[PATCH] MIPS: MIPS16 symbol annotation interpretation fix

["Maciej W. Rozycki" <macro at codesourcery dot com>]

Hi,

 It makes no sense for the ISA mode bit to override MIPS16 information 
stored in the associated symbol.  For example it causes a MIPS16 BREAK 
instruction to be used for standard MIPS code if a software breakpoint is 
explicitly requested at an address that has the ISA bit set even if the 
location is within a function known to be standard MIPS code.

 The change below fixes that for mips_pc_is_mips16 and mips_next_pc which 
both should only fall back to examining the ISA mode bit if no symbol 
annotation is available.

 Regression tested successfully for mips-sde-elf (MIPS32 and MIPS16 
multilibs, big- and little-endian each) and mips-linux-gnu.  OK to apply?

2011-11-23  Maciej W. Rozycki  <macro@codesourcery.com>

	gdb/
	* mips-tdep.c (mips_pc_is_mips16): Reverse the order of checks
	performed to determine whether an address refers to standard
	MIPS or MIPS16 code.
	(mips16_next_pc): Use mips_pc_is_mips16 instead of
	is_mips16_addr.

  Maciej

gdb-mips-pc-is-mips16.diff
Index: gdb-fsf-trunk-quilt/gdb/mips-tdep.c
===================================================================
--- gdb-fsf-trunk-quilt.orig/gdb/mips-tdep.c	2011-11-23 02:34:31.000000000 +0000
+++ gdb-fsf-trunk-quilt/gdb/mips-tdep.c	2011-11-23 02:42:05.435578274 +0000
@@ -1018,18 +1018,15 @@ mips_pc_is_mips16 (CORE_ADDR memaddr)
 {
   struct minimal_symbol *sym;
 
-  /* If bit 0 of the address is set, assume this is a MIPS16 address.  */
-  if (is_mips16_addr (memaddr))
-    return 1;
-
-  /* A flag indicating that this is a MIPS16 function is stored by elfread.c in
-     the high bit of the info field.  Use this to decide if the function is
-     MIPS16 or normal MIPS.  */
+  /* A flag indicating that this is a MIPS16 function is stored by
+     elfread.c in the high bit of the info field.  Use this to decide
+     if the function is MIPS16 or normal MIPS.  Otherwise if bit 0 of
+     the address is set, assume this is a MIPS16 address.  */
   sym = lookup_minimal_symbol_by_pc (memaddr);
   if (sym)
     return msymbol_is_special (sym);
   else
-    return 0;
+    return is_mips16_addr (memaddr);
 }
 
 /* MIPS believes that the PC has a sign extended value.  Perhaps the
@@ -1606,7 +1603,7 @@ mips16_next_pc (struct frame_info *frame
 static CORE_ADDR
 mips_next_pc (struct frame_info *frame, CORE_ADDR pc)
 {
-  if (is_mips16_addr (pc))
+  if (mips_pc_is_mips16 (pc))
     return mips16_next_pc (frame, pc);
   else
     return mips32_next_pc (frame, pc);