+{
49+ _Bool ret;
50+ /* This just needs to compile, no runtime test. (And it doesn't compile
51+ only with certain internal checking added that's not committed). */
52+ if (0)
53+ ret = 0 != (!!(addr > limit - size));
54+}
55+
56+int main()
57+{
58+ void *r;
59+ _brk_start = 1024;
60+ _brk_end = 1024;
61+ r = extend_brk (4096, 16);
62+ if (!r)
63+ printf("wrong4\n");
64+ else
65+ printf("okay\n");
66+ bla();
67+ return 0;
68+}
tests/tests2/88_codeopt.expect+2−0
@@ -0,0 +1,2 @@
1+okay
2+okay
tests/tests2/Makefile+1−1
@@ -59,7 +59,7 @@ all test: $(filter-out $(SKIP),$(TESTS)) · 58 unmodified lines
5959 $(TCC) $< -o ./$*.exe $(FILTER) 2>&1 && \
6060 ./$*.exe $(ARGS) >$*.output 2>&1 || true; \
6161 fi
62− @diff -Nbu $(SRC)/$*.expect $*.output && rm -f $*.output
62+ @diff -Nbu $(SRC)/$*.expect $*.output && rm -f $*.output $*.exe
6363
6464 # automatically generate .expect files with gcc:
6565 %.expect : %.c

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