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author | Richard Henderson | 2014-03-31 18:57:06 +0200 |
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committer | Richard Henderson | 2014-05-15 07:33:35 +0200 |
commit | 7b7066b1db4e0609055c1f7f4ba58732c6ea06df (patch) | |
tree | 52dfbc90264651f0e4b2e61caaffead2e983aa75 /tcg/s390/tcg-target.c | |
parent | tcg-s390: Allow immediate operands to add2 and sub2 (diff) | |
download | qemu-7b7066b1db4e0609055c1f7f4ba58732c6ea06df.tar.gz qemu-7b7066b1db4e0609055c1f7f4ba58732c6ea06df.tar.xz qemu-7b7066b1db4e0609055c1f7f4ba58732c6ea06df.zip |
tcg-s390: Improve setcond
There are a variety of common cases for which we can use carry tricks to
avoid a conditional branch. On very new hardware, use LOAD ON CONDITION
instead of a conditional branch.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'tcg/s390/tcg-target.c')
-rw-r--r-- | tcg/s390/tcg-target.c | 97 |
1 files changed, 91 insertions, 6 deletions
diff --git a/tcg/s390/tcg-target.c b/tcg/s390/tcg-target.c index e912f436ca..e235130a43 100644 --- a/tcg/s390/tcg-target.c +++ b/tcg/s390/tcg-target.c @@ -1135,15 +1135,100 @@ static int tgen_cmp(TCGContext *s, TCGType type, TCGCond c, TCGReg r1, return tcg_cond_to_s390_cond[c]; } -static void tgen_setcond(TCGContext *s, TCGType type, TCGCond c, +static void tgen_setcond(TCGContext *s, TCGType type, TCGCond cond, TCGReg dest, TCGReg c1, TCGArg c2, int c2const) { - int cc = tgen_cmp(s, type, c, c1, c2, c2const); + int cc; + + switch (cond) { + case TCG_COND_GTU: + case TCG_COND_GT: + do_greater: + /* The result of a compare has CC=2 for GT and CC=3 unused. + ADD LOGICAL WITH CARRY considers (CC & 2) the carry bit. */ + tgen_cmp(s, type, cond, c1, c2, c2const); + tcg_out_movi(s, type, dest, 0); + tcg_out_insn(s, RRE, ALCGR, dest, dest); + return; + + case TCG_COND_GEU: + do_geu: + /* We need "real" carry semantics, so use SUBTRACT LOGICAL + instead of COMPARE LOGICAL. This needs an extra move. */ + tcg_out_mov(s, type, TCG_TMP0, c1); + if (c2const) { + tcg_out_movi(s, TCG_TYPE_I64, dest, 0); + if (type == TCG_TYPE_I32) { + tcg_out_insn(s, RIL, SLFI, TCG_TMP0, c2); + } else { + tcg_out_insn(s, RIL, SLGFI, TCG_TMP0, c2); + } + } else { + if (type == TCG_TYPE_I32) { + tcg_out_insn(s, RR, SLR, TCG_TMP0, c2); + } else { + tcg_out_insn(s, RRE, SLGR, TCG_TMP0, c2); + } + tcg_out_movi(s, TCG_TYPE_I64, dest, 0); + } + tcg_out_insn(s, RRE, ALCGR, dest, dest); + return; + + case TCG_COND_LEU: + case TCG_COND_LTU: + case TCG_COND_LT: + /* Swap operands so that we can use GEU/GTU/GT. */ + if (c2const) { + tcg_out_movi(s, type, TCG_TMP0, c2); + c2 = c1; + c2const = 0; + c1 = TCG_TMP0; + } else { + TCGReg t = c1; + c1 = c2; + c2 = t; + } + if (cond == TCG_COND_LEU) { + goto do_geu; + } + cond = tcg_swap_cond(cond); + goto do_greater; + + case TCG_COND_NE: + /* X != 0 is X > 0. */ + if (c2const && c2 == 0) { + cond = TCG_COND_GTU; + goto do_greater; + } + break; - /* Emit: r1 = 1; if (cc) goto over; r1 = 0; over: */ - tcg_out_movi(s, type, dest, 1); - tcg_out_insn(s, RI, BRC, cc, (4 + 4) >> 1); - tcg_out_movi(s, type, dest, 0); + case TCG_COND_EQ: + /* X == 0 is X <= 0 is 0 >= X. */ + if (c2const && c2 == 0) { + tcg_out_movi(s, TCG_TYPE_I64, TCG_TMP0, 0); + c2 = c1; + c2const = 0; + c1 = TCG_TMP0; + goto do_geu; + } + break; + + default: + break; + } + + cc = tgen_cmp(s, type, cond, c1, c2, c2const); + if (facilities & FACILITY_LOAD_ON_COND) { + /* Emit: d = 0, t = 1, d = (cc ? t : d). */ + tcg_out_movi(s, TCG_TYPE_I64, dest, 0); + tcg_out_movi(s, TCG_TYPE_I64, TCG_TMP0, 1); + tcg_out_insn(s, RRF, LOCGR, dest, TCG_TMP0, cc); + } else { + /* Emit: d = 1; if (cc) goto over; d = 0; over: */ + tcg_out_movi(s, type, dest, 1); + tcg_out_insn(s, RI, BRC, cc, (4 + 4) >> 1); + tcg_out_movi(s, type, dest, 0); + } } static void tgen_movcond(TCGContext *s, TCGType type, TCGCond c, TCGReg dest, |