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[Bug debug/54693] VTA guality issues with loops
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 01 Oct 2012 15:26:10 +0000
- Subject: [Bug debug/54693] VTA guality issues with loops
- Auto-submitted: auto-generated
- References: <bug-54693-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54693
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-10-01 15:26:10 UTC ---
In VRP it is jump threading that performs the first CFG transformation, and the
second one happens as two merge_block opportunities during cleanup_tree_cfg.
Doing the new DEBUG stmt insertion upon merge_blocks would be weird, perhaps
some pass should just in addition to what it does now try to detect at least
the simple cases, where at the end of more than one predecessor block are live
debug stmts for some decl, and they use invariants or SSA_NAMEs that appear
together in some PHI - then adding a DEBUG stmt at the start of the bb with a
PHI might improve debug info quality, something var-tracking won't be able to
figure out due to the conditional.