[Bug debug/39368] New: loc_descriptor doesn't call delegitimize_address on MEMs

[Bug debug/39368] New: loc_descriptor doesn't call delegitimize_address on MEMs

[amylaar at gcc dot gnu dot org]

For a RISC target that doesn't allow memory-indirect addressing, the
proper way to represent an access of a symbol found in the GOT is to
first load the symbol from the GOT into a register, and then use
that register for memory access or call as needed.

For proper scheduling and instruction selection, the symbol load
source should be represented as what it is, i.e. a MEM.
So we have a (MEM (unspec ... UNSPEC_GOT)) .
For the purposes of debug output, this should be translated back into
the symbol_ref it represents.

However, loc_descriptor looks only into the address inside a MEM,
it does not process the entire mem with targetm.delegitimize_address.
I.e. there is no way to get rid of the MEM if it is not nested in
another MEM.


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           Summary: loc_descriptor doesn't call delegitimize_address on MEMs
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: amylaar at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39368

[Bug debug/39368] loc_descriptor doesn't call delegitimize_address on MEMs

[amylaar at gcc dot gnu dot org]

------- Comment #1 from amylaar at gcc dot gnu dot org  2009-03-05 02:30 -------
patch is here:
http://gcc.gnu.org/ml/gcc-patches/2009-03/msg00267.html


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amylaar at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
OtherBugsDependingO|                            |39363
              nThis|                            |
         AssignedTo|unassigned at gcc dot gnu   |amylaar at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
           Keywords|                            |patch
   Last reconfirmed|0000-00-00 00:00:00         |2009-03-05 02:30:29
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39368

[Bug debug/39368] loc_descriptor doesn't call delegitimize_address on MEMs

[jakub at gcc dot gnu dot org]

------- Comment #2 from jakub at gcc dot gnu dot org  2010-05-26 07:03 -------
Not sure whether this patch is still needed now that var-tracking already
delegitimizes MEMs (and their addresses) too.
That said, if you have a testcase where this is still needed, the patch looks
reasonable, so you might want to ping it.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39368