[Bug 590859] Re: wrong code (wrong order) generated with -O2

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** Changed in: gcc
   Importance: Unknown => Medium

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Title:
  wrong code (wrong order) generated with -O2

Status in The GNU Compiler Collection:
  Invalid
Status in “gcc-4.4” package in Ubuntu:
  Invalid

Bug description:
  Binary package hint: gcc-4.4

  Hi,

  Description:	Ubuntu 10.04 LTS
  Release:	10.04

  gcc:
    Installed: 4:4.4.3-1ubuntu1
    Candidate: 4:4.4.3-1ubuntu1
    Version table:
   *** 4:4.4.3-1ubuntu1 0
          500 http://ftp.crihan.fr/ubuntu/ lucid/main Packages
          100 /var/lib/dpkg/status

  Cross-compiling to x86 code

  When compiling with :
  gcc -O2 -m32 -c -o proc.o proc.c
  The generated code is  :
     0x000000af <+175>:	movl   $0x0,%gs:0x4
     0x000000ba <+186>:	lgdtl  (%edx)
     0x000000bd <+189>:	mov    $0x18,%edx
     0x000000c2 <+194>:	mov    %edx,%gs
     0x000000c4 <+196>:	mov    %eax,%gs:0x0

  When compiling with :
  gcc -O1 -m32 -c -o proc.o proc.c
     0x000000af <+175>:	lgdtl  (%edx)
     0x000000b2 <+178>:	mov    $0x18,%edx
     0x000000b7 <+183>:	mov    %edx,%gs
     0x000000b9 <+185>:	mov    %eax,%gs:0x0
     0x000000bf <+191>:	movl   $0x0,%gs:0x4

  The first code is wrong : register GS is used (movl   $0x0,%gs:0x4)
  before loading the GDT (lgdtl  (%edx))

  It seems to be working fine with GCC version 4.3.4 (Ubuntu
  4.3.4-10ubuntu1)

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