[Bug rtl-optimization/60763] [4.9 Regression] ICE in extract_insn starting with rev 208984

[meissner at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60763

Michael Meissner <meissner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |meissner at gcc dot gnu.org

--- Comment #8 from Michael Meissner <meissner at gcc dot gnu.org> ---
Richard's analysis agrees with mine.  The problem is with adding the check for
REG_CANNOT_CHANGE_MODE_P, it breaks the direct moves between GPRs and VSX
registers for SF.  Because internally within the PowerPC, SFmode is stored as
DFmode, CANNOT_CHANGE_MODE_CLASS returns true.  The original direct mvoe code
should not have generated a (SUBREG:DI (REG:SF ...)) in this case, since that
is illegal.