From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57799) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VFRyz-0004Gc-Tl for qemu-devel@nongnu.org; Fri, 30 Aug 2013 12:55:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VFRyu-00066t-EX for qemu-devel@nongnu.org; Fri, 30 Aug 2013 12:55:37 -0400 Received: from hall.aurel32.net ([2001:470:1f0b:4a8::1]:45225) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VFRyt-000637-Up for qemu-devel@nongnu.org; Fri, 30 Aug 2013 12:55:32 -0400 Date: Fri, 30 Aug 2013 18:55:14 +0200 From: Aurelien Jarno Message-ID: <20130830165514.GA15529@ohm.aurel32.net> References: <1377813961-12208-1-git-send-email-rth@twiddle.net> <1377813961-12208-3-git-send-email-rth@twiddle.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1377813961-12208-3-git-send-email-rth@twiddle.net> Subject: Re: [Qemu-devel] [PATCH v2 2/7] tcg-i386: Don't perform GETPC adjustment in TCG code List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: qemu-devel@nongnu.org On Thu, Aug 29, 2013 at 03:05:56PM -0700, Richard Henderson wrote: > Since we now perform it inside the helper, no need to do it here. > This also lets us perform a tail-call from the store slow path to > the helper. > > Signed-off-by: Richard Henderson > --- > tcg/i386/tcg-target.c | 34 ++++++++++++++-------------------- > 1 file changed, 14 insertions(+), 20 deletions(-) > > diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c > index 12a7ca3..84f17fe 100644 > --- a/tcg/i386/tcg-target.c > +++ b/tcg/i386/tcg-target.c > @@ -1470,12 +1470,6 @@ static void add_qemu_ldst_label(TCGContext *s, > } > } > > -/* See the GETPC definition in include/exec/exec-all.h. */ > -static inline uintptr_t do_getpc(uint8_t *raddr) > -{ > - return (uintptr_t)raddr - 1; > -} > - > /* > * Generate code for the slow path for a load at the end of block > */ > @@ -1509,14 +1503,14 @@ static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *l) > tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, l->mem_index); > ofs += 4; > > - tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, do_getpc(l->raddr)); > + tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, (uintptr_t)l->raddr); > } else { > tcg_out_mov(s, TCG_TYPE_PTR, tcg_target_call_iarg_regs[0], TCG_AREG0); > /* The second argument is already loaded with addrlo. */ > tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[2], > l->mem_index); > tcg_out_movi(s, TCG_TYPE_PTR, tcg_target_call_iarg_regs[3], > - do_getpc(l->raddr)); > + (uintptr_t)l->raddr); > } > > tcg_out_calli(s, (tcg_target_long)qemu_ld_helpers[s_bits]); > @@ -1571,6 +1565,7 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l) > int opc = l->opc; > int s_bits = opc & 3; > uint8_t **label_ptr = &l->label_ptr[0]; > + TCGReg retaddr; > > /* resolve label address */ > *(uint32_t *)label_ptr[0] = (uint32_t)(s->code_ptr - label_ptr[0] - 4); > @@ -1603,10 +1598,10 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l) > tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, l->mem_index); > ofs += 4; > > - tcg_out_sti(s, TCG_TYPE_I32, TCG_REG_ESP, ofs, do_getpc(l->raddr)); > + retaddr = TCG_REG_EAX; > + tcg_out_movi(s, TCG_TYPE_I32, retaddr, (uintptr_t)l->raddr); > + tcg_out_st(s, TCG_TYPE_I32, retaddr, TCG_REG_ESP, ofs); > } else { > - uintptr_t pc; > - > tcg_out_mov(s, TCG_TYPE_PTR, tcg_target_call_iarg_regs[0], TCG_AREG0); > /* The second argument is already loaded with addrlo. */ > tcg_out_mov(s, (opc == 3 ? TCG_TYPE_I64 : TCG_TYPE_I32), > @@ -1614,20 +1609,19 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l) > tcg_out_movi(s, TCG_TYPE_I32, tcg_target_call_iarg_regs[3], > l->mem_index); > > - pc = do_getpc(l->raddr); > if (ARRAY_SIZE(tcg_target_call_iarg_regs) > 4) { > - tcg_out_movi(s, TCG_TYPE_PTR, tcg_target_call_iarg_regs[4], pc); > - } else if (pc == (int32_t)pc) { > - tcg_out_sti(s, TCG_TYPE_PTR, TCG_REG_ESP, 0, pc); > + retaddr = tcg_target_call_iarg_regs[4]; > + tcg_out_movi(s, TCG_TYPE_PTR, retaddr, (uintptr_t)l->raddr); > } else { > - tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_RAX, pc); > - tcg_out_st(s, TCG_TYPE_PTR, TCG_REG_RAX, TCG_REG_ESP, 0); > + retaddr = TCG_REG_RAX; > + tcg_out_movi(s, TCG_TYPE_PTR, retaddr, (uintptr_t)l->raddr); > + tcg_out_st(s, TCG_TYPE_PTR, retaddr, TCG_REG_ESP, 0); > } > } > > - tcg_out_calli(s, (tcg_target_long)qemu_st_helpers[s_bits]); > - > - tcg_out_jmp(s, (tcg_target_long)l->raddr); > + /* "Tail call" to the helper, with the return address back inline. */ > + tcg_out_push(s, retaddr); > + tcg_out_jmp(s, (tcg_target_long)qemu_st_helpers[s_bits]); > } Reviewed-by: Aurelien Jarno -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurelien@aurel32.net http://www.aurel32.net