[Bug debug/43516] [4.5 Regression] "-fcompare-debug failure" at -O2

[jakub at gcc dot gnu dot org]

------- Comment #10 from jakub at gcc dot gnu dot org  2010-03-26 10:42 -------
In particular, for -g0 the alias set of that unsigned 1 bit type actually
changes.
This is on the #c1 testcase, with
-g -fcompare-debug=-gtoggle pr43516.c -O2 -fdump-final-insns=/tmp/1
resp.
-g0 -fcompare-debug=-gtoggle pr43516.c -O2 -fdump-final-insns=/tmp/2
Putting a breakpoint on new_alias_set when it returns 41 or more, when it
returns 41 in the backtrace is first get_alias_set for the signed 1 bit type
that c_common_signed_type returned, then 2 frames up get_alias_set for the
problematic unsigned 1 bit type.  In -g0 case a few get_alias_set calls on this
unsigned 1 bit type suddenly c_common_signed_type returns a different type,
which doesn't have alias set computed, while for -g it doesn't.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43516