[Bug tree-optimization/19708] New: tree optimizer doesn't meet asm constraints

[Bug tree-optimization/19708] New: tree optimizer doesn't meet asm constraints

[amodra at bigpond dot net dot au]

Found when attempting to compile powerpc64-linux glibc using current mainline gcc,
the attached cut-down testcase results in

tcboff.i: In function 'dummy':
tcboff.i:24: warning: asm operand 0 probably doesn't match constraints
tcboff.i:24: error: impossible constraint in 'asm'

-- 
           Summary: tree optimizer doesn't meet asm constraints
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: amodra at bigpond dot net dot au
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: powerpc*-linux, i686-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19708

[Bug tree-optimization/19708] tree optimizer doesn't meet asm constraints

[amodra at bigpond dot net dot au]

------- Additional Comments From amodra at bigpond dot net dot au  2005-01-30 10:47 -------
Created an attachment (id=8106)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=8106&action=view)
testcase


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19708

[Bug tree-optimization/19708] tree optimizer doesn't meet asm constraints

[amodra at bigpond dot net dot au]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  GCC build triplet|powerpc*-linux, i686-linux  |
 GCC target triplet|                            |powerpc*-linux, i686-linux
      Known to work|                            |3.4.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19708

[Bug middle-end/19708] [4.0 Regression] fold does not fold "&int_cst->a"

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-30 14:08 -------
The problem is that we don't fold "&4294938544B->D.1116.header.multiple_threads" to the offset but 
I remember there was a reason why we don't.

The reason why this works in 3.4.4 is that we "fold' that in the front-end before getting anywhere.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|tree-optimization           |middle-end
     Ever Confirmed|                            |1
 GCC target triplet|powerpc*-linux, i686-linux  |
           Keywords|                            |rejects-valid
   Last reconfirmed|0000-00-00 00:00:00         |2005-01-30 14:08:31
               date|                            |
            Summary|tree optimizer doesn't meet |[4.0 Regression] fold does
                   |asm constraints             |not fold "&int_cst->a"
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19708

[Bug middle-end/19708] [4.0 Regression] does not fold "&int_cst->a" to just INT_CST

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-30 14:14 -------
The easiest fix would be to fold it in the front-end for all INT_CST's like the following with a slight 
comment fix above:
Index: c-typeck.c
===============================================================
====
RCS file: /cvs/gcc/gcc/gcc/c-typeck.c,v
retrieving revision 1.415
diff -u -p -r1.415 c-typeck.c
--- c-typeck.c  29 Jan 2005 16:12:38 -0000      1.415
+++ c-typeck.c  30 Jan 2005 14:13:00 -0000
@@ -2683,7 +2683,7 @@ build_unary_op (enum tree_code code, tre
         when we have proper support for integer constant expressions.  */
       val = get_base_address (arg);
       if (val && TREE_CODE (val) == INDIRECT_REF
-         && integer_zerop (TREE_OPERAND (val, 0)))
+          && TREE_CODE (TREE_OPERAND (val, 0)) == INTEGER_CST)
        return fold_convert (argtype, fold_offsetof (arg));
 
       val = build1 (ADDR_EXPR, argtype, arg);


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.0 Regression] fold does  |[4.0 Regression] does not
                   |not fold "&int_cst->a"      |fold "&int_cst->a" to just
                   |                            |INT_CST


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19708

[Bug middle-end/19708] [4.0 Regression] does not fold "&int_cst->a" to just INT_CST

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-01 00:20 -------
: Search converges between 2004-08-30-trunk (#529) and 2004-08-31-trunk (#530).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19708

[Bug middle-end/19708] [4.0 Regression] does not fold "&int_cst->a" to just INT_CST

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-02-09 22:18 -------
Andrew, your patch is wrong; fold_offsetof assumes a zero base.

Alan, I have no particular interest in fixing this.  See how the 
alpha tcb-offsets.def file addresses this same problem.

If this turns out to be Absolutely Necessary, ie affects more than
just the nptl build, we can consider adding more hacks in this area
to accomodate, but at present I just don't think it's worth it.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WONTFIX


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19708