re PR tree-optimization/51581 (Integer division by constant is not vectorized)

	PR tree-optimization/51581
	* expr.h (choose_multiplier): New prototype.
	* expmed.c (choose_multiplier): No longer static.
	Change multiplier_ptr from rtx * to UHWI *.
	(expand_divmod): Adjust callers.
	* tree-vect-patterns.c (vect_recog_sdivmod_pow2_pattern):
	Renamed to...
	(vect_recog_divmod_pattern): ... this.  Pass bb_vinfo as last
	argument to new_stmt_vec_info.  Attempt to optimize also divisions
	by non-pow2 constants if integer vector division isn't supported.
	* tree-vect-stmts.c (vect_analyze_stmt): If node != NULL,
	don't look at pattern stmts and sequences.

	* gcc.c-torture/execute/pr51581-1.c: New test.
	* gcc.c-torture/execute/pr51581-2.c: New test.
	* gcc.dg/vect/pr51581-1.c: New test.
	* gcc.dg/vect/pr51581-2.c: New test.
	* gcc.dg/vect/pr51581-3.c: New test.
	* gcc.target/i386/avx-pr51581-1.c: New test.
	* gcc.target/i386/avx-pr51581-2.c: New test.
	* gcc.target/i386/avx2-pr51581-1.c: New test.
	* gcc.target/i386/avx2-pr51581-2.c: New test.
	* gcc.dg/vect/slp-26.c (main1): Divide by 0x8031 instead of 3.

From-SVN: r188656

gcc/ChangeLog

+2012-06-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/51581
+	* expr.h (choose_multiplier): New prototype.
+	* expmed.c (choose_multiplier): No longer static.
+	Change multiplier_ptr from rtx * to UHWI *.
+	(expand_divmod): Adjust callers.
+	* tree-vect-patterns.c (vect_recog_sdivmod_pow2_pattern):
+	Renamed to...
+	(vect_recog_divmod_pattern): ... this.  Pass bb_vinfo as last
+	argument to new_stmt_vec_info.  Attempt to optimize also divisions
+	by non-pow2 constants if integer vector division isn't supported.
+	* tree-vect-stmts.c (vect_analyze_stmt): If node != NULL,
+	don't look at pattern stmts and sequences.
+
 2012-06-15  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR middle-end/53590

gcc/expmed.c

@@ -2363,8 +2363,6 @@ static bool choose_mult_variant (enum machine_mode, HOST_WIDE_INT,
 				 struct algorithm *, enum mult_variant *, int);
 static rtx expand_mult_const (enum machine_mode, rtx, HOST_WIDE_INT, rtx,
 			      const struct algorithm *, enum mult_variant);
-static unsigned HOST_WIDE_INT choose_multiplier (unsigned HOST_WIDE_INT, int,
-						 int, rtx *, int *, int *);
 static unsigned HOST_WIDE_INT invert_mod2n (unsigned HOST_WIDE_INT, int);
 static rtx extract_high_half (enum machine_mode, rtx);
 static rtx expand_mult_highpart (enum machine_mode, rtx, rtx, rtx, int, int);
@@ -3293,10 +3291,10 @@ ceil_log2 (unsigned HOST_WIDE_INT x)
    Using this function, x/D will be equal to (x * m) >> (*POST_SHIFT_PTR),
    where m is the full HOST_BITS_PER_WIDE_INT + 1 bit multiplier.  */
 
-static
 unsigned HOST_WIDE_INT
 choose_multiplier (unsigned HOST_WIDE_INT d, int n, int precision,
-		   rtx *multiplier_ptr, int *post_shift_ptr, int *lgup_ptr)
+		   unsigned HOST_WIDE_INT *multiplier_ptr,
+		   int *post_shift_ptr, int *lgup_ptr)
 {
   HOST_WIDE_INT mhigh_hi, mlow_hi;
   unsigned HOST_WIDE_INT mhigh_lo, mlow_lo;
@@ -3368,12 +3366,12 @@ choose_multiplier (unsigned HOST_WIDE_INT d, int n, int precision,
   if (n < HOST_BITS_PER_WIDE_INT)
     {
       unsigned HOST_WIDE_INT mask = ((unsigned HOST_WIDE_INT) 1 << n) - 1;
-      *multiplier_ptr = GEN_INT (mhigh_lo & mask);
+      *multiplier_ptr = mhigh_lo & mask;
       return mhigh_lo >= mask;
     }
   else
     {
-      *multiplier_ptr = GEN_INT (mhigh_lo);
+      *multiplier_ptr = mhigh_lo;
       return mhigh_hi;
     }
 }
@@ -4053,10 +4051,9 @@ expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
 	  {
 	    if (unsignedp)
 	      {
-		unsigned HOST_WIDE_INT mh;
+		unsigned HOST_WIDE_INT mh, ml;
 		int pre_shift, post_shift;
 		int dummy;
-		rtx ml;
 		unsigned HOST_WIDE_INT d = (INTVAL (op1)
 					    & GET_MODE_MASK (compute_mode));
 
