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tcg-mips: Simplify brcond2

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Emitting a single branch instead of (up to) 3, using setcond2
to generate the composite compare.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2014-04-15 22:47:22 -07:00
parent 1db1c4d7d9
commit 3401fd259e
1 changed files with 21 additions and 58 deletions
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79
tcg/mips/tcg-target.c
View file

@ -764,70 +764,33 @@ static void tcg_out_setcond2(TCGContext *s, TCGCond cond, TCGReg ret,
}
}
/* XXX: we implement it at the target level to avoid having to
handle cross basic blocks temporaries */
static void tcg_out_brcond2(TCGContext *s, TCGCond cond, TCGArg arg1,
TCGArg arg2, TCGArg arg3, TCGArg arg4,
int label_index)
static void tcg_out_brcond2(TCGContext *s, TCGCond cond, TCGReg al, TCGReg ah,
TCGReg bl, TCGReg bh, int label_index)
{
tcg_insn_unit *label_ptr;
TCGCond b_cond = TCG_COND_NE;
TCGReg tmp = TCG_TMP1;
switch(cond) {
case TCG_COND_NE:
tcg_out_brcond(s, TCG_COND_NE, arg2, arg4, label_index);
tcg_out_brcond(s, TCG_COND_NE, arg1, arg3, label_index);
return;
case TCG_COND_EQ:
break;
case TCG_COND_LT:
case TCG_COND_LE:
tcg_out_brcond(s, TCG_COND_LT, arg2, arg4, label_index);
break;
case TCG_COND_GT:
case TCG_COND_GE:
tcg_out_brcond(s, TCG_COND_GT, arg2, arg4, label_index);
break;
case TCG_COND_LTU:
case TCG_COND_LEU:
tcg_out_brcond(s, TCG_COND_LTU, arg2, arg4, label_index);
break;
case TCG_COND_GTU:
case TCG_COND_GEU:
tcg_out_brcond(s, TCG_COND_GTU, arg2, arg4, label_index);
/* With branches, we emit between 4 and 9 insns with 2 or 3 branches.
With setcond, we emit between 3 and 10 insns and only 1 branch,
which ought to get better branch prediction. */
switch (cond) {
case TCG_COND_EQ:
case TCG_COND_NE:
b_cond = cond;
tmp = tcg_out_reduce_eq2(s, TCG_TMP0, TCG_TMP1, al, ah, bl, bh);
break;
default:
tcg_abort();
/* Minimize code size by prefering a compare not requiring INV. */
if (mips_cmp_map[cond] & MIPS_CMP_INV) {
cond = tcg_invert_cond(cond);
b_cond = TCG_COND_EQ;
}
tcg_out_setcond2(s, cond, tmp, al, ah, bl, bh);
break;
}
label_ptr = s->code_ptr;
tcg_out_opc_br(s, OPC_BNE, arg2, arg4);
tcg_out_nop(s);
switch(cond) {
case TCG_COND_EQ:
tcg_out_brcond(s, TCG_COND_EQ, arg1, arg3, label_index);
break;
case TCG_COND_LT:
case TCG_COND_LTU:
tcg_out_brcond(s, TCG_COND_LTU, arg1, arg3, label_index);
break;
case TCG_COND_LE:
case TCG_COND_LEU:
tcg_out_brcond(s, TCG_COND_LEU, arg1, arg3, label_index);
break;
case TCG_COND_GT:
case TCG_COND_GTU:
tcg_out_brcond(s, TCG_COND_GTU, arg1, arg3, label_index);
break;
case TCG_COND_GE:
case TCG_COND_GEU:
tcg_out_brcond(s, TCG_COND_GEU, arg1, arg3, label_index);
break;
default:
tcg_abort();
}
reloc_pc16(label_ptr, s->code_ptr);
tcg_out_brcond(s, b_cond, tmp, TCG_REG_ZERO, label_index);
}
static void tcg_out_movcond(TCGContext *s, TCGCond cond, TCGReg ret,