Add a vect_element_align_preferred target selector

This patch adds a target selector for targets whose
preferred_vector_alignment is the alignment of one element.  We'll never
peel in that case, and the step of a loop that operates on normal (as
opposed to packed) elements will always divide the preferred alignment.

2017-11-09  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* doc/sourcebuild.texi (vect_element_align_preferred): Document.

gcc/testsuite/
	* lib/target-supports.exp
	(check_effective_target_vect_element_align_preferred): New proc.
	(check_effective_target_vect_peeling_profitable): Test it.
	* gcc.dg/vect/no-section-anchors-vect-31.c: Don't expect peeling
	if vect_element_align_preferred.
	* gcc.dg/vect/no-section-anchors-vect-64.c: Likewise.
	* gcc.dg/vect/pr65310.c: Likewise.
	* gcc.dg/vect/vect-26.c: Likewise.
	* gcc.dg/vect/vect-54.c: Likewise.
	* gcc.dg/vect/vect-56.c: Likewise.
	* gcc.dg/vect/vect-58.c: Likewise.
	* gcc.dg/vect/vect-60.c: Likewise.
	* gcc.dg/vect/vect-89-big-array.c: Likewise.
	* gcc.dg/vect/vect-89.c: Likewise.
	* gcc.dg/vect/vect-92.c: Likewise.
	* gcc.dg/vect/vect-peel-1.c: Likewise.
	* gcc.dg/vect/vect-outer-3a-big-array.c: Expect the step to
	divide the alignment if vect_element_align_preferred.
	* gcc.dg/vect/vect-outer-3a.c: Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r254593

gcc/ChangeLog

@@ -2,6 +2,12 @@
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 
+	* doc/sourcebuild.texi (vect_element_align_preferred): Document.
+
+2017-11-09  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
 	* doc/sourcebuild.texi (vect_perm_short, vect_perm_byte): Document
 	previously undocumented selectors.
 	(vect_perm3_byte, vect_perm3_short, vect_perm3_int): Document.

gcc/doc/sourcebuild.texi

@@ -1383,6 +1383,10 @@ have different type from the value operands.
 @item vect_double
 Target supports hardware vectors of @code{double}.
 
+@item vect_element_align_preferred
+The target's preferred vector alignment is the same as the element
+alignment.
+
 @item vect_float
 Target supports hardware vectors of @code{float}.
 

gcc/testsuite/ChangeLog

@@ -2,6 +2,30 @@
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 
+	* lib/target-supports.exp
+	(check_effective_target_vect_element_align_preferred): New proc.
+	(check_effective_target_vect_peeling_profitable): Test it.
+	* gcc.dg/vect/no-section-anchors-vect-31.c: Don't expect peeling
+	if vect_element_align_preferred.
+	* gcc.dg/vect/no-section-anchors-vect-64.c: Likewise.
+	* gcc.dg/vect/pr65310.c: Likewise.
+	* gcc.dg/vect/vect-26.c: Likewise.
+	* gcc.dg/vect/vect-54.c: Likewise.
+	* gcc.dg/vect/vect-56.c: Likewise.
+	* gcc.dg/vect/vect-58.c: Likewise.
+	* gcc.dg/vect/vect-60.c: Likewise.
+	* gcc.dg/vect/vect-89-big-array.c: Likewise.
+	* gcc.dg/vect/vect-89.c: Likewise.
+	* gcc.dg/vect/vect-92.c: Likewise.
+	* gcc.dg/vect/vect-peel-1.c: Likewise.
+	* gcc.dg/vect/vect-outer-3a-big-array.c: Expect the step to
+	divide the alignment if vect_element_align_preferred.
+	* gcc.dg/vect/vect-outer-3a.c: Likewise.
+
+2017-11-09  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
 	* lib/target-supports.exp (vect_perm_supported): New proc.
 	(check_effective_target_vect_perm3_int): Likewise.
 	(check_effective_target_vect_perm3_short): Likewise.

gcc/testsuite/gcc.dg/vect/no-section-anchors-vect-31.c

@@ -94,4 +94,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 4 loops" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 2 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 2 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/no-section-anchors-vect-64.c

@@ -91,4 +91,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 3 loops" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 2 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 2 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/pr65310.c

