------- Additional Comments From dorit at il dot ibm dot com 2005-08-28 13:47
-------
The patch below fixes the problem.
We fail on this assert:
gcc_assert (evolution_part != NULL_TREE);
in 'vect_update_ivs_after_vectorizer'.
This happens because we assume that 'vect_update_ivs_after_vectorizer' is
called only if 'vect_can_advance_ivs_p' passes
successfully. 'vect_can_advance_ivs_p' is supposed to be called during the
analysis phase if we suspect that loop peeling will be required. Currently we
only call it when we discover that peeling-for-loop-bound will be required, but
we should also call it if peeling-for-alignment is required (cause usually it
also involves peeling-for-loop-bound). The patch below adds the missing check.
This bit is actually included in Keith's versioning-for-alignment patch
(http://gcc.gnu.org/ml/gcc-patches/2005-08/msg01372.html), which hopefully is
going to be approved soon (I'd rather wait for that, than create a conflict for
Keith's patch).
Even when this ICE is solved, this is not the end of the story, because this
loop should get vectorized, and we are going to fail because of an invariant
phi (phi with evolution NULL, that we don't know how to handle). This goes back
to http://gcc.gnu.org/ml/gcc-patches/2005-08/msg00905.html. Hopefully
Ira/Sebastian have a solution to resolve this.
Below is the loop from the testcase;
This:
D.2219_59 = PHI <D.2248_8(3), D.2248_8(1)>
is the invariant phi:
# BLOCK 2 freq:10000
# PRED: 3 [100.0%] (fallthru,exec) 1 [100.0%] (fallthru,exec)
# ivtmp.36D.2301_17 = PHI <ivtmp.36D.2301_18(3), 32(1)>;
# TMT.9D.2268_2 = PHI <TMT.9D.2268_27(3), TMT.9D.2268_45(1)>;
# D.2219_59 = PHI <D.2248_8(3), D.2248_8(1)>;
# __iD.2254_58 = PHI <__iD.2254_24(3), 0(1)>;
<L3>:;
# TMT.9D.2268_27 = V_MAY_DEF <TMT.9D.2268_2>;
thisD.2217_6->master_handle_set_D.2206.mask_D.2146.fds_bitsD.2134
[__iD.2254_58] = 0;
__iD.2254_24 = __iD.2254_58 + 1;
ivtmp.36D.2301_18 = ivtmp.36D.2301_17 - 1;
if (ivtmp.36D.2301_18 != 0) goto <L11>; else goto <L12>;
# SUCC: 3 [96.9%] (dfs_back,true,exec) 4 [3.1%]
(dfs_back,loop_exit,false,exec)
# BLOCK 3 freq:9687
# PRED: 2 [96.9%] (dfs_back,true,exec)
<L11>:;
goto <bb 2> (<L3>);
# SUCC: 2 [100.0%] (fallthru,exec)
Patch:
Index: tree-vect-analyze.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-vect-analyze.c,v
retrieving revision 2.35
diff -c -3 -p -r2.35 tree-vect-analyze.c
*** tree-vect-analyze.c 13 Aug 2005 17:28:41 -0000 2.35
--- tree-vect-analyze.c 28 Aug 2005 13:26:31 -0000
*************** vect_enhance_data_refs_alignment (loop_v
*** 955,960 ****
--- 955,965 ----
TODO: - consider accesses that are known to have the same
alignment, even if that alignment is unknown. */
+ /* Often peeling for alignment will require peeling for loop-bound, which in
+ turn requires that we know how to adjust the loop ivs after the loop. */
+ if (!vect_can_advance_ivs_p (loop_vinfo))
+ LOOP_PEELING_FOR_ALIGNMENT (loop_vinfo) = 0;
+
if (LOOP_PEELING_FOR_ALIGNMENT (loop_vinfo))
{
int mis;
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |sebastian dot pop at cri dot
| |ensmp dot fr
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23350
