[Bug middle-end/21111] IA-64 NaT consumption faults due to uninitialized register reads

[wilson at gcc dot gnu dot org]

------- Additional Comments From wilson at gcc dot gnu dot org  2005-04-19 20:41 -------
Created an attachment (id=8684)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=8684&action=view)
synthetic IA-64 testcase to generate NaT consumption fault

Compile this with -O, and it will fail with gcc-2.96 and gcc-4.0.0.  We get an
illegal instruction signal.  It works with gcc-3.0 and gcc-3.3 and presumably
with every other gcc-3.x release.

If you use gcc-4.0.0 to compile with -O -S, and look at the assembly code, you
can see that r8 is being used uninitialized, which fails if r8 happens to have
the NaT bit set.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21111