re PR tree-optimization/63666 (FAIL: gcc.dg/vect/pr45752.c (internal compiler error))

2014-11-03  Marc Glisse  <marc.glisse@inria.fr>

	PR tree-optimization/63666
	* fold-const.c: Include "optabs.h".
	(fold_ternary_loc) <VEC_PERM_EXPR>: Avoid canonicalizing a
	can_vec_perm_p permutation to one that is not.

From-SVN: r217033

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bcfbd9b44abda2db2a6bf4e06b94fe934d834710..f31c42b9395ee1bc5c3b3397c0c35580673639e7 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2014-11-03  Marc Glisse  <marc.glisse@inria.fr>
+
+       PR tree-optimization/63666
+       * fold-const.c: Include "optabs.h".
+       (fold_ternary_loc) <VEC_PERM_EXPR>: Avoid canonicalizing a
+       can_vec_perm_p permutation to one that is not.
+
 2014-11-03  Zhenqiang Chen  <zhenqiang.chen@arm.com>
 
        * ifcvt.c (noce_try_store_flag_mask): Check rtx cost.

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 625829545478e81a30f682eb1319bd14a47252a3..78d51829bfe20b8308aaf53bb9c824f9cc9b17ff 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -82,6 +82,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "ipa-ref.h"
 #include "cgraph.h"
 #include "generic-match.h"
+#include "optabs.h"
 
 /* Nonzero if we are folding constants inside an initializer; zero
    otherwise.  */
@@ -14196,16 +14197,19 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
     case VEC_PERM_EXPR:
       if (TREE_CODE (arg2) == VECTOR_CST)
        {
-         unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i, mask;
-         unsigned char *sel = XALLOCAVEC (unsigned char, nelts);
+         unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i, mask, mask2;
+         unsigned char *sel = XALLOCAVEC (unsigned char, 2 * nelts);
+         unsigned char *sel2 = sel + nelts;
          bool need_mask_canon = false;
+         bool need_mask_canon2 = false;
          bool all_in_vec0 = true;
          bool all_in_vec1 = true;
          bool maybe_identity = true;
          bool single_arg = (op0 == op1);
          bool changed = false;
 
-         mask = single_arg ? (nelts - 1) : (2 * nelts - 1);
+         mask2 = 2 * nelts - 1;
+         mask = single_arg ? (nelts - 1) : mask2;
          gcc_assert (nelts == VECTOR_CST_NELTS (arg2));
          for (i = 0; i < nelts; i++)
            {
@@ -14216,13 +14220,10 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
              /* Make sure that the perm value is in an acceptable
                 range.  */
              wide_int t = val;
-             if (wi::gtu_p (t, mask))
-               {
-                 need_mask_canon = true;
-                 sel[i] = t.to_uhwi () & mask;
-               }
-             else
-               sel[i] = t.to_uhwi ();
+             need_mask_canon |= wi::gtu_p (t, mask);
+             need_mask_canon2 |= wi::gtu_p (t, mask2);
+             sel[i] = t.to_uhwi () & mask;
+             sel2[i] = t.to_uhwi () & mask2;
 
              if (sel[i] < nelts)
                all_in_vec1 = false;
@@ -14264,6 +14265,17 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
          if (op0 == op1 && !single_arg)
            changed = true;
 
+         /* Some targets are deficient and fail to expand a single
+            argument permutation while still allowing an equivalent
+            2-argument version.  */
+         if (need_mask_canon && arg2 == op2
+             && !can_vec_perm_p (TYPE_MODE (type), false, sel)
+             && can_vec_perm_p (TYPE_MODE (type), false, sel2))
+           {
+             need_mask_canon = need_mask_canon2;
+             sel = sel2;
+           }
+
          if (need_mask_canon && arg2 == op2)
            {
              tree *tsel = XALLOCAVEC (tree, nelts);