tree-outof-ssa.h (ssaexpand): Add partitions_for_undefined_values.

	* tree-outof-ssa.h (ssaexpand): Add partitions_for_undefined_values.
	(always_initialized_rtx_for_ssa_name_p): New predicate.
	* tree-outof-ssa.c (remove_ssa_form): Initialize new field of SA.
	(finish_out_of_ssa): Free new field of SA.
	* tree-ssa-coalesce.h (get_undefined_value_partitions): Declare.
	* tree-ssa-coalesce.c: Include tree-ssa.h.
	(get_parm_default_def_partitions): Remove extern keyword.
	(get_undefined_value_partitions): New function.
	* expr.c (expand_expr_real_1) <expand_decl_rtl>: For a SSA_NAME, do
	not set SUBREG_PROMOTED_VAR_P on the sub-register if it may contain
	uninitialized bits.
	* loop-iv.c (iv_get_reaching_def): Disqualify all subregs.

From-SVN: r253530

1 files changed, 26 insertions, 7 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 2f8432d..134ee73 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9909,24 +9909,43 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
 	  && GET_MODE (decl_rtl) != dmode)
 	{
 	  machine_mode pmode;
+	  bool always_initialized_rtx;
 
 	  /* Get the signedness to be used for this variable.  Ensure we get
 	     the same mode we got when the variable was declared.  */
 	  if (code != SSA_NAME)
-	    pmode = promote_decl_mode (exp, &unsignedp);
+	    {
+	      pmode = promote_decl_mode (exp, &unsignedp);
+	      always_initialized_rtx = true;
+	    }
 	  else if ((g = SSA_NAME_DEF_STMT (ssa_name))
 		   && gimple_code (g) == GIMPLE_CALL
 		   && !gimple_call_internal_p (g))
-	    pmode = promote_function_mode (type, mode, &unsignedp,
-					   gimple_call_fntype (g),
-					   2);
+	    {
+	      pmode = promote_function_mode (type, mode, &unsignedp,
+					    gimple_call_fntype (g), 2);
+	      always_initialized_rtx
+		= always_initialized_rtx_for_ssa_name_p (ssa_name);
+	    }
 	  else
-	    pmode = promote_ssa_mode (ssa_name, &unsignedp);
+	    {
+	      pmode = promote_ssa_mode (ssa_name, &unsignedp);
+	      always_initialized_rtx
+		= always_initialized_rtx_for_ssa_name_p (ssa_name);
+	    }
+
 	  gcc_assert (GET_MODE (decl_rtl) == pmode);
 
 	  temp = gen_lowpart_SUBREG (mode, decl_rtl);
-	  SUBREG_PROMOTED_VAR_P (temp) = 1;
-	  SUBREG_PROMOTED_SET (temp, unsignedp);
+
+	  /* We cannot assume anything about an existing extension if the
+	     register may contain uninitialized bits.  */
+	  if (always_initialized_rtx)
+	    {
+	      SUBREG_PROMOTED_VAR_P (temp) = 1;
+	      SUBREG_PROMOTED_SET (temp, unsignedp);
+	    }
+
 	  return temp;
 	}