Regehr: GCC 4.8 (pre-release) Breaks Broken SPEC 2006 Benchmarks

Regehr: GCC 4.8 (pre-release) Breaks Broken SPEC 2006 Benchmarks

Posted Mar 23, 2013 18:27 UTC (Sat) by mjw (subscriber, #16740)
In reply to: Regehr: GCC 4.8 Breaks Broken SPEC 2006 Benchmarks by ssam
Parent article: Regehr: GCC 4.8 Breaks Broken SPEC 2006 Benchmarks

Note that the original article was testing a pre-release GCC 4.8. The final version of GCC 4.8 contains the following bug fix:

Bug 53265 - Warn when undefined behavior implies smaller iteration count

And the GCC 4.8 Release Notes were updated to explain:

In some loops that have known constant number of iterations, but undefined behavior is known to occur in the loop before reaching or during the last iteration, GCC will warn about the undefined behavior in the loop instead of deriving lower upper bound of the number of iterations for the loop. The warning can be disabled with -Wno-aggressive-loop-optimizations.

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