@@ -18,5 +18,5 @@ int t(b *a)
 /* The memory access is through a pointer of type c which means
    *ptr is not aligned.  */
 
-/* { dg-final { scan-tree-dump "can't force alignment" "vect" } } */
-/* { dg-final { scan-tree-dump-not "misalign = 0" "vect" } } */
+/* { dg-final { scan-tree-dump "can't force alignment" "vect" { xfail vect_element_align_preferred } } } */
+/* { dg-final { scan-tree-dump-not "misalign = 0" "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-26.c

@@ -37,4 +37,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-54.c

@@ -61,4 +61,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-56.c

@@ -70,5 +70,5 @@ int main (void)
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" { xfail { vect_no_align && { ! vect_hw_misalign } } } } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 2 "vect" { xfail { vect_no_align || vect_element_align } } } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 1 "vect" { target { vect_element_align } } } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 0 "vect" { xfail { vect_element_align } } } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { target { vect_element_align } } } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 0 "vect" { target { { ! vect_element_align } || vect_element_align_preferred} } } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { target { vect_element_align && { ! vect_element_align_preferred } } } } } */

gcc/testsuite/gcc.dg/vect/vect-58.c

@@ -59,4 +59,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-60.c

@@ -71,5 +71,5 @@ int main (void)
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" { xfail { vect_no_align && { ! vect_hw_misalign } } } } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 2 "vect" { xfail { vect_no_align || vect_element_align } } } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 1 "vect" { target { vect_element_align } } } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 0 "vect" { xfail { vect_element_align } } } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { target { vect_element_align } } } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 0 "vect" { target { { ! vect_element_align } || vect_element_align_preferred } } } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { target { vect_element_align && { ! vect_element_align_preferred } } } } } */

gcc/testsuite/gcc.dg/vect/vect-89-big-array.c

@@ -46,4 +46,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-89.c

@@ -50,4 +50,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-92.c

@@ -98,4 +98,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 3 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 0 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 3 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 3 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-outer-3a-big-array.c

@@ -49,4 +49,4 @@ int main (void)
 }
 
 /* { dg-final { scan-tree-dump-times "OUTER LOOP VECTORIZED" 1 "vect" { xfail { vect_no_align && { ! vect_hw_misalign } } } } } */
-/* { dg-final { scan-tree-dump-times "step doesn't divide the vector alignment" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "step doesn't divide the vector alignment" 1 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-outer-3a.c

@@ -49,4 +49,4 @@ int main (void)
 }
 
 /* { dg-final { scan-tree-dump-times "OUTER LOOP VECTORIZED" 1 "vect" { xfail { vect_no_align && { ! vect_hw_misalign } } } } } */
-/* { dg-final { scan-tree-dump-times "step doesn't divide the vector alignment" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "step doesn't divide the vector alignment" 1 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/gcc.dg/vect/vect-peel-1.c

@@ -49,4 +49,4 @@ int main (void)
 
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Vectorizing an unaligned access" 1 "vect" { target { { vect_element_align } && { vect_aligned_arrays } } } } } */
-/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Alignment of access forced using peeling" 1 "vect" { xfail vect_element_align_preferred } } } */

gcc/testsuite/lib/target-supports.exp

@@ -3290,7 +3290,8 @@ proc check_effective_target_vect_peeling_profitable { } {
     } else {
 	set et_vect_peeling_profitable_saved($et_index) 1
         if { ([istarget s390*-*-*]
-	      && [check_effective_target_s390_vx]) } {
+	      && [check_effective_target_s390_vx])
+	     || [check_effective_target_vect_element_align_preferred] } {
 	    set et_vect_peeling_profitable_saved($et_index) 0
         }
     }
@@ -6342,6 +6343,13 @@ proc check_effective_target_vect_natural_alignment { } {
     return $et_vect_natural_alignment
 }
 
+# Return 1 if the target doesn't prefer any alignment beyond element
+# alignment during vectorization.
+
+proc check_effective_target_vect_element_align_preferred { } {
+    return [check_effective_target_vect_variable_length]
+}
+
 # Return 1 if vector alignment (for types of size 32 bit or less) is reachable, 0 otherwise.
 
 proc check_effective_target_vector_alignment_reachable { } {