From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:41691) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TBsmr-0002EG-Vf for qemu-devel@nongnu.org; Wed, 12 Sep 2012 15:39:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TBsmq-0003lq-Pi for qemu-devel@nongnu.org; Wed, 12 Sep 2012 15:39:49 -0400 Message-ID: <5050E502.3070106@weilnetz.de> Date: Wed, 12 Sep 2012 21:39:46 +0200 From: Stefan Weil MIME-Version: 1.0 References: <1347473022-17017-1-git-send-email-sw@weilnetz.de> <20120912191451.GB6791@ohm.aurel32.net> In-Reply-To: <20120912191451.GB6791@ohm.aurel32.net> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] w64: Fix calls of TCG helper functions with 5 arguments List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aurelien Jarno Cc: Blue Swirl , Peter Maydell , qemu-devel@nongnu.org, qemu-stable@nongnu.org Am 12.09.2012 21:14, schrieb Aurelien Jarno: > On Wed, Sep 12, 2012 at 07:12:47PM +0100, Peter Maydell wrote: >> On 12 September 2012 19:03, Stefan Weil wrote: >>> diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c >>> index da17bba..43b5572 100644 >>> --- a/tcg/i386/tcg-target.c >>> +++ b/tcg/i386/tcg-target.c >>> @@ -118,7 +118,7 @@ static void patch_reloc(uint8_t *code_ptr, int type, >>> static inline int tcg_target_get_call_iarg_regs_count(int flags) >>> { >>> if (TCG_TARGET_REG_BITS == 64) { >>> - return 6; >>> + return ARRAY_SIZE(tcg_target_call_iarg_regs); >>> } >>> >>> return 0; >> >> Hmm. Why can't we just return the array size in all cases? >> Is there something special about 32 bit x86? I checked, and >> all our other TCG targets return the same value as the size of >> the iarg_regs array (either using ARRAY_SIZE or by just returning >> the right number)... >> > > On 32-bit x86, all arguments are now being passed on the stack, that's > why the function returns 0. On the other hand when the change has been > done, the registers haven't been removed from tcg_target_call_iarg_regs. > > I think this patch is fine enough for 1.2, but a better patch is needed > for master. I noticed that Blue switched from register arguments to arguments on the stack, but don't know the reason for that change. Maybe 32 bit x86 can also use a mixture of register / stack arguments. This needs more testing and is the main reason why I did not change tcg_target_call_iarg_regs for 32 bit and return ARRAY_SIZE for both 32 and 64 bit. I'd prefer to get the patch in master soon because it is a minimalistic change which fixes the now unusable 64 bit mode on Windows. An additional patch can still be applied on top. Of course any better patch which also fixes 64 bit Windows and which comes soon would also be very acceptable. Regards Stefan