The PR53636 fix 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. The same new FAIL also appears on powerpc64-linux.
The problem is that SLP tests *all* accesses within the basic block for alignment, even those that aren't actually part of a SLP instance. This is of course broken, but that bug had been hidden by the PR53636 problem (due to which accesses were considered aligned that actually are not). The fix for this problem is to only check *relevant* accesses for alignment. (This requires moving the alignment check until after relevant statements are actually marked ...) I'm testing a fix.
Author: uweigand Date: Tue Jun 26 09:05:48 2012 New Revision: 188979 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=188979 Log: PR tree-optimization/53729 PR tree-optimization/53636 * tree-vect-slp.c (vect_slp_analyze_bb_1): Delay call to vect_verify_datarefs_alignment until after statements have been marked as relevant/irrelevant. * tree-vect-data-refs.c (vect_verify_datarefs_alignment): Skip irrelevant statements. (vect_enhance_data_refs_alignment): Use STMT_VINFO_RELEVANT_P instead of STMT_VINFO_RELEVANT. (vect_get_data_access_cost): Do not check for supportable alignment before calling vect_get_load_cost/vect_get_store_cost. * tree-vect-stmts.c (vect_get_store_cost): Do not abort when handling unsupported alignment. (vect_get_load_cost): Likewise. Modified: trunk/gcc/ChangeLog trunk/gcc/tree-vect-data-refs.c trunk/gcc/tree-vect-slp.c trunk/gcc/tree-vect-stmts.c
Fixed.