combine.c (make_compound_operation): If force_to_mode re-expanded the compound…

combine.c (make_compound_operation): If force_to_mode re-expanded the compound use gen_lowpart instead to convert to...

	* combine.c (make_compound_operation) <SUBREG>: If force_to_mode
	re-expanded the compound use gen_lowpart instead to convert to the
	desired mode.

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

From-SVN: r149781

gcc/ChangeLog

 2009-07-18  Adam Nemet  <anemet@caviumnetworks.com>
 
+	* combine.c (make_compound_operation) <SUBREG>: If force_to_mode
+	re-expanded the compound use gen_lowpart instead to convert to the
+	desired mode.
+
+2009-07-18  Adam Nemet  <anemet@caviumnetworks.com>
+
 	* combine.c (try_widen_shift_mode): Add COUNT, OUTER_CODE and
 	OUTER_CONST arguments.
 	<LSHIFTRT>: Use them to allow widening if the bits shifted in from

gcc/combine.c

@@ -7061,6 +7061,12 @@ make_compound_operation (rtx x, enum rtx_code in_code)
 	    if (GET_CODE (newer) != SUBREG)
 	      newer = make_compound_operation (newer, in_code);
 
+	    /* force_to_mode can expand compounds.  If it just re-expanded the
+	       compound use gen_lowpart instead to convert to the desired
+	       mode.  */
+	    if (rtx_equal_p (newer, x))
+	      return gen_lowpart (GET_MODE (x), tem);
+
 	    return newer;
 	  }
 

gcc/testsuite/ChangeLog

 2009-07-18  Adam Nemet  <anemet@caviumnetworks.com>
 
+	* gcc.target/mips/ext-2.c: New test.
+
+2009-07-18  Adam Nemet  <anemet@caviumnetworks.com>
+
 	* gcc.target/mips/octeon-exts-7.c: New test.
 	* gcc.target/mips/octeon-exts-2.c: Revert previous change.
 	* gcc.target/mips/octeon-exts-5.c: Likewise.

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

+/* Turn the truncate,zero_extend,lshiftrt sequence before the or into a
+   zero_extract.  The truncate is due to TARGET_PROMOTE_PROTOTYPES, the
+   zero_extend to PROMOTE_MODE.  */
+/* { dg-do compile } */
+/* { dg-options "-O isa_rev>=2 -mgp64" } */
+/* { dg-final { scan-assembler "\tdext\t" } } */
+/* { dg-final { scan-assembler-not "and" } } */
+/* { dg-final { scan-assembler-not "srl" } } */
+
+void
+f (unsigned char x, unsigned char *r)
+{
+  *r = 0x50 | (x >> 4);
+}