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authorRichard Henderson <rth@twiddle.net>2012-09-20 07:55:51 -0700
committerRichard Henderson <rth@twiddle.net>2013-01-05 12:18:45 -0800
commitde379661d5c7cc1d219000d0741f5d96ced56553 (patch)
treed80804dc9accf33004d2e46c9bdbca0f7a4123a4
parentf24c49c24a4979fe50eff7afe18f371f5809177d (diff)
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>
-rw-r--r--target-s390x/translate.c39
1 files changed, 17 insertions, 22 deletions
diff --git a/target-s390x/translate.c b/target-s390x/translate.c
index cfe3766e81..2949bb1fc4 100644
--- a/target-s390x/translate.c
+++ b/target-s390x/translate.c
@@ -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);
}