4.13. Platform-specific Flags
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## 4.13. Platform-specific Flags

Some flags only make sense for particular target platforms.

`-mv8`:

  (SPARC machines) Means to pass the like-named option to GCC; it says to use the Version 8 SPARC instructions, notably integer multiply and divide. The similar `-m*` GCC options for SPARC also work, actually.

`-monly-[32]-regs`:

  (iX86 machines) GHC tries to “steal” four registers from GCC, for performance reasons; it almost always works. However, when GCC is compiling some modules with four stolen registers, it will crash, probably saying:

      Foo.hc:533: fixed or forbidden register was spilled.
      This may be due to a compiler bug or to impossible asm
      statements or clauses.

  Just give some registers back with `-monly-N-regs`. Try `3' first, then `2'. If `2' doesn't work, please report the bug to us.

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