[Bug middle-end/20491] [4.0/4.1 Regression] internal compiler error: in subreg_regno_offset, at rtlanal.c:3042

[kenner at vlsi1 dot ultra dot nyu dot edu]

------- Additional Comments From kenner at vlsi1 dot ultra dot nyu dot edu  2005-03-24 12:33 -------
Subject: Re:  [PR middle-end/20491] combine generates bad subregs

    Combine doesn't ensure the subregs it generates are valid.  In most
    cases, insn recog will reject the invalid subregs, or reload will
    some how make them fit, but if the constraint of the insn or the asm
    operand is "X", this won't work, so I think we're better off ensuring
    we don't ever introduce subregs of non-REGs.

Aside from calling recog combine doesn't check that *anything* it generates
is valid.  Why should subregs be different?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20491