regcache (Re: GDB respin)

[Michal Ludvig]

Andrew Cagney wrote:
> Can someone post backtraces?
> 
>      49    gdb.log:../../gdb-head/gdb/sentinel-frame.c:102: 
> internal-error: Function sentinal_frame_pop called
> 
> Er, this should shouldn't happen.  Backtrace?
> 
>       3    gdb.log:../../gdb-head/gdb/regcache.c:713: internal-error: 
> regcache_raw_read: Assertion `regcache != NULL && buf != NULL' failed.
> 
> Again, the caller is pretty messed up.
> 
>       5    gdb.log:../../gdb-head/gdb/gdbarch.c:4271: internal-error: 
> gdbarch: gdbarch_store_return_value invalid
>       2    gdb.log:&"../../gdb-head/gdb/gdbarch.c:4252: internal-error: 
> gdbarch: gdbarch_extract_return_value invalid\n"
>       6    gdb.log:../../gdb-head/gdb/gdbarch.c:4252: internal-error: 
> gdbarch: gdbarch_extract_return_value invalid

The problem on x86-64 is probably caused by the regbuf vs. regcache 
usage. This is a part of the patch that broke the testsuite:

diff -u -p -r1.33 -r1.34
--- gdb/x86-64-tdep.c   26 Oct 2002 10:37:45 -0000      1.33
+++ gdb/x86-64-tdep.c   26 Oct 2002 16:56:34 -0000      1.34
@@ -925,11 +925,35 @@ x86_64_init_abi (struct gdbarch_info inf
+  set_gdbarch_long_double_bit (gdbarch, 128);
+  set_gdbarch_ps_regnum (gdbarch, 17); /* %eflags */
+  set_gdbarch_stab_reg_to_regnum (gdbarch, x86_64_dwarf2_reg_to_regnum);
+  set_gdbarch_dwarf_reg_to_regnum (gdbarch, x86_64_dwarf2_reg_to_regnum);
+  set_gdbarch_extract_return_value (gdbarch, NULL);
+  set_gdbarch_store_return_value (gdbarch, NULL);
+  set_gdbarch_extract_struct_value_address (gdbarch, NULL);

If I comment out last three lines (those return_value related), the 
testsuite performs much better. But all the other lines seem have some 
influence on the results.

I'm about to convert x86-64 target to use regcache, but am not sure what 
must be done for it. Could someone please briefly explain me what is 
regcache all about and what must be changed in order to have the target 
regcache-compilant?

As I was looking to the sources I believe, that only 
x86_64_store_return_value() and x86_64_extract_return_value() must be 
modified. Am I right or not?

Thanks.

Michal Ludvig
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