extend DECL_GIMPLE_REG_P to all types

This extends DECL_GIMPLE_REG_P to all types so we can clear
TREE_ADDRESSABLE even for integers with partial defs, not just
complex and vector variables.  To make that transition easier
the patch inverts DECL_GIMPLE_REG_P to DECL_NOT_GIMPLE_REG_P
since that makes the default the current state for all other
types besides complex and vectors.

For the testcase in PR94703 we're able to expand the partial
def'ed local integer to a register then, producing a single
movl rather than going through the stack.

On i?86 this execute FAILs gcc.dg/torture/pr71522.c because
we now expand a round-trip through a long double automatic var
to a register fld/fst which normalizes the value.  For that
during RTL expansion we're looking for problematic punnings
of decls and avoid pseudos for those - I chose integer or
BLKmode accesses on decls with modes where precision doesn't
match bitsize which covers the XFmode case.

2020-05-07  Richard Biener  <rguenther@suse.de>

	PR middle-end/94703
	* tree-core.h (tree_decl_common::gimple_reg_flag): Rename ...
	(tree_decl_common::not_gimple_reg_flag): ... to this.
	* tree.h (DECL_GIMPLE_REG_P): Rename ...
	(DECL_NOT_GIMPLE_REG_P): ... to this.
	* gimple-expr.c (copy_var_decl): Copy DECL_NOT_GIMPLE_REG_P.
	(create_tmp_reg): Simplify.
	(create_tmp_reg_fn): Likewise.
	(is_gimple_reg): Check DECL_NOT_GIMPLE_REG_P for all regs.
	* gimplify.c (create_tmp_from_val): Simplify.
	(gimplify_bind_expr): Likewise.
	(gimplify_compound_literal_expr): Likewise.
	(gimplify_function_tree): Likewise.
	(prepare_gimple_addressable): Set DECL_NOT_GIMPLE_REG_P.
	* asan.c (create_odr_indicator): Do not clear DECL_GIMPLE_REG_P.
	(asan_add_global): Copy it.
	* cgraphunit.c (cgraph_node::expand_thunk): Force args
	to be GIMPLE regs.
	* function.c (gimplify_parameters): Copy
	DECL_NOT_GIMPLE_REG_P.
	* ipa-param-manipulation.c
	(ipa_param_body_adjustments::common_initialization): Simplify.
	(ipa_param_body_adjustments::reset_debug_stmts): Copy
	DECL_NOT_GIMPLE_REG_P.
	* omp-low.c (lower_omp_for_scan): Do not set DECL_GIMPLE_REG_P.
	* sanopt.c (sanitize_rewrite_addressable_params): Likewise.
	* tree-cfg.c (make_blocks_1): Simplify.
	(verify_address): Do not verify DECL_GIMPLE_REG_P setting.
	* tree-eh.c (lower_eh_constructs_2): Simplify.
	* tree-inline.c (declare_return_variable): Adjust and
	generalize.
	(copy_decl_to_var): Copy DECL_NOT_GIMPLE_REG_P.
	(copy_result_decl_to_var): Likewise.
	* tree-into-ssa.c (pass_build_ssa::execute): Adjust comment.
	* tree-nested.c (create_tmp_var_for): Simplify.
	* tree-parloops.c (separate_decls_in_region_name): Copy
	DECL_NOT_GIMPLE_REG_P.
	* tree-sra.c (create_access_replacement): Adjust and
	generalize partial def support.
	* tree-ssa-forwprop.c (pass_forwprop::execute): Set
	DECL_NOT_GIMPLE_REG_P on decls we introduce partial defs on.
	* tree-ssa.c (maybe_optimize_var): Handle clearing of
	TREE_ADDRESSABLE and setting/clearing DECL_NOT_GIMPLE_REG_P
	independently.
	* lto-streamer-out.c (hash_tree): Hash DECL_NOT_GIMPLE_REG_P.
	* tree-streamer-out.c (pack_ts_decl_common_value_fields): Stream
	DECL_NOT_GIMPLE_REG_P.
	* tree-streamer-in.c (unpack_ts_decl_common_value_fields): Likewise.
	* cfgexpand.c (avoid_type_punning_on_regs): New.
	(discover_nonconstant_array_refs): Call
	avoid_type_punning_on_regs to avoid unsupported mode punning.

	lto/
	* lto-common.c (compare_tree_sccs_1): Compare
	DECL_NOT_GIMPLE_REG_P.

	c/
	* gimple-parser.c (c_parser_parse_ssa_name): Do not set
	DECL_GIMPLE_REG_P.

	cp/
	* optimize.c (update_cloned_parm): Copy DECL_NOT_GIMPLE_REG_P.

