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PR 14042: C++ abstraction penalty (tree-ssa regression/opportunity)
- From: "Timothy J. Wood" <tjw at omnigroup dot com>
- To: gcc at gcc dot gnu dot org
- Date: Sun, 8 Feb 2004 18:30:27 -0800
- Subject: PR 14042: C++ abstraction penalty (tree-ssa regression/opportunity)
Since people are working on getting tree-ssa performing as well as or
better than 3.4, I thought I'd mention this PR. This is an
optimization regression/opportunity in that tree-ssa currently
generates worse code than 3.4 and even what 3.4 generates is far from
optimal. The problem presents itself when you have two stack allocated
instances of a C++ class -- with only one, 3.4 will inline all the
operations on the class, but with two instances, it starts writing them
to the stack. In the given test case, this causes an inner loop to
have tons of load/store operations.
-tim