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Re: bfd/cpu-powerpc.c problems


On Thu, Apr 18, 2002 at 05:41:07PM -0400, Elena Zannoni wrote:
> 
> When this change went in,
> http://sources.redhat.com/ml/binutils/2002-02/msg00146.html
> 
> the function bfd_lookup_arch stopped returning a list of all the
> powerpc machines when called with arch==bfd_arch_powerpc, and machine==0 as
> parameters. This in turn caused the "set architecture" command in gdb
> to behave incorrectly.
> 
> The problem is the lack of a pointer to the first element of the
> bfd_powerpc_archs array from the entry for the default machine. Gdb is
> relying on retrieving a chain of all the machines available starting
> from the default one.

I wasn't aware that gdb used bfd_lookup_arch in this way, and the
description of bfd_lookup_arch says nothing about the order of
entries in the list.  I guess I can claim gdb is relying on
undocumented behaviour.

The reason the order was changed was so that bfd_default_set_arch_mach
works properly when the default target is bfd_mach_ppc64.  The trouble
being that with bfd_mach_ppc == 0 and the bfd_mach_ppc entry being at
the head of the list results in a non-default entry being returned
with mach == 0.  So the change I made is actually a bug fix.

OK, to accommodate gdb without changing the interface to lookup_arch
or bfd_mach_ppc value, we can do this:

bfd/ChangeLog
	* archures.c (bfd_lookup_arch): Add comment on list order.
	(bfd_default_set_arch_mach): Use bfd_lookup_arch.
	* cpu-powerpc.c (bfd_powerpc_archs): Re-order so that the default
	is always at head of list.

If there are no objections, I'll commit this in a day or so.

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre

Index: bfd/archures.c
===================================================================
RCS file: /cvs/src/src/bfd/archures.c,v
retrieving revision 1.47
diff -u -p -r1.47 archures.c
--- bfd/archures.c	13 Mar 2002 07:30:45 -0000	1.47
+++ bfd/archures.c	19 Apr 2002 00:43:49 -0000
@@ -604,21 +604,9 @@ bfd_default_set_arch_mach (abfd, arch, m
      enum bfd_architecture arch;
      unsigned long mach;
 {
-  const bfd_arch_info_type * const *app, *ap;
-
-  for (app = bfd_archures_list; *app != NULL; app++)
-    {
-      for (ap = *app; ap != NULL; ap = ap->next)
-	{
-	  if (ap->arch == arch
-	      && (ap->mach == mach
-		  || (mach == 0 && ap->the_default)))
-	    {
-	      abfd->arch_info = ap;
-	      return true;
-	    }
-	}
-    }
+  abfd->arch_info = bfd_lookup_arch (arch, mach);
+  if (abfd->arch_info != NULL)
+    return true;
 
   abfd->arch_info = &bfd_default_arch_struct;
   bfd_set_error (bfd_error_bad_value);
@@ -985,7 +973,9 @@ DESCRIPTION
 	Look for the architecure info structure which matches the
 	arguments @var{arch} and @var{machine}. A machine of 0 matches the
 	machine/architecture structure which marks itself as the
-	default.
+	default.  gdb relies on the default arch being the first
+	entry for the given ARCH so that all the entries for that
+	arch can be accessed via ap->next.
 */
 
 const bfd_arch_info_type *
Index: bfd/cpu-powerpc.c
===================================================================
RCS file: /cvs/src/src/bfd/cpu-powerpc.c,v
retrieving revision 1.8
diff -u -p -r1.8 cpu-powerpc.c
--- bfd/cpu-powerpc.c	5 Feb 2002 03:35:14 -0000	1.8
+++ bfd/cpu-powerpc.c	19 Apr 2002 00:43:56 -0000
@@ -50,6 +50,65 @@ powerpc_compatible (a,b)
 
