The testcase from PR 16975 shows the tree-ssa aliasing pass can be slow.
You can get the testcase from:
<http://www.math.purdue.edu/~lucier/GNATS/GNATS-12/_num.i.gz>
Here is the results from my build (yes with --disable-checking):
tree PTA : 35.74 (38%) usr 0.12 ( 1%) sys 37.63 (33%) wall
Note this testcase has a large number of computed gotos.
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Summary: [4.0 Regression] tree-ssa aliasing slow
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Keywords: compile-time-hog
Severity: normal
Priority: P2
Component: tree-optimization
AssignedTo: dnovillo at gcc dot gnu dot org
ReportedBy: pinskia at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18419