[Bug debug/44832] [4.6 Regression] -fcompare-debug failure for C++ i386.c

["amylaar at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #11 from amylaar at gcc dot gnu dot org  2010-07-07 02:16 -------
(In reply to comment #10)
> ;; Function void ix86_expand_vector_init_general(bool, machine_mode, rtx, rtx) 
> Compiling the reduced testcase in a subdirectory of the r160832 gcc build
> directory with:
>  ../g++ -B.. -da -march=pentiumpro -mtune=generic -m32 t.c --dump-tree-all -g
> -S  -fdump-unnumbered
> , I see this in the final dump:

Hmm, that's actually the same as for r160828; but still, r160828 passes the
-fcompare-debug debug test with the reduced test case, while r160832 fails it.
Running this test with --save-temps and diffing the output shows that somehow
we end up with different tmp_var_id_num values for variables created by
tree-ssa-pre.c:

--- t.gkd       2010-07-07 03:02:40.831101079 +0100
+++ t.gk.gkd    2010-07-07 03:02:40.886978157 +0100
@@ -454,9 +454,9 @@
 (insn:TI# 0 0 t.c:78 (set (reg/f:SI 2 cx [116])
         (mem/s/f:SI (plus:SI (mult:SI (reg/v:SI 0 ax [orig:80 i ] [80])
                     (const_int 4 [0x4]))
-                (reg/f:SI 3 bx [orig:95 pretmp.21 ] [95])) [ *pretmp.21_81 S4
A32]))# {*movsi_1} (expr_list:REG_EQUIV (mem/s/f:SI (plus:SI (mult:SI (reg/v:SI
0 ax [orig:80 i ] [80])
+                (reg/f:SI 3 bx [orig:95 pretmp.21 ] [95])) [ *pretmp.21_82 S4
A32]))# {*movsi_1} (expr_list:REG_EQUIV (mem/s/f:SI (plus:SI (mult:SI (reg/v:SI
0 ax [orig:80 i ] [80])
                     (const_int 4 [0x4]))
-                (reg/f:SI 3 bx [orig:95 pretmp.21 ] [95])) [ *pretmp.21_81 S4
A32])
+                (reg/f:SI 3 bx [orig:95 pretmp.21 ] [95])) [ *pretmp.21_82 S4
A32])
         (nil)))
 (insn:TI# 0 0 t.c:78 (set (mem/s/f:SI (plus:SI (plus:SI (mult:SI (reg/v:SI 0
ax [orig:80 i ] [80])
                         (const_int 4 [0x4]))


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44832