re PR middle-end/32897 (Invalid rematerialisation of subregs)

gcc/
	PR middle-end/32897
	* reload.c (find_reloads): Check that the memory returned by
	find_reloads_toplev was not the result of forcing a constant
	to memory.
	(find_reloads_toplev): Always use simplify_gen_subreg to get
	the subreg of a constant.  If the result is also a constant,
	but not a legitimate one, force it into the constant pool
	and reload its address.

gcc/testsuite/
	* gcc.dg/torture/pr32897.c: New test.

From-SVN: r127536

gcc/ChangeLog

+2007-08-16  Richard Sandiford  <richard@codesourcery.com>
+
+	PR middle-end/32897
+	* reload.c (find_reloads): Check that the memory returned by
+	find_reloads_toplev was not the result of forcing a constant
+	to memory.
+	(find_reloads_toplev): Always use simplify_gen_subreg to get
+	the subreg of a constant.  If the result is also a constant,
+	but not a legitimate one, force it into the constant pool
+	and reload its address.
+
 2007-08-15  David Edelsohn  <edelsohn@gnu.org>
 
 	* config/rs6000/rs6000.c (rs6000_rtx_costs): Add CLZ, CTZ, and

gcc/reload.c

@@ -2794,7 +2794,8 @@ find_reloads (rtx insn, int replace, int ind_levels, int live_known,
 	      && MEM_P (op)
 	      && REG_P (reg)
 	      && (GET_MODE_SIZE (GET_MODE (reg))
-		  >= GET_MODE_SIZE (GET_MODE (op))))
+		  >= GET_MODE_SIZE (GET_MODE (op)))
+	      && reg_equiv_constant[REGNO (reg)] == 0)
 	    set_unique_reg_note (emit_insn_before (gen_rtx_USE (VOIDmode, reg),
 						   insn),
 				 REG_EQUAL, reg_equiv_memory_loc[REGNO (reg)]);
@@ -4600,14 +4601,6 @@ find_reloads_toplev (rtx x, int opnum, enum reload_type type,
       int regno = REGNO (SUBREG_REG (x));
       rtx tem;
 
-      if (subreg_lowpart_p (x)
-	  && regno >= FIRST_PSEUDO_REGISTER
-	  && reg_renumber[regno] < 0
-	  && reg_equiv_constant[regno] != 0
-	  && (tem = gen_lowpart_common (GET_MODE (x),
-					reg_equiv_constant[regno])) != 0)
-	return tem;
-
       if (regno >= FIRST_PSEUDO_REGISTER
 	  && reg_renumber[regno] < 0
 	  && reg_equiv_constant[regno] != 0)
@@ -4616,6 +4609,15 @@ find_reloads_toplev (rtx x, int opnum, enum reload_type type,
 	    simplify_gen_subreg (GET_MODE (x), reg_equiv_constant[regno],
 				 GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x));
 	  gcc_assert (tem);
+	  if (CONSTANT_P (tem) && !LEGITIMATE_CONSTANT_P (tem))
+	    {
+	      tem = force_const_mem (GET_MODE (x), tem);
+	      i = find_reloads_address (GET_MODE (tem), &tem, XEXP (tem, 0),
+					&XEXP (tem, 0), opnum, type,
+					ind_levels, insn);
+	      if (address_reloaded)
+		*address_reloaded = i;
+	    }
 	  return tem;
 	}
 

gcc/testsuite/ChangeLog

+2007-08-16  Richard Sandiford  <richard@codesourcery.com>
+
+	* gcc.dg/torture/pr32897.c: New test.
+
 2007-08-16  Paolo Carlini  <pcarlini@suse.de>
 
 	PR c++/31132

gcc/testsuite/gcc.dg/torture/pr32897.c

+/* { dg-options "-G0" { target mips*-*-* } } */
+
+volatile int g[32];
+long long gll;
+double gd;
+
+#define MULTI(X) \
+	X( 1), X( 2), X( 3), X( 4), X( 5), X( 6), X( 7), X( 8), X( 9), X(10), \
+	X(11), X(12), X(13), X(14), X(15), X(16), X(17), X(18), X(19), X(20), \
+	X(21), X(22), X(23), X(24), X(25), X(26), X(27), X(28), X(29), X(30)
+
+#define DECLARE(INDEX) x##INDEX
+#define COPY_IN(INDEX) x##INDEX = g[INDEX]
+#define COPY_OUT(INDEX) g[INDEX] = x##INDEX
+
+void
+test (int n)
+{
+  union { long long l; double d; } u = { 0x12345678 };
+  gll = u.l;
+  int MULTI (DECLARE);
+  MULTI (COPY_IN);
+  MULTI (COPY_OUT);
+  MULTI (COPY_OUT);
+  MULTI (COPY_OUT);
+  gd = u.d;
+}