[PATCH] Disassemble over end of line table sequence.

["Andrew Burgess" <aburgess at broadcom dot com>]

Within gdb we use line number 0 to mark the end of a sequence within the 
line number tables. When disassembling with source code we sort the 
lines based on the line number. As a result if a request is made to 
disassemble a range of addresses that includes an end of sequence marker 
the disassemble command will give an error rather than any sensible output.

In the included test I request a disassembly for a range of addresses 
that spans a function boundary, currently this will fail. With the fix 
the disassembly I get back still does not quite cover the complete range 
of addresses requested, I am treating this problem as a separate issue 
to be fixed in a later patch, here I am only interested in ordering the 
lines correctly so that I get something sensible back rather than an error.

Thanks,

Andrew



gdb/

2010-12-10  Andrew Burgess  <aburgess@broadcom.com>

          * (compare_lines): Sort by pc for entries where the line
            number is 0, these are the end of sequence markers.

gdb/testsuite/

2010-12-10  Andrew Burgess  <aburgess@broadcom.com>

          * gdb.disasm/disasm-end-cu-1.c, gdb.disasm/disasm-end-cu-2.c,
            gdb.disasm/disasm-end-cu.exp: New test for disassembling
            over the boundary between two compilation units.


diff --git a/gdb/disasm.c b/gdb/disasm.c
index 9fa34a0..2259f3e 100644
--- a/gdb/disasm.c
+++ b/gdb/disasm.c
@@ -77,12 +77,22 @@ compare_lines (const void *mle1p, const void *mle2p)
   mle1 = (struct dis_line_entry *) mle1p;
   mle2 = (struct dis_line_entry *) mle2p;

-  val = mle1->line - mle2->line;
-
-  if (val != 0)
-    return val;
+  /* Work with end of sequence markers
+     where the line number is set to 0 */
+  if ( mle1->line == 0 || mle2->line == 0 )
+    {
+      val = mle1->start_pc - mle2->start_pc;
+      if ( val == 0 )
+        val = mle1->line - mle2->line;
+    }
+  else
+    {
+      val = mle1->line - mle2->line;
+      if (val == 0)
+        val = mle1->start_pc - mle2->start_pc;
+    }

-  return mle1->start_pc - mle2->start_pc;
+  return val;
 }

 static int
diff --git a/gdb/testsuite/gdb.disasm/disasm-end-cu-1.c 
b/gdb/testsuite/gdb.disasm/disasm-end-cu-1.c
new file mode 100644
index 0000000..c031778
--- /dev/null
+++ b/gdb/testsuite/gdb.disasm/disasm-end-cu-1.c
@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+void
+dummy_1 ()
+{
+  printf("In dummy_1 ()\n");
+}
+
+int
+main ()
+{
+  printf("Hello World!\n");
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.disasm/disasm-end-cu-2.c 
b/gdb/testsuite/gdb.disasm/disasm-end-cu-2.c
new file mode 100644
index 0000000..7fddb87
--- /dev/null
+++ b/gdb/testsuite/gdb.disasm/disasm-end-cu-2.c
@@ -0,0 +1,13 @@
+#include <stdio.h>
+
+void
+dummy_2 ()
+{
+  printf("In dummy_2 ()\n");
+}
+
+void
+dummy_3 ()
+{
+  printf("In dummy_3 ()\n");
+}
diff --git a/gdb/testsuite/gdb.disasm/disasm-end-cu.exp 
b/gdb/testsuite/gdb.disasm/disasm-end-cu.exp
new file mode 100644
index 0000000..fdbd179
--- /dev/null
+++ b/gdb/testsuite/gdb.disasm/disasm-end-cu.exp
@@ -0,0 +1,70 @@
+# Copyright 2010 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+# For now pick a sampling of likely targets.
+if {![istarget *-*-linux*]
+    && ![istarget *-*-gnu*]
+    && ![istarget *-*-elf*]
+    && ![istarget *-*-openbsd*]
+    && ![istarget arm-*-eabi*]
+    && ![istarget powerpc-*-eabi*]} {
+    return 0
+}
+
+# This test tries to disassemble over the boundary between two compilation
+# units displaying source lines. This checks that the disassemble routine
+# can handle our use of line number 0 to mark the end of sequence.
+
+if { [prepare_for_testing disasm-end-cu.exp "disasm-end-cu" 
{disasm-end-cu-1.c disasm-end-cu-2.c} {debug}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+set main_addr [get_hexadecimal_valueof "&main" "0"]
+set dummy_3_addr [get_hexadecimal_valueof "&dummy_3" "0"]
+
+if {$main_addr == 0 || $dummy_3_addr == 0 || $dummy_3_addr <= $main_addr} {
+    fail "Unable to extract required addresses, or addresses out of order"
+    return -1
+}
+
+send_gdb "disassemble /m ${main_addr},${dummy_3_addr}\n"
+gdb_expect {
+    -re "Dump of assembler code from ${main_addr} to 
${dummy_3_addr}:\r\nEnd of assembler dump\." {
+        fail "No output from the disassemble command"
+    }
+
+    -re "Line number 0 out of range;.* has $decimal lines\." {
+        fail "The disassemble command failed"
+    }
+
+    -re "Dump of assembler code from ${main_addr} to 
${dummy_3_addr}:\r\n.*main.*End of assembler dump\." {
+        pass "disassemble command returned some output"
+    }
+
+    -re ".*$gdb_prompt $" {
+        fail "Unexpected output from disassemble command"
+    }
+
+    timeout {
+        fail "(timeout) waiting for output of disassemble command"
+    }
+}
+
+gdb_stop_suppressing_tests;