gdb: include the base address in in-memory bfd filenames

The struct target_buffer (in gdb_bfd.c) is used to hold information
about an in-memory BFD object created by GDB.  For now this mechanism
is used by GDB when loading information about JIT symfiles.

This commit updates target_buffer (in gdb_bfd.c) to be more C++ like,
and, at the same time, adds the base address of the symfile into the
BFD filename.

Right now, every in-memory BFD is given the filename "<in-memory>".
This filename is visible in things like 'maint info symtabs' and
'maint info line-table'.  If there are multiple in-memory BFD objects
then it can be hard to match keep track if which BFD is which.  This
commit changes the name to be "<in-memory@ADDRESS>" where ADDRESS is
replaced with the base address for where the in-memory symbol file was
read from.

As an example of how this is useful, here's the output of 'maint info
jit' showing a single loaded JIT symfile:

  (gdb) maintenance info jit
  jit_code_entry address symfile address    symfile size
  0x00000000004056b0     0x0000000007000000 17320

And here's part of the output from 'maint info symtabs':

  (gdb) maintenance info symtabs
  ...snip...
  { objfile <in-memory@0x7000000> ((struct objfile *) 0x5258250)
    { ((struct compunit_symtab *) 0x4f0afb0)
      debugformat DWARF 4
      producer GNU C17 9.3.1 20200408 (Red Hat 9.3.1-2) -mtune=generic -march=x86-64 -g -fno-stack-protector -fpic
      name jit-elf-solib.c
      dirname /tmp/binutils-gdb/build/gdb/testsuite
      blockvector ((struct blockvector *) 0x5477850)
      user ((struct compunit_symtab *) (null))
  	{ symtab /tmp/binutils-gdb/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/jit-elf-solib.c ((struct symtab *) 0x4f0b030)
  	  fullname (null)
  	  linetable ((struct linetable *) 0x5477880)
  	}
    }
  }

I've added a new test that checks the new in-memory file names are
generated correctly, and also checks that the in-memory JIT files can
be dumped back out using 'dump binary memory'.

2 files changed, 31 insertions, 3 deletions

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 44cc28b..ae3a46c 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -8164,6 +8164,28 @@ proc cmp_file_string { file str msg } {
     }
 }
 
+# Compare FILE1 and FILE2 as binary files.  Return 0 if the files are
+# equal, otherwise, return non-zero.
+
+proc cmp_binary_files { file1 file2 } {
+    set fd1 [open $file1]
+    fconfigure $fd1 -translation binary
+    set fd2 [open $file2]
+    fconfigure $fd2 -translation binary
+
+    set blk_size 1024
+    while {true} {
+	set blk1 [read $fd1 $blk_size]
+	set blk2 [read $fd2 $blk_size]
+	set diff [string compare $blk1 $blk2]
+	if {$diff != 0 || [eof $fd1] || [eof $fd2]} {
+	    close $fd1
+	    close $fd2
+	    return $diff
+	}
+    }
+}
+
 # Does the compiler support CTF debug output using '-gctf' compiler
 # flag?  If not then we should skip these tests.  We should also
 # skip them if libctf was explicitly disabled.
diff --git a/gdb/testsuite/lib/jit-elf-helpers.exp b/gdb/testsuite/lib/jit-elf-helpers.exp
index b699917..80ba769 100644
--- a/gdb/testsuite/lib/jit-elf-helpers.exp
+++ b/gdb/testsuite/lib/jit-elf-helpers.exp
@@ -74,9 +74,13 @@ proc compile_jit_elf_main_as_so {main_solib_srcfile main_solib_binfile options}
 # Compile jit-elf-solib.c as a shared library in multiple copies and
 # upload them to the target.
 #
+# OPTIONS_LIST is a list of additional options to pass through to
+# gdb_compile_shlib.
+#
 # On success, return a list of target path to the shared libraries.
 # On failure, return -1.
-proc compile_and_download_n_jit_so {jit_solib_basename jit_solib_srcfile count} {
+proc compile_and_download_n_jit_so {jit_solib_basename jit_solib_srcfile \
+					count {options_list {}}} {
     global jit_load_address jit_load_increment
     set binfiles_target {}
 
@@ -93,9 +97,11 @@ proc compile_and_download_n_jit_so {jit_solib_basename jit_solib_srcfile count}
 	# compiled shared library against a fixed base address.  Combined
 	# with mapping the resulting binary to the same fixed base it allows
 	# to dynamically execute functions from it without any further adjustments.
+	set fname [format "jit_function_%04d" $i]
 	set options [list \
-	    additional_flags=-DFUNCTION_NAME=[format "jit_function_%04d" $i] \
-	    text_segment=$addr]
+			 ${options_list} \
+			 additional_flags=-DFUNCTION_NAME=$fname \
+			 text_segment=$addr]
 	if { [gdb_compile_shlib ${jit_solib_srcfile} ${binfile} \
 		  $options] != "" } {
 	    set f [file tail $binfile]