git: rtld-elf - save/restore args fp regs as well (clang)

Matthew Dillon dillon at
Sun Nov 9 13:32:42 PST 2014

commit 9631883ec7333a05f8e824cb63b405893a1707ff
Author: Matthew Dillon <dillon at>
Date:   Sun Nov 9 13:27:54 2014 -0800

    rtld-elf - save/restore args fp regs as well (clang)
    * Note: this has no real effect on gcc based systems.
    * fp registers %xmm0-7 can be used for arguments to procedures.  With
      GCC we didn't have to save/restore them for the rtld binder because
      rtld didn't use any FP registers and GCC did not insert any for
      structural copies.
      But CLANG does, so the binder has to save/restore these registers or
      dynamically linked calls which take FP arguments will explode on the
      first call.
    * For example, A simple clang program to printf("%f", 1.0); a few times...
      the first output would be 0.0 instead of 1.0 due to the binder blowing
      away the procedure argument to dtoa().  The bug also blows up awk and
      dports and... well.
    Reported-by: marino

Summary of changes:
 libexec/rtld-elf/x86_64/rtld_start.S | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

DragonFly BSD source repository

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