re PR target/40697 (inefficient code to extract least bits from an integer value)

gcc/
	PR target/40697
	* optabs.c (avoid_expensive_constant): Use rtx_cost to find out
	the cost of loading the constant rather than assuming
	COSTS_N_INSNS (1).
	* config/arm/arm.c (thumb1_rtx_costs) <case CONST_INT>: If the
	outer code is AND, do the same tests as the andsi3 expander and
	return COSTS_N_INSNS (1) if and is cheap.

testsuite/
	PR target/40697
	* gcc.target/arm/thumb-andsi.c: New test.

From-SVN: r157582

gcc/ChangeLog

@@ -4,6 +4,14 @@
 	* ira-lives.c (check_and_make_def_conflict): Ignore conflict for a
 	use that may match DEF.
 
+	PR target/40697
+	* optabs.c (avoid_expensive_constant): Use rtx_cost to find out
+	the cost of loading the constant rather than assuming
+	COSTS_N_INSNS (1).
+	* config/arm/arm.c (thumb1_rtx_costs) <case CONST_INT>: If the
+	outer code is AND, do the same tests as the andsi3 expander and
+	return COSTS_N_INSNS (1) if and is cheap.
+	
 2010-03-19  Michael Matz  <matz@suse.de>
 
 	PR c++/43116

gcc/config/arm/arm.c

@@ -6228,6 +6228,15 @@ thumb1_rtx_costs (rtx x, enum rtx_code code, enum rtx_code outer)
       else if ((outer == IOR || outer == XOR || outer == AND)
 	       && INTVAL (x) < 256 && INTVAL (x) >= -256)
 	return COSTS_N_INSNS (1);
+      else if (outer == AND)
+	{
+	  int i;
+	  /* This duplicates the tests in the andsi3 expander.  */
+	  for (i = 9; i <= 31; i++)
+	    if ((((HOST_WIDE_INT) 1) << i) - 1 == INTVAL (x)
+		|| (((HOST_WIDE_INT) 1) << i) - 1 == ~INTVAL (x))
+	      return COSTS_N_INSNS (2);
+	}
       else if (outer == ASHIFT || outer == ASHIFTRT
 	       || outer == LSHIFTRT)
 	return 0;

gcc/optabs.c

@@ -1389,11 +1389,11 @@ static rtx
 avoid_expensive_constant (enum machine_mode mode, optab binoptab,
 			  rtx x, bool unsignedp)
 {
+  bool speed = optimize_insn_for_speed_p ();
   if (mode != VOIDmode
       && optimize
       && CONSTANT_P (x)
-      && rtx_cost (x, binoptab->code, optimize_insn_for_speed_p ())
-                   > COSTS_N_INSNS (1))
+      && rtx_cost (x, binoptab->code, speed) > rtx_cost (x, SET, speed))
     {
       if (CONST_INT_P (x))
 	{

gcc/testsuite/ChangeLog

@@ -2,7 +2,10 @@
 
 	PR rtl-optimization/42258
 	* gcc.target/arm/thumb1-mul-moves.c: New test.
-	
+
+	PR target/40697
+	* gcc.target/arm/thumb-andsi.c: New test.
+
 2010-03-19  Michael Matz  <matz@suse.de>
 
 	PR c++/43116

gcc/testsuite/gcc.target/arm/thumb-andsi.c

+/* { dg-do compile } */
+/* { dg-options "-Os -mthumb -march=armv5te" } */
+
+unsigned get_least_bits(unsigned value)
+{
+  return value << 9 >> 9;
+}
+
+/* { dg-final { scan-assembler "lsl" } } */
+/* { dg-final { scan-assembler "lsr" } } */