@@ -4118,7 +4115,8 @@ expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
 			      = (shift_cost[speed][compute_mode][post_shift - 1]
 				 + shift_cost[speed][compute_mode][1]
 				 + 2 * add_cost[speed][compute_mode]);
-			    t1 = expand_mult_highpart (compute_mode, op0, ml,
+			    t1 = expand_mult_highpart (compute_mode, op0,
+						       GEN_INT (ml),
 						       NULL_RTX, 1,
 						       max_cost - extra_cost);
 			    if (t1 == 0)
@@ -4149,7 +4147,8 @@ expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
 			    extra_cost
 			      = (shift_cost[speed][compute_mode][pre_shift]
 				 + shift_cost[speed][compute_mode][post_shift]);
-			    t2 = expand_mult_highpart (compute_mode, t1, ml,
+			    t2 = expand_mult_highpart (compute_mode, t1,
+						       GEN_INT (ml),
 						       NULL_RTX, 1,
 						       max_cost - extra_cost);
 			    if (t2 == 0)
@@ -4262,8 +4261,7 @@ expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
 		else if (size <= HOST_BITS_PER_WIDE_INT)
 		  {
 		    choose_multiplier (abs_d, size, size - 1,
-				       &mlr, &post_shift, &lgup);
-		    ml = (unsigned HOST_WIDE_INT) INTVAL (mlr);
+				       &ml, &post_shift, &lgup);
 		    if (ml < (unsigned HOST_WIDE_INT) 1 << (size - 1))
 		      {
 			rtx t1, t2, t3;
@@ -4275,8 +4273,8 @@ expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
 			extra_cost = (shift_cost[speed][compute_mode][post_shift]
 				      + shift_cost[speed][compute_mode][size - 1]
 				      + add_cost[speed][compute_mode]);
-			t1 = expand_mult_highpart (compute_mode, op0, mlr,
-						   NULL_RTX, 0,
+			t1 = expand_mult_highpart (compute_mode, op0,
+						   GEN_INT (ml), NULL_RTX, 0,
 						   max_cost - extra_cost);
 			if (t1 == 0)
 			  goto fail1;
@@ -4356,10 +4354,9 @@ expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
       /* We will come here only for signed operations.  */
 	if (op1_is_constant && HOST_BITS_PER_WIDE_INT >= size)
 	  {
-	    unsigned HOST_WIDE_INT mh;
+	    unsigned HOST_WIDE_INT mh, ml;
 	    int pre_shift, lgup, post_shift;
 	    HOST_WIDE_INT d = INTVAL (op1);
-	    rtx ml;
 
 	    if (d > 0)
 	      {
@@ -4399,8 +4396,8 @@ expand_divmod (int rem_flag, enum tree_code code, enum machine_mode mode,
 			extra_cost = (shift_cost[speed][compute_mode][post_shift]
 				      + shift_cost[speed][compute_mode][size - 1]
 				      + 2 * add_cost[speed][compute_mode]);
-			t3 = expand_mult_highpart (compute_mode, t2, ml,
-						   NULL_RTX, 1,
+			t3 = expand_mult_highpart (compute_mode, t2,
+						   GEN_INT (ml), NULL_RTX, 1,
 						   max_cost - extra_cost);
 			if (t3 != 0)
 			  {

gcc/expr.h

@@ -243,6 +243,13 @@ extern rtx emit_store_flag (rtx, enum rtx_code, rtx, rtx, enum machine_mode,
 /* Like emit_store_flag, but always succeeds.  */
 extern rtx emit_store_flag_force (rtx, enum rtx_code, rtx, rtx,
 				  enum machine_mode, int, int);
+
+/* Choose a minimal N + 1 bit approximation to 1/D that can be used to
+   replace division by D, and put the least significant N bits of the result
+   in *MULTIPLIER_PTR and return the most significant bit.  */
+extern unsigned HOST_WIDE_INT choose_multiplier (unsigned HOST_WIDE_INT, int,
+						 int, unsigned HOST_WIDE_INT *,
+						 int *, int *);
 
