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target-s390: Tidy comparisons 

After full conversion, we can audit the uses of LTGT cc ops
and see that none of the instructions can ever set CC=3.
Thus we can extend the table to treat that bit as ignored.

This fixes a regression wrt the pre-conversion translation
in which NE was used for both m=6 and m=7.

Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2012-09-20 07:55:51 -07:00
parent f24c49c24a
commit de379661d5
1 changed files with 17 additions and 22 deletions
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39
target-s390x/translate.c
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@ -577,30 +577,29 @@ static void account_inline_branch(DisasContext *s, int cc_op)
}
/* Table of mask values to comparison codes, given a comparison as input.
For a true comparison CC=3 will never be set, but we treat this
conservatively for possible use when CC=3 indicates overflow. */
For such, CC=3 should not be possible. */
static const TCGCond ltgt_cond[16] = {
TCG_COND_NEVER, TCG_COND_NEVER, /* | | | x */
TCG_COND_GT, TCG_COND_NEVER, /* | | GT | x */
TCG_COND_LT, TCG_COND_NEVER, /* | LT | | x */
TCG_COND_NE, TCG_COND_NEVER, /* | LT | GT | x */
TCG_COND_EQ, TCG_COND_NEVER, /* EQ | | | x */
TCG_COND_GE, TCG_COND_NEVER, /* EQ | | GT | x */
TCG_COND_LE, TCG_COND_NEVER, /* EQ | LT | | x */
TCG_COND_GT, TCG_COND_GT, /* | | GT | x */
TCG_COND_LT, TCG_COND_LT, /* | LT | | x */
TCG_COND_NE, TCG_COND_NE, /* | LT | GT | x */
TCG_COND_EQ, TCG_COND_EQ, /* EQ | | | x */
TCG_COND_GE, TCG_COND_GE, /* EQ | | GT | x */
TCG_COND_LE, TCG_COND_LE, /* EQ | LT | | x */
TCG_COND_ALWAYS, TCG_COND_ALWAYS, /* EQ | LT | GT | x */
};
/* Table of mask values to comparison codes, given a logic op as input.
For such, only CC=0 and CC=1 should be possible. */
static const TCGCond nz_cond[16] = {
/* | | x | x */
TCG_COND_NEVER, TCG_COND_NEVER, TCG_COND_NEVER, TCG_COND_NEVER,
/* | NE | x | x */
TCG_COND_NE, TCG_COND_NE, TCG_COND_NE, TCG_COND_NE,
/* EQ | | x | x */
TCG_COND_EQ, TCG_COND_EQ, TCG_COND_EQ, TCG_COND_EQ,
/* EQ | NE | x | x */
TCG_COND_ALWAYS, TCG_COND_ALWAYS, TCG_COND_ALWAYS, TCG_COND_ALWAYS,
TCG_COND_NEVER, TCG_COND_NEVER, /* | | x | x */
TCG_COND_NEVER, TCG_COND_NEVER,
TCG_COND_NE, TCG_COND_NE, /* | NE | x | x */
TCG_COND_NE, TCG_COND_NE,
TCG_COND_EQ, TCG_COND_EQ, /* EQ | | x | x */
TCG_COND_EQ, TCG_COND_EQ,
TCG_COND_ALWAYS, TCG_COND_ALWAYS, /* EQ | NE | x | x */
TCG_COND_ALWAYS, TCG_COND_ALWAYS,
};
/* Interpret MASK in terms of S->CC_OP, and fill in C with all the
@ -1463,9 +1462,7 @@ static ExitStatus op_cj(DisasContext *s, DisasOps *o)
bool is_imm;
DisasCompare c;
/* Bit 3 of the m3 field is reserved and should be zero.
Choose to ignore it wrt the ltgt_cond table above. */
c.cond = ltgt_cond[m3 & 14];
c.cond = ltgt_cond[m3];
if (s->insn->data) {
c.cond = tcg_unsigned_cond(c.cond);
}
@ -1831,9 +1828,7 @@ static ExitStatus op_ct(DisasContext *s, DisasOps *o)
TCGv_i32 t;
TCGCond c;
/* Bit 3 of the m3 field is reserved and should be zero.
Choose to ignore it wrt the ltgt_cond table above. */
c = tcg_invert_cond(ltgt_cond[m3 & 14]);
c = tcg_invert_cond(ltgt_cond[m3]);
if (s->insn->data) {
c = tcg_unsigned_cond(c);
}