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Don't allow section switches in local asm instructions

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GCC wouldn't be able to implement this either (due to the separate
phases of compilation and assembly).  We could allow it but it
makes not much sense and actively can confuse broken code into
segfaulting TCC.  At least we can warn.

Warning exposes a problem in tcctest, and fixing that gives us
an opportunity to also test .pushsection/.popsection and .previous
directive support.
This commit is contained in:
Michael Matz 2019-05-30 21:31:35 +02:00
parent 1dd6842654
commit d04ce7772c
2 changed files with 10 additions and 2 deletions
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8
tccasm.c
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@ -1146,6 +1146,7 @@ ST_FUNC void asm_instr(void)
ASMOperand operands[MAX_ASM_OPERANDS];
int nb_outputs, nb_operands, i, must_subst, out_reg;
uint8_t clobber_regs[NB_ASM_REGS];
Section *sec;
next();
/* since we always generate the asm() instruction, we can ignore
@ -1220,8 +1221,15 @@ ST_FUNC void asm_instr(void)
asm_gen_code(operands, nb_operands, nb_outputs, 0,
clobber_regs, out_reg);
/* We don't allow switching section within inline asm to
bleed out to surrounding code. */
sec = cur_text_section;
/* assemble the string with tcc internal assembler */
tcc_assemble_inline(tcc_state, astr1.data, astr1.size - 1, 0);
if (sec != cur_text_section) {
tcc_warning("inline asm tries to change current section");
use_section1(tcc_state, sec);
}
/* restore the current C token */
next();

4
tests/tcctest.c
View File

@ -3438,10 +3438,10 @@ void asm_dot_test(void)
case 2:
asm(".text; jmp .+6; .int 123; mov .-4"RX",%eax; jmp p0");
case 3:
asm(".data; Y=.; .int 999; X=Y; .int 456; X=.-4");
asm(".pushsection \".data\"; Y=.; .int 999; X=Y; .int 456; X=.-4; .popsection");
asm(".text; mov X"RX",%eax; jmp p0");
case 4:
asm(".data; X=.; .int 789; Y=.; .int 999");
asm(".data; X=.; .int 789; Y=.; .int 999; .previous");
asm(".text; mov X"RX",%eax; X=Y; jmp p0");
case 0:
asm(".text; p0=.; mov %%eax,%0;" : "=m"(r)); break;