 /* Functions from builtins.c:  */
 extern rtx expand_builtin (tree, rtx, rtx, enum machine_mode, int);

gcc/testsuite/ChangeLog

+2012-06-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/51581
+	* gcc.c-torture/execute/pr51581-1.c: New test.
+	* gcc.c-torture/execute/pr51581-2.c: New test.
+	* gcc.dg/vect/pr51581-1.c: New test.
+	* gcc.dg/vect/pr51581-2.c: New test.
+	* gcc.dg/vect/pr51581-3.c: New test.
+	* gcc.target/i386/avx-pr51581-1.c: New test.
+	* gcc.target/i386/avx-pr51581-2.c: New test.
+	* gcc.target/i386/avx2-pr51581-1.c: New test.
+	* gcc.target/i386/avx2-pr51581-2.c: New test.
+	* gcc.dg/vect/slp-26.c (main1): Divide by 0x8031 instead of 3.
+
 2012-06-15  Richard Guenther  <rguenther@suse.de>
 
 	* gcc.c-torture/execute/20120615-1.c: New testcase.

gcc/testsuite/gcc.c-torture/execute/pr51581-1.c

+/* PR tree-optimization/51581 */
+
+extern void abort (void);
+
+#define N 4096
+int a[N], c[N];
+unsigned int b[N], d[N];
+
+__attribute__((noinline, noclone)) void
+f1 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = a[i] / 3;
+}
+
+__attribute__((noinline, noclone)) void
+f2 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    d[i] = b[i] / 3;
+}
+
+__attribute__((noinline, noclone)) void
+f3 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = a[i] / 18;
+}
+
+__attribute__((noinline, noclone)) void
+f4 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    d[i] = b[i] / 18;
+}
+
+__attribute__((noinline, noclone)) void
+f5 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = a[i] / 19;
+}
+
+__attribute__((noinline, noclone)) void
+f6 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    d[i] = b[i] / 19;
+}
+
+#if __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
+__attribute__((noinline, noclone)) void
+f7 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = (int) ((unsigned long long) (a[i] * 0x55555556LL) >> 32) - (a[i] >> 31);
+}
+
+__attribute__((noinline, noclone)) void
+f8 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    d[i] = ((unsigned int) ((b[i] * 0xaaaaaaabULL) >> 32) >> 1);
+}
+
+__attribute__((noinline, noclone)) void
+f9 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = (((int) ((unsigned long long) (a[i] * 0x38e38e39LL) >> 32)) >> 2) - (a[i] >> 31);
+}
+
+__attribute__((noinline, noclone)) void
+f10 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    d[i] = (unsigned int) ((b[i] * 0x38e38e39ULL) >> 32) >> 2;
+}
+
+__attribute__((noinline, noclone)) void
+f11 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = (((int) ((unsigned long long) (a[i] * 0x6bca1af3LL) >> 32)) >> 3) - (a[i] >> 31);
+}
+
+__attribute__((noinline, noclone)) void
+f12 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      unsigned int tmp = (b[i] * 0xaf286bcbULL) >> 32;
+      d[i] = (((b[i] - tmp) >> 1) + tmp) >> 4;
+    }
+}
+#endif
+
+int
+main ()
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      asm ("");
+      a[i] = i - N / 2;
+      b[i] = i;
+    }
+  a[0] = -__INT_MAX__ - 1;
+  a[1] = -__INT_MAX__;
+  a[N - 1] = __INT_MAX__;
+  b[N - 1] = ~0;
+  f1 ();
+  f2 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] / 3 || d[i] != b[i] / 3)
+      abort ();
+  f3 ();
+  f4 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] / 18 || d[i] != b[i] / 18)
+      abort ();
+  f5 ();
+  f6 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] / 19 || d[i] != b[i] / 19)
+      abort ();
+#if __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
+  f7 ();
+  f8 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] / 3 || d[i] != b[i] / 3)
+      abort ();
+  f9 ();
+  f10 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] / 18 || d[i] != b[i] / 18)
+      abort ();
+  f11 ();
+  f12 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] / 19 || d[i] != b[i] / 19)
+      abort ();
+#endif
+  return 0;
+}

