calls.c (precompute_arguments): Check promoted_for_signed_and_unsigned_p and set the promoted mode.

gcc
2014-08-08  Kugan Vivekanandarajah  <kuganv@linaro.org>

	* calls.c (precompute_arguments): Check
	 promoted_for_signed_and_unsigned_p and set the promoted mode.
	(promoted_for_signed_and_unsigned_p): New function.
	(expand_expr_real_1): Check promoted_for_signed_and_unsigned_p
	and set the promoted mode.
	* expr.h (promoted_for_signed_and_unsigned_p): New function definition.
	* cfgexpand.c (expand_gimple_stmt_1): Call emit_move_insn if
	SUBREG is promoted with SRP_SIGNED_AND_UNSIGNED.

gcc/testsuite
2014-08-08  Kugan Vivekanandarajah  <kuganv@linaro.org>

	* gcc.dg/zero_sign_ext_test.c: New test.

From-SVN: r213750

1 files changed, 34 insertions, 1 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 1242031..58b87ba 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -68,6 +68,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-ssa-address.h"
 #include "cfgexpand.h"
 #include "builtins.h"
+#include "tree-ssa.h"
 
 #ifndef STACK_PUSH_CODE
 #ifdef STACK_GROWS_DOWNWARD
@@ -9224,6 +9225,35 @@ expand_expr_real_2 (sepops ops, rtx target, enum machine_mode tmode,
 }
 #undef REDUCE_BIT_FIELD
 
+/* Return TRUE if value in SSA is zero and sign extended for wider mode MODE
+   using value range information stored.  Return FALSE otherwise.
+
+   This is used to check if SUBREG is zero and sign extended and to set
+   promoted mode SRP_SIGNED_AND_UNSIGNED to SUBREG.  */
+
+bool
+promoted_for_signed_and_unsigned_p (tree ssa, enum machine_mode mode)
+{
+  wide_int min, max;
+
+  if (ssa == NULL_TREE
+      || TREE_CODE (ssa) != SSA_NAME
+      || !INTEGRAL_TYPE_P (TREE_TYPE (ssa))
+      || (TYPE_PRECISION (TREE_TYPE (ssa)) != GET_MODE_PRECISION (mode)))
+    return false;
+
+  /* Return FALSE if value_range is not recorded for SSA.  */
+  if (get_range_info (ssa, &min, &max) != VR_RANGE)
+    return false;
+
+  /* Return true (to set SRP_SIGNED_AND_UNSIGNED to SUBREG) if MSB of the
+     smaller mode is not set (i.e.  MSB of ssa is not set).  */
+  if (!wi::neg_p (min, SIGNED) && !wi::neg_p(max, SIGNED))
+    return true;
+  else
+    return false;
+
+}
 
 /* Return TRUE if expression STMT is suitable for replacement.  
    Never consider memory loads as replaceable, because those don't ever lead 
@@ -9527,7 +9557,10 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
 
 	  temp = gen_lowpart_SUBREG (mode, decl_rtl);
 	  SUBREG_PROMOTED_VAR_P (temp) = 1;
-	  SUBREG_PROMOTED_SET (temp, unsignedp);
+	  if (promoted_for_signed_and_unsigned_p (ssa_name, mode))
+	    SUBREG_PROMOTED_SET (temp, SRP_SIGNED_AND_UNSIGNED);
+	  else
+	    SUBREG_PROMOTED_SET (temp, unsignedp);
 	  return temp;
 	}