expmed.c (extract_bit_field_1): Also use a temporary and convert_extracted_bit_field when...

	* expmed.c (extract_bit_field_1): Also use a temporary and
	convert_extracted_bit_field when the conversion from ext_mode to
	the target mode requires explicit truncation.

testsuite/
	* gcc.c-torture/execute/20081117-1.c: New test.

From-SVN: r141960

gcc/ChangeLog

+2008-11-17  Adam Nemet  <anemet@caviumnetworks.com>
+
+	* expmed.c (extract_bit_field_1): Also use a temporary and
+	convert_extracted_bit_field when the conversion from ext_mode to
+	the target mode requires explicit truncation.
+
 2008-11-17  Richard Sandiford  <rdsandiford@googlemail.com>
 
 	* config/mips/mips.h (REG_ALLOC_ORDER): Put accumulators first.

gcc/expmed.c

@@ -1533,7 +1533,13 @@ extract_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
 
       if (GET_MODE (xtarget) != ext_mode)
 	{
-	  if (REG_P (xtarget))
+	  /* Don't use LHS paradoxical subreg if explicit truncation is needed
+	     between the mode of the extraction (word_mode) and the target
+	     mode.  Instead, create a temporary and use convert_move to set
+	     the target.  */
+	  if (REG_P (xtarget)
+	      && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (GET_MODE (xtarget)),
+					GET_MODE_BITSIZE (ext_mode)))
 	    {
 	      xtarget = gen_lowpart (ext_mode, xtarget);
 	      if (GET_MODE_SIZE (ext_mode)

gcc/testsuite/ChangeLog

+2008-11-17  Adam Nemet  <anemet@caviumnetworks.com>
+
+	* gcc.c-torture/execute/20081117-1.c: New test.
+
 2008-11-17  Richard Sandiford  <rdsandiford@googlemail.com>
 
 	* gcc.target/mips/dspr2-MULT.c: Just check for $ac1 and $ac2.

gcc/testsuite/gcc.c-torture/execute/20081117-1.c

+extern void abort (void);
+
+struct s
+{
+  unsigned long long a:16;
+  unsigned long long b:32;
+  unsigned long long c:16;
+};
+
+__attribute__ ((noinline)) unsigned
+f (struct s s, unsigned i)
+{
+  return s.b == i;
+}
+
+struct s s = { 1, 0x87654321u, 2};
+
+int
+main ()
+{
+  if (!f (s, 0x87654321u))
+    abort ();
+  return 0;
+}