gcc/testsuite/gcc.c-torture/execute/pr51581-2.c

+/* PR tree-optimization/51581 */
+
+extern void abort (void);
+
+#define N 4096
+int a[N], c[N];
+unsigned int b[N], d[N];
+
+__attribute__((noinline, noclone)) void
+f1 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = a[i] % 3;
+}
+
+__attribute__((noinline, noclone)) void
+f2 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    d[i] = b[i] % 3;
+}
+
+__attribute__((noinline, noclone)) void
+f3 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = a[i] % 18;
+}
+
+__attribute__((noinline, noclone)) void
+f4 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    d[i] = b[i] % 18;
+}
+
+__attribute__((noinline, noclone)) void
+f5 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    c[i] = a[i] % 19;
+}
+
+__attribute__((noinline, noclone)) void
+f6 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    d[i] = b[i] % 19;
+}
+
+#if __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
+__attribute__((noinline, noclone)) void
+f7 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      int x = (int) ((unsigned long long) (a[i] * 0x55555556LL) >> 32) - (a[i] >> 31);
+      c[i] = a[i] - x * 3;
+    }
+}
+
+__attribute__((noinline, noclone)) void
+f8 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      unsigned int x = ((unsigned int) ((b[i] * 0xaaaaaaabULL) >> 32) >> 1);
+      d[i] = b[i] - x * 3;
+    }
+}
+
+__attribute__((noinline, noclone)) void
+f9 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      int x = (((int) ((unsigned long long) (a[i] * 0x38e38e39LL) >> 32)) >> 2) - (a[i] >> 31);
+      c[i] = a[i] - x * 18;
+    }
+}
+
+__attribute__((noinline, noclone)) void
+f10 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      unsigned int x = (unsigned int) ((b[i] * 0x38e38e39ULL) >> 32) >> 2;
+      d[i] = b[i] - x * 18;
+    }
+}
+
+__attribute__((noinline, noclone)) void
+f11 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      int x = (((int) ((unsigned long long) (a[i] * 0x6bca1af3LL) >> 32)) >> 3) - (a[i] >> 31);
+      c[i] = a[i] - x * 19;
+    }
+}
+
+__attribute__((noinline, noclone)) void
+f12 (void)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      unsigned int tmp = (b[i] * 0xaf286bcbULL) >> 32;
+      unsigned int x = (((b[i] - tmp) >> 1) + tmp) >> 4;
+      d[i] = b[i] - x * 19;
+    }
+}
+#endif
+
+int
+main ()
+{
+  int i;
+  for (i = 0; i < N; i++)
+    {
+      asm ("");
+      a[i] = i - N / 2;
+      b[i] = i;
+    }
+  a[0] = -__INT_MAX__ - 1;
+  a[1] = -__INT_MAX__;
+  a[N - 1] = __INT_MAX__;
+  b[N - 1] = ~0;
+  f1 ();
+  f2 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] % 3 || d[i] != b[i] % 3)
+      abort ();
+  f3 ();
+  f4 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] % 18 || d[i] != b[i] % 18)
+      abort ();
+  f5 ();
+  f6 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] % 19 || d[i] != b[i] % 19)
+      abort ();
+#if __SIZEOF_INT__ == 4 && __SIZEOF_LONG_LONG__ == 8
+  f7 ();
+  f8 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] % 3 || d[i] != b[i] % 3)
+      abort ();
+  f9 ();
+  f10 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] % 18 || d[i] != b[i] % 18)
+      abort ();
+  f11 ();
+  f12 ();
+  for (i = 0; i < N; i++)
+    if (c[i] != a[i] % 19 || d[i] != b[i] % 19)
+      abort ();
+#endif
+  return 0;
+}

gcc/testsuite/gcc.dg/vect/pr51581-1.c

+/* PR tree-optimization/51581 */
+
+#include "tree-vect.h"
+
+#define main main1
+#include "../../gcc.c-torture/execute/pr51581-1.c"
+#undef main
+
+int
+main ()
+{
+  int i;
+  check_vect ();
+  asm ("");
+  return main1 ();
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */

