Re: [RFC][patch] Allow to disassemble line.

Paul Pluzhnikov
2009-10-21T00:22:37Z

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On Mon, Oct 19, 2009 at 11:30 AM, Tom Tromey <tromey@redhat.com> wrote:

>>>>>> "Paul" == Paul Pluzhnikov <ppluzhnikov@google.com> writes:
>
> Paul> This patch still lacks documentation and test case updates. I'll work up
> Paul> the complete patch if this one is OK.
>
> It looks reasonable to me.

Here is updated patch with documentation and testsuite fixes.

Thanks,
--
Paul Pluzhnikov

2009-10-20 Paul Pluzhnikov <ppluzhnikov@google.com>

* defs.h (pc_prefix): New prototype.
* disasm.c (dump_insns): Mark current instruction.
* printcmd.c (do_examine): Likewise.
(pc_prefix): New function.
* stack.c (print_frame_info): Disassemble entire current line.

doc/ChangeLog

2009-10-20 Paul Pluzhnikov <ppluzhnikov@google.com>

* gdb.texi (Machine Code): Mention current pc marker, update examples.
(Memory): Likewise.

testsuite/ChangeLog

2009-10-20 Paul Pluzhnikov <ppluzhnikov@google.com>

* gdb.base/consecutive.exp: Adjust.
* gdb.base/display.exp: Likewise.
* gdb.base/pc-fp.exp: Likewise.
* gdb.base/sigbpt.exp: Likewise.

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Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.634
diff -u -p -u -r1.634 gdb.texinfo
--- doc/gdb.texinfo 19 Oct 2009 09:51:42 -0000 1.634
+++ doc/gdb.texinfo 21 Oct 2009 00:14:17 -0000
@@ -6525,6 +6525,9 @@ program counter of the selected frame.
command is a program counter value; @value{GDBN} dumps the function
surrounding this value. Two arguments specify a range of addresses
(first inclusive, second exclusive) to dump.
+
+If the range of memory being disassembled contains current program counter,
+the instruction at that location is shown with a @code{=>} marker.
@end table

The following example shows the disassembly of a range of addresses of
@@ -6533,38 +6536,39 @@ HP PA-RISC 2.0 code:
@smallexample
(@value{GDBP}) disas 0x32c4 0x32e4
Dump of assembler code from 0x32c4 to 0x32e4:
-0x32c4 <main+204>: addil 0,dp
-0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26
-0x32cc <main+212>: ldil 0x3000,r31
-0x32d0 <main+216>: ble 0x3f8(sr4,r31)
-0x32d4 <main+220>: ldo 0(r31),rp
-0x32d8 <main+224>: addil -0x800,dp
-0x32dc <main+228>: ldo 0x588(r1),r26
-0x32e0 <main+232>: ldil 0x3000,r31
+ 0x32c4 <main+204>: addil 0,dp
+ 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26
+ 0x32cc <main+212>: ldil 0x3000,r31
+ 0x32d0 <main+216>: ble 0x3f8(sr4,r31)
+ 0x32d4 <main+220>: ldo 0(r31),rp
+ 0x32d8 <main+224>: addil -0x800,dp
+ 0x32dc <main+228>: ldo 0x588(r1),r26
+ 0x32e0 <main+232>: ldil 0x3000,r31
End of assembler dump.
@end smallexample

-Here is an example showing mixed source+assembly for Intel x86:
+Here is an example showing mixed source+assembly for Intel x86, when the
+program is stopped just after function prologue:

@smallexample
(@value{GDBP}) disas /m main
Dump of assembler code for function main:
5 @{
-0x08048330 <main+0>: push %ebp
-0x08048331 <main+1>: mov %esp,%ebp
-0x08048333 <main+3>: sub $0x8,%esp
-0x08048336 <main+6>: and $0xfffffff0,%esp
-0x08048339 <main+9>: sub $0x10,%esp
+ 0x08048330 <main+0>: push %ebp
+ 0x08048331 <main+1>: mov %esp,%ebp
+ 0x08048333 <main+3>: sub $0x8,%esp
+ 0x08048336 <main+6>: and $0xfffffff0,%esp
+ 0x08048339 <main+9>: sub $0x10,%esp

6 printf ("Hello.\n");
-0x0804833c <main+12>: movl $0x8048440,(%esp)
-0x08048343 <main+19>: call 0x8048284 <puts@@plt>
+=> 0x0804833c <main+12>: movl $0x8048440,(%esp)
+ 0x08048343 <main+19>: call 0x8048284 <puts@@plt>

7 return 0;
8 @}
-0x08048348 <main+24>: mov $0x0,%eax
-0x0804834d <main+29>: leave
-0x0804834e <main+30>: ret
+ 0x08048348 <main+24>: mov $0x0,%eax
+ 0x0804834d <main+29>: leave
+ 0x0804834e <main+30>: ret

End of assembler dump.
@end smallexample
@@ -7244,6 +7248,18 @@ with just @samp{x/7}. If you use @key{R
the repeat count @var{n} is used again; the other arguments default as
for successive uses of @code{x}.

