RE: [PATCH] ICE: in vectorizable_load, at tree-vect-stmts.c:9173

[Yangfei (Felix)]

Hi!
> -----Original Message-----
> From: Yangfei (Felix)
> Sent: Monday, March 30, 2020 5:28 PM
> To: gcc-patches@gcc.gnu.org
> Cc: 'rguent...@suse.de' <rguent...@suse.de>
> Subject: [PATCH] ICE: in vectorizable_load, at tree-vect-stmts.c:9173
> 
> Hi,
> 
> New bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94398
> 
> With -mstrict-align, aarch64_builtin_support_vector_misalignment will returns
> false when misalignment factor is unknown at compile time.
> Then vect_supportable_dr_alignment returns dr_unaligned_unsupported,
> which triggers the ICE.  I have pasted the call trace on the bug report.
> 
> vect_supportable_dr_alignment is expected to return either dr_aligned or
> dr_unaligned_supported for masked operations.
> But it seems that this function only catches internal_fn IFN_MASK_LOAD &
> IFN_MASK_STORE.
> We are emitting a mask gather load here for this test case.
> As backends have their own vector misalignment support policy, I am supposing
> this should be better handled in the auto-vect shared code.
> 

I can only reply to comment on the bug here as my account got locked by the 
bugzilla system for now. 
The way Richard (rsandifo) suggests also works for me and I agree it should be 
more consistent and better for compile time. 
One question here: when will a IFN_MASK_LOAD/IFN_MASK_STORE be passed to 
vect_supportable_dr_alignment? 

New patch:
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 12beef6..2825023 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -8051,8 +8051,15 @@ vectorizable_store (stmt_vec_info stmt_info, 
gimple_stmt_iterator *gsi,
   auto_vec<tree> dr_chain (group_size);
   oprnds.create (group_size);

-  alignment_support_scheme
-    = vect_supportable_dr_alignment (first_dr_info, false);
+  /* Strided accesses perform only component accesses, alignment
+     is irrelevant for them.  */
+  if (STMT_VINFO_STRIDED_P (first_dr_info->stmt)
+      && !STMT_VINFO_GROUPED_ACCESS (first_dr_info->stmt))
+    alignment_support_scheme = dr_unaligned_supported;
+  else
+    alignment_support_scheme
+      = vect_supportable_dr_alignment (first_dr_info, false);
+
   gcc_assert (alignment_support_scheme);
   vec_loop_masks *loop_masks
     = (loop_vinfo && LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)
@@ -9168,8 +9175,15 @@ vectorizable_load (stmt_vec_info stmt_info, 
gimple_stmt_iterator *gsi,
       ref_type = reference_alias_ptr_type (DR_REF (first_dr_info->dr));
     }

-  alignment_support_scheme
-    = vect_supportable_dr_alignment (first_dr_info, false);
+  /* Strided accesses perform only component accesses, alignment
+     is irrelevant for them.  */
+  if (STMT_VINFO_STRIDED_P (first_dr_info->stmt)
+      && !STMT_VINFO_GROUPED_ACCESS (first_dr_info->stmt))
+    alignment_support_scheme = dr_unaligned_supported;
+  else
+    alignment_support_scheme
+      = vect_supportable_dr_alignment (first_dr_info, false);
+
   gcc_assert (alignment_support_scheme);
   vec_loop_masks *loop_masks
     = (loop_vinfo && LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)