[PATCH] Fix store_bit_field_1 (PR target/38707)

[Jakub Jelinek]

Hi!

This patch fixes
-FAIL: gcc.c-torture/execute/20050121-1.c compilation,  -O0  (internal compiler error)
-UNRESOLVED: gcc.c-torture/execute/20050121-1.c execution,  -O0
-FAIL: gcc.c-torture/execute/20050121-1.c compilation,  -O1  (internal compiler error)
-UNRESOLVED: gcc.c-torture/execute/20050121-1.c execution,  -O1
-FAIL: gcc.c-torture/execute/20050121-1.c compilation,  -O2  (internal compiler error)
-UNRESOLVED: gcc.c-torture/execute/20050121-1.c execution,  -O2
-FAIL: gcc.c-torture/execute/20050121-1.c compilation,  -O3 -fomit-frame-pointer  (internal compiler error)
-UNRESOLVED: gcc.c-torture/execute/20050121-1.c execution,  -O3 -fomit-frame-pointer
-FAIL: gcc.c-torture/execute/20050121-1.c compilation,  -O3 -g  (internal compiler error)
-UNRESOLVED: gcc.c-torture/execute/20050121-1.c execution,  -O3 -g
-FAIL: gcc.dg/compat/scalar-return-4 c_compat_y_tst.o compile,  (internal compiler error)
-UNRESOLVED: gcc.dg/compat/scalar-return-4 c_compat_x_tst.o-c_compat_y_tst.o link
-UNRESOLVED: gcc.dg/compat/scalar-return-4 c_compat_x_tst.o-c_compat_y_tst.o execute
on i686-linux with RUNTESTFLAGS=--target_board=unix/-m32/-mtune=pentium-m
Earlier store_bit_field_1 wraps op0 into a subreg, so that it has integral
mode, but when unsuccessfully attempting movstrict* insn this is undone,
so it can't be masked etc.

Fixed by working on a temporary instead of op0, so that when movstrict*
expansion fails, op0 is untouched.

Bootstrapped/regtested on i686-linux, ok for trunk?

2009-01-03  Jakub Jelinek  <jakub@redhat.com>

	PR target/38707
	* expmed.c (store_bit_field_1): Don't modify op0 if movstrict insn
	can't be used.

--- gcc/expmed.c.jj	2008-11-18 19:24:09.000000000 +0100
+++ gcc/expmed.c	2009-01-03 16:47:25.000000000 +0100
@@ -1,7 +1,7 @@
 /* Medium-level subroutines: convert bit-field store and extract
    and shifts, multiplies and divides to rtl instructions.
    Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -532,6 +532,7 @@ store_bit_field_1 (rtx str_rtx, unsigned
       int icode = optab_handler (movstrict_optab, fieldmode)->insn_code;
       rtx insn;
       rtx start = get_last_insn ();
+      rtx arg0 = op0;
 
       /* Get appropriate low part of the value being stored.  */
       if (GET_CODE (value) == CONST_INT || REG_P (value))
@@ -552,11 +553,11 @@ store_bit_field_1 (rtx str_rtx, unsigned
 	  gcc_assert (GET_MODE (SUBREG_REG (op0)) == fieldmode
 		      || GET_MODE_CLASS (fieldmode) == MODE_INT
 		      || GET_MODE_CLASS (fieldmode) == MODE_PARTIAL_INT);
-	  op0 = SUBREG_REG (op0);
+	  arg0 = SUBREG_REG (op0);
 	}
 
       insn = (GEN_FCN (icode)
-		 (gen_rtx_SUBREG (fieldmode, op0,
+		 (gen_rtx_SUBREG (fieldmode, arg0,
 				  (bitnum % BITS_PER_WORD) / BITS_PER_UNIT
 				  + (offset * UNITS_PER_WORD)),
 				  value));

	Jakub