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tcg/i386: Add support for fence

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Generate a 'lock orl $0,0(%esp)' instruction for ordering instead of
mfence which has similar ordering semantics.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Message-Id: <20160714202026.9727-3-bobby.prani@gmail.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Pranith Kumar 2016-07-14 16:20:14 -04:00 committed by Richard Henderson
parent f65e19bc2c
commit a7d00d4eff
1 changed files with 17 additions and 0 deletions
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17
tcg/i386/tcg-target.inc.c
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@ -686,6 +686,18 @@ static inline void tcg_out_pushi(TCGContext *s, tcg_target_long val)
}
}
static inline void tcg_out_mb(TCGContext *s, TCGArg a0)
{
/* Given the strength of x86 memory ordering, we only need care for
store-load ordering. Experimentally, "lock orl $0,0(%esp)" is
faster than "mfence", so don't bother with the sse insn. */
if (a0 & TCG_MO_ST_LD) {
tcg_out8(s, 0xf0);
tcg_out_modrm_offset(s, OPC_ARITH_EvIb, ARITH_OR, TCG_REG_ESP, 0);
tcg_out8(s, 0);
}
}
static inline void tcg_out_push(TCGContext *s, int reg)
{
tcg_out_opc(s, OPC_PUSH_r32 + LOWREGMASK(reg), 0, reg, 0);
@ -2131,6 +2143,9 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
}
break;
case INDEX_op_mb:
tcg_out_mb(s, args[0]);
break;
case INDEX_op_mov_i32: /* Always emitted via tcg_out_mov. */
case INDEX_op_mov_i64:
case INDEX_op_movi_i32: /* Always emitted via tcg_out_movi. */
@ -2196,6 +2211,8 @@ static const TCGTargetOpDef x86_op_defs[] = {
{ INDEX_op_add2_i32, { "r", "r", "0", "1", "ri", "ri" } },
{ INDEX_op_sub2_i32, { "r", "r", "0", "1", "ri", "ri" } },
{ INDEX_op_mb, { } },
#if TCG_TARGET_REG_BITS == 32
{ INDEX_op_brcond2_i32, { "r", "r", "ri", "ri" } },
{ INDEX_op_setcond2_i32, { "r", "r", "r", "ri", "ri" } },