gcc/testsuite/gcc.dg/vect/pr51581-2.c

+/* PR tree-optimization/51581 */
+
+#include "tree-vect.h"
+
+#define main main1
+#include "../../gcc.c-torture/execute/pr51581-2.c"
+#undef main
+
+int
+main ()
+{
+  int i;
+  check_vect ();
+  asm ("");
+  return main1 ();
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */

gcc/testsuite/gcc.dg/vect/pr51581-3.c

+/* PR tree-optimization/51581 */
+
+#include "tree-vect.h"
+
+int a[8], b[8];
+unsigned int c[8], d[8];
+
+void
+f1 (void)
+{
+  a[0] = b[0] / 8;
+  a[1] = b[1] / 8;
+  a[2] = b[2] / 8;
+  a[3] = b[3] / 8;
+  a[4] = b[4] / 8;
+  a[5] = b[5] / 8;
+  a[6] = b[6] / 8;
+  a[7] = b[7] / 8;
+}
+
+void
+f2 (void)
+{
+  c[0] = d[0] / 3;
+  c[1] = d[1] / 3;
+  c[2] = d[2] / 3;
+  c[3] = d[3] / 3;
+  c[4] = d[4] / 3;
+  c[5] = d[5] / 3;
+  c[6] = d[6] / 3;
+  c[7] = d[7] / 3;
+}
+
+void
+f3 (void)
+{
+  a[0] = b[0] / 8;
+  a[1] = b[1] / 4;
+  a[2] = b[2] / 8;
+  a[3] = b[3] / 4;
+  a[4] = b[4] / 8;
+  a[5] = b[5] / 4;
+  a[6] = b[6] / 8;
+  a[7] = b[7] / 4;
+}
+
+void
+f4 (void)
+{
+  c[0] = d[0] / 3;
+  c[1] = d[1] / 5;
+  c[2] = d[2] / 3;
+  c[3] = d[3] / 5;
+  c[4] = d[4] / 3;
+  c[5] = d[5] / 5;
+  c[6] = d[6] / 3;
+  c[7] = d[7] / 5;
+}
+
+void
+f5 (void)
+{
+  a[0] = b[0] / 14;
+  a[1] = b[1] / 15;
+  a[2] = b[2] / 14;
+  a[3] = b[3] / 15;
+  a[4] = b[4] / 14;
+  a[5] = b[5] / 15;
+  a[6] = b[6] / 14;
+  a[7] = b[7] / 15;
+}
+
+void
+f6 (void)
+{
+  c[0] = d[0] / 6;
+  c[1] = d[1] / 5;
+  c[2] = d[2] / 6;
+  c[3] = d[3] / 5;
+  c[4] = d[4] / 6;
+  c[5] = d[5] / 5;
+  c[6] = d[6] / 13;
+  c[7] = d[7] / 5;
+}
+
+int
+main ()
+{
+  int i;
+  check_vect ();
+  asm ("");
+  for (i = 0; i < 8; i++)
+    {
+      asm ("");
+      b[i] = i - 4;
+      d[i] = i - 4;
+    }
+  f1 ();
+  f2 ();
+  for (i = 0; i < 8; i++)
+    if (a[i] != b[i] / 8 || c[i] != d[i] / 3)
+      abort ();
+  f3 ();
+  f4 ();
+  for (i = 0; i < 8; i+= 2)
+    if (a[i] != b[i] / 8 || a[i + 1] != b[i + 1] / 4
+	|| c[i] != d[i] / 3 || c[i + 1] != d[i + 1] / 5)
+      abort ();
+  f5 ();
+  f6 ();
+  for (i = 0; i < 8; i+= 2)
+    if (a[i] != b[i] / 14 || a[i + 1] != b[i + 1] / 15
+	|| c[i] != d[i] / (i == 6 ? 13 : 6) || c[i + 1] != d[i + 1] / 5)
+      abort ();
+  return 0;
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */

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

@@ -10,7 +10,7 @@ main1 ()
 {
   int i;
   unsigned short in[N*8] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63};
-  unsigned short out[N*8], a[N], b[N] = {3,6,9,12,15,18,21,24};
+  unsigned short out[N*8], a[N], b[N] = {3,0x8031,0x7fff,0x8032,0xffff,0,0x8030,0x8000};
 
   /* Partial SLP is not supported.  */
   for (i = 0; i < N; i++)
@@ -20,7 +20,7 @@ main1 ()
       out[i*4 + 2] = in[i*4 + 2];
       out[i*4 + 3] = in[i*4 + 3];
 
