rs6000.c (rs6000_gimple_fold_builtin): Add handling for early folding of vector stores (ALTIVEC_BUILTIN_ST_*).

[gcc]

2017-09-25  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add handling
	for early folding of vector stores (ALTIVEC_BUILTIN_ST_*).
	(rs6000_builtin_valid_without_lhs): New helper function.
	* config/rs6000/rs6000-c.c (altivec_resolve_overloaded_builtin):
	Remove obsoleted code for handling ALTIVEC_BUILTIN_VEC_ST.

From-SVN: r253152

gcc/ChangeLog

@@ -1,3 +1,11 @@
+2017-09-25  Will Schmidt  <will_schmidt@vnet.ibm.com>
+
+	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add handling
+	for early folding of vector stores (ALTIVEC_BUILTIN_ST_*).
+	(rs6000_builtin_valid_without_lhs): New helper function.
+	* config/rs6000/rs6000-c.c (altivec_resolve_overloaded_builtin):
+	Remove obsoleted code for handling ALTIVEC_BUILTIN_VEC_ST.
+
 2017-09-25  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	* target.h (vec_perm_indices): Use unsigned short rather than

gcc/config/rs6000/rs6000-c.c

@@ -6472,78 +6472,6 @@ altivec_resolve_overloaded_builtin (location_t loc, tree fndecl,
       return stmt;
     }
 
-  /* Expand vec_st into an expression that masks the address and
-     performs the store.  We need to expand this early to allow
-     the best aliasing, as by the time we get into RTL we no longer
-     are able to honor __restrict__, for example.  We may want to
-     consider this for all memory access built-ins.
-
-     When -maltivec=be is specified, or the wrong number of arguments
-     is provided, simply punt to existing built-in processing.  */
-
-  if (fcode == ALTIVEC_BUILTIN_VEC_ST
-      && (BYTES_BIG_ENDIAN || !VECTOR_ELT_ORDER_BIG)
-      && nargs == 3)
-    {
-      tree arg0 = (*arglist)[0];
-      tree arg1 = (*arglist)[1];
-      tree arg2 = (*arglist)[2];
-
-      /* Construct the masked address.  Let existing error handling take
-	 over if we don't have a constant offset.  */
-      arg1 = fold (arg1);
-
-      if (TREE_CODE (arg1) == INTEGER_CST)
-	{
-	  if (!ptrofftype_p (TREE_TYPE (arg1)))
-	    arg1 = build1 (NOP_EXPR, sizetype, arg1);
-
-	  tree arg2_type = TREE_TYPE (arg2);
-	  if (TREE_CODE (arg2_type) == ARRAY_TYPE && c_dialect_cxx ())
-	    {
-	      /* Force array-to-pointer decay for C++.  */
-	      arg2 = default_conversion (arg2);
-	      arg2_type = TREE_TYPE (arg2);
-	    }
-
-	  /* Find the built-in to make sure a compatible one exists; if not
-	     we fall back to default handling to get the error message.  */
-	  for (desc = altivec_overloaded_builtins;
-	       desc->code && desc->code != fcode; desc++)
-	    continue;
-
-	  for (; desc->code == fcode; desc++)
-	    if (rs6000_builtin_type_compatible (TREE_TYPE (arg0), desc->op1)
-		&& rs6000_builtin_type_compatible (TREE_TYPE (arg1), desc->op2)
-		&& rs6000_builtin_type_compatible (TREE_TYPE (arg2),
-						   desc->op3))
-	      {
-		tree addr = fold_build2_loc (loc, POINTER_PLUS_EXPR, arg2_type,
-					     arg2, arg1);
-		tree aligned
-		  = fold_build2_loc (loc, BIT_AND_EXPR, arg2_type,
-				     addr, build_int_cst (arg2_type, -16));
-
-		tree arg0_type = TREE_TYPE (arg0);
-		if (TYPE_MODE (arg0_type) == V2DImode)
-		  /* Type-based aliasing analysis thinks vector long
-		     and vector long long are different and will put them
-		     in distinct alias classes.  Force our address type
-		     to be a may-alias type to avoid this.  */
-		  arg0_type
-		    = build_pointer_type_for_mode (arg0_type, Pmode,
-						   true/*can_alias_all*/);
-		else
-		  arg0_type = build_pointer_type (arg0_type);
-		aligned = build1 (NOP_EXPR, arg0_type, aligned);
-		tree stg = build_indirect_ref (loc, aligned, RO_NULL);
-		tree retval = build2 (MODIFY_EXPR, TREE_TYPE (stg), stg,
-				      convert (TREE_TYPE (stg), arg0));
-		return retval;
-	      }
-	}
-    }
-
   for (n = 0;
        !VOID_TYPE_P (TREE_VALUE (fnargs)) && n < nargs;
        fnargs = TREE_CHAIN (fnargs), n++)

gcc/config/rs6000/rs6000.c

@@ -16157,6 +16157,25 @@ rs6000_fold_builtin (tree fndecl, int n_args ATTRIBUTE_UNUSED,
 #endif
 }
 
