From mboxrd@z Thu Jan 1 00:00:00 1970 From: mol@pengutronix.de (Michael Olbrich) Date: Tue, 11 Sep 2012 15:07:34 +0200 Subject: GCC 4.6.x miscompiling arm-linux? In-Reply-To: <20120911124226.27fa248b@archvile> References: <20120910171654.1d4972b2@archvile> <20120911092753.7b8315d4@archvile> <20120911084853.GT24458@pengutronix.de> <20120911113139.3b7b879f@archvile> <20120911102905.GC14994@pengutronix.de> <20120911124226.27fa248b@archvile> Message-ID: <20120911130734.GD14994@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Sep 11, 2012 at 12:42:26PM +0200, David Jander wrote: > On Tue, 11 Sep 2012 12:29:05 +0200 > Michael Olbrich wrote: > > > On Tue, Sep 11, 2012 at 11:31:39AM +0200, David Jander wrote: > > > On Tue, 11 Sep 2012 10:48:53 +0200 > > > Sascha Hauer wrote: > > > > > > > On Tue, Sep 11, 2012 at 09:27:53AM +0200, David Jander wrote: > > > > > > > > > > Hi Matt, > > > > > > > > > > > @ Function supports interworking. > > > > > > @ args = 0, pretend = 0, frame = 0 > > > > > > @ frame_needed = 0, uses_anonymous_args = 0 > > > > > > @ link register save eliminated. > > > > > > cmp r0, #9 > > > > > > mov r3, #0 > > > > > > str r3, [r1, #0] > > > > > > mov r0, #0 > > > > > > strgt r3, [r1, #4] > > > > > > bx lr > > > > > > .size flexcan_chip_start, .-flexcan_chip_start > > > > > > .ident "GCC: (GNU) 4.3.3" > > > > > > .section .note.GNU-stack,"",%progbits > > > > > > > > > > > > I think this looks correct. Perhaps you could try the angstrom arm5te > > > > > > toolchain and see if it's a toolchain issue? > > > > > > > > > > Yes, this looks a lot better, and is exactly what I get when I compile this > > > > > code with CodeSourcery GCC-4.4.1 > > > > > > > > > > I have tries building gcc-4.6.3 also with OSELAS/PTXdist, and it gives the > > > > > same (wrong) result as with gcc-4.6.2 > > > > > > > > AFAIK our OSELAS/PTXdist Toolchains use Linaro patches, this would > > > > explain why both have the same result. > > > > No, OSELAS Toolchains only uses the Linaro GCC for Cortex-A8/-A9 > > > > > It would indeed, if I had just used OSELAS as-is, but I didn't ;-) > > > I made a copy of > > > arm-v5te-linux-gnueabi_gcc-4.6.2_glibc-2.14.1_binutils-2.21.1a_kernel-2.6.39-sanitized.ptxconfig > > > and replaced the version string 4.6.2 with 4.6.3. AFAIK, this way PTXdist will > > > download pristine gcc-4.6.3 sources and not apply any patches, since there is > > > no directory named patches/gcc-4.6.3, right? Can I assume that I have an > > > unpatched version of gcc-4.6.3 then? > > > > Correct. This way you'll get gcc-4.6.3 without any patches. > > > > > Btw, Here's what I get from it: > > > > > > flexcan_chip_start: > > > @ args = 0, pretend = 0, frame = 0 > > > @ frame_needed = 0, uses_anonymous_args = 0 > > > @ link register save eliminated. > > > mov r3, #0 > > > cmp r0, #9 > > > str r3, [r1, #0] > > > ldrle r3, [r1, #4] > > > mov r0, #0 > > > str r3, [r1, #4] > > > bx lr > > > .size flexcan_chip_start, .-flexcan_chip_start > > > .ident "GCC: (OSELAS.Toolchain-2011.11.1) 4.6.3" > > > .section .note.GNU-stack,"",%progbits > > > > How can I reproduce this output? I'd like to test this with different > > toolchain versions. > > I basically do this: > > $ /opt/OSELAS.Toolchain-2011.11.1/arm-v5te-linux-gnueabi/gcc-4.6.3-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized/bin/arm-v5te-linux-gnueabi-gcc-4.6.3 -Os -S -o - -x c - > > struct flexcan_regs { > unsigned int mcr; > unsigned int rxfgmask; > }; > > #define flexcan_read(a) (*(volatile unsigned int *)(a)) > #define flexcan_write(v,a) (*(volatile unsigned int *)(a) = (v)) > > int flexcan_chip_start(int ver, struct flexcan_regs *regs) > { > flexcan_write(0, ®s->mcr); > > if (ver >= 10) > flexcan_write(0, ®s->rxfgmask); > > return 0; > } > > > > Wrong code. > > > See the version string? It is clearly not an existing OSELAS version. > > > > Hmmm, so far it seems all tested gcc-4.6.x versions produce wrong code, > > correct? > > Looks like that, yes. Including the Linaro gcc releases it seems. I rebuilt the toolchain with Linaro GCC 4.6-2012.08 and the result is the same. Regards, Michael -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |