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tcg/optimize: add known-zero bits compute for load ops

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Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Aurelien Jarno 2013-09-03 08:27:39 +02:00 committed by Richard Henderson
parent f096dc9618
commit c8d7027253
1 changed files with 25 additions and 1 deletions
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26
tcg/optimize.c
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@ -779,13 +779,37 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
mask = temps[args[3]].mask | temps[args[4]].mask;
break;
CASE_OP_32_64(ld8u):
case INDEX_op_qemu_ld8u:
mask = 0xff;
break;
CASE_OP_32_64(ld16u):
case INDEX_op_qemu_ld16u:
mask = 0xffff;
break;
case INDEX_op_ld32u_i64:
#if TCG_TARGET_REG_BITS == 64
case INDEX_op_qemu_ld32u:
#endif
mask = 0xffffffffu;
break;
CASE_OP_32_64(qemu_ld):
{
TCGMemOp mop = args[def->nb_oargs + def->nb_iargs];
if (!(mop & MO_SIGN)) {
mask = (2ULL << ((8 << (mop & MO_SIZE)) - 1)) - 1;
}
}
break;
default:
break;
}
/* 32-bit ops (non 64-bit ops and non load/store ops) generate 32-bit
results */
if (!(tcg_op_defs[op].flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_64BIT))) {
if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_64BIT))) {
mask &= 0xffffffffu;
}