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[Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307
- From: "zadeck at naturalbridge dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 10 Jan 2009 01:57:27 -0000
- Subject: [Bug rtl-optimization/38774] [4.4 Regression] ice in df_refs_verify, at df-scan.c:4307
- References: <bug-38774-12544@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from zadeck at naturalbridge dot com 2009-01-10 01:57 -------
Created an attachment (id=17068)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17068&action=view)
patch to cause df to verify after every patch
this is a combine bug. The df verification fails after combine makes some
modification to the cc arg of insn 28 in the foo function that bypasses the
implicit and explicit calls to mark the insn as being changed.
I am looking into trying to figure out what path thru combine is doing this.
However, if some combine expert (or just someone who wants to prove that they
have better skill with the debugger than I do) wants to get there first, be my
guest. I have attached a patch that improves some of the debugging and causes
df to verify after every pass. This patch causes the failure to move from
being in ira, to the start of if conversion after combine.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38774