gcc-patches-ow...@gcc.gnu.org wrote on 27/03/2011 03:40:44 PM: > > Hi, > > the attached testcase exhibits a corruption of the SSA form: > > t.c: In function 'foo': > t.c:9:10: error: definition in block 2 follows the use > for SSA_NAME: vect_p.7_12 in statement: > # VUSE <.MEM_6(D)> > vect_var_.8_13 = MEM[(struct R *)vect_p.7_12]; > t.c:9:10: internal compiler error: verify_ssa failed > Please submit a full bug report, > with preprocessed source if appropriate. > See <http://gcc.gnu.org/bugs.html> for instructions. > > introduced by SLP on x86-64 at -O2 -ftree-vectorize -fno-vect-cost-model. > > This is a wrong statement rewriting in vectorizable_load. Before SLP we have: > > D.2687_1 = arg.d2; > D.2688_2 = arg.d1; > D.2689_3 = 0.0 - D.2688_2; > D.2690_4 = D.2687_1 * D.2689_3; > D.2692.d1 = D.2690_4; > > vect_check_interleaving computes that field d1 is accessed before field d2 > because the structure is defined as > > struct R { > double d1; > double d2; > }; > > but it's the opposite in the code. So, in vectorizable_load, > first_stmt is the > load of d1 and new statements are wrongly inserted _after_ the load of d2. > Note that, on release branches (4.5 and 4.6 at least), you get wrong code. > > Proposed fix attached. It adds a GSI parameter to vect_create_data_ref_ptr. > Tested on {i586,x86_64}-suse-linux, OK for the mainline?
> Index: tree-vect-data-refs.c > =================================================================== > --- tree-vect-data-refs.c (revision 171572) > +++ tree-vect-data-refs.c (working copy) > @@ -2922,9 +2922,10 @@ vect_create_addr_base_for_vector_ref (gi > 2. AT_LOOP: the loop where the vector memref is to be created. > 3. OFFSET (optional): an offset to be added to the initial address accessed > by the data-ref in STMT. > - 4. ONLY_INIT: indicate if vp is to be updated in the loop, or remain > + 4. BSI: location where the new stmts are to be placed if there is no loop GSI? > + 5. ONLY_INIT: indicate if vp is to be updated in the loop, or remain > pointing to the initial address. > - 5. TYPE: if not NULL indicates the required type of the data-ref. > + 6. TYPE: if not NULL indicates the required type of the data-ref. > > Output: > 1. Declare a new ptr to vector_type, and have it point to the base of the OK for the mainline otherwise. Thanks, Ira > And the branches? > > > 2011-03-27 Eric Botcazou <ebotca...@adacore.com> > > * tree-vectorizer.h (vect_create_data_ref_ptr): Adjust prototype. > * tree-vect-data-refs.c (vect_create_data_ref_ptr): Add GSI parameter. > Insert new statements at it in lieu of STMT. > (vect_setup_realignment): Adjust call to vect_create_data_ref_ptr. > * tree-vect-stmts.c (vectorizable_store): Likewise. > (vectorizable_load): Likewise. > > > 2011-03-27 Eric Botcazou <ebotca...@adacore.com> > > * gcc.dg/slp-1.c: New test. > > > -- > Eric Botcazou > [attachment "p.diff" deleted by Ira Rosen/Haifa/IBM] [attachment > "t.c" deleted by Ira Rosen/Haifa/IBM]
