gas/

2007-09-26  Jan Beulich  <jbeulich@novell.com>

	* config/tc-i386.h (md_register_arithmetic): Define.
	* config/tc-ia64.h (md_register_arithmetic): Likewise.
	* doc/internals.texi: Document md_register_arithmetic.
	* expr.c (make_expr_symbol): Force O_register expressions into
	reg_section.
	(expr): Provide default for md_register_arithmetic. Don't resolve
	adding/subtracting constants to/from registers if
	md_register_arithmetic is zero.

5 files changed, 36 insertions, 4 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 6a9bb54023..9cf0f71d32 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,5 +1,16 @@
 2007-09-26  Jan Beulich  <jbeulich@novell.com>
 
+	* config/tc-i386.h (md_register_arithmetic): Define.
+	* config/tc-ia64.h (md_register_arithmetic): Likewise.
+	* doc/internals.texi: Document md_register_arithmetic.
+	* expr.c (make_expr_symbol): Force O_register expressions into
+	reg_section.
+	(expr): Provide default for md_register_arithmetic. Don't resolve
+	adding/subtracting constants to/from registers if
+	md_register_arithmetic is zero.
+
+2007-09-26  Jan Beulich  <jbeulich@novell.com>
+
 	* dw2gencfi.c: Conditionalize whole body upon TARGET_USE_CFIPOP.
 	(cfi_finish): Add second empty instance.
 
diff --git a/gas/config/tc-i386.h b/gas/config/tc-i386.h
index e55d5cad5e..65e300a4f7 100644
--- a/gas/config/tc-i386.h
+++ b/gas/config/tc-i386.h
@@ -272,6 +272,8 @@ extern int tc_i386_fix_adjustable (struct fix *);
 extern int i386_parse_name (char *, expressionS *, char *);
 #define md_parse_name(s, e, m, c) i386_parse_name (s, e, c)
 
+#define md_register_arithmetic 0
+
 extern const struct relax_type md_relax_table[];
 #define TC_GENERIC_RELAX_TABLE md_relax_table
 
diff --git a/gas/config/tc-ia64.h b/gas/config/tc-ia64.h
index 725e6eaa44..d0b0b1b09f 100644
--- a/gas/config/tc-ia64.h
+++ b/gas/config/tc-ia64.h
@@ -130,6 +130,7 @@ extern void ia64_convert_frag (fragS *);
 #endif /* TE_HPUX */
 #define md_flush_pending_output()	ia64_flush_pending_output ()
 #define md_parse_name(s,e,m,c)		ia64_parse_name (s, e, c)
+#define md_register_arithmetic		0
 #define tc_canonicalize_symbol_name(s)	ia64_canonicalize_symbol_name (s)
 #define tc_canonicalize_section_name(s)	ia64_canonicalize_symbol_name (s)
 #define md_optimize_expr(l,o,r)		ia64_optimize_expr (l, o, r)
diff --git a/gas/doc/internals.texi b/gas/doc/internals.texi
index c63a2dbd77..a97ead386c 100644
--- a/gas/doc/internals.texi
+++ b/gas/doc/internals.texi
@@ -1045,6 +1045,16 @@ pointer, for any expression that can not be recognized.  When the function
 is called, @code{input_line_pointer} will point to the start of the
 expression.
 
+@item md_register_arithmetic
+@cindex md_register_arithmetic
+If this macro is defined and evaluates to zero then GAS will not fold
+expressions that add or subtract a constant to/from a register to give
+another register.  For example GAS's default behaviour is to fold the
+expression "r8 + 1" into "r9", which is probably not the result
+intended by the programmer.  The default is to allow such folding,
+since this maintains backwards compatibility with earlier releases of
+GAS.
+
 @item tc_unrecognized_line
 @cindex tc_unrecognized_line
 If you define this macro, GAS will call it when it finds a line that it can not
diff --git a/gas/expr.c b/gas/expr.c
index b88328502e..4f4d380ff9 100644
--- a/gas/expr.c
+++ b/gas/expr.c
@@ -95,7 +95,9 @@ make_expr_symbol (expressionS *expressionP)
   symbolP = symbol_create (FAKE_LABEL_NAME,
 			   (expressionP->X_op == O_constant
 			    ? absolute_section
-			    : expr_section),
+			    : expressionP->X_op == O_register
+			      ? reg_section
+			      : expr_section),
 			   0, &zero_address_frag);
   symbol_set_value_expression (symbolP, expressionP);
 
@@ -1722,7 +1724,11 @@ expr (int rankarg,		/* Larger # is higher rank.  */
 	}
       else
 #endif
-      if (op_left == O_add && right.X_op == O_constant)
+#ifndef md_register_arithmetic
+# define md_register_arithmetic 1
+#endif
+      if (op_left == O_add && right.X_op == O_constant
+	  && (md_register_arithmetic || resultP->X_op != O_register))
 	{
 	  /* X + constant.  */
 	  resultP->X_add_number += right.X_add_number;
@@ -1745,12 +1751,14 @@ expr (int rankarg,		/* Larger # is higher rank.  */
 	  resultP->X_op = O_constant;
 	  resultP->X_add_symbol = 0;
 	}
-      else if (op_left == O_subtract && right.X_op == O_constant)
+      else if (op_left == O_subtract && right.X_op == O_constant
+	       && (md_register_arithmetic || resultP->X_op != O_register))
 	{
 	  /* X - constant.  */
 	  resultP->X_add_number -= right.X_add_number;
 	}
-      else if (op_left == O_add && resultP->X_op == O_constant)
+      else if (op_left == O_add && resultP->X_op == O_constant
+	       && (md_register_arithmetic || right.X_op != O_register))
 	{
 	  /* Constant + X.  */
 	  resultP->X_op = right.X_op;