+When examining machine instructions, instruction at current program counter
+is shown with a @code{=>} marker. For example:
+
+@smallexample
+(@value{GDBP}) x/5i $pc-6
+ 0x804837f <main+11>: mov %esp,%ebp
+ 0x8048381 <main+13>: push %ecx
+ 0x8048382 <main+14>: sub $0x4,%esp
+=> 0x8048385 <main+17>: movl $0x8048460,(%esp)
+ 0x804838c <main+24>: call 0x80482d4 <puts@@plt>
+@end smallexample
+
@cindex @code{$_}, @code{$__}, and value history
The addresses and contents printed by the @code{x} command are not saved
in the value history because there is often too much of them and they
Index: defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.256
diff -u -p -u -r1.256 defs.h
--- defs.h 19 Oct 2009 09:51:40 -0000 1.256
+++ defs.h 21 Oct 2009 00:14:17 -0000
@@ -608,6 +608,7 @@ extern int build_address_symbolic (CORE_
int *unmapped);

extern void print_address (struct gdbarch *, CORE_ADDR, struct ui_file *);
+extern const char *pc_prefix (CORE_ADDR);

/* From source.c */

Index: disasm.c
===================================================================
RCS file: /cvs/src/src/gdb/disasm.c,v
retrieving revision 1.33
diff -u -p -u -r1.33 disasm.c
--- disasm.c 11 Jul 2009 14:04:23 -0000 1.33
+++ disasm.c 21 Oct 2009 00:14:17 -0000
@@ -113,6 +113,7 @@ dump_insns (struct gdbarch *gdbarch, str
num_displayed++;
}
ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
+ ui_out_text (uiout, pc_prefix (pc));
ui_out_field_core_addr (uiout, "address", gdbarch, pc);

if (!build_address_symbolic (pc, 0, &name, &offset, &filename,
Index: printcmd.c
===================================================================
RCS file: /cvs/src/src/gdb/printcmd.c,v
retrieving revision 1.165
diff -u -p -u -r1.165 printcmd.c
--- printcmd.c 19 Oct 2009 09:51:41 -0000 1.165
+++ printcmd.c 21 Oct 2009 00:14:17 -0000
@@ -725,6 +725,26 @@ print_address (struct gdbarch *gdbarch,
print_address_symbolic (addr, stream, asm_demangle, " ");
}

+/* Return a prefix for instruction address:
+ "=> " for current instruction, else " ". */
+
+const char *
+pc_prefix (CORE_ADDR addr)
+{
+ if (has_stack_frames ())
+ {
+ struct frame_info *frame;
+ CORE_ADDR pc;
+
+ frame = get_selected_frame (NULL);
+ pc = get_frame_pc (frame);
+
+ if (pc == addr)
+ return "=> ";
+ }
+ return " ";
+}
+
/* Print address ADDR symbolically on STREAM. Parameter DEMANGLE
controls whether to print the symbolic name "raw" or demangled.
Global setting "addressprint" controls whether to print hex address
@@ -817,6 +837,8 @@ do_examine (struct format_data fmt, stru
while (count > 0)
{
QUIT;
+ if (format == 'i')
+ fputs_filtered (pc_prefix (next_address), gdb_stdout);
print_address (next_gdbarch, next_address, gdb_stdout);
printf_filtered (":");
for (i = maxelts;
Index: stack.c
===================================================================
RCS file: /cvs/src/src/gdb/stack.c,v
retrieving revision 1.208
diff -u -p -u -r1.208 stack.c
--- stack.c 19 Oct 2009 09:51:42 -0000 1.208
+++ stack.c 21 Oct 2009 00:14:17 -0000
@@ -643,8 +643,7 @@ print_frame_info (struct frame_info *fra
/* If disassemble-next-line is set to on and there is line debug
messages, output assembly codes for next line. */
if (disassemble_next_line == AUTO_BOOLEAN_TRUE)
- do_gdb_disassembly (get_frame_arch (frame), -1,
- get_frame_pc (frame), sal.end);
+ do_gdb_disassembly (get_frame_arch (frame), -1, sal.pc, sal.end);
}

if (print_what != LOCATION)
Index: testsuite/gdb.base/consecutive.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/consecutive.exp,v
retrieving revision 1.9
diff -u -p -u -r1.9 consecutive.exp
--- testsuite/gdb.base/consecutive.exp 3 Jan 2009 05:58:03 -0000 1.9
+++ testsuite/gdb.base/consecutive.exp 21 Oct 2009 00:14:17 -0000
@@ -64,7 +64,7 @@ set stop_addr 0

