On Tue, Jun 19, 2012 at 11:36 PM, Mikael Pettersson <mi...@it.uu.se> wrote: > Richard Guenther writes: > > On Fri, Jun 15, 2012 at 5:00 PM, Ulrich Weigand <uweig...@de.ibm.com> > wrote: > > > Richard Guenther wrote: > > >> On Fri, Jun 15, 2012 at 3:13 PM, Ulrich Weigand <uweig...@de.ibm.com> > wrote: > > >> > However, there is a second case where we need to check every pass: if > > >> > we're not actually vectorizing any loop, but are performing > basic-block > > >> > SLP. In this case, it would appear that we need the same check as > > >> > described in the comment above, i.e. to verify that the stride is a > > >> > multiple of the vector size. > > >> > > > >> > The patch below adds this check, and this indeed fixes the invalid > access > > >> > I was seeing in the test case (in the final assembler, we now get a > > >> > vld1.16 instead of vldr). > > >> > > > >> > Tested on arm-linux-gnueabi with no regressions. > > >> > > > >> > OK for mainline? > > >> > > >> Ok. > > > > > > Thanks for the quick review; I've checked this in to mainline now. > > > > > > I just noticed that the test case also crashes on 4.7, but not on 4.6. > > > > > > Would a backport to 4.7 also be OK, once testing passes? > > > > Yes. Please leave it on mainline a few days to catch fallout from > > autotesters. > > This patch caused > > FAIL: gcc.dg/vect/bb-slp-16.c scan-tree-dump-times slp "basic block > vectorized using SLP" 1 > > on sparc64-linux. Comparing the pre and post patch dumps for that file shows > > 22: vect_compute_data_ref_alignment: > 22: misalign = 4 bytes of ref MEM[(unsigned int *)pout_90 + 28B] > 22: vect_compute_data_ref_alignment: > -22: force alignment of arr[i_87] > -22: misalign = 0 bytes of ref arr[i_87] > +22: SLP: step doesn't divide the vector-size. > +22: Unknown alignment for access: arr > > (lots of stuff that's simply gone) > > -22: BASIC BLOCK VECTORIZED > - > -22: basic block vectorized using SLP > +22: not vectorized: unsupported unaligned store.arr[i_87] > +22: not vectorized: unsupported alignment in basic block.
In this testcase the alignment of arr[i] should be irrelevant - it is not part of the stmts that are going to be vectorized. But of course this may be simply an odering issue in how we analyze data-references / statements in basic-block vectorization (thus we possibly did not yet declare the arr[i] = i statement as not taking part in the vectorization). The line > -22: force alignment of arr[i_87] is odd, too - as said we do not need to touch arr when vectorizing the basic-block. Ulrich, can you look into this or do you want me to take a look here? Mikael - please open a bugreport for this. Thanks, Richard. > /Mikael