	* gcc.dg/tree-ssa/pr94703.c: New testcase.

1 files changed, 35 insertions, 31 deletions

diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index 4f4ab2b..c47b963 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -1583,8 +1583,8 @@ non_rewritable_lvalue_p (tree lhs)
   return true;
 }
 
-/* When possible, clear TREE_ADDRESSABLE bit or set DECL_GIMPLE_REG_P bit and
-   mark the variable VAR for conversion into SSA.  Return true when updating
+/* When possible, clear TREE_ADDRESSABLE bit, set or clear DECL_NOT_GIMPLE_REG_P
+   and mark the variable VAR for conversion into SSA.  Return true when updating
    stmts is required.  */
 
 static void
@@ -1597,24 +1597,11 @@ maybe_optimize_var (tree var, bitmap addresses_taken, bitmap not_reg_needs,
       || bitmap_bit_p (addresses_taken, DECL_UID (var)))
     return;
 
-  if (TREE_ADDRESSABLE (var)
-      /* Do not change TREE_ADDRESSABLE if we need to preserve var as
-	 a non-register.  Otherwise we are confused and forget to
-	 add virtual operands for it.  */
-      && (!is_gimple_reg_type (TREE_TYPE (var))
-	  || TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE
-	  || TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE
-	  || !bitmap_bit_p (not_reg_needs, DECL_UID (var))))
+  bool maybe_reg = false;
+  if (TREE_ADDRESSABLE (var))
     {
       TREE_ADDRESSABLE (var) = 0;
-      /* If we cleared TREE_ADDRESSABLE make sure DECL_GIMPLE_REG_P
-         is unset if we cannot rewrite the var into SSA.  */
-      if ((TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE
-	   || TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE)
-	  && bitmap_bit_p (not_reg_needs, DECL_UID (var)))
-	DECL_GIMPLE_REG_P (var) = 0;
-      if (is_gimple_reg (var))
-	bitmap_set_bit (suitable_for_renaming, DECL_UID (var));
+      maybe_reg = true;
       if (dump_file)
 	{
 	  fprintf (dump_file, "No longer having address taken: ");
@@ -1623,20 +1610,36 @@ maybe_optimize_var (tree var, bitmap addresses_taken, bitmap not_reg_needs,
 	}
     }
 
-  if (!DECL_GIMPLE_REG_P (var)
-      && !bitmap_bit_p (not_reg_needs, DECL_UID (var))
-      && (TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE
-	  || TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE)
-      && !TREE_THIS_VOLATILE (var)
-      && (!VAR_P (var) || !DECL_HARD_REGISTER (var)))
+  /* For register type decls if we do not have any partial defs
+     we cannot express in SSA form mark them as DECL_NOT_GIMPLE_REG_P
+     as to avoid SSA rewrite.  For the others go ahead and mark
+     them for renaming.  */
+  if (is_gimple_reg_type (TREE_TYPE (var)))
     {
-      DECL_GIMPLE_REG_P (var) = 1;
-      bitmap_set_bit (suitable_for_renaming, DECL_UID (var));
-      if (dump_file)
+      if (bitmap_bit_p (not_reg_needs, DECL_UID (var)))
 	{
-	  fprintf (dump_file, "Now a gimple register: ");
-	  print_generic_expr (dump_file, var);
-	  fprintf (dump_file, "\n");
+	  DECL_NOT_GIMPLE_REG_P (var) = 1;
+	  if (dump_file)
+	    {
+	      fprintf (dump_file, "Has partial defs: ");
+	      print_generic_expr (dump_file, var);
+	      fprintf (dump_file, "\n");
+	    }
+	}
+      else if (DECL_NOT_GIMPLE_REG_P (var))
+	{
+	  maybe_reg = true;
+	  DECL_NOT_GIMPLE_REG_P (var) = 0;
+	}
+      if (maybe_reg && is_gimple_reg (var))
+	{
+	  if (dump_file)
+	    {
+	      fprintf (dump_file, "Now a gimple register: ");
+	      print_generic_expr (dump_file, var);
+	      fprintf (dump_file, "\n");
+	    }
+	  bitmap_set_bit (suitable_for_renaming, DECL_UID (var));
 	}
     }
 }
@@ -1669,7 +1672,8 @@ is_asan_mark_p (gimple *stmt)
   return false;
 }
 
-/* Compute TREE_ADDRESSABLE and DECL_GIMPLE_REG_P for local variables.  */
+/* Compute TREE_ADDRESSABLE and whether we have unhandled partial defs
+   for local variables.  */
 
 void
 execute_update_addresses_taken (void)