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Fix structure passing i386 PE

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The orignal code does:
    push eax/edx/size
    call alloca
    pop  eax/edx/size

The pop does not work because the stack pointer has changed.
To make this also work with bound checking the code is now
using the stack probing from alloca.
This commit is contained in:
herman ten brugge 2020-07-08 15:48:15 +02:00
parent 20fa63488a
commit 9d75f14107
1 changed files with 13 additions and 8 deletions
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21
i386-gen.c
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@ -419,14 +419,19 @@ ST_FUNC void gfunc_call(int nb_args)
/* allocate the necessary size on stack */
#ifdef TCC_TARGET_PE
if (size >= 0x4096) {
o(0x5250);
oad(0x68, size);
vpush_global_sym(&func_old_type, TOK_alloca);
gcall_or_jmp(0);
vtop--;
o(0x585a58);
oad(0xec81, 8); /* sub $8, %esp */
} else
/* cannot call alloca with bound checking. Do stack probing. */
o(0x50); // push %eax
oad(0xb8, size - 4); // mov size-4,%eax
oad(0x3d, 4096); // p1: cmp $4096,%eax
o(0x1476); // jbe <p2>
oad(0x248485,-4096); // test %eax,-4096(%esp)
oad(0xec81, 4096); // sub $4096,%esp
oad(0x2d, 4096); // sub $4096,%eax
o(0xe5eb); // jmp <p1>
o(0xc429); // p2: sub %eax,%esp
oad(0xc481, size - 4); // add size-4,%esp
o(0x58); // pop %eax
}
#endif
oad(0xec81, size); /* sub $xxx, %esp */
/* generate structure store */