diff mbox

[RFC,3/3] Enable zero/sign extension elimination

Message ID 54B9C4CC.8070806@linaro.org
State New
Headers show

Commit Message

Kugan Vivekanandarajah Jan. 17, 2015, 2:11 a.m. UTC 
Re-enable zero/sign extension elimination using value range that
includes wrapped attribute.

Thanks,
Kugan


gcc/ChangeLog:

2015-01-16  Kugan Vivekanandarajah  <kuganv@linaro.org>

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

Patch

diff --git a/gcc/calls.c b/gcc/calls.c
index 36aa19f..71d2469 100644
--- a/gcc/calls.c
+++ b/gcc/calls.c
@@ -1620,7 +1620,10 @@  precompute_arguments (int num_actuals, struct arg_data *args)
 	      args[i].initial_value
 		= gen_lowpart_SUBREG (mode, args[i].value);
 	      SUBREG_PROMOTED_VAR_P (args[i].initial_value) = 1;
-	      SUBREG_PROMOTED_SET (args[i].initial_value, args[i].unsignedp);
+	      if (promoted_for_signed_and_unsigned_p (args[i].tree_value))
+		SUBREG_PROMOTED_SET (args[i].initial_value, SRP_SIGNED_AND_UNSIGNED);
+	      else
+		SUBREG_PROMOTED_SET (args[i].initial_value, args[i].unsignedp);
 	    }
 	}
     }
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 8926e8f..39d52db 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -3410,7 +3410,13 @@  expand_gimple_stmt_1 (gimple stmt)
 					  GET_MODE (target), temp, unsignedp);
 		  }
 
-		convert_move (SUBREG_REG (target), temp, unsignedp);
+		if ((SUBREG_PROMOTED_GET (target) == SRP_SIGNED_AND_UNSIGNED)
+		    && (GET_CODE (temp) == SUBREG)
+		    && (GET_MODE (target) == GET_MODE (temp))
+		    && (GET_MODE (SUBREG_REG (target)) == GET_MODE (SUBREG_REG (temp))))
+		  emit_move_insn (SUBREG_REG (target), SUBREG_REG (temp));
+		else
+		  convert_move (SUBREG_REG (target), temp, unsignedp);
 	      }
 	    else if (nontemporal && emit_storent_insn (target, temp))
 	      ;
diff --git a/gcc/expr.c b/gcc/expr.c
index fc22862..48a5d13 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -174,6 +174,39 @@  static void emit_single_push_insn (machine_mode, rtx, tree);
 static void do_tablejump (rtx, machine_mode, rtx, rtx, rtx, int);
 static rtx const_vector_from_tree (tree);
 
+/* 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)
+{
+  wide_int min, max;
+  bool ovf;
+
+  if (ssa == NULL_TREE
+      || TREE_CODE (ssa) != SSA_NAME
+      || !INTEGRAL_TYPE_P (TREE_TYPE (ssa)))
+    return false;
+
+  /* Return FALSE if value_range is not recorded for SSA.  */
+  if (get_range_info (ssa, &min, &max, &ovf) != VR_RANGE)
+    return false;
+
+  if (ovf)
+    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;
+
+}
+
 
 /* This is run to set up which modes can be used
    directly in memory and to initialize the block move optab.  It is run
@@ -9656,7 +9689,10 @@  expand_expr_real_1 (tree exp, rtx target, 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))
+	    SUBREG_PROMOTED_SET (temp, SRP_SIGNED_AND_UNSIGNED);
+	  else
+	    SUBREG_PROMOTED_SET (temp, unsignedp);
 	  return temp;
 	}
 
diff --git a/gcc/expr.h b/gcc/expr.h
index a7638b8..8fb1339 100644
--- a/gcc/expr.h
+++ b/gcc/expr.h
@@ -288,6 +288,7 @@  extern rtx expand_expr_real_1 (tree, rtx, machine_mode,
 			       enum expand_modifier, rtx *, bool);
 extern rtx expand_expr_real_2 (sepops, rtx, machine_mode,
 			       enum expand_modifier);
+extern bool promoted_for_signed_and_unsigned_p (tree);
 
 /* Generate code for computing expression EXP.
    An rtx for the computed value is returned.  The value is never null.