Your message dated Sat, 1 Jan 2011 14:27:43 +0100 with message-id <[email protected]> and subject line Re: Bug#608550: gcc-4.3-mips-linux-gnu: gcc produces incorrect assembler for a/b - it doesn't do anything. has caused the Debian Bug report #608550, regarding gcc-4.3-mips-linux-gnu: gcc produces incorrect assembler for a/b - it doesn't do anything. to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact [email protected] immediately.) -- 608550: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=608550 Debian Bug Tracking System Contact [email protected] with problems
--- Begin Message ---Package: gcc-4.3-mips-linux-gnu Version: 4.3.5-4 Severity: grave Tags: upstream Justification: renders package unusable With compile options -O0 -static -DMIPS -mips1 -mabi=32 -msoft-float -mno-memcpy gcc produces incorrect code for division (and I suppose, %) from C. Test code can be simply: main() { int a,b,c; c = a/b; } compile to assembler with above flags. Read, or compile to object code and disassemble. The eyes-on read shows: bne $3,$0,1f #!!! ergh! Should be beq div $0,$2,$3 break 7 1: mflo $2 The divide is protected by a "branch around the divide if the denominator is NOT equal to zero". It should be "IS equal to zero". Checking the disassembly of the object code shows: 1c: 14600002 bnez v1,28 <main+0x28> (File Offset: 0x68) 20: 0043001a div zero,v0,v1 24: 0007000d break 0x7 28: 00001012 mflo v0 which is as indicated by the assembler source. No, the problem does not go away if the result from the division is used in the source code. I haven't tested with optimization but I see no reason to suppose that peephole optimization filters after the generation will patch this up (except where they excise it). -- System Information: LSB Version: core-2.0-ia32:core-2.0-noarch:core-3.0-ia32:core-3.0-noarch:core-3.1-ia32:core-3.1-noarch:core-3.2-ia32:core-3.2-noarch:cxx-3.0-ia32:cxx-3.0-noarch:cxx-3.1-ia32:cxx-3.1-noarch:cxx-3.2-ia32:cxx-3.2-noarch:desktop-3.1-ia32:desktop-3.1-noarch:desktop-3.2-ia32:desktop-3.2-noarch:graphics-2.0-ia32:graphics-2.0-noarch:graphics-3.0-ia32:graphics-3.0-noarch:graphics-3.1-ia32:graphics-3.1-noarch:graphics-3.2-ia32:graphics-3.2-noarch:languages-3.2-ia32:languages-3.2-noarch:multimedia-3.2-ia32:multimedia-3.2-noarch:printing-3.2-ia32:printing-3.2-noarch:qt4-3.1-ia32:qt4-3.1-noarch Distributor ID: Ubuntu NO It's NOT! SOmebody please tell me where that is! Description: Ubuntu 8.04.1 NYAAAA! No it's not. This is Debian Unstable. Release: 8.04 Nix. Codename: hardyArchitecture: i386 (i686) Nonsense. Where that come from? Kernel: Linux 2.6.31.2-SMP (SMP w/1 CPU core; PREEMPT) Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968) (ignored: LC_ALL set to C) Shell: /bin/sh linked to /bin/bash Versions of packages gcc-4.3-mips-linux-gnu depends on: ii binutils-mips-linux-gnu 2.20.1-15 The GNU binary utilities, for mips ii cpp-4.3-mips-linux-gnu 4.3.5-4 The GNU C preprocessor ii gcc-4.3-mips-linux-gnu-base 4.3.5-4 The GNU Compiler Collection (base ii libc6 2.11.2-7 Embedded GNU C Library: Shared lib ii libgcc1-mips-cross 1:4.4.5-10 GCC support library (for cross-com ii libgomp1 4.4.5-10 GCC OpenMP (GOMP) support library Versions of packages gcc-4.3-mips-linux-gnu recommends: ii libc6-dev-mips-cross 2.11.2-2 Embedded GNU C Library: Developmen Versions of packages gcc-4.3-mips-linux-gnu suggests: pn gcc-4.3-doc <none> (no description available) pn gcc-4.3-locales <none> (no description available) pn gcc-4.3-multilib-mips-linux-g <none> (no description available) pn libgcc1-dbg-mips-cross <none> (no description available) pn libgomp1-dbg-mips-cross <none> (no description available) pn libmudflap0-4.3-dev-mips-cros <none> (no description available) pn libmudflap0-dbg-mips-cross <none> (no description available) -- no debconf information
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--- Begin Message ---On Sat, Jan 01, 2011 at 12:45:49PM +0100, Peter T. Breuer wrote: > Package: gcc-4.3-mips-linux-gnu Where this package comes from? It is not in the debian archive. > Version: 4.3.5-4 > Severity: grave > Tags: upstream > Justification: renders package unusable > > With compile options > > -O0 -static -DMIPS -mips1 -mabi=32 -msoft-float -mno-memcpy > > gcc produces incorrect code for division (and I suppose, %) from C. > > Test code can be simply: > > > main() { > int a,b,c; > c = a/b; > } > > compile to assembler with above flags. Read, or compile to object code > and disassemble. The eyes-on read shows: > > bne $3,$0,1f #!!! ergh! Should be beq > div $0,$2,$3 > break 7 > 1: > mflo $2 > > The divide is protected by a "branch around the divide if the denominator > is NOT equal to zero". It should be "IS equal to zero". I strongly disagree, the code is correct: * if v1 is equal to 0, the following sequence is executed: bne $3,$0,1f div $0,$2,$3 break 7 In short a division by 0 will trap. * if v1 is different than 0, the following sequence is executed: bne $3,$0,1f div $0,$2,$3 mflo $2 The quotient now in v0. As the generated code is correct, I am closing the bug. -- Aurelien Jarno GPG: 1024D/F1BCDB73 [email protected] http://www.aurel32.net
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