send_gdb "x /2i \$pc\n"
gdb_expect {
- -re "$hex.*${nl}($hex).*$gdb_prompt $" {
+ -re "=> $hex.*${nl} ($hex).*$gdb_prompt $" {
set bp_addr $expect_out(1,string)
pass "get breakpoint address for foo"
}
Index: testsuite/gdb.base/display.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/display.exp,v
retrieving revision 1.18
diff -u -p -u -r1.18 display.exp
--- testsuite/gdb.base/display.exp 28 May 2009 01:05:14 -0000 1.18
+++ testsuite/gdb.base/display.exp 21 Oct 2009 00:14:17 -0000
@@ -91,7 +91,7 @@ gdb_test "break 19" ".*Breakpoint 4.
gdb_test "info disp" ".*There are no auto-display expressions now..*" "inf disp"
gdb_test "disp i" ".*1: i = 0.*" "display i"
gdb_test "disp/x j" ".*2: /x j = 0x0.*" "display j"
-gdb_test "disp/i &k" ".*3: x/i &k(\r\n| )$hex:.*" "display &k"
+gdb_test "disp/i &k" ".*3: x/i &k(\r\n| ) $hex:.*" "display &k"
gdb_test "disp/f f" ".*4: /f f = 3.1415*" "display/f f"
gdb_test "disp/s &sum" ".*5: x/s &sum $hex.*sum.:.*" "display/s &sum"

Index: testsuite/gdb.base/pc-fp.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/pc-fp.exp,v
retrieving revision 1.12
diff -u -p -u -r1.12 pc-fp.exp
--- testsuite/gdb.base/pc-fp.exp 14 Feb 2009 00:27:56 -0000 1.12
+++ testsuite/gdb.base/pc-fp.exp 21 Oct 2009 00:14:17 -0000
@@ -63,7 +63,7 @@ set valueof_fp [get_hexadecimal_valueof
# display since that encodes and then decodes the expression parameter
# (and hence uses the mechanisms we're trying to test).

-gdb_test "display/i \$pc" "1: x/i +\\\$pc( +|\r\n)${valueof_pc}.*"
+gdb_test "display/i \$pc" "1: x/i +\\\$pc( +|\r\n)=> ${valueof_pc}.*"
gdb_test "display/w \$fp" "2: x/xw +\\\$fp +${valueof_fp}.*"

# FIXME: cagney/2002-09-04: Should also check that ``info registers
Index: testsuite/gdb.base/sigbpt.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/sigbpt.exp,v
retrieving revision 1.15
diff -u -p -u -r1.15 sigbpt.exp
--- testsuite/gdb.base/sigbpt.exp 5 Feb 2009 13:59:18 -0000 1.15
+++ testsuite/gdb.base/sigbpt.exp 21 Oct 2009 00:14:17 -0000
@@ -93,12 +93,12 @@ gdb_test "advance *bowler" "bowler.*" "a
set test "stepping to fault"
set signame "SIGSEGV"
gdb_test_multiple "stepi" "$test" {
- -re "Program received signal (SIGBUS|SIGSEGV).*pc(\r\n| *) *(0x\[0-9a-f\]*).*$gdb_prompt $" {
+ -re "Program received signal (SIGBUS|SIGSEGV).*pc(\r\n| *) *=> (0x\[0-9a-f\]*).*$gdb_prompt $" {
set signame $expect_out(1,string)
set segv_addr $expect_out(3,string)
pass "$test"
}
- -re " .*pc(\r\n| *)(0x\[0-9a-f\]*).*bowler.*$gdb_prompt $" {
+ -re " .*pc(\r\n| *)=> (0x\[0-9a-f\]*).*bowler.*$gdb_prompt $" {
set bowler_addrs [concat $expect_out(2,string) $bowler_addrs]
send_gdb "stepi\n"
exp_continue
@@ -110,7 +110,7 @@ gdb_test_multiple "stepi" "$test" {

set test "get insn after fault"
gdb_test_multiple {x/2i $pc} "$test" {
- -re "(0x\[0-9a-f\]*).*bowler.*(0x\[0-9a-f\]*).*bowler.*$gdb_prompt $" {
+ -re "=> (0x\[0-9a-f\]*).*bowler.*(0x\[0-9a-f\]*).*bowler.*$gdb_prompt $" {
set bowler_addrs [concat $expect_out(2,string) $bowler_addrs]
pass "$test"
}
@@ -199,7 +199,7 @@ proc stepi_out { name args } {
-re "pc(\r\n| *)[after_segv] .*bowler.*$gdb_prompt $" {
kfail gdb/1702 "$test (skipped fault insn)"
}
- -re "pc(\r\n| *)0x\[a-z0-9\]* .*bowler.*$gdb_prompt $" {
+ -re "pc(\r\n| *)=> 0x\[a-z0-9\]* .*bowler.*$gdb_prompt $" {
kfail gdb/1702 "$test (corrupt pc)"
}
}
@@ -244,12 +244,12 @@ proc cont_out { name args } {
# inserted at the faulting instruction. Note that the breakpoint
# instruction wasn't executed, rather the inferior was SIGTRAPed
# with the PC at the breakpoint.
- gdb_test "continue" "Breakpoint.*pc(\r\n| *)[at_segv] .*" \
+ gdb_test "continue" "Breakpoint.*pc(\r\n| *)=> [at_segv] .*" \
"${name}; continue to breakpoint at fault"

# Now single step the faulted instrction at that breakpoint.
gdb_test "stepi" \
- "Program received signal ${signame}.*pc(\r\n| *)[at_segv] .*" \
+ "Program received signal ${signame}.*pc(\r\n| *)=> [at_segv] .*" \
"${name}; stepi fault"

# Clear any breakpoints