[Bug rtl-optimization/13931] [3.4/4.0/4.1 Regression] combiner much slower on big basic blocks

["ian at airs dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #34 from ian at airs dot com  2005-10-08 05:51 -------
I am able to recreate the problem with a hppa64-hp-hpux11 cross-compiler, in
the sense that combine does lose the REG_DEAD note when compiling the
gcc.c-torture/compile/920501-13.c test case with -O1.  In the current compiler,
the compilation succeeds.  A REG_UNUSED note is added by the
recompute_reg_usage pass, the unused register is allocated, and the allocated
register is later eliminated during the combine_stack_adjustments pass.  So it
works but the overall effect is not ideal since we allocate an unneccessary
register.

I'll see if we can avoid losing the REG_DEAD note in the combine pass.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13931