 const bfd_arch_info_type bfd_powerpc_archs[] =
 {
+#if BFD_DEFAULT_TARGET_SIZE == 64 /* default arch must come first.  */
+  {
+    64,	/* 64 bits in a word */
+    64,	/* 64 bits in an address */
+    8,	/* 8 bits in a byte */
+    bfd_arch_powerpc,
+    bfd_mach_ppc64,
+    "powerpc",
+    "powerpc:common64",
+    3,
+    true, /* default for 64 bit target */
+    powerpc_compatible,
+    bfd_default_scan,
+    &bfd_powerpc_archs[1]
+  },
+  {
+    32,	/* 32 bits in a word */
+    32,	/* 32 bits in an address */
+    8,	/* 8 bits in a byte */
+    bfd_arch_powerpc,
+    bfd_mach_ppc, /* for the POWER/PowerPC common architecture */
+    "powerpc",
+    "powerpc:common",
+    3,
+    false,
+    powerpc_compatible,
+    bfd_default_scan,
+    &bfd_powerpc_archs[2],
+  },
+#else
+  {
+    32,	/* 32 bits in a word */
+    32,	/* 32 bits in an address */
+    8,	/* 8 bits in a byte */
+    bfd_arch_powerpc,
+    bfd_mach_ppc, /* for the POWER/PowerPC common architecture */
+    "powerpc",
+    "powerpc:common",
+    3,
+    true, /* default for 32 bit target */
+    powerpc_compatible,
+    bfd_default_scan,
+    &bfd_powerpc_archs[1],
+  },
+  {
+    64,	/* 64 bits in a word */
+    64,	/* 64 bits in an address */
+    8,	/* 8 bits in a byte */
+    bfd_arch_powerpc,
+    bfd_mach_ppc64,
+    "powerpc",
+    "powerpc:common64",
+    3,
+    false,
+    powerpc_compatible,
+    bfd_default_scan,
+    &bfd_powerpc_archs[2]
+  },
+#endif
   {
     32,	/* 32 bits in a word */
     32,	/* 32 bits in an address */
@@ -62,7 +121,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[1]
+    &bfd_powerpc_archs[3]
   },
   {
     32,	/* 32 bits in a word */
@@ -76,7 +135,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[2]
+    &bfd_powerpc_archs[4]
   },
   {
     32,	/* 32 bits in a word */
@@ -90,7 +149,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[3]
+    &bfd_powerpc_archs[5]
   },
   {
     32,	/* 32 bits in a word */
@@ -104,7 +163,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[4]
+    &bfd_powerpc_archs[6]
   },
   {
     32,	/* 32 bits in a word */
@@ -118,7 +177,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[5]
+    &bfd_powerpc_archs[7]
   },
   {
     64,	/* 64 bits in a word */
@@ -132,7 +191,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[6]
+    &bfd_powerpc_archs[8]
   },
   {
     64,	/* 64 bits in a word */
@@ -146,7 +205,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[7]
+    &bfd_powerpc_archs[9]
   },
   {
     64,	/* 64 bits in a word */
@@ -160,7 +219,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[8]
+    &bfd_powerpc_archs[10]
   },
   {
     64,	/* 64 bits in a word */
@@ -174,7 +233,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[9]
+    &bfd_powerpc_archs[11]
   },
   {
     64,	/* 64 bits in a word */
@@ -188,7 +247,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[10]
+    &bfd_powerpc_archs[12]
   },
   {
     32,	/* 32 bits in a word */
@@ -202,7 +261,7 @@ const bfd_arch_info_type bfd_powerpc_arc
     false, /* not the default */
     powerpc_compatible,
     bfd_default_scan,
-    &bfd_powerpc_archs[11]
+    &bfd_powerpc_archs[13]
   },
   {
     32,       /* 32 bits in a word */
@@ -214,34 +273,6 @@ const bfd_arch_info_type bfd_powerpc_arc
     "powerpc:MPC8XX",
     3,
     false, /* not the default */
-    powerpc_compatible,
-    bfd_default_scan,
-    &bfd_powerpc_archs[12]
-  },
-  {
-    64,	/* 64 bits in a word */
-    64,	/* 64 bits in an address */
-    8,	/* 8 bits in a byte */
-    bfd_arch_powerpc,
-    bfd_mach_ppc64,
-    "powerpc",
-    "powerpc:common64",
-    3,
-    BFD_DEFAULT_TARGET_SIZE == 64, /* default for 64 bit target */
-    powerpc_compatible,
-    bfd_default_scan,
-    &bfd_powerpc_archs[13]
-  },
-  {
-    32,	/* 32 bits in a word */
-    32,	/* 32 bits in an address */
-    8,	/* 8 bits in a byte */
-    bfd_arch_powerpc,
-    bfd_mach_ppc, /* for the POWER/PowerPC common architecture */
-    "powerpc",
-    "powerpc:common",
-    3,
-    BFD_DEFAULT_TARGET_SIZE != 64, /* default for 32 bit target */
     powerpc_compatible,
     bfd_default_scan,
     0


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