expmed.c (store_bit_field_1): Properly truncate the paradoxical subreg of op0 to the original op0.

	* expmed.c (store_bit_field_1): Properly truncate the paradoxical
	subreg of op0 to the original op0.

testsuite/
	* gcc.target/mips/ins-2.c: New test.

From-SVN: r143288

gcc/ChangeLog

+2009-01-11  Adam Nemet  <anemet@caviumnetworks.com>
+
+	* expmed.c (store_bit_field_1): Properly truncate the paradoxical
+	subreg of op0 to the original op0.
+
 2009-01-11  Laurent GUERBY <laurent@guerby.net>
 
 	* doc/sourcebuild.texi (Source Tree): Move up intl and fixinc.

gcc/expmed.c

@@ -749,6 +749,16 @@ store_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
       if (pat)
 	{
 	  emit_insn (pat);
+
+	  /* If the mode of the insertion is wider than the mode of the
+	     target register we created a paradoxical subreg for the
+	     target.  Truncate the paradoxical subreg of the target to
+	     itself properly.  */
+	  if (!TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (GET_MODE (op0)),
+				      GET_MODE_BITSIZE (op_mode))
+	      && (REG_P (xop0)
+		  || GET_CODE (xop0) == SUBREG))
+	      convert_move (op0, xop0, true);
 	  return true;
 	}
       delete_insns_since (last);

gcc/testsuite/ChangeLog

+2009-01-11  Adam Nemet  <anemet@caviumnetworks.com>
+
+	* gcc.target/mips/ins-2.c: New test.
+
 2009-01-11  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR testsuite/38809

gcc/testsuite/gcc.target/mips/ins-2.c

+/* { dg-do compile } */
+/* { dg-options "-O -meb isa_rev>=2 -mgp64" } */
+/* { dg-final { scan-assembler-times "\tins\t|\tdins\t" 1 } } */
+/* { dg-final { scan-assembler-times "\tsll\t|\tins\t" 1 } } */
+
+/* When inserting something into the top bit of a 32-bit structure,
+   we must make sure that the register remains properly sign-extended.
+   There are two ways of doing this:
+ 
+     - use purely 32-bit bit manipulations (a single INS, matched twice here).
+     - use a 64-bit bit manipulation (DINS), and sign-extend the result.  We
+     check for this extension using SLL.  */
+
+struct s
+{
+  int a:3;
+  int b:29;
+};
+
+NOMIPS16 void
+f (int a)
+{
+  struct s s;
+  asm volatile ("" : "=r"(s));
+  s.a = a;
+  asm volatile ("" :: "r"(s));
+}