tcg/i386: omit a few REXW prefixes in softmmu code

When computing the TLB address we are likely to mask out the high
32-bits by using shr + and. We can use 32-bit instructions in that
case. This saves 2 bytes per TLB access.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Message-Id: <1437306632-20655-1-git-send-email-aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Aurelien Jarno 2015-07-19 13:50:32 +02:00 committed by Richard Henderson
parent 352bcb0a2b
commit 08b0b23be6

View file

@ -1178,8 +1178,8 @@ static inline void tcg_out_tlb_load(TCGContext *s, TCGReg addrlo, TCGReg addrhi,
const TCGReg r0 = TCG_REG_L0;
const TCGReg r1 = TCG_REG_L1;
TCGType ttype = TCG_TYPE_I32;
TCGType htype = TCG_TYPE_I32;
int trexw = 0, hrexw = 0;
TCGType tlbtype = TCG_TYPE_I32;
int trexw = 0, hrexw = 0, tlbrexw = 0;
int s_mask = (1 << (opc & MO_SIZE)) - 1;
bool aligned = (opc & MO_AMASK) == MO_ALIGN || s_mask == 0;
@ -1189,12 +1189,15 @@ static inline void tcg_out_tlb_load(TCGContext *s, TCGReg addrlo, TCGReg addrhi,
trexw = P_REXW;
}
if (TCG_TYPE_PTR == TCG_TYPE_I64) {
htype = TCG_TYPE_I64;
hrexw = P_REXW;
if (TARGET_PAGE_BITS + CPU_TLB_BITS > 32) {
tlbtype = TCG_TYPE_I64;
tlbrexw = P_REXW;
}
}
}
tcg_out_mov(s, htype, r0, addrlo);
tcg_out_mov(s, tlbtype, r0, addrlo);
if (aligned) {
tcg_out_mov(s, ttype, r1, addrlo);
} else {
@ -1203,12 +1206,12 @@ static inline void tcg_out_tlb_load(TCGContext *s, TCGReg addrlo, TCGReg addrhi,
tcg_out_modrm_offset(s, OPC_LEA + trexw, r1, addrlo, s_mask);
}
tcg_out_shifti(s, SHIFT_SHR + hrexw, r0,
tcg_out_shifti(s, SHIFT_SHR + tlbrexw, r0,
TARGET_PAGE_BITS - CPU_TLB_ENTRY_BITS);
tgen_arithi(s, ARITH_AND + trexw, r1,
TARGET_PAGE_MASK | (aligned ? s_mask : 0), 0);
tgen_arithi(s, ARITH_AND + hrexw, r0,
tgen_arithi(s, ARITH_AND + tlbrexw, r0,
(CPU_TLB_SIZE - 1) << CPU_TLB_ENTRY_BITS, 0);
tcg_out_modrm_sib_offset(s, OPC_LEA + hrexw, r0, TCG_AREG0, r0, 0,