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tcg-ppc64: Look through a constant function descriptor 

Especially in the user-only configurations, a direct branch into
the executable may be in range.

Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2013-08-31 06:30:45 -07:00
parent d40f3cb112
commit b0940da012
1 changed files with 19 additions and 4 deletions
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23
tcg/ppc64/tcg-target.c
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@ -173,14 +173,17 @@ static const int tcg_target_callee_save_regs[] = {
TCG_REG_R31 TCG_REG_R31
}; };
static inline bool in_range_b(tcg_target_long target)
{
return target == sextract64(target, 0, 26);
}
static uint32_t reloc_pc24_val(void *pc, tcg_target_long target) static uint32_t reloc_pc24_val(void *pc, tcg_target_long target)
{ {
tcg_target_long disp; tcg_target_long disp;
disp = target - (tcg_target_long)pc; disp = target - (tcg_target_long)pc;
if ((disp << 38) >> 38 != disp) { assert(in_range_b(disp));
tcg_abort();
}
return disp & 0x3fffffc; return disp & 0x3fffffc;
} }
@ -694,7 +697,7 @@ static void tcg_out_b(TCGContext *s, int mask, tcg_target_long target)
tcg_target_long disp; tcg_target_long disp;
disp = target - (tcg_target_long)s->code_ptr; disp = target - (tcg_target_long)s->code_ptr;
if ((disp << 38) >> 38 == disp) { if (in_range_b(disp)) {
tcg_out32(s, B | (disp & 0x3fffffc) | mask); tcg_out32(s, B | (disp & 0x3fffffc) | mask);
} else { } else {
tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_R0, (tcg_target_long)target); tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_R0, (tcg_target_long)target);
@ -717,6 +720,18 @@ static void tcg_out_call(TCGContext *s, tcg_target_long arg, int const_arg)
int ofs = 0; int ofs = 0;
if (const_arg) { if (const_arg) {
/* Look through the descriptor. If the branch is in range, and we
don't have to spend too much effort on building the toc. */
intptr_t tgt = ((intptr_t *)arg)[0];
intptr_t toc = ((intptr_t *)arg)[1];
intptr_t diff = tgt - (intptr_t)s->code_ptr;
if (in_range_b(diff) && toc == (uint32_t)toc) {
tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_R2, toc);
tcg_out_b(s, LK, tgt);
return;
}
/* Fold the low bits of the constant into the addresses below. */ /* Fold the low bits of the constant into the addresses below. */
ofs = (int16_t)arg; ofs = (int16_t)arg;
if (ofs + 8 < 0x8000) { if (ofs + 8 < 0x8000) {