+/*  Helper function to sort out which built-ins may be valid without having
+    a LHS.  */
+static bool
+rs6000_builtin_valid_without_lhs (enum rs6000_builtins fn_code)
+{
+  switch (fn_code)
+    {
+    case ALTIVEC_BUILTIN_STVX_V16QI:
+    case ALTIVEC_BUILTIN_STVX_V8HI:
+    case ALTIVEC_BUILTIN_STVX_V4SI:
+    case ALTIVEC_BUILTIN_STVX_V4SF:
+    case ALTIVEC_BUILTIN_STVX_V2DI:
+    case ALTIVEC_BUILTIN_STVX_V2DF:
+      return true;
+    default:
+      return false;
+    }
+}
+
 /* Fold a machine-dependent built-in in GIMPLE.  (For folding into
    a constant, use rs6000_fold_builtin.)  */
 
@@ -16184,8 +16203,9 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
   if (!rs6000_fold_gimple)
     return false;
 
-  /* Generic solution to prevent gimple folding of code without a LHS.  */
+  /* Prevent gimple folding for code that does not have a LHS, unless it is
-  if (!gimple_call_lhs (stmt))
+   allowed per the rs6000_builtin_valid_without_lhs helper function.  */
+  if (!gimple_call_lhs (stmt) && !rs6000_builtin_valid_without_lhs (fn_code))
     return false;
 
   switch (fn_code)
@@ -16587,7 +16607,54 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
 	 gsi_replace (gsi, g, true);
 	 return true;
       }
-
+    /* Vector stores.  */
+    case ALTIVEC_BUILTIN_STVX_V16QI:
+    case ALTIVEC_BUILTIN_STVX_V8HI:
+    case ALTIVEC_BUILTIN_STVX_V4SI:
+    case ALTIVEC_BUILTIN_STVX_V4SF:
+    case ALTIVEC_BUILTIN_STVX_V2DI:
+    case ALTIVEC_BUILTIN_STVX_V2DF:
+      {
+	 /* Do not fold for -maltivec=be on LE targets.  */
+	 if (VECTOR_ELT_ORDER_BIG && !BYTES_BIG_ENDIAN)
+	    return false;
+	 arg0 = gimple_call_arg (stmt, 0); /* Value to be stored.  */
+	 arg1 = gimple_call_arg (stmt, 1); /* Offset.  */
+	 tree arg2 = gimple_call_arg (stmt, 2); /* Store-to address.  */
+	 location_t loc = gimple_location (stmt);
+	 tree arg0_type = TREE_TYPE (arg0);
+	 /* Use ptr_type_node (no TBAA) for the arg2_type.
+	  FIXME: (Richard)  "A proper fix would be to transition this type as
+	  seen from the frontend to GIMPLE, for example in a similar way we
+	  do for MEM_REFs by piggy-backing that on an extra argument, a
+	  constant zero pointer of the alias pointer type to use (which would
+	  also serve as a type indicator of the store itself).  I'd use a
+	  target specific internal function for this (not sure if we can have
+	  those target specific, but I guess if it's folded away then that's
+	  fine) and get away with the overload set."
+	  */
+	 tree arg2_type = ptr_type_node;
+	 /* POINTER_PLUS_EXPR wants the offset to be of type 'sizetype'.  Create
+	    the tree using the value from arg0.  The resulting type will match
+	    the type of arg2.  */
+	 gimple_seq stmts = NULL;
+	 tree temp_offset = gimple_convert (&stmts, loc, sizetype, arg1);
+	 tree temp_addr = gimple_build (&stmts, loc, POINTER_PLUS_EXPR,
+				       arg2_type, arg2, temp_offset);
+	 /* Mask off any lower bits from the address.  */
+	 tree aligned_addr = gimple_build (&stmts, loc, BIT_AND_EXPR,
+					  arg2_type, temp_addr,
+					  build_int_cst (arg2_type, -16));
+	 gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
+	/* The desired gimple result should be similar to:
+	 MEM[(__vector floatD.1407 *)_1] = vf1D.2697;  */
+	 gimple *g;
+	 g = gimple_build_assign (build2 (MEM_REF, arg0_type, aligned_addr,
+					   build_int_cst (arg2_type, 0)), arg0);
+	 gimple_set_location (g, loc);
+	 gsi_replace (gsi, g, true);
+	 return true;
+      }
     default:
 	if (TARGET_DEBUG_BUILTIN)
 	   fprintf (stderr, "gimple builtin intrinsic not matched:%d %s %s\n",