From: Richard Biener <rguenther@suse.de>
Date: Thu, 29 Apr 2021 09:52:08 +0000 (+0200)
Subject: tree-optimization/100253 - fix bogus aligned vectorized loads/stores
X-Git-Tag: releases/gcc-11.2.0~449
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c980fbf5505dc2f50136d501b67dc3fbf4b08b0d;p=thirdparty%2Fgcc.git

tree-optimization/100253 - fix bogus aligned vectorized loads/stores

At some point DR_MISALIGNMENT was supposed to be -1 when the
access was not element aligned.  That's obviously not true at this
point so this adjusts both store and load vectorizing to no longer
assume this which in turn allows simplifying the code.

2021-04-29  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/100253
	* tree-vect-stmts.c (vectorizable_load): Do not assume
	element alignment when DR_MISALIGNMENT is -1.
	(vectorizable_store): Likewise.

	* g++.dg/pr100253.C: New testcase.

(cherry picked from commit af4ccaa7515b8e72449448c509916575831e6292)
---

diff --git a/gcc/testsuite/g++.dg/pr100253.C b/gcc/testsuite/g++.dg/pr100253.C
new file mode 100644
index 000000000000..0102caa7df86
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr100253.C
@@ -0,0 +1,33 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-tree-bit-ccp -ftree-slp-vectorize" } */
+
+#include <vector>
+
+struct T
+{
+};
+
+struct S
+{
+  std::vector < std::vector < T > > v;
+  char x;
+  char y[16];
+  char z[16];
+};
+
+S s, g[1];
+
+void
+foo (char *buf)
+{
+  s = g[*buf];
+}
+
+char c;
+
+int
+main ()
+{
+  foo (&c);
+  return 0;
+}
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 4c01e82ff394..bd2a1c89e670 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -8166,6 +8166,7 @@ vectorizable_store (vec_info *vinfo,
 		  && TREE_CODE (dataref_ptr) == SSA_NAME)
 		set_ptr_info_alignment (get_ptr_info (dataref_ptr), align,
 					misalign);
+	      align = least_bit_hwi (misalign | align);
 
 	      if (memory_access_type == VMAT_CONTIGUOUS_REVERSE)
 		{
@@ -8187,7 +8188,6 @@ vectorizable_store (vec_info *vinfo,
 	      /* Arguments are ready.  Create the new vector stmt.  */
 	      if (final_mask)
 		{
-		  align = least_bit_hwi (misalign | align);
 		  tree ptr = build_int_cst (ref_type, align * BITS_PER_UNIT);
 		  gcall *call
 		    = gimple_build_call_internal (IFN_MASK_STORE, 4,
@@ -8202,7 +8202,6 @@ vectorizable_store (vec_info *vinfo,
 		  tree final_len
 		    = vect_get_loop_len (loop_vinfo, loop_lens,
 					 vec_num * ncopies, vec_num * j + i);
-		  align = least_bit_hwi (misalign | align);
 		  tree ptr = build_int_cst (ref_type, align * BITS_PER_UNIT);
 		  machine_mode vmode = TYPE_MODE (vectype);
 		  opt_machine_mode new_ovmode
@@ -8241,14 +8240,10 @@ vectorizable_store (vec_info *vinfo,
 					  : build_int_cst (ref_type, 0));
 		  if (aligned_access_p (first_dr_info))
 		    ;
-		  else if (DR_MISALIGNMENT (first_dr_info) == -1)
-		    TREE_TYPE (data_ref)
-		      = build_aligned_type (TREE_TYPE (data_ref),
-					    align * BITS_PER_UNIT);
 		  else
 		    TREE_TYPE (data_ref)
 		      = build_aligned_type (TREE_TYPE (data_ref),
-					    TYPE_ALIGN (elem_type));
+					    align * BITS_PER_UNIT);
 		  vect_copy_ref_info (data_ref, DR_REF (first_dr_info->dr));
 		  new_stmt = gimple_build_assign (data_ref, vec_oprnd);
 		  vect_finish_stmt_generation (vinfo, stmt_info, new_stmt, gsi);
@@ -9452,10 +9447,10 @@ vectorizable_load (vec_info *vinfo,
 			&& TREE_CODE (dataref_ptr) == SSA_NAME)
 		      set_ptr_info_alignment (get_ptr_info (dataref_ptr),
 					      align, misalign);
+		    align = least_bit_hwi (misalign | align);
 
 		    if (final_mask)
 		      {
-			align = least_bit_hwi (misalign | align);
 			tree ptr = build_int_cst (ref_type,
 						  align * BITS_PER_UNIT);
 			gcall *call
@@ -9472,7 +9467,6 @@ vectorizable_load (vec_info *vinfo,
 			  = vect_get_loop_len (loop_vinfo, loop_lens,
 					       vec_num * ncopies,
 					       vec_num * j + i);
-			align = least_bit_hwi (misalign | align);
 			tree ptr = build_int_cst (ref_type,
 						  align * BITS_PER_UNIT);
 			gcall *call
@@ -9548,14 +9542,10 @@ vectorizable_load (vec_info *vinfo,
 			  = fold_build2 (MEM_REF, ltype, dataref_ptr, offset);
 			if (alignment_support_scheme == dr_aligned)
 			  ;
-			else if (DR_MISALIGNMENT (first_dr_info) == -1)
-			  TREE_TYPE (data_ref)
-			    = build_aligned_type (TREE_TYPE (data_ref),
-						  align * BITS_PER_UNIT);
 			else
 			  TREE_TYPE (data_ref)
 			    = build_aligned_type (TREE_TYPE (data_ref),
-						  TYPE_ALIGN (elem_type));
+						  align * BITS_PER_UNIT);
 			if (ltype != vectype)
 			  {
 			    vect_copy_ref_info (data_ref,