as: s390 Options

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1 9.40.1 Options
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1 The following table lists all available s390 specific options:
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1 '-m31 | -m64'
1      Select 31- or 64-bit ABI implying a word size of 32- or 64-bit.
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1      These options are only available with the ELF object file format,
1      and require that the necessary BFD support has been included (on a
1      31-bit platform you must add -enable-64-bit-bfd on the call to the
1      configure script to enable 64-bit usage and use s390x as target
1      platform).
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1 '-mesa | -mzarch'
1      Select the architecture mode, either the Enterprise System
1      Architecture (esa) mode or the z/Architecture mode (zarch).
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1      The 64-bit instructions are only available with the z/Architecture
1      mode.  The combination of '-m64' and '-mesa' results in a warning
1      message.
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1 '-march=CPU'
1      This option specifies the target processor.  The following
1      processor names are recognized: 'g5' (or 'arch3'), 'g6', 'z900' (or
1      'arch5'), 'z990' (or 'arch6'), 'z9-109', 'z9-ec' (or 'arch7'),
1      'z10' (or 'arch8'), 'z196' (or 'arch9'), 'zEC12' (or 'arch10'),
1      'z13' (or 'arch11'), 'z14' (or 'arch12'), 'z15' (or 'arch13'), and
1      'z16' (or 'arch14').
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1      Assembling an instruction that is not supported on the target
1      processor results in an error message.
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1      The processor names starting with 'arch' refer to the edition
1      number in the Principle of Operations manual.  They can be used as
1      alternate processor names and have been added for compatibility
1      with the IBM XL compiler.
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1      'arch3', 'g5' and 'g6' cannot be used with the '-mzarch' option
1      since the z/Architecture mode is not supported on these processor
1      levels.
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1      There is no 'arch4' option supported.  'arch4' matches
1      '-march=arch5 -mesa'.
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1 '-mregnames'
1      Allow symbolic names for registers.
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1 '-mno-regnames'
1      Do not allow symbolic names for registers.
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1 '-mwarn-areg-zero'
1      Warn whenever the operand for a base or index register has been
1      specified but evaluates to zero.  This can indicate the misuse of
1      general purpose register 0 as an address register.
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