arm.c (thumb1_compute_save_reg_mask): Make sure scratch reg does not overlap return value.

2007-07-12  Paul Brook  <paul@codesourcery.com>

	gcc/
	* config/arm/arm.c (thumb1_compute_save_reg_mask): Make sure scratch
	reg does not overlap return value.

From-SVN: r126604

gcc/ChangeLog

+2007-07-12  Paul Brook  <paul@codesourcery.com>
+
+	* config/arm/arm.c (thumb1_compute_save_reg_mask): Make sure scratch
+	reg does not overlap return value.
+
 2007-07-12  Daniel Berlin  <dberlin@dberlin.org>
 
 	* tree-ssa-pre.c (get_expression_vuses): Move out side-effect.

gcc/config/arm/arm.c

@@ -10182,6 +10182,10 @@ thumb1_compute_save_reg_mask (void)
 	 have to push it.  Use LAST_LO_REGNUM as our fallback
 	 choice for the register to select.  */
       reg = thumb_find_work_register (1 << LAST_LO_REGNUM);
+      /* Make sure the register returned by thumb_find_work_register is
+	 not part of the return value.  */
+      if (reg * UNITS_PER_WORD <= arm_size_return_regs ())
+	reg = LAST_LO_REGNUM;
 
       if (! call_used_regs[reg])
 	mask |= 1 << reg;