-      a[i] = b[i] / 3;
+      a[i] = b[i] / 0x8031;
     }
 
   /* check results:  */
@@ -30,7 +30,7 @@ main1 ()
          || out[i*4 + 1] != in[i*4 + 1]
          || out[i*4 + 2] != in[i*4 + 2]
          || out[i*4 + 3] != in[i*4 + 3]
-         || a[i] != b[i] / 3)
+	 || a[i] != b[i] / 0x8031)
         abort ();
     }
 

gcc/testsuite/gcc.target/i386/avx-pr51581-1.c

+/* PR tree-optimization/51581 */
+/* { dg-do run } */
+/* { dg-options "-O2 -ftree-vectorize -mavx -fno-vect-cost-model" } */
+/* { dg-require-effective-target avx } */
+
+#ifndef CHECK_H
+#define CHECK_H "avx-check.h"
+#endif
+#ifndef TEST
+#define TEST avx_test
+#endif
+
+#define main main1
+#include "../../gcc.c-torture/execute/pr51581-1.c"
+#undef main
+
+#include CHECK_H
+
+static void
+TEST (void)
+{
+  main1 ();
+}

gcc/testsuite/gcc.target/i386/avx-pr51581-2.c

+/* PR tree-optimization/51581 */
+/* { dg-do run } */
+/* { dg-options "-O2 -ftree-vectorize -mavx -fno-vect-cost-model" } */
+/* { dg-require-effective-target avx } */
+
+#ifndef CHECK_H
+#define CHECK_H "avx-check.h"
+#endif
+#ifndef TEST
+#define TEST avx_test
+#endif
+
+#define main main1
+#include "../../gcc.c-torture/execute/pr51581-2.c"
+#undef main
+
+#include CHECK_H
+
+static void
+TEST (void)
+{
+  main1 ();
+}

gcc/testsuite/gcc.target/i386/avx2-pr51581-1.c

+/* PR tree-optimization/51581 */
+/* { dg-do run } */
+/* { dg-options "-O2 -ftree-vectorize -mavx2 -fno-vect-cost-model" } */
+/* { dg-require-effective-target avx2 } */
+
+#define CHECK_H "avx2-check.h"
+#define TEST avx2_test
+
+#include "avx-pr51581-1.c"

gcc/testsuite/gcc.target/i386/avx2-pr51581-2.c

+/* PR tree-optimization/51581 */
+/* { dg-do run } */
+/* { dg-options "-O2 -ftree-vectorize -mavx2 -fno-vect-cost-model" } */
+/* { dg-require-effective-target avx2 } */
+
+#define CHECK_H "avx2-check.h"
+#define TEST avx2_test
+
+#include "avx-pr51581-2.c"

gcc/tree-vect-stmts.c

@@ -5361,7 +5361,9 @@ vect_analyze_stmt (gimple stmt, bool *need_to_vectorize, slp_tree node)
 
      Pattern statement needs to be analyzed instead of the original statement
      if the original statement is not relevant.  Otherwise, we analyze both
-     statements.  */
+     statements.  In basic blocks we are called from some SLP instance
+     traversal, don't analyze pattern stmts instead, the pattern stmts
+     already will be part of SLP instance.  */
 
   pattern_stmt = STMT_VINFO_RELATED_STMT (stmt_info);
   if (!STMT_VINFO_RELEVANT_P (stmt_info)
@@ -5390,6 +5392,7 @@ vect_analyze_stmt (gimple stmt, bool *need_to_vectorize, slp_tree node)
         }
     }
   else if (STMT_VINFO_IN_PATTERN_P (stmt_info)
+	   && node == NULL
            && pattern_stmt
            && (STMT_VINFO_RELEVANT_P (vinfo_for_stmt (pattern_stmt))
                || STMT_VINFO_LIVE_P (vinfo_for_stmt (pattern_stmt))))
@@ -5406,6 +5409,7 @@ vect_analyze_stmt (gimple stmt, bool *need_to_vectorize, slp_tree node)
    }
 
   if (is_pattern_stmt_p (stmt_info)
+      && node == NULL
       && (pattern_def_seq = STMT_VINFO_PATTERN_DEF_SEQ (stmt_info)))
     {
       gimple_stmt_iterator si;