Re: [patch/mips, rfc] Don't define FP_REGNUM

[Andrew Cagney <ac131313@ges.redhat.com>]

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Thanks for eyeballing this.

> For the MIPS to work, a custom virtual_frame_pointer() function would be 
>> needed.  I don't see any point in implementing this, though, as there is 
>> no tracepoint target to test it against.  Anyway, coments on this aspect 
>> of the patch?    If not, I'll check it in.
>> 
>> [Hmm, need to mention this in the NEWS file.  The MIPS $fp will finally 
>> behave as specified in the documentation.]
> 
> 
> Looks good to me.  And there may someday be a tracepoint target to
> test it against - I hope to add tracepoints to gdbserver, eventually.
> When that happens I can revisit this.

I've so far checked in the attached...

Andrew


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2002-09-17  Andrew Cagney  <ac131313@redhat.com>

	* arch-utils.c (legacy_virtual_frame_pointer): If FP_REGNUM is
	invalid, return SP_REGNUM.

Index: arch-utils.c
===================================================================
RCS file: /cvs/src/src/gdb/arch-utils.c,v
retrieving revision 1.68
diff -u -r1.68 arch-utils.c
--- arch-utils.c	14 Sep 2002 09:40:36 -0000	1.68
+++ arch-utils.c	17 Sep 2002 21:17:58 -0000
@@ -423,8 +423,19 @@
 			      int *frame_regnum,
 			      LONGEST *frame_offset)
 {
-  gdb_assert (FP_REGNUM >= 0);
-  *frame_regnum = FP_REGNUM;
+  /* FIXME: cagney/2002-09-13: This code is used when identifying the
+     frame pointer of the current PC.  It is assuming that a single
+     register and an offset can determine this.  I think it should
+     instead generate a byte code expression as that would work better
+     with things like Dwarf2's CFI.  */
+  if (FP_REGNUM >= 0 && FP_REGNUM < NUM_REGS)
+    *frame_regnum = FP_REGNUM;
+  else if (SP_REGNUM >= 0 && SP_REGNUM < NUM_REGS)
+    *frame_regnum = SP_REGNUM;
+  else
+    /* Should this be an internal error?  I guess so, it is reflecting
+       an architectural limitation in the current design.  */
+    internal_error (__FILE__, __LINE__, "No virtual frame pointer available");
   *frame